Brake question on my '63

I reported here on this forum 2-3 weeks ago that I completed the changeover to a dual-master cylinder setup for a '67 on my '63, which has drum/drum brakes. After a few more miles, I still almost launch myself through the windshield due to a super sensitive brake pedal at very low speeds because of a ridiculous amount of over-assist. The changeover included the installation of a brass distribution valve, which I'm told is different from a proportioning valve required for disc/drum setups. So I'm told there's no real adjustment there. My mechanic says it may be that the front brakes need more adjustment to reduce sensitivity. The rears grab first as they should, but maybe not enough?

Also just to be sure, which part of the master cylinder serves which brake system (front or rear)? I thought that the reservoir closest to the booster is for the front system, while the one that's closer to the front of the engine serves the rear. (I don't have my shop manual handy here at the office).

Any advice as to how to reduce over-assist at very low speeds is appreciated. At higher speeds the pedal assist feels fine but pulling out of my driveway or into a gas station or parking lot makes it look as if I'm driving drunk!

Jan, the front reservoir serves the front brakes. The rear is for the rear.

Jan-

If the brakes have all been assembled correctly, including the automatic adjuster mechanism, then you need to apply the brakes repeatedly while backing up to adjust all 4 wheels out to proper adjustment. I don't know if you knew this. On my car, I can hear the little adjuster wheel clicking now and then when I apply the brakes firmly in reverse. When you hear no click, they are adjusted out correctly.

The line from the front port (the front reservoir) must go to the front wheels.

The rear brakes should not engage first. On a drum/drum car, they should all engage at the same time.

Front/back proportioning is taken care of by the different wheel cylinder diameters. Larger wheel cylinders in front provide more braking force up there.

It does not sound like you have over-assist at low speeds. It sounds like your brakes are grabbing.

Do you have new linings (new shoes)? Sometimes brakes are grabby when you have new linings contacting freshly turned drum surfaces. As that surface wears smooth, the brakes won't grab so much.

Do you ever have a chatter when you apply the brakes? Your wheel bearing nuts may not be tight enough. There is a procedure in the shop manual on how to set the bearing nut correctly. Easy to check.

I reported here on this forum 2-3 weeks ago that I completed the changeover to a dual-master cylinder setup for a '67 on my '63, which has drum/drum brakes. After a few more miles, I still almost launch myself through the windshield due to a super sensitive brake pedal at very low speeds because of a ridiculous amount of over-assist. The changeover included the installation of a brass distribution valve, which I'm told is different from a proportioning valve required for disc/drum setups. So I'm told there's no real adjustment there. My mechanic says it may be that the front brakes need more adjustment to reduce sensitivity. The rears grab first as they should, but maybe not enough?

Also just to be sure, which part of the master cylinder serves which brake system (front or rear)? I thought that the reservoir closest to the booster is for the front system, while the one that's closer to the front of the engine serves the rear. (I don't have my shop manual handy here at the office).

Any advice as to how to reduce over-assist at very low speeds is appreciated. At higher speeds the pedal assist feels fine but pulling out of my driveway or into a gas station or parking lot makes it look as if I'm driving drunk!

Hi Jan,

On my conversion, I used the front portion of the Cylinder for the front, and rear for the rear. (As you have already seen, LOL) My guess is that the proportioning problem comes from the use of the distribution valve you wrote about. I know you get the benifit of a Brake warning lamp, but this may be "Over Proportioniong" the system. As Jim said earlier no added proportioning is needed an the wheel cylinders should provide what you need. On the conversion I did I just used t-fittings (refer to diagram) and don't seem to have the over assist issue. The other thing you did (I think) was to add the 67 Booster, I don't know how that might effect things. I can't imagine that would cause an issue though.

If remember correctly, My Chevelle used similar sized Wheel Cylinders and a distribution valve on the 4 wheel drum system. If the Buick system uses different sized wheel cylinders to accomplish this then the use of the block may be the issue. I know it sucks because of the plumbing involved, but could you bypass the Prop valve, with tees and try it without the added proportioning? The part numbers should be on the diagram I made. Good luck and keep us posted on your progress!

Tim

Did you also replace the booster? Make sure you dont have the brake linings/shoes reversed. The long linings go to the rear, short linings to the front.

Tom

Did you also replace the booster? Make sure you dont have the brake linings/shoes reversed. The long linings go to the rear, short linings to the front.

Tom

Excellent point, Tom, about the primary and secondary shoes! Because he had a mechanic do the work, I assumed the guy knew about this, but... never should assume. He might have the long shoe linings in the front position... easy mistake to make. And it will make the brakes very grabby.

Jan, go ask the mechanic to pull the brake drums and look at the length of the lining on the front shoe of each wheel. Tell him about the grabby brake problem. And if he connected the front port to the rear wheels, have him reverse the lines.

Thanks to one and all for your knowledge and advice! I'm bringing it in Thursday so I'll provide an update after that.

Thanks to one and all for your knowledge and advice! I'm bringing it in Thursday so I'll provide an update after that.

Here's one, I was watching Fast & Loud and they had a Mopar product with the same problem. They said it was a Disc inside the booster and had the booster rebuilt. LOL for what its worth, I just thought is was funny it was the same problem.........

Tim

"I know it sucks because of the plumbing involved, but could you bypass the Prop valve with tees and try it without the added proportioning?" Tim Kaber

So that's what we did today - we took out the distribution block and plumbed in a 3-way tee per Tim's diagram (thanks, Tim.) Everything else checked out: shoes (not new) are in the right positions, front and rear systems are plumbed to the proper m/cyl ports, wheel bearing nuts tightened to spec. This reduced the "grabiness" at very low speeds enough so that I can live with it if I remember it requires a light touch at crawling speeds. (My daily driver is an Audi A3, not something that needs a lead foot to stop.)At 20 mph and above the Riv brakes feel really good, with what I think is the right amount of assist. So let me ask: do other first-gen Riv owners have the same experience at low speeds? Years ago my brother had a '66 Wildcat that I thought was ridiculously over-assisted (or grabby) at low speeds, and I know these earlier Riv brake systems were designed to meet the needs of women drivers as well. I'd love to hear from other owners...

Did you also replace the booster?

Tom

Did you also replace the booster?

Tom

I replaced the booster with a new one for a '67 when I did the conversion, but did not have one handy today to swap out to see if it made a difference.

Jan,

As I have owned my 63 for a long time, I can provide some insights to my brakes, and what I have learned about the 63-65 brake systems as well. First, I still have the stock set up in my car with the single master cylinder. I also have original Delco-Moraine asbestos lined shoes on all 4 wheels. It can be slighty grabby below 5mph, but overall it is very predictable and they stop the car very well.

As people have changed out their brake linings, I have heard complaints about their brakes being too grabby at low speeds, and not feeling like they did before. So what's the difference? The difference is that the brake linings are no longer made from asbestos. The newer material is different and that is causing issues with cars with front drum brakes. I confirmed this when talking to a rep from Centric.

So as long as we have our front drum brake set ups, the only options are to either learn to live with it or look for some NOS linings. Of course the other option is to convert the front over to a disc set up.

"I know it sucks because of the plumbing involved, but could you bypass the Prop valve with tees and try it without the added proportioning?" Tim Kaber

So that's what we did today - we took out the distribution block and plumbed in a 3-way tee per Tim's diagram (thanks, Tim.) Everything else checked out: shoes (not new) are in the right positions, front and rear systems are plumbed to the proper m/cyl ports, wheel bearing nuts tightened to spec. This reduced the "grabiness" at very low speeds enough so that I can live with it if I remember it requires a light touch at crawling speeds. (My daily driver is an Audi A3, not something that needs a lead foot to stop.)At 20 mph and above the Riv brakes feel really good, with what I think is the right amount of assist. So let me ask: do other first-gen Riv owners have the same experience at low speeds? Years ago my brother had a '66 Wildcat that I thought was ridiculously over-assisted (or grabby) at low speeds, and I know these earlier Riv brake systems were designed to meet the needs of women drivers as well. I'd love to hear from other owners...

I have not noticed any "Grabbiness" in the Riviera since working on the brake system. However, I will say the 4 wheel power drum set up on my 1970 Chevelle was pretty grabby. I drove it like that for 30 years. In fact the reason I got the car was because of the grabby brakes. My Dad bought the car for my Mom when I was 14. We had had VW Bugs before that. The Chevelle had power drum brakes on all four corners, the first time my Mom drove it she about hit her face on the steering wheel, from the braking, more than one time! She parked it and didn't really drive it again! My Dad wanted to sell it, but I had given up on Bugs and there was no turning back! It still sits in the garage at my childhood home that I also still have, LOL! A few years ago I added a Disc brake conversion, for the money it is the best thing I ever did to that car.

Jan, I'm glad that helped you a little in solving your brake issue. If it seems acceptable, I would try it for a while and see if you get used to it. I did do a quite a bit of fiddling with the shoe adjustment on ours to get the feel "Just Right" for me. I sounds like you are on the right track. I guess I do remember a learning curve after the conversion. Now I don't even think about it. Good Luck!

Tim

The brake reliner I use has three levels of shoe non-asbestos material, gentle stop, performance, and "put you on your nose". For the past 15 years or so I have dropped off the shoes and drums to be renewed, ground, and fitted. The cars stop fine. Sometimes it is hard to remember that the cars are 50 years old and working at a different technological level than that 3 year old daily driver. My car was built 5 years before we put a man on the moon, a pretty significant event of the late Iron Age.

One has to remember it is a braking system that can include mud filled wheel cylinders, delaminated hoses, and weak return springs. Mix that with liberal amounts or "my mechanic says" and "I looked it up on Google" and a flawed perception results.

Take a 22 year old woman out on a date and then try a 50 year old (one still in good shape). There will be a difference there, too.

Bernie

Thanks, Tim - I rechecked all my parts numbers and unless I got a defective new booster, I'll try a light pedal touch at crawl speeds. My mechanic (I know Bernie cringes at those words) mentioned that he may be able to install some kind of assist limiter, but at this point we have to know, as Jim Cannon says, whether its the assist or the linings. In fact I printed out all these responses and had him read through them before he picked up a wrench.

As for your final comment, Bernie, my wife is just a tad older than a '63 model but still very much in fine shape - she's a fitness instructor. And as for a 22-year old, maybe a car, but I don't know that a 1992 model would grab me (pardon the pun) other than a Riv. And unlike a '63, at my age I'm sure they would be more aggravation that anything else in the longer run! But I get your point...