FL. driving breaks

[Guest Bobby Valines]

Went back to the yard today, I have been giving it a lot of thought and the best I'm coming up with is, a 4 port with no anti lock breaks and 4 disk. Ill just have to run another line for the back. Hoping that the holes in fire wall line up but I'm thinking they will, the booster is smaller so that should help. I'M also thinking I should take the break peddle and linkage.

[Guest steakneggs]

Don't use a 4-port! It is probably a diagonal flow design like the one I have. One of the chambers goes to one front wheel and one rear and the other chamber goes to the other two. It's a crappy design that accomplishes nothing. Plus you will spend more time running that extra line and dealing with the rear prop valve than all the other conversion hassles. Contact D-A-N-I-E-L or 7654321 and find out which unit they used. Steak

[Guest Bobby Valines]

I could also use the two port with the proportion valve but its hard to find one that has rear disk. I think Daniel used the ABS system.

[Guest simplyconnected]

Steak, that's the way it was plumbed! The Corvette 4-port M/C I bought (new) has two front ports that are tied together, and two rear ports that are tied together. If you don't need all four, just plug one! Usually only one line goes to the rear because it tees off at the diff, regardless if you use a proportional valve or not. (You still use one rear line).

The reason they sell four-port is for convenience of choice; either plumb from the fender side, or the engine side. Some applications don't have the real estate for a choice. Those guys plug TWO ports (one on the rear and one on the front, both on the same side. Then, they use two tees down the line.)

Again, if you have four drums, there's no need for a proportional valve (we never needed them in the old days). Same story if you have four disks. Disk brakes require about 200psi more than drum brakes.

Bobby Valiens, the M/C puts out the same pressure, front and rear. That's why you need a proprotional valve for mixed brakes.

Here's the M/C's:

[Guest steakneggs]

If you're sure that it is not a diagonal-flow m/c, a 4-port unit would be acceptable. You can plug one of the rear ports to make it a 3-port. You still need a proportioning valve with 4-wheel disk because the rears have less weight on them and they will lock with equal fluid pressure. You have a prop valve already by the L rear wheel so you'd be good to go. But all the 4-port units I see in junk yards have prop valves attached to the rear ports already and can't be removed because the port they screw into is not a flare port (it's an O ring port). If there is a 4-port unit that is front-rear and has no prop valves I say grab it. That's assuming that it meets the other criteria (stud spacing and pushrod length). Steak

[Guest Bobby Valines]

OK so the one and only one I found 4 port with no prop valve is the best bet. Should just have to adapt excising lines to it and be done, Sounds easy. Ya right. I cant tell you people how much I appreciate all the input. Thank you.

[Ronnie]

Before starting the changeover I would like to offer this as an alternative:

1 - Vacuum booster and master cylinder from '91 Reatta. It has 2 outlet ports. It should bolt up with no problems.

2. 2 short sections of steel brake tubing to go between the master cylinder and the proportioning valve below.

3 - Stock proportioning valve (combo valve) from 67-81 model Camero It has 2 inlet ports to connect to the master cylinder. It has 2 outlet ports for the front brakes and 1 outlet port for the rear brakes. (See the photo I supplied above)

4 - Attach stock Reatta brake lines to the proportioning valve.

5 - Drive car. If braking is not even then remove the stock Reatta proportioning valve and install an adjustable proportioning valve if needed.

6 - Disable ABS light.

I believe that setup will be the best way to go. Parts are readily available and it should be a bolt on changeover. Only modifications would be if there is a difference in the flares used on the tubing.

If my Teves goes bad and I can't afford to get it working, that is the parts I will try.

The master cylinder and booster from Autozone can be bought for about $200 for rebuilt units. Combo valve would be a dealer or junk yard item.

[Guest simplyconnected]

Just a note, sometimes they mount the proprotioning valve directly under the M/C with a small bracket. (It keeps lines real short.)

Other methods include mounting to the frame or firewall:

Left side mounting

Right side mounting

[Guest steakneggs]

The '91 Reatta unit also came on that year's Eldo, Seville, Toronado, and Riviera in case you want to scour the junk yards one more time. Maybe you can let your fingers do the walking. I still maintain that you do not need to add a prop valve valve because you have one there already doubling as a T on the rear circuit. You will have to T the front lines and do some reflaring. You might also have to ream out the pushrod hole to fit the brake pedal pin. 7654321 I believe used this unit but hasn't been heard from in awhile. Steak

[Ronnie]

The reason I keep pushing the valve from the Camero is to try to make it a bolt on job by it having all the correct inlet and outlet ports. It would also avoid adding Tees and having to make flares to the tubing which requires special tools that a lot of people wanting to do the changeover may not have.

Another consideration is, done wrong, a flare can cause a dangerous situation. The actual proportional action of the valve may not be needed but I doubt it would hurt to have it there. I just believe the valve would make a neater and more professional looking job.

[Guest simplyconnected]

Steak, I can buy double-flared lines (complete with nuts) in any length from my local auto parts store. I think they all have them; they're cheap!

Double-flaring tools are available everywhere, too (including Harbor Freight). The only lines I found more difficult, were stainless steel lines. Stainless can be double-flared, but you have to buy very good quality flaring tools for that.

[Guest Bobby Valines]

Simp thats good to here. Went to the yard today that had the 4 port non ABS 4 disk break. could not get it off dident have the right swivel so ill have to go back. Its off a 90 buick reagle thats why im thinking the holes will line up. The break lines on the reatta are plenty long enough. The only thing bothering me is blocking off that 4th port. The booster from the yard ill keep but the master cylinder ill use for a core. Im trying to do this as cheap as possible but it is breaks it has to be right. Finding a 91 reatta in the junk yard would be great but I dont think its going to happen. Thats why i dont mind going there, looking for a reatta and maybe a supercharger. Ronnie the 91 reatta master cylinder had ABS dosent that matter? Im just thinking the pressure would be greater going through the ABS system. By the way I liked what you said on that other thread.

[Guest steakneggs]

Make sure that the 4-port m/c you choose doesn't have two aluminum or brass things screwed into the rear ports. Those are the prop valves that can't be removed (see earlier post). Using a separate prop valve might make for a cleaner looking installation (actually the tee could be hidden below the m/c), but if you have too much proportioning (you might find out the hard way, front wheel lockup on a curve) you will have to remove one of them. The m/c's that are designed to work with a separate ABS should work fine without the ABS. If you get one at a junk yard, cut the lines so you get the nipples. Steak

[padgett]

If the two rear ports have are siamesed (have a common chamber) you should be able to block one without a problem. The operative worrd is "should", I have not tried it but hydraulically it should work. Make sure you use a plug designed for the purpose.

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bobby Valines</div><div class="ubbcode-body">Ronnie the 91 reatta master cylinder had ABS dosent that matter? Im just thinking the pressure would be greater going through the ABS system. By the way I liked what you said on that other thread. </div></div>I don't think it would matter. The pistons in the '91 master cylinder should be the correct size for all the Reatta calipers.

[Guest simplyconnected]

Use a pair of diagonal cutters, like Steak said, and cut the junk yard brake line back from the nut about two inches. If you need a plug, you can make it from one of the lines you cut. Just fold the end over and braze it, or buy a brass plug from the auto parts store. They have them in "flare" but they are expensive.

[Guest Bobby Valines]

I was thinking the same thing besouse im not sure how easy it will be to get a plug that fits right. A plug sure would look better.

[padgett]

The Teves accumulator is pressurized to over 2200 psi but that is to have a reserve. AFAIR the pressure in the brake lines is the same as for any passenger car braking system. The force on the tires is a function of the caliper piston diameter and the diameter of the rotor and you modulate it with your foot.

[Ronnie]

Are you saying all master cylinders have the same piston size? I don't what to argue but I doubt that is the case.

With the same amount of force applied to the brake pedal, a smaller MC piston will apply more pressure to a given size caliper piston, resulting in more clamping force on the rotor than a larger MC piston. The trade off would be a longer pedal travel due to the smaller MC piston moving less fluid in a piston bore of the same length.

With all other perimeters remaining the same, a larger piston in the master cylinder would have the opposite effect.

I don't know that any of that will matter much as far as braking power in this application since the vacuum booster is helping supply the power. You could possibly notice a difference in the length of travel of the brake pedal between two master cylinders with different sized pistons.

I thought I would throw that out since we are trying to come up with a properly sized braking system to replace the Teves system.

[Guest Bobby Valines]

My first car was a 67 mustang it had a new thing called (power disk break) all you had to do was look at the break pedal and it would put your head through the windshield. Thats another thing we have to look out for. Personally I would rather have it a little harder to push than to easy. IM thinking that 90 Regal should be perfect weight of the cars should be close and im thinking the disk breaks are the same.

[Guest simplyconnected]

I'm with Ronnie. Since disk pads don't retract like drum shoes, there won't be much flow. There's no need to go past one inch on the M/C, it will make the pedal harder with no advantage.

Bendix, Wagner, etc., made brake systems for many decades (for everyone's cars). With drums, they made rear pistons smaller, so rear shoe pressure would proportionally match front shoe pressure. Disk/disk systems do the same, using a smaller piston in the rear.

Dual M/C's put out the same pressure, front & rear, (because the M/C piston sizes are identical). If you need to fine-tweek using an adjustable proportional valve that's ok, but most folks won't know the difference. Truth is, rear brakes don't do much braking; that's why they last so long.

Your foot pedal pressure controls the power booster. That's where the real feel comes from, and that's why boosters come in different diameters. Want a "hard" pedal? Get a small diameter booster. If it's too small, you might as well go with manual brakes, especially in a light car. Remember, power brakes came out when our cars were two tons or more. '50's cars had four 11" and 12" drums with linings of 1-1/2", and 16" tires. Women had to stand on the brake pedal. In the country, it was common practice to blow through stops because stopping was more a bother than necessary.

[Guest steakneggs]

Whether it's got more or less pressure, the difference can be adjusted by foot pressure. I don't know whether my converted brakes are easier or harder than the Teves. It failed before I got tags. It's about the same as our '99 Regal. The easiest way to make a plug is to melt the pinched end with a acetylene torch. If you send them to me I'll do dem fer nuttin. They're not the best looking things though. Steak