Scarebird 69 Riv Conversion

[Guest Yardley]

I am at the end of my rope here y'all. Years ago I did a Scarebird front disc brake conversion on my 69 Riv. Right off the bat the pedal was terrible. So I swapped in a master cylinder from a 69 Riv disc brake car. The pedal improved but was still all the way to the floor. I have since added a hold off valve. I have also added a 10 lb residual valve in the rear.

The brakes are still barely adequate. I cannot hold back the car at all with the brake when brake-torquing it. Just rolls ahead. And the pedal uses all of its travel to stop the car. I'm tired of "just living with it". If I had the gonads I'd have my drums relined and put them back on.

I've swapped out the calipers and brake lines many times with no change. Power bled the brakes, so there is no air in the system.

The 2000 Chevy Astro van the calipers come from has a master cylinder with a 1 1/4" more. Our Rivs have a 1 1/8" bore. It just feels like I cannot move enough fluid to clamp the calipers.

Has anyone else done this conversion?

Thanks.

Yardley

Edited June 2, 2012 by MCHinson (see edit history)

[MCHinson]

Yardley,

Welcome to the AACA Discussion Forum. I have deleted your duplicate post in the General Forum. I have also slightly edited your post to make it compliant with the Forum Rules and moved it to the Riviera Specific Forum. Hopefully someone here can help you with your suggestions on resolving your brake problem.

[RivNut]

Why did you opt for an aftermarket conversion when you could have just as easily did a year for year, model for model, OE swap.

Have you contacted Scarebird and ask them what they might have for a solution.

From my experience with the older 1st generation and some 2nd generation Rivieras ('69 included) you have to match the master cylinder to the power booster. Buick installed both Delco-Morraine and Bendix systems on their cars. You can't mix Bendix and Delco parts although they will bolt up. Each system has its own section in the chassis manual for each year. They're that different. If you don't have access to a chassis manual for '69, I'd start there.

Mixing and matching parts is always difficult to analyse, especially if no one has done the exact same thing as you have.

[fatbuick]

I don't know if it could be this but;

A drum booster only puts out 800 psi, disc brakes require 1200 psi

To maintain pedal ratio the original master cylinder bore also needs to be maintained.

By going to a larger bore it should make the pedal isn't harder than normal so I don't get it.

I would try a 67-69 Buick booster from a disc brake car.

[Guest Yardley]

Why did you opt for an aftermarket conversion when you could have just as easily did a year for year, model for model, OE swap.

Have you contacted Scarebird and ask them what they might have for a solution.

From my experience with the older 1st generation and some 2nd generation Rivieras ('69 included) you have to match the master cylinder to the power booster. Buick installed both Delco-Morraine and Bendix systems on their cars. You can't mix Bendix and Delco parts although they will bolt up. Each system has its own section in the chassis manual for each year. They're that different. If you don't have access to a chassis manual for '69, I'd start there.

Mixing and matching parts is always difficult to analyse, especially if no one has done the exact same thing as you have.

Hi. Ever try finding calipers for a 69 Riv? Unobtanium. Like I said in my post, scarebird claims they should work. And yes, I have the correct master for my booster.

Tony, I never thought of the booster! I figured vacuum was vacuum. I had my original restored by Jim Weise, so I was content to use it because it was done up correctly, but I'll swap it out and see. You'd think that if it was required Scarebird would mention that...

[fatbuick]

Rotors are also unobtainium.

When I converted my Wildact to discs I couldn't even lock up the wheels on gravel. I upgraded to a dual diaphragm booster and kept a 1" bore like original MC. Brakes work great.

Best of luck.

[Guest Yardley]

I am running a TA 413 cam. Not great vacuum. I just hooked up my Harbor Freight vacuum pump to my drum brake booster and I have FANTASTIC pedal response! So I will swap boosters and see if it helps. If not I have to run a vacuum pump.

Nobody ever mentioned lack of vacuum as a contributor to NO BRAKES. Everyone just mentions that it make a hard pedal. Well, my pedal isn't hard, it just goes to the floor.

My apologies to Scarebird. I'm sure a factory cam would give you a good brake pedal.