56 Buick Scarebird vs. Wilwood?

[buicktom]

Got the brake parts this week and installed them today. Installation was very easy with the Scarebird parts. I add some photos for everybody who will do the switch to front disc, too. After everything was installed I made my first test drive with the the old power master cylinder. Brake power was good but will be better after a longer brake in period. I had no clearance poblems with the caliper and the wheel.

Next step will be the change of the power master cylinder.

Edited March 13, 2016 by buicktom (see edit history)

[buicktom]

Have a question about the stock brake fluid distributer block or valve on the left side of the frame under the left front door.

How does it work, which port is for the front and rear and does it give more power to the front brakes?

Couldn't find anything about it in the shop manual.

 

Thomas

[Beemon]

I think the block is 53/47. It should say in the manual, page 9-2 under Approx. % of Total Braking Power on... As for which port is front or back, just follow the front line to the block. I'm pretty sure the front most port is the front. I have my block sitting on a shelf, as I replaced it for disc/disc. It's also not very useful for a dual stage master cylinder since it only has one entry port and not two. If you keep the stock MC in place, then keep the block. Otherwise you'd be better off replacing it.

[buicktom]

Thanks Beemon. I only wanted to understand what for it is and how it works. It is more like a residual valve, which holds the pressure in the lines.

[Beemon]

Thanks Beemon. I only wanted to understand what for it is and how it works. It is more like a residual valve, which holds the pressure in the lines.

It does both. It's a residual valve and proportioning block. You can still use it if you T your two MC ports into one line, but then you loose the whole point of going to a dual MC: having two separate lines in case of brake failure. Disc/Drum and Disc/Disc also have different proportioning settings for optimal braking conditions that the stock proportioning block is not capable of. I have heard it's okay to use for Disc/Drum conversions, but it might be harder braking.

Edited March 16, 2016 by Beemon (see edit history)

[buicktom]

^{My main goal is switching to a dual MC. Last weekend I mounted the dual diaphragm booster and the Opel Corsa master cylinder into my 56 Buick.  The length of the combo fits perfect. After bleeding the system I saw the used Corsa master cylinder leeking. I ordered a new one and hope to have the time to put it in and test it next weekend.}

[buicktom]

Time for a little update.

After some days of vacation I tried it again with the new Opel Corsa master cylinder. The same problem as before. The Corsa MC has a special seal to the push rod of the Corsa power booster, but the push rod of 7" power booster is to small for the seal. So it is leaking again. I thought about using the Opel Corsa power booster, but it is to big for the original place. I have to go another way.

Edited April 5, 2016 by buicktom (see edit history)

[Beemon]

Thomas,

 

I've concluded myself that the best way to mount any style of new master cylinder on the car is to put the master cylinder on the firewall where the air plenum is. I went and pulled a spare air plenum off a junkyard 56 and am going to cut a 5x5 square in it and hang a brake pedal. Having a 1x1 pedal ratio for the master cylinder is already a bad choice, but I was also trying to do minimal fabrications. For you being over seas, your best bet if going this route would to be a fabrication of a flat piece of sheet metal to go over the air plenum box and mount directly to the firewall. I've also considered this, but want to keep the plenum in mine so I'm going to try the cutting method first. The 1956 Buick is just weird in the way they did things up until 1957 when they mounted the booster on the firewall in similar fashion I plan to carry out. I'll need to find a place to mount the washer jar, but I think I'll find a way to hang it off the master cylinder mounting hole. If this doesn't work for me, I'm going to reconsider the stock master cylinder...

[buicktom]

I found a new way to use the Corsa Master Cylinder and the 7" dual diaphragm power booster. I ordered an original used Corsa power booster. After I got it I dismantled it because I want the original push rod.

 

Now I measured the push rod of the 7" powerbooster. It is 9.5 mm ( 0.37"). Now I drilled a 9.5 mm hole into the 14 mm ( 0.55") alloy push rod. I cut off the wider part of the new push rod. The length is than 63 mm (2.48").

 

Now I took the seal out of the booster.

 

What seal did I use with the new push rod? First I thought to use the seal of the Corsa booster, but believe it or not the seal of the 7" booster works perfectly with the Corsa seal. You also have to make the hole in the washer wider to fit.

 

 

 

If you drill the hole in the new push rod deep enough you can use the the adjusting screw of the smaller push rod for adjusting the bigger one, but be carefull and drill it not to deep.

Tommorrow I am going to put the new combo on its place. Hope everything will work.

 

Thomas

 

[buicktom]

Everything worked and no leaking, but brake power wasn't good enough to use the como right now. I am going back to the original power brake unit for this summer.

I ordered a rebuilt kit with leather seal yesterday. Will try it again next winter.

Does anybody know how much vacuum the engine should build up on the power brake unit?

 

Thomas

[Beemon]

Your reservoir will store the maximum vacuum from the engine, so on decel for me it's usually 25 inches of vacuum. At idle I get around 16-17 currently.

 

My brake power is also somewhat inadequate, so I've been looking into trying this next:

 

The picture is off of a 1958 Buick, but the same idea still applies. If you want a new style master cylinder, the only way to get the best brake power is with a larger pedal ratio of around 4/5:1 from the stock 1:1. The only issue I would have is relocating the washer jar, but 1957 has already done this setup and they put the jar front passenger side next to the radiator. I'm convinced it's either this way or an under the floor style master, and I'd rather not put one below the frame. Or stick with the original and hope it holds up with 20 cars around you in modern traffic.

Edited April 11, 2016 by Beemon (see edit history)

[Beemon]

Thomas,

 

I had a discussion with the engineering division chair (pretty nice guy, retiring next year, lead me through Statics, Dynamics, Mechanics of Materials and Thermodynamics) and we got to talking about old cars, particularly my Buick. Since this is an issue we're both trying to resolve, I brought it up.

 

First of all, the position angle of the master cylinder is set up to fail every single time. Take a look at the reservoir on the original master cylinder, it feeds through the top and at the back of the master cylinder so air bubbles cannot become trapped in the bore. Unless you bleed a new master completely level or near level to allow the air to escape to the reservoir, it will collect at the high points.This creates a spongey feel and even if bled correctly, the piston can suck air back in thru turbulence, especially on steep downhill roads. The OEM cylinder gets around this by having fluid feed into it at it's highest point, where it bolts to the booster.

 

Second, using the stock pedal ratio will always be weak. Due to fluid dynamics, larger bore delivers more fluid but less pressure, hence larger pedal ratios, but we already knew this part. Since no one makes a master cylinder remotely close to our original bore in a power setup, this setup will always be inadequate and require more effort to stop the cars. The only way to circumvent this is to increase pedal ratio, either by relocating to the firewall or under the car (not at the toe board). This requires extensive fabrication in the body/frame and guess work to achieve the proper pedal.

 

Basically what he told me is that single or dual master cylinder, the car isn't going to stop if the line blows, whichever setup you go with. As soon as a line blows in a dual MC, the spongey factor multiplies and you're really going to be using the emergency brake the entire time. I have first hand experience with this also. My daily driver is a 2002 Jeep Liberty. I live in the suburbs, but it's rural enough for game such as deer and elk. One day on my way to visit my girlfriend, a deer popped out in front of me and I had enough reaction to hit the brakes, at the expense of blowing the front rubber brake line to the driver side caliper.

 

 

 

 

I want to take the time to point out that when I removed my original MC from my Buick, it was before this had happened and every shop I had ever talked to said dual MC is the way to go for safety and insurance. It's a gimmick, all it does is proportion the fluid and apply even pressure. I know first hand because when my line blew in my Jeep, which has ABS and a dual port MC, I had no brakes and had to limp home with the E-brake. This was last fall, too, a few months after I got my Buick back on the road.

 

Basically what it comes down to is how stock do you want it? Going disc or drum is irrelevant because fluid pressure is generated by the MC to lock them up. In the kits provided, the vehicles used a 1.1" bore (front caliper kit) and a 1" bore (rear caliper kit) master cylinder, so we can assume the calipers are within reason that they should work within our parameters and pedal ratio is the key to proper brakes. If you want a new style, you can't mount it in the stock location and expect results - it needs to be relocated up or down. I've also seen remote MC setup where they're in the trunk, and I've also seen electronic assist boosters, but you will always run into the 1:1 pedal ratio error not giving enough pressure. If you're fine with the original setup, save up to have it rebuilt and sleeved so it's rust proof and get the lifetime warranty.

 

My engineering teacher basically called me an idiot in a much more, professionally worded manner that basically spelled out KISS (Keep It Simple Stupid). I was adamant, hearing it from everyone on every forum I ever visited, and I concede now that doing any type of stock mounted MC that's not the stock MC is begging for disaster.

 

Now don't get me wrong, I still feel discs are FAR superior to drums (self adjusting, quicker heat dissipation, almost little to no travel time when engaging pads, no spring fatigue), and they can be adapted to the stock MC. Just tee off the single outlet to go front to back and run it through a proportioning block. You shouldn't use the original, but I have heard it works for disc/drum.

 

Personally I'm on the fence myself, retaining the stock MC or mounting a firewall booster, but will most likely revert back to the stock MC as you have done every single time. Less fabrication/expense. I'm personally done dumping money into magic fixes for my brakes...

Edited April 11, 2016 by Beemon (see edit history)

[NTX5467]

I'm not sure I totally agree with your instructor's take on the dual MC systems.  Study the mechanical advantage of different sizes of cylinder bores in the MC and the wheel cylinders on drum systems, too.  Which end of the brake system fails can probably influence how the pedal feels, too!

 

I learned to drive with power drum brakes.  When we got our first car with power discs on the front, I noticed the pedal was a little spongier than the prior car (same brand and similar boosters) with power drum brakes.  Just part of the breed, it appears . . . disc vs drum.  With the CORRECT linings, drum brakes can be very credible in performance.  By "correct", I mean "metallic content" in the lining material.  There's a decent trade-off in cold braking and lining metallic content, although drum brakes can be more sensitive in this area than power disc systems.

 

With any drum system, you need to have the widest drums available for your vehicle AND similarly-wide linings.  Unfortunately, we don't have the wide availability of a diverse group of lining materials now as we did in the 1960-70s.  But even with the "normal replacement linings", the power systems were "touchy" and would easily lock the wheels.  I've got a '70 Skylark with power drums on it.  When I would be moving it around, after being used to driving a power disc/drum car I have, it would take a few easy brake applications on the Skylark lest I "eat steering wheel" on that first brake application, even just moving the cars in the driveway.

 

Chevy used a segmented full metallic lining on the 1961 Impala SS cars, as factory equipment.  The drag racers took them off as it was harder to stage the car with the metallic linings than with normal linings.  But in road racing activities, the segmented metallic linings worked well.  There were some hybrid lining materials, back then, with the "VelveTouch" linings scoring well in brake durability tests at Daytona (on a '60 Ford sedan). 

 

Did you investigate the street rod brake kits which use an "underfloor" MC and booster?  Or is the area underfloor on the Buick more restrictive than an older Ford?

 

BEFORE we had dual master cylinders and the "failure switch block", there was one line from the MC and it went to a divider block on the frame rail, then front to rear.  The division of braking power was orchestrated with different wheel cylinder bores, front and rear, with the initial mechanical advantage being in how the MC bore related to the wheel cylinder bores.  Rear shoe widths were usually a little narrower, too, for less braking power in the rear section (considering weight distribution changes in the braking mode).  With the dual system, the divider block switch detects fluid loss from one circuit or the other . . . no distribution changes.  The divider block becomes a proportioning valve only on the power disc systems.  But I believe that if you study the earlier 4 wheel disc systems on the '63 Corvettes, you'll not find a proportioning block in the mix, WITH a dual master cylinder.

 

As I recall, with the dual MC, with only one end of the system operational, braking distances will be longer, period.  BUT you'll still have "brakes".  Nobody ever said that losing one end will keep all of the same system performance intact.  And to me, "one" end is better than "no end" with a single MC.

 

Modern "emergency brakes" are not the same as we used to have!  Rather than "parking brakes", many are now "park assist brakes" an are not substantial enough to use in the prior orientation of "emergency brakes".

 

USA OEM brake systems used to be designed to "lock the rear wheels" first, disc or drum.  In about the earlier 1980s (think Chevy Citation), the orientation became "lock the front wheels first" (a more European orientation?).  And that was with the front-bias in braking system sizing, due to weight transfer during braking.

 

ANY braking system is a balancing act of sorts.  Enough capacity to not fade easily during continued heavy-duty use, while still stopping the vehicle quickly and straight during it all.  Easy pedal pressure levels, and something that is durable with reliability. 

 

In the later 1960s, some factory performance vehicle braking systems could get close to "1G" in stopping performance with power disc/drum systems AND enough tire under them to not lock-up easily.  Personally, I feel this was due more to lining material than system design, as the same brake hardware was used on different GM cars that didn't perform quite so well.

 

What about finding which drums can fit your car that are WIDER, which will allow for wider brake shoes inside of them and also interface with your stock backing plates (OR backing plates from a more modern vehicle)?  AND, while you're at it, you can research the friction co-efficients of various braking lining materials for best performance with drum brake systems.

 

Thanks for those great pictures, Tom!

 

NTX5467

 

[Beemon]

Thank you NTX5467, I always admire and respect your write-ups.

 

My understanding of the brake system, as you said, is all about the bore sizes. However, since the front wheel cylinders are 1 1/8" and the rears are 1" in diameter, I was able to look up what type of vehicles would have similar specs with MC bore size and 1" to 1 1/8" was pretty common through the 60s with a 4:1 or similar pedal ratio, MC mounted on the firewall. This leads me to believe if calipers engineered for 1" to 1 1/8" MC setup were used on these cars with pedals, then it should work here. Again it's all fluid dynamics and what sets the brakes in all system is the pressure applied to the fluid in the MC bore. The Buick MC has a 17/32" bore, but a 1:1 pedal ratio. The smaller bore applies more pressure to the fluid for a much smaller pedal ratio, but it doesn't do much in the way of displacing fluid. That's why the proportioning block on the frame rail was both a prop block and a residual valve, to keep fluid from seeping back to the master cylinder and leaving the lines primed. On the mid 60s with the 1 inch masters, such as the Corvette, they were all firewall mounted so they could displace fluid better and also apply pressure with the larger pedal ratio. This is what Thomas and I have been hunting for, a small bore master cylinder. Unfortunately no one makes them in a 1/2" bore unless it's a compact manual brake system, which doesn't take advantage of a power system. As far as under the car master cylinders go, I can't recall what it looks like down there because I still don't have my car back, but the dual exhaust makes room pretty scarce. Plus the frame rail is not 5" tall, so any type of power assisted system will hang below the frame rail. Filling and maintaining the system will also be a hassle if one does not buy a remote fill master cylinder. This is my driving factor for believing it should either be on the firewall or in the stock location, and as I've come to find out and obviously stated, only the stock MC will fit in the stock location.

 

Funny you mention shoe lining, and a huge factor in going to discs for me, when I was buying shoes to get the car rolling before I did the front disc conversion, and later the rear disc, was that I could not get the car to stop well. I later looked it up and I guess it had to do with shelf wear on the pads themselves making them extremely brittle and re-lining them is out of the question unless they're riveted to the shoe. Even after the front disc brakes, not too long ago my rear discs wouldn't lock up when applying the parking brake on steep inclines. When I pulled the shoes for the rear disc setup, the shoes were worn in but they we're almost smooth to the touch like the lining was just wearing in such a way it was more of a lubricant than a friction material. Unfortunately, as it appears, the restoration hobby is becoming increasingly expensive and increasingly sparse. Many things like brake shoes aren't being made new unless special ordered. In the late 80s, when my uncle took the Buick on in his high school autoshop class (the guy who's responsible for tearing down my 322 and not putting it back together when he found the rocker arms chipped beyond repair), all the parts to get the Buick well maintained and back on the road were readily available. In comparison, some 20-30 years later, the best I can find are wheel cylinders and bearings, and the occasional regulators, brushes and condensers. TPart demand is already heavily dependent on private owners who manufacture their own parts, pretty soon it will be the only outlet for vintage parts. Another reason why I went to disc, these parts are used heavily by restomod guys and are readily available over the counter. In 10-20 years, that will also change and so on and so forth.

 

I can't really speak for the braking performance of drum brakes because I was born into an era that did away with them, so I guess I don't know any better, but the drums are as good as the tuning done to them. Some people like them tighter than others for braking, and I think that's where most of the appeal comes from, because you can make them tighter for stiffer brakes or back them off for a more relaxed brake pedal feel. My father never liked him. He said he ruined a fishing trip one year jumping in his father's 1968 Plymouth Satellite and dropping it in reverse, locking up the auto adjuster and having to call a tow truck. His bi-annual adjustment didn't go over very well either, stating he spent quite a bit of time on each wheel to the point of frustration. Ever since I started working on this car, the pressure has been put on for disc brakes from my parents, my grandfather and every shop I've dropped into. I would love to keep the dual MC setup, but that also means some timely and expensive fabrications and parts are also included with what I have already invested into the car. It would require removing or modifying the fresh air plenum and relocating or removing the washer jar, which I'm not too fond of doing because it all works on my car. It's a nasty trade off, but if the original MC is rebuilt correctly by the right people who give you a lifetime warranty, then it should be as good, if not better than a modern MC. As you also stated, parking brakes then vs now are also much different. And if a line happens to blow, it would most likely be a rubber one and not a steal line, which are readily available and should be replaced when doing a restoration regardless.

 

Anyways, thanks for the write up again. When I end up putting the original MC back in the car, I'll post the setup with a modern prop block for disc/disc. Would mount in the same location as the stock block, just Tee off the original master cylinder line so it splits and goes into both inlets. I'm still not sold on the dual master ideology as I've posted above with my mishap, all brakes were gone in the system and relied only on the parking brake to stop. While it may be true that it keeps one line from going out vs the whole system, my system popped on the front and the rear brakes either were unresponsive or didn't have enough pressure because there was no fluid in the front half of the MC bore to keep the back half piston from creating pressure. I'm a firm believe that it wouldn't have mattered how many ports the master cylinder had, there were no brakes period, and it was scary all the same.

[NTX5467]

Thanks for the kind words and comments and "family history".  As for the '68 Satellite, unless it had the factory trailer tow package OR was a police/taxi vehicle (which usually had manual-adjust brakes), then the brakes should have been auto-adjusted brakes (using the stops in Reverse to do the adjusting). 

 

The key to the initial adjustment on self-adjusting brakes is to use the inside-outside brake caliper gauge.  You use one side to measure the drum's inner diameter, then take the other side of the caliper and adjust the brake shoes to that dimension.  Whatever "clearance" between the shoes and drum is designed into the caliper itself, I believe.  Otherwise, you do the "spinning wheel/small screwdriver" routine.

 

On some of the mid-80s (or later) GM master cylinders, which were aluminum, it seemed like the cylinder bores were smaller, but they also had screw-in residual pressure valves between the master cylinder fluid outlets and the lines.  But from the angles the lines came off at, probably would not work for the under-car location.

 

In looking for the undercar booster/MC street rod kit, I found the CPP (www.classicperform.com ) ad, which has a universal firewall brake booster kit, complete with pedal (with adj ratios), booster, MC, prop valve item, for "Starting from $279.00"  Looks like they also have booster/MC combos (with small diameter dual diaphragm boosters).  They might be the ones who have the under car boosters, too?

 

Another thing I found was the ad for Borgeson Steering items.  A friend put that power system under his '54 Ford Ranch Wagon and he raves about how much better it drives.  They show a kit for '55+ Chevies, but not Buicks specifically.

 

I also remembered that for 1970 1/2, disc brakes were on the front of Chevy Camaros, non-power.  Not sure how their MC cylinder sizing was or even if it was different.  A friend had one back then, after he got married.  I asked him how much pedal pressure it took and he didn't act like it was excessive, compared to a non-power full drum system.

 

Take care and keep us posted.

NTX5467

[buicktom]

Hello Beemon and NTX5467,

 

Thanks for your great explanations. When I put the Corsa/ Dual Booster Combo into my 56 the last time, I had not much vacuum on my system. I had no difference between runing and stopped engine. First I have to look for that vacuum problem. Maybe the diaphragm of the vacuum pump is bad. But this is no problem because I don't use the vacuum wiper anymore. I changed to an electric wiper. Think I block the line on the T-connector on the intake manifold. Hope it will solve the problem.

 

Another way to go with dual brake system is to go with something which is working like an hydraulic clutch. On the mounting plate is enough room to mount a donator cylinder.  You can buy it with different diameter (0.5",0.625,  0.7" and many more). The clutch cylinder is also available in different sizes. I think you can reach with different sizes of donater and clutch cylinders something like a better pedal ratio. But this is only my theory. Building a mounting bracket for the clutch cylinder on the powerbooster/ dual master cylinder combo should be no great problem. The only thing which makes it curious on my mind is to use a "single brake" to activate the new "dual brake system". This will be a possibility but not this summer. Now it is time to go back on the road with the 56.

But I have to check with the German car Inspection, if this way will be accepted or it is a no go.

 

Happy Buicking

Thomas

 

 

[buicktom]

One thing I forgot: When you measure your brake pedal you will see that the length from the mounting bolt to the master cylinder push rod connection is as nearly two time longer than the length from the push rod connection to the push plate.

We don't have a 1 : 1 pedal Ratio. It is more 2: 1.  It is more worse. Or am I wrong with my thoughts?

Thomas

[Beemon]

Thanks for the measurements, yes that is much worse. That's not a 2:1 ratio, that is a 1:2 ratio. I did some numbers up for you. 

 

As shown,  F1 is the force applied by the foot while F2 is the force applied by the master cylinder. In a 1:1 ratio,  F2=2F1, or double the foot force being applied to the Mc. In a 2:1, F2=3F1, which is larger than a 1:1. But in a 1:2 ratio, F2=1.5F1, which is worse than a 1:1 ratio. To put into perspective,  a 4:1 ratio nets F2=5F1. (Not 6:1, Typo )

 

In case a, using the F2 ratios attained and assuming F1 is about 10 foot pounds (in your case, Newtons... don't remember the conversion off the top of my head), a 1 1/8" bore master is equivalent to a .3375" master in the stock location, so the stock mc is more than adequate. Furthermore, in case d, the equivalent to the stock mc is a 1.77" bore mc with a 4:1 pedal. 

 

In case b, the amount of force applied to a 1 1/8" bore mc mounted in the stock position is equivalent to more than two times the stock master cylinder. Likewise, in case c, (just noticed I messed up the calculation, it should be 1/5F2=F1) the stock mc with a 4:1 pedal would require roughly half as much force.

 

I hope this kind of helps. This does not take into consideration wheel cylinders vs calipers, but shows a relationship with operational capacity. Master cylinders generate pressure by fluid displacement of the bore, so the only thing that is relevant is the bore size and not volume of fluid. 

 

I want to bring up case b because the force is determined by the lever arm. For double the effort, you need to put more force on the pedal than 10ft lbs. The lever can only throw so much before you bottom out, so you will never achieve the top end of the stock throw arm, it will always be approximately half as effective.  If you're at half of the throw at 10ft lbs to coast to a stop, not even an emergency stop with the stock mc, then the full throw off the pedal arm will be required for a 1 1/8" bore mc in the stock location. That's why any other mc in the stock location is nothing but trouble. 

[buicktom]

Hello Beemon,

 

Thank you for your calculation. It is really a big problem to find the right combination for the the original Location, but I believe there is a possibility.

Still waiting for my parts to rebuilt the original power booster.

 

Thanks Thomas

[buicktom]

Do I need a residual valve too, if I have a pressure regulater valve in the line to the rear brake?

Thomas

[Beemon]

What type of system are you using? The original or your modified? If you're using the original, then the residual valve is built into the pressure regulator block. If not, then yes you need a residual valve for both the front and back brake lines. This keeps fluid from re-entering the master cylinder if it is mounted below the calipers, which it is in our case. It's 10lbs for drums and 2lbs for disc.

 

How far are you planning to go Thomas? The whole system or just the front discs with the original system? I only ask because I hate beating a dead horse, but please take it from me: unless you are going completely modified and redoing the entire system, then go all disc/disc with a brand new master cylinder in the proper position, otherwise a front disc conversion will work with the stock system without modification to the rest. I'm not sure how far you've gotten, but my brake modifications have been almost as expensive as my engine rebuild and I have had little gains. IIRC you're better off finding a pair of aluminum 45 fin drums and pounding the original hub off and pressing the 56 hub on than going to a full on conversion. Discs on the front work just the same, but then its about whether you want period correct drums or discs.

 

Here is my pitfall. I put discs on the front. I wanted more (and pressured by family) to put a dual master cylinder in the stock location. I went a step further (and also pressured by family to remove all drums) and put discs on the back. My braking hasn't been as good as I'd like it, so now I'm going to reinstall the original master and proportioning block. I'm afraid when I do, my braking will still be inadequate because I've already spent the money on the other parts. So then I have to take the rears back to drums and check if its inadequate before I go to the front discs. I'm hoping that's not the case because I spent quite a bit of money on the brakes that changing them too much would just mean putting more dead weight in the garage.

 

The reality is that you can't leave one thing constant in the equation. Unless you can manufacture the perfect set of hardware to fit your system, you're always using a hodgepodge of components engineered by different people for other cars that were only intended for those cars. The front discs work, to what extent is conjecture and you hear differently from folks who are stock vs folks who have done the conversion. Personally I went to front drums because I like to drive my car yearly. It hasn't been on the road in 30 years, it needed to be driven. I live on hills and 20 miles from Seattle, where there is constant traffic and a small street race scene filled with hatchback Hondas and the like. I can't tell you how many times I've been cut off or my brake distance has been cut in half on both level and steep driving conditions where I feel the discs have ultimately helped me. But as to how well it's helped me is up in the air. They could be marginally better or worse depending on (at the time using stock MC) how well they work with the other equipment. They could be worse than drums, but only being 24 and never driven a car with front drums, I think they're better because they're discs. They could be better but I'd never really know unless I buy new drums and hardware and invest going back to stock (which I'll most likely have to do). What I do know is that car manufacturers went to disc due to their heat dissipation ability and other gains, but then car geometry has also changed significantly in the last 60 years as well.

 

Sorry to ramble, the brakes on this old Buick has been something I've fought for, too. I don't like to admit failure in places I've been a proponent for, especially when I've spent quite a bit of money on said places, but that's the joy in learning from costly mistakes I suppose.

[buicktom]

I have rebuilt my stock power brake unit to get the 56 back on the road for the summer. With some smaller modification I changed the padle ratio from 1:2 to 1:1. That's no great progress but will hopefully increase the brake power.

 

 

Next winter I will try to convert to a dual brake system on stock location again. Disc in the front and drum in the rear is for me okay. For that I will change the pedal system. Here is my idea:

 

I don't know if it will work, but it is worth to try it. There is enough room under the dashboard.

What do you think about it?

 

Thomas

[Beemon]

 

I did some work looking at your design. I apologize if you saw my previous post, but mislabeled my information. With a setup like this, you might be able to net a force on the brake cylinder than is 8 times that of the initial force on the pedal, versus a pedal that's 3/2 in the stock location. By all means go for it, let us know how it turns out!

Edited May 9, 2016 by Beemon (see edit history)

[NTX5467]

I might be incorrect, but it's been my belief that the residual pressure valve is IN the master cylinder.  In the circa 1967 or so systems, when dual master cylinders became standard equipment, the "divider block" was just that and also had the switch to indicate when fluid was lost from one of the two brake fluid circuits.  No more, no less.  When disc brakes were used on the front, then it also took on the function of "pressure limiter" so that more pressure would go to the front discs (as they take higher fluid pressure to work!) and normal pressure to the rear drums . . . aka "proportioning valve"., plus the fluid loss switch.

 

I fully understand the need for better braking power in your locale's general terrain.  Although the brake type CAN influence stopping power and fade resistance, it's the FRICTION MATERIAL that ultimately affects braking performance AND fade resistance.  The "given" in this equation is a properly-machined AND surface finished brake friction contact surface, even on drum brakes.

 

I've never really understood "why", but GM vehicles from the '50s-'60s had a bad reputation for braking performance greatly diminishing when water got into the brakes themselves.  Drive through a puddle and "no brakes" . . . that might be a little extreme, but you get the point.  Fords and Chryslers didn't seem to have that problem, or at least as seriously as similar GM cars.  Back then, drivers were cautioned that when their brakes got wet, to ride the brake a little to heat the drums and dry-out the linings . . . so that when they DID need the brakes, they'd be ready (rather than otherwise).

 

Unfortunately, to me, your exercise seems to be a little convoluted with too many twists and turns.  Sorry, just the way it seems to me.  It seems to me that there are way too many brake systems you could look at the specs on and see some similarities to what's on your Buick.  Like the relationship of master cylinder bore and wheel cylinder bore sizes, front and rear.  For the drum systems.  Then, take the same similar system and update that to when they went to disc brakes, too see how the various things changed.  In this last comparison, it's somewhat important to look at only THOSE model years in particular.  Reason that in the earlier 1980s, when fuel economy was becoming important, a newer-style caliper was developed to allow a decrease in the brake pad residual pressure, yet still have enough contact to keep the rotors dried-off in wet environments.  This became known (at least in GM) as "Quick Take-up" and was on the first Chevy Citations, with other vehicles probably quietly upgrading to this design.  Also, as brakes were downsized, the pad material became more "metallic" in nature, rather than the prior asbestos-based friction material.  Metallic linings had been available for police use since the middle 1950s, but they generally took "heat" to work correctly.  This meant they were NOT popular with drag racers who used their foot brakes to stage the vehicles on the staring line.  The 1961 Chevy Impala SS came standard with them, but the drag racers soon put "normal" linings on their cars so they could stage the car at the staring line.  On a road course, the metallic worked very well when "hot".  The factory OEM linings from the middle 1970s were becoming more of a hybrid between the normal materials and metallic, aka "semi-metallic".

 

Here's my theory.  Find a vehicle of about the same weight as your Buick (possibly a '77 Buick LeSabre or similar GM car with disc/drums).  Look at the diameter of the rear wheel cylinders and compare it to your Buick.  Then, in something like the Scarebird list, see what front calipers are being used.  Then look at the master cylinders and their specs.  Another vehicle to compare the disc/drum to 4whl discs is the last-gen Buick Roadmaster sedans (with rear drums) and the similar Impalas (with 4 whl discs . . . in THREE brake option codes!).  Look at how things did or did not change between the rr drums and rr disc vehicles, with respect to the master cylinders.  In the case of the Impalas, the rear discs were attached via a bracket to the axle housing, rather than having specific rear axle housing (as the 1979 Firebird WS-6 cars).

 

To me, keeping the master cylinders and calipers generally matched to a particular model year range would be key (considering your previous comments about fluid displacement).  Bur once you can get a handle on these various relationships, THEN you can find one of the street rod brake system vendors that have a range of boosters and master cylinders available.  Possibly www.rockauto.com can be a good research source, too.  In this search, the issues of physical dimensions and other related issues can be further investigated.

 

Sometime in the earlier 1970s, "the feds" put some limits upon just how much maximum pedal pressure was needed to stop a vehicle in an emergency situation.  Seems like it's 40 lbs of foot pressure on the brake pedal?  This meant changes in friction material composition (among other things).

 

In those earlier factory power disc/drum brake systems, the vehicles came with a dual-diaphragm power brake booster.  Generally, they were smaller in diameter but longer in length.  This was for the added pressure which disc brakes needed to work.  In later years, some changes were made and single-diaphragm boosters were used.

 

When I go my new '77 Camaro, I was not impressed with its stopping power.  Too much pedal travel, it seemed.  Our shop foreman mentioned that non-power brake vehicles had one hole on the pedal for non-power brakes (more leverage) and one for use with power brakes (a little less leverage).  What finally got the car to stop as it should was some COPO 9C-1 1977 Nova Police front brake pads.  Later, I replaced the rear drums (9.5"x2") with 1981 Z-28 Export rear brakes (11"x2") (which were the same size as on the 1977 Monte Carlo and later '77+ Caprice police cars).  That's how GM should have built it to start with!

 

One other thing to consider is the respective size of the brake lines themselves, for the various applications.  A small thing, but something which can affect the "fluid displacement" orientation.

 

Personally, I like upgrades which are OEM-based as they strike me as being a little more robust in nature and design . . . if that matters.  That link to the street rod brake cylinder/booster vendor is in one of my previous posts, I believe.

 

In general, from what I've seen, the Scarebird parts lists are pretty decent.  Some some finessing to find parts which will fit under the floorboard of your Buick can be, as y'all have discovered, a little challenging.

 

Keep us posted,

NTX5467

 

 

[Beemon]

The stock proportioning valve is also a residual valve. It has a spring and check ball in it so fluid doesn't drain back into the master cylinder because it's mounted below the wheel cylinders. 

 

I guess that's one pro to discs, there are far more available pads locally. 

 

I also agree with you. As I stated above, you really have to change the whole system and nothing can be left constant, including the stock mounting location. I've given up at this point on adapting "modern" brakes because the only way to really do it justice is remove the air plenum and put a hole in the firewall ad others have done. 

[buicktom]

Hello NTX5467,

 

Thanks for your explanation. I always thought to take a complete system of a well braking car into the Buick should be the best way. Problem is the space on the stock location.

I will see, if my idea will work or not next winter. I will be back.

Two weekends ago I spent a lot of time with some Fiat 2300 S Coupe Owners. Nice small cars (early 60s) with not much space in the engine compartment. These cars have a dual master cylinder mounted on the floorboard. This master cylinder feeds two power booster single master cylinder units which are located on each front corners of the compartment.

One is for the front and the other for the rear.

 

You see not enough space on the right places was always a problem.

Beemon, thanks for your calculation again.

Yesterday I put off the valve inside the stock proportioning valve, because I only want to use is as distributer block. In the front line I put a 2 lbs residual valve and in the rear line a adjustable pressure regulator and a 10 lbs residual valve. Think and hope this will work.

Now I have to bleed the system and an find my vacuum leak.

 

Thomas

[Beemon]

I didn't even stop to think about using slave master cylinders. You see hot rod guys putting three manual master cylinders in compact spaces that all feed into one line. Your Fiat explanation just reminded me.

 

 

Perhaps a bit excessive, but it's all manual brake power. The only thing I would change would be to make the two separate pedals one whole pedal, but I believe one is for a clutch. I know nothing about these systems to be honest. I'm also seen electric motor assisted boost that you can set yourself, as well as remote mounted master cylinders as these people did:

 

I believe this is also an electric boost system. Their contact information is on their website, you can give them a call or email and see if they can help you out. Just some ideas.

 

[Guest]

On 5/10/2016 at 0:30 AM, Beemon said:

I didn't even stop to think about using slave master cylinders. You see hot rod guys putting three manual master cylinders in compact spaces that all feed into one line. Your Fiat explanation just reminded me.

 

 

Perhaps a bit excessive, but it's all manual brake power. The only thing I would change would be to make the two separate pedals one whole pedal, but I believe one is for a clutch. I know nothing about these systems to be honest. I'm also seen electric motor assisted boost that you can set yourself, as well as remote mounted master cylinders as these people did:

 

I believe this is also an electric boost system. Their contact information is on their website, you can give them a call or email and see if they can help you out. Just some ideas.

 

Greetings. Very interesting!

Edited May 12, 2016 by Guest
Dim bulb! (see edit history)

[Beemon]

The pressure is exerted by the piston. It's not the original mc causing too little pressure, it's the newer large bore mc that are not putting out the required pressure. To my knowledge you cannot sleeve these without having access to smaller pistons because they actuate within a bore similar to a car engine piston. The original mc piston is pushed into a fluid reservoir and displaces fluid that way, there is no bore that it rides in. 

 

The only manufacturer that makes the correct piston is Wilwood but it's a manual clutch master cylinder. 

[buicktom]

On my post of the 13. April I described this possibility, too.

 

Another way to go with dual brake system is to go with something which is working like an hydraulic clutch. On the mounting plate is enough room to mount a donator cylinder.  You can buy it with different diameter (0.5",0.625,  0.7" and many more). The clutch cylinder is also available in different sizes. I think you can reach with different sizes of donater and clutch cylinders something like a better pedal ratio. But this is only my theory. Building a mounting bracket for the clutch cylinder on the powerbooster/ dual master cylinder combo should be no great problem. The only thing which makes it curious on my mind is to use a "single brake" to activate the new "dual brake system".

 

I have everything for this kind of project in my garage. Different sized cylinders for sleeve and master and a master cylinder of an Astro Van AWD. Last should fit perfectly to the Astro Van calipers. I would prefer to mount it into the engine compartment. But I believe there is not enough room for it. But the the trunk is a great place?!?!

 

I will see what I do next winter.

[Beemon]

Thomas,

 

I don't remember if this came up before, but someone has made a bolt in kit that you may be interested in. It's on Ebay right here.

 

Might be worth checking out, but be warned:

Quote

It is significantly more safe because if you get a leak in part of your brake system, you still have half of your brakes! 

 

This line itself is pretty misleading, which leads me to believe the creator of the kit may not know a thing or two about how hydraulic systems work.

 

Either way, just thought I would pass it on.

[buicktom]

Hello Beemon,

Thanks for your information. But I did it like E Muscle. LLC. Today I made my first test drive with my new brake system. I put this unit into my 56 trunk. http://www.ebay.de/itm/171831259342?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT .

67-72 Chevy Truck 11" Power booster with master and  valve.

As donater cylinder I used a .75" master cylinder http://www.ebay.de/itm/230910285120?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And as slave cylinder I bought a VW T4 Clutch cylinder http://www.ebay.de/itm/KUPPLUNGSNEHMERZYLINDER-NEHMER-ZYLINDER-fur-KUPPLUNG-NEHMERZYLINDER-VW-/380746597697?hash=item58a6440541

After I had everything in my trunk, I connected the unit with the brake lines. As vacuum line I uses 3/8" line out of a mixture of  Copper, Ni and Ferum.

First test drive was very good. Afer a short  brake in time, the brake power was better as with the stock set up. May be an Chevy Astro Master cylinder for my Astro AWD front calipers will be a better choice. May be I will check this opportunity in winter, because I have a new Astro MC in stock. But now the Buick is driveable again and back on the road after this hassle.

Thomas

[MrEarl]

 

 

any chance of an update on how well this set up has worked over time

 

 

On 7/16/2016 at 11:09 AM, buicktom said:

Hello Beemon,

Thanks for your information. But I did it like E Muscle. LLC. Today I made my first test drive with my new brake system. I put this unit into my 56 trunk. http://www.ebay.de/itm/171831259342?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT .

67-72 Chevy Truck 11" Power booster with master and  valve.

As donater cylinder I used a .75" master cylinder http://www.ebay.de/itm/230910285120?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And as slave cylinder I bought a VW T4 Clutch cylinder http://www.ebay.de/itm/KUPPLUNGSNEHMERZYLINDER-NEHMER-ZYLINDER-fur-KUPPLUNG-NEHMERZYLINDER-VW-/380746597697?hash=item58a6440541

After I had everything in my trunk, I connected the unit with the brake lines. As vacuum line I uses 3/8" line out of a mixture of  Copper, Ni and Ferum.

First test drive was very good. Afer a short  brake in time, the brake power was better as with the stock set up. May be an Chevy Astro Master cylinder for my Astro AWD front calipers will be a better choice. May be I will check this opportunity in winter, because I have a new Astro MC in stock. But now the Buick is driveable again and back on the road after this hassle.

Thomas

 

[60FlatTop]

I never saw that trunk installation picture before, I saw Mr. Earl's fingerprints on the section and had to look.

 

I am picturing a border stop in one of the European countries. The border guard looks in the trunk and stares. His partner says "Vas ist das?" He slowly mumbles "Antiblockiersystem?". "Ya"

 

The same setup was under the hood of a '66 Sunbeam Alpine I had.

Bernie

[mackensen]

5-26-20  FYI I installed Wilwood kit on my 1955 special two years ago. Easy half day install used original brake lines, and brackets. The hard part was booster master cyd. install  under floor. you will need vac. pump for proper operation.

[mcdarrunt]

Drove my 37 Special for 40 years with drum brakes which nearly got me in serious trouble three years ago in Kansas City during a monsoon. All the drums got wet but the two on the right side were under water which gave zero stopping power. Put on the Scarebird disc kit using the Riviera rotors. They work just as good under water as above and would not go back to drums---PERIOD.

 

 

[Ben Bruce aka First Born]

3 hours ago, mcdarrunt said:

Drove my 37 Special for 40 years with drum brakes which nearly got me in serious trouble three years ago in Kansas City during a monsoon. All the drums got wet but the two on the right side were under water which gave zero stopping power. Put on the Scarebird disc kit using the Riviera rotors. They work just as good under water as above and would not go back to drums---PERIOD.

 

 

 

 Evan, would you help me do that to mine?

 

  Ben

[RivNut]

When considering whether to to go Scarebird or Wilwood, just think about where you get your replacement parts. NAPA down the street or by mail order.

 

Change master cylinders to a disk/drum one or maybe a proportioning valve, and get the parts suggested and follow the instructions in the kit.

Edited May 30, 2020 by RivNut (see edit history)