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Jeff_Miller

1936 Special master cylinder blasphemy or good upgrade?

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Jeff:

FIRST: I didn't do it - it was that way when I got the car, and both mechanics who worked on it reassembled it after a rebuild the way they disassembled it.

The end of the rod which goes into the Master cylinder has a "Ball" which normally is between the piston and a slotted washer, both of which have an indentation to match the curve of the ball. In the case of my Master Cylinder, the washer was reversed, forcing the rod, and also the piston farther into the Master Cylinder, blocking the relief passage and ultimately allowing pressure to build and not release the brakes. After I discovered this incorrect assembly, the system works as it was designed and the big Buick drives (AND STOPS) like a dream!

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Slotted washer :confused: I think I too must be the beneficiary of some previous owner modifications. My washer has no slot in it. The pushrod itself is also suspect as I believe it is too long.

Ever since I got the car I have been unable to figure out why I could not adjust the brake stop so that when the brake was released it didn't clobber the floor board. After taking things apart this time it became more obvious that the pushrod was more than a little strange. Perhaps I too have been experiencing leakage because of the way the PO put this thing together. I guess that is even more reason to swap out the cylinder for a new dual setup.

I haven't made much progress on getting a new master cylinder mostly because getting specific dimensions from what I see online seems to be like pulling teeth. I looked into power boosters but after taking the pedals out to measure it is clear that trying to get a power booster and master cylinder in that space isn't going to happen. I'm not really sure how the vendors claim it is a bolt in replacement but I sure wish they would share some of whatever it is they are smoking. Hmm... I wonder if they are located in CO?

I'm now looking at three potential manual dual master cylinders but getting specific dimensions is like pulling teeth.

Warning, minor rant below:

I've contacted JEGs, Summit, a number of lesser known suppliers, manufactures like wilwood and strange engineering, and of course numerous e-bay vendors. I'm using email because it is convenient and I don't really have good access to sit on a phone during normal working hours. As such, it seems to take several days for one exchange of communication. I have had multiple vendors simply not bother to answer questions until I ask a second time. When they do respond they seem to answer only part of the questions I asked.

When I contact vendors I am looking for their expertise or at least a little effort to dig out the dimensions I asked for. One "expert" vendor simply reiterated what I thought I needed and steered me toward a more expensive solution that was less attractive because it needed additional residual valves. I searched their site and found that they sold a master cylinder with the same bore, built in residual valves, and a built in remote reservoir for less but somehow the "expert" missed that - coincidence? Of course he didn't bother to offer any dimensions for the solution he provided but he was good at giving me lots of part numbers.

Other vendors simply point me to the manufactures website. Some of those websites have more details but not all the details I want. The strange engineering site had absolutely horrible information and they don't respond to questions. Wilwood's site is better once you figure out that you need to click a navigation tab that isn't obvious and then click on the "i" icon but it frustrated the heck out of me trying to get to the info the first time. Some vendors actually quoted me back information that was just plain incorrect.

It seems that in my trials I've amassed more knowledge about the theory of this then all of the vendors I've talked to and that is just plain scary. Unfortunately I still can't get the dimensions that I so desperately need. I'm down to 3 possible cylinders now and I figure I'll try to sort this out for one more week. If I'm still left hanging I figure I'll have to order stuff so that I can measure it and then send it back if fabrication will be too invasive on the existing structure. My fabrication desires are to try to limit things to additional brackets being bolted on with only a small number of additional drill holes. I do not want to have to cut frames or weld onto it. The reason is so that if either I want to or some future owner wants to, the car can be converted back with minimal effort.

Jeff

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Jeff,

I urge you to contact my friend and Buick expert Doug Seybold in Ohio. His email is 40BuickGuy@gmail.com, and his phone is (440) 835-1193. I believe your 1936 is essentially identical to my 1937 (mine is a Roadmaster). Doug is extremely well-versed in all of these cars, and specializes in restoration of 1940-41 Buicks. His Restoration shop is located in Westlake, Ohio, a suburb of Cleveland. I'm certain that Doug can supply you with an already rebuilt unit - and rod if required, or can get yours right. Tell him I gave you his name. They don't call him 40BuickGuy for nothing!

Good luck, and please let me know how you make out.

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JEFF, tHE SLOTTED WASHER I MENTION SHOULD ALSO BE DISHED WRAPPING AROUND THE EXTERNAL PART OF THE BALL ON THE ROD SO THAT THE WASHER AND THE CONCAVE SURFACE OF THE PISTON ENCOMPASS THE BALL-END OF THE ROD. THIS MAY ALLOW THE PISTON TO RETRACT PROPERLY -- NO NEED TO HAVE TO CONVERT TO DUAL AND PB

OOPS !! Apologies for the all-caps --- I wasn't watching the screen -- didn't mean to yell --- sorry!!!

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I once owned a dual master cylindered, power-braked 1977 Chevrolet Impala that suffered a partial brake loss because one of the steel lines to the rear wheels rusted through and ruptured, allowing all the hydraulic fluid for the rear drums to leak out. A noticeable loss of braking effect and the red BRAKE idiot light illuminating let me know. This was during heavy rush hour traffic, but I still managed to have enough braking power to limp into a brake shop conveniently situated right nearby. The car was only eleven years old at the time.

I've often wondered if simply a retrofit of all stainless steel hydraulic brake lines during a brake rebuild would allay most of the concerns of driving an older Buick with the single reservoir master cylinder. Then one wouldn't have to worry about converting to a dual master cylinder for added safety.

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Hi,

I've often wondered if simply a retrofit of all stainless steel hydraulic brake lines during a brake rebuild would allay most of the concerns of driving an older Buick with the single reservoir master cylinder.

I have two observations about this.

1) Using stainless lines is tempting, but it is not within the purview of most home mechanics. Stainless tubing is notoriously unforgiving and is very difficult to double-flare. The flare can easily develop a split in the forming process unless specialized tooling is used in a controlled environment. This is not work for most of us in-our-garage-type mechanics to do.

2) Failures happen also at flex hoses, at wheel cylinders, in the master cylinder--indeed anywhere where there fluid could escape if "something" failed. A redundant system just makes good safety sense to me. It's the same reason why commercial jets have 100% redundant hydraulic systems.

Adapting a modern dual system cylinder to an already-existing car can present problems with alignments and linkages. In my Cord's case, the replacement cylinder fit exactly in the same position as the original one, and the linkages require no alteration at all. I am the first to concede that it is easier to do if the car is totally disassembled, as my Cord is. It's MUCH easier to do if everything lines up without using a cutting torch or welder.

--Tom

--Tom

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Tom,

Looking at your pictures and knowing that you ordered from JEGs it makes me wonder if you are using the "JEGS Performance Products#555-631405" cylinder.

I looked at that cylinder and exchanged a number of emails with them and it sounds like a close fit. JEGs indicated that the distance from the center of the pushrod to the side of the cylinder was 1.75". Unfortunately, when I measure the current cylinder it is only 1.25" from the center of the pushrod to the side that mounts to the bracket in the frame. I think a 1/2" deflection over 4" is too much so it sounds like I'd have to replace the bracket or cut away some of it to use that master cylinder.

If it is convenient and this is your cylinder, could you verify the measurement that JEGs provided?

Thanks,

Jeff

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Hi Jeff,

My cylinder is part number 555-631402. The car is down at my warehouse for the winter, and I won't be able to get there until the weekend. But I'll get you dimensions at that time. The bore is 1-1/32, for what that's worth.

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I did not use the two pentagonal brackets that came with the cylinder--they're used to reinforce the firewall if you mount the cylinder on the firewall. In my case I had a clone to the original mounting bracket made with its compound angles and TWO, rather than the original THREE, mounting holes.

EDIT: Hey--I just noticed something--did Jegs give you that 1-3/4 dimension correctly? From their drawing it looks like 1-3/4 might be the width of the sideways mounting bosses--meaning that the distance from center line to the mounting edge is HALF of that. Look at the drawing above to see what I mean: it's labelled "0.875" from center line to about where the sideways bosses end. In that case, you may be able to mount up to your bracket with only a spacer block(s) between your cylinder and the bracket.

I'll get back to you on those field-measured dimensions.

--Tom

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Edited by trp3141592
Observed drawing more closely (see edit history)

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Hi Tom,

Ok, so that is the same cylinder, you just bought the version with the brackets.

I previously looked at those pictures of the brackets but it didn't dawn on me that I could derive the width measurement that I need (DOH!). Thanks for pointing this out.

Looking at the diagram I think the 1.75" from the center of the pushrod to the outside ear of the mounting tab is probably correct and a bit too large for my needs. However, as you point out, if I take advantage of the side mount option and grind off that ear I should be able to get the 1.25" that I need.

It was the side mount option of this cylinder that put it on my radar. I'm really glad you helped me see that with a bit of modification that this will likely be the solution I need. The only other option I had left was the Wilwood 260-7563 but that would require a bit more fabrication to make it work.

BTW: It looks like I'll need to order an eye nut or something similar to connect the rod to my pedal. I see JEGs has options but I wondered if you had to do that as well. Also, is there anything on the cylinder to capture the pushrod or does it just float on the cylinder and gets captured by aligning the brake pedal with the cylinder?

Thanks for all the help.

Jeff

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Hi,

Also, is there anything on the cylinder to capture the pushrod or does it just float on the cylinder and gets captured by aligning the brake pedal with the cylinder?

Glad that it looks like you can make this work! With a spacer between the bosses and your bracket, you can get the exact dimension you need.

I would expect that you would use your existing hardware to operate the cylinder. If not, a variety of clevises and similar chandlery are available at mcmaster.com. (My favorite on-line hardware and material supplier.)

The pushrod that comes with the new master cylinder gets trapped in place against the piston by a spring-loaded clip. It is not free to fall out.

Keep me posted! :-)

--Tom

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Tom,

Thanks for all the help. I ordered parts last night and it is looking like they will get to me early next week. Hopefully I'll have an update by the end of next week.

Jeff

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Jeff,

I urge you to contact my friend and Buick expert Doug Seybold in Ohio. His email is 40BuickGuy@gmail.com, and his phone is (440) 835-1193. I believe your 1936 is essentially identical to my 1937 (mine is a Roadmaster). Doug is extremely well-versed in all of these cars, and specializes in restoration of 1940-41 Buicks. His Restoration shop is located in Westlake, Ohio, a suburb of Cleveland. I'm certain that Doug can supply you with an already rebuilt unit - and rod if required, or can get yours right. Tell him I gave you his name. They don't call him 40BuickGuy for nothing!

Good luck, and please let me know how you make out.

Marty,

Thanks for the encouragement and contact. If the parts I ordered don't work I'll be sure to give Doug a call.

Jeff

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Well it is going to be tight but I think it is going to work.

Here is the cylinder shortly after I unpacked it. A big issue for me is the length and if you look at the pushrod you can see that I was already experimenting with trying to thread it further in to try to solve that issue.

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This image is after I cut off the ear and threaded the pushrod. The tape is close to where the rubber boot will end on the rod but it is also just about where I need to have a 3/8" eye connected to mount to the pedal. The plan is to cut the pushrod to be closer to the cylinder so that when I thread on the capture nut the nut will be entirely within the boot. The eye will connect to the nut and I'll be able to screw it in and out a bit for some adjustment. I verified there is going to be sufficient travel in the cylinder to depress the brake fully and that even if I thread the nut on fully there is still enough clearance for the rod to swing as much as it did normally.

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These next two pictures show the cylinder mocked up on the bracket that held the original cylinder. I still need to fabricate spacers and cut the pushrod but otherwise these modifications are complete. Total impact on the originality of the car are two extra holes in the original bracket and different lines connecting the cylinder with the rest of the brake system.

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In addition to looking for stock to make spacers out of I'm still looking for an end to put on this thing. I ordered an end from JEGs that I knew was too large of a diameter but I thought I'd be able to find a bushing locally to cut the 5/8" inner diameter down to the 3/8" that my pedal requires. After several plastic bag hardware stores and big box improvement centers I now realize the folly of that approach. I found a steel end rod at McMaster Carr that I might order as well as this extra pricey option from JEGs that looks very appealing.

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The tolerances are extremely tight and if I had much more than 1/4" of maneuvering room I'd be surprised.

The lesson learned on this effort was that you do not put the pushrod into the cylinder to mock things up. I did that to get better measurements and to help guide me in lining things up but as soon as it popped in I realized I'd screwed up. I could not get the rod out again no matter what I tried so that led to doing fabrication and threading with it in the cylinder; what a pain! I really want to get this thing into the car to verify all is well but after the first issue with the pushrod I figure I'll wait until I figure out the end portion so that I can play with everything on the bench instead of while standing on my head in the car.

Thanks to everyone for you input. More pictures to follow after it gets in the car.

Jeff

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Hi,

I like the Jegs option if only because the business end of this link will conform to any minor mis-alignment. A year after it's installed you won't remember or care about the slight additional cost of this live ink compared to the steel one from McMaster.

You can check with ball bearing suppliers, such as Motion Industries, for a bronze (not Oil-Lite) bushing to use in the part you originally ordered. Set the bushing in Locktite Red and it's there forever. You want a bronze bushing because the Locktite Red may not permanently secure an Oil-Lite bushing.

--Tom

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Yup, I decided the JEGs expensive option was the way to go if for no reason other than it should give me a little room for slop when lining things up.

I spent the morning talking to all the automotive supply places in town and not surprisingly they didn't carry anything like that. What was surprising was that they couldn't order anything like it either.

Jeff

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I don't know about the US but here in Aus I have found that finding someone that actually knows something about cars AND sells parts is far and few between.

Latest example was I was looking for a rubber boot/gator (??) that goes between the door pillar and the door and carries the speaker wire, central locking wires etc. My model Hilux didn't come with this but the model up did. The guy was totally stuffed as I couldn't supply a VIN number and just wasn't interested in pursuing it further.

Same dope then couldn't sell me a bottle of injector cleaner as the bar code scanner wouldn't scan. Good grief !!!!!!

Danny

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Hi Danny,

I have to wonder if the injector cleaner that could not be scanned came from the States. If so, the clerk should have turned it upside-down for scanning in its native tongue.

...Just sayin'... :o

--Tom

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Well after several delays from FedEx delivering my package to the wrong place, work, emergency shower demolition, and illness I just finally got a chance to try bolting things together today.

It was a serious struggle to try to get bolted in (have I said yet that I sure wish I had a lift?). Tolerances are also extremely tight but it does fit, is aligned, and has full travel.

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The donut on the end of the pushrod is a bit wider than the last push rod so I might need to drill another hole in the brake pedal pin to be able to insert a cotter pin.

Plumbing will be the next task. The cylinder has 1/2-20 fittings but it came with 3/8-24 adapters. The residual valves I got also have 3/8-24 fittings. Will it be ok to go from the 3/8-24 adapters at the cylinder, through the residual valve and than to up to 1/2-20 to match up with the rest of the brake fittings? I was disappointed with this at first but then realized that the hole in the bore of the cylinder is probably even smaller so there is already some increase in volume as you leave the cylinder.

Jeff

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Question. What will you do to the floor pan to aid in filling the reservoirs? I have a '38 Roadmaster and Special and it is frustrating to get fluid into the master cylinders the way the hole in the floor is. I have had to use a funnel and that usually leads to a mess. Fortunately since both cars have DOT-5 I never have to add fluid - but I did have to fill them when rebuilding the brake systems.

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Question. What will you do to the floor pan to aid in filling the reservoirs?

Great question; I wish I knew the answer but I'm still working on that.

For a long time I was going to go the route of remote reservoirs that were designed to work with a wilwood cylinder. That cylinder was ultimately too long and when I gave up on that cylinder I gave up on the remote reservoirs.

This new cylinder sits much higher and has bigger holes to pour fluid into so I don't expect to have as many problems with it as I did with trying to fill my old master cylinder but I still need to be able to get access to it.

I happen to have good access to the cylinder if I remove the entire floor panel under my feet but I'm adding carpet and attaching the carpet such that I can retain that ability is going to be a challenge.

I have two current thoughts.

1) Is to have carpet made that has a permanently installed section from the seat to the back of the compartment. The front section would be attached permanently to the firewall area but from where the floorboards become horizontal would only be attached with something like hook and loop tape or possibly some other modern automotive connector. Doing this should allow me to flip the carpet up to get access to the panel under my feet to fill the reservoir. Unfortunately it makes it difficult to finish on the door jam. I'd probably overlap the back with the front and put the back section under the kick plates and then have the front section bound and have it lie on top of the back section. I'm a little concerned about how this might cause issues with binding and bunching when I move the seat.

2) Is to make the carpet a permanent installation. It is easy to conceive of as carpeting everything and then cutting around the opening for the floor panel. In practice I'd cut the floor portion to overlap into the area the floor panel sits. I'd then capet the panel separately and overlap it to the sides as well. Most likely I'd need to cut the panel a bit smaller to address the overlap but the intent is to make the fit fairly tight so as to keep dust and noise out. Now being able to secure the panel as well as easily extract it is the challenge that I'm working on. I could see adding something like a flush pull that would sit in the carpet and lift up to extract the panel. If I could find something like that with a latching mechanism that I could adapt that would be my ultimate solution.

Jeff

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I'll be really interested in your eventual solution. My Roadmaster has carpet in the front, and while a royal PITA, getting at the master cylinder to check it, it is possible.

However, for the Special I have one of the reproduction rubber floor mats and I expect that it will be a whole lot harder to deal with when checking fluid level.

I might add, while I do check the hydraulic fluid level occasionally, I have never had to add any since changing to DOT-5.

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