Drum Front Brakes - Car pulls left when stopping. Thoughts

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68 Pontiac Lemans. Drum brakes all around. Prior owner put a brake booster on car. Front brakes were previously overhauled by prior owner - all new hardware and new lines from master cylinder to front wheels. Everything visually looks good. I bled the brakes so I am getting fluid to the brakes. I had the car on jacks and tires off. When pushing the brake pedal the drums cannot be rotated by hand. So I am assuming the brakes are getting fluid and the internal mechanisms are working. The car pulls a heavy left when braking. What else can I look at or test? Thanks . . . JIMB
 
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Assuming that the shoes were installed correctly, and all hardware is in good shape, you will need to adjust the shoes so they have the same amount of drag. You want them to feel like they have a very slight resistance to turning by hand. Other than that, check to make sure you don't have a weeping wheel cylinder on the right from. That would allow the left to put more pressure on the shoes than on the right.
 
These are self adjusting brakes. By backing up the car the brakes should reset themselves to the correct settings . . Right? And, what is a "weeping wheel cylinder" ? How do I check for this? Thanks . . . JIMB
 
A weeping wheel cylinder is on that has a small seal leak, usually found by inserting a small pick or screwdriver into the rubber boot where the rod comes out of it, and pull it away from the rod slightly. If you see any fluid ooze out, you need to replace the wheel cylinder.
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Pulling to one side

The "mystery" problem when all appears to be normal, and everything is adjusted correctly, and yet the vehicle pulls to onw side or the other is frequently when:
A brake hose is collapsed on the inside and fluid is not travelling through it -- and of course, you can't see that from the outside -- but if you force air through it and it's fine, "suck air out of it" (Be careful you don't ingest brake fluid, of course.) That may be your problem.
I have all U.S.A. made parts for this vehicle -- Master & Wheel Cylinders, Brake shoes and brake hoses, wheel bearings & seals, brake hardware, brake emergency cables, and BRAKE DRUMS -- Front & Rear....

If you need me, call -- Craig -- 516 - 485 - 1935....New York:)
 
Back to this issue. I noticed the seal for my master cylinder cap was leaking. So, I went to replace the rubber seal that seats under the top cap (what is held on by the bracket.) The rubber seal I was about to buy was a round rubber seal. Mine is square. After looking closer I believe someone put a master cylinder on my car for Disc brakes. It is square and looks like the master cylinder for power disc brakes I see for sale in some of the classic part sellers (ie: Ames or NPD) and all my brakes are drum. How can I tell what master cylinder someone put on the car? Is there some decoding numbers I can find. Thanks . . . JIMB
 
You can not interchange drum and disk brake masters because the disk master does not have a residual pressure valve. Read the link below. They may have installed a drum brake master/booster from a newer year. Looking at page 242 in the Ames catalog it appears that both drum and disk, R129W and R129WB, have round end masters. Starting with 1970 they appear to go to square end masters. You may want to give them a call just to verify if this is correct.


http://www.mpbrakes.com/technical-support/reference-master-cylinders.cfm
 
What I think I have here is a Disc/Drum Master Cylinder. See pics. Large front fluid bowl with smaller back fluid bowl. Can someone confirm this with me before I go and replace the master cylinder.

This may be why my brakes are squishy (technical term) and my car pulls to the left. But hard to fix and really determine issues when incorrect equipment is installed. I will go buy a Drum/Drum Master Cylinder today and install. Any advice on buying a master cylinder or installing. I assume I will need to bleed my lines once the new master cylinder is installed.

Oh, and one other thing I have noticed . . When I apply the brakes then release the brake pedal, my brake pedal never really came all the way back up thus leaving my brake lights on sometimes. Again, maybe a symptom of not having the right master cylinder installed.

AND . . do I need to worry about if the current power booster installed is correct for installing a drum brake master cylinder . . or is a power booster a power booster for any type of master cylinder????
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You are correct, looks like a front disk master. Unfortunately Ames also shows a different booster for drums versus disk. You could remove both lines from the master and see if you can see past the brass seats. The front passage would be blocked by the residual pressure valve if you have a true drum master along with the rear passage having the valve.

R130R 1967-72 Original Style Power Brake Booster,
All Exc. Disc. Brakes (RE) ............................. 179.00/ea.
R130V 1967-72 Original Style Power Brake Booster,
All w/Disc. Brakes (RE) ................................. 179.00/ea.
 
Drums vs. Disc

The master cylinder you have depicted is a Front Disc - Rear Drum master cylinder indeed (that is an 18M1878 DELCO) Master Cylinder....

Front Disc - Rear Drum and 4 wheel drum Power Brake Boosters and Master Cylinders are unfortunately VERY VERY Different.

You are clearly having problems because this system is mismatched. Somebody may have "started" a disc brake conversion, encountered problems, abandoned the project, and sold the car. That's the easy way out --- I see it all the time.....

I am involved in only the classic and original cars and parts -- Call me and we'll get you squared away whichever way you want to go......
Craig -- 516 - 485 - 1935.....New York:):)
 
Update. I am going to keep the master cylinder and booster I have because I was going to upgrade the fronts to disc brakes anyway. I did some research and found that I cannot install disc brakes on the front because I have 14 inch wheels (original wheels) and there is not enough space for the calipers. So, I have to have bigger wheels, 15 inch minimum, to install the disc brakes. I went ahead and purchased 17 inch rims. I had to so I could install the disc brakes and make the car safe to drive. Wife bought it!!!! :D All I needed. Rims and disc brakes should be here next week. More to come later.
 
should be a great car once all is together
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I am in the middle of putting new spindles on for new front disc brakes. Old spindle off. Installing new spindle. Bottom nut when on fine. Top nut not so much. The top nut goes onto the ball joint bolt then the entire nut and bolt start turning together. How do I stop the bolt from turning so I can get the nut on this thing ?? I tried using the cotter pin hole to hold the bolt but I can only go so far before I run out of cotter pin hole.
 
You cannt push the rubber boot on the ball join up a little and grab it with a vise grip? You are sure the threads on the ball joint are clean and dont have any burrs on them?
 
Yea . . the threads on the bolt are stripped. Just went to the store and picked up a new upper ball joint. More to come.
 
New front disc brakes installed - fairly easy having never done that before. Car has stopped pulling to left. I bought the disc brakes that lower the front of the car by 2 inches. When I bought them I did not think 2 inches was going to be that much. But wow. its a huge difference. Looks great. I also bought 17 inch wheels from Ron's Rims and staggered the fronts and back tires. Fronts are 215/50 and backs are 235/45. Could have gone bigger in the back but looks ok. See pics.
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Those rims sure are an improvement and good to hear you can stop the car in a straight line.
 
Interesting development on the brakes. Took the car out yesterday and was riding down the road and everything seemed ok. Couple stops and all good. Went to stop one time and the brake pedal went all the way to the floor. I pulled up the brake with my foot and it worked fine again. A few minutes later the same thing - brake pedal went all the way to the floor. This morning I re-bled all the brakes (back right, back left, front right, front left). No leaks and master cylinder was full and holding fluid. Went to pull out of the driveway and brakes seemed ok. Went to brake at the end of the driveway and the pedal went all the way to the floor. I DO NOT have a proportioning valve on my system. I have read several posts that say I need one and some people say their system is fine without one. Thoughts on what is going on and need of proportioning valve. Thanks . . .JIMB
 
You have an old master and you bled the brakes using the assistant pumps the peddle and you crack the bleeder, correct? If so and you had corrosion spots on the inner bore of the master the rubber seals on the master piston slid past the spots during bleeding and were damaged. If I'm correct so far, you need to disassemble the master and check how badly it is corroded. If only mildly clean up with some very mild emery paper and get a rebuild kit. I always use gravity bleeding to do the system takes more time but less chance of a problem with master later on. You are sure no caliper or wheel cylinder leakage?
 
I do have an old master and booster - I cannot tell you how old because the previous owner installed it. So, I am not even sure it was working in the car it came from. I used the gravity method for bleeding brakes. Have not looked into the master for corrosion spots. I can push the brake pedal all the way to the floor. Sometimes it does seam stiff and other times is real squishy. I am sure there are no leaks on any caliper or wheel cylinder. Oh, and the brake pedal does not normally return all the way up into its resting position. I sometimes have to pull it up with me foot. Sometimes I can feel the brake dragging on the car until I bring the pedal up with my foot. Because it is the BRAKES . . . . I am thinking about buying a new Booster & MC with a proportioning valve. Just to be on the safe side.
 
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