New brake mods

[turbofabricator]

I just finished installing a manual master cylinder from a S-10 truck. It is a bolt-on deal. I did fabricate a new push rod out of 1/2" stock. (Although, I figure you can get one from a Bone-Yard) I made it adjustable to set it up and then welded it after the final adjustment. I also swapped the brake lines so the rear brakes run off the primary side and won't bleed down on the starting line. (NHRA Stock Eliminator guys do this ) I then removed the combination valve on the frame rail and used an adjustable one from Wilwood, up top, where I can get to it easily. I also installed the line lock and used the stock brake warning light to illuminate when the line lock is triggered. When I was testing the brakes out on Friday (before the test and tune session that would be the maiden voyage of the 'Alcoholic Twins') I popped the right rear wheel cylinder and almost became a permanant fixture in the garage wall So, I also replaced the wheel cylinders with the trusty S-10 manual ones. Needless to say, I didn't make it to the track. I'll have to wait until the BOP (Buick-Olds-Pontiac) race this week-end in Bremerton, Wa. Now, All I have to do is pressure bleed them and give it a test drive. So here's a list of the parts that I used on the Twin Turbo T-Type brake modification:
1984 Chevy S-10 manual master cylinder
1984 chevy S-10 rear wheel cylinders-manual brakes
Wilwood 4 piston front brakes
wilwood adjustable porportioning valve
braided -3 front and -4 rear brake hoses
TCI Roll-Control
various store bought and custom fittings
stock powermaster firewall adaptor
custom grade '8' 1/2" pushrod
swapped brake lines on the master cylinder

 

[Grandnat]

Good info thanks.

I might be doing this on my stage car and might be emailing you for more info.

 

[Scott Atk]

Have you driven it yet?? How's the performance? pedal feel?? Thanks, Scott

 

[Quiky One]

Good info there.

Thanks Jason

 

[turbofabricator]

I drove it last night and even let Geno drive it to see if he liked the brake mods. (he'll be converting his car soon ) They hold 2 lbs of boost no problem in Gene's GRAVEL parking lot The pedal is VERY firm and does require more leg pressure, but they are VERY controlable and predictable. If you mainly cuize your car or race it I would HIGHLY recommend the manual conversion especially with the Wilwood front discs and S-10 rear cylinders. I also removed the aluminum drums and installed new iron drums for more strength. I should have done this YEARS ago. It took a little research to figure out what parts I needed, but by using factory engineered parts I feel confident in the performance and reliability of the system.

 

[S2V6RACER]

How much for the S-10 cylinder vs. the Strange cylinder?

 

[turbofabricator]

The manual S-10 master cylinder was $30 for a re-built one (Cardone 10-1905) and it is a bolt on deal. The Powermaster firewall adaptor bracket and pedal is what's needed. You'll have to fab a push rod, although the factory S-10 push rod should work, but I don't know for sure. The rear brakes should hold just about anything I can put to them (until backing plate fails, or drum explodes )

 

[Scott Atk]

Thanks for the update Ken. Couple more questions. Do you see any reason why this wouldn't work with the factory prop. (combination) valve? Also, you mentioned that you need to reuse parts off the powermaster? That might be an issue for me since I'm currently running vacuum setup.

 

[turbofabricator]

The factory combination valve should work fine, BUT altering the factory brakes MUST be performed by a certified brake mechanic, and not for highway use. That disclaimer being stated, the adaptor bracket (firewall to PM) is needed or you can fab a new one. There are a ton of them floating around in the Buick community, though. The stock powermaster (PM) pedal will be needed, as the pivot point is different than on the vacuum pedal assy. You could (for off highway use) redrill the pedal assy for a higher pivot point. The pedal that came off my T-Type had a new hole drilled in it for the vacuum brake conversion that came on the car when I bought it. I can't stress enough that ANY brake modification must be performed by someone VERY familiar with brake function and design. I have seen some REAL scary things done by back yard mechanics in regaurds to brakes. I would definatly error on the side of OVERKILL when it comes to brakes. The Powermaster system is scary at best, and about 17 years ago I almost had a serious accident when the PM failed! The dealership was ZERO help and that's when I went to vacuum on my first GN. I prefere manual brakes on a race car, and had the time to science out the system. It works GREAT on my car and application, but it may not be right for everyone. If you do attempt to perform the mods., make sure you use a good quality flairing tool and test the tool out on scrap tubing BEFORE you cut your system apart. You won't need to modify brake lines if you don't install line-lock and an adjustable porportioning valve. The manual S-10 master cylinder is a bolt-on deal. You will probably need to fabricate a new push rod, which requires a torch to heat a 1/2" rod red hot to hammer flat on one end and a drill to drill it out for the pedal pin. The stock S-10 push rod might work, but good luck trying to find one of those.

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

That pedal must be really stiff to push. That master is a "2 stage" piston. It has a large piston to push out a large volume fo fluid, and then goes into bypass at 100psi. It's o.k., if you can hold the car. In the 60's most fast cars had 4 speeds and drum brakes. Kick it out of gear, and lock up those drums. Not so with an automatic trans and disc brakes. Be very careful about the depth of the push rod hole. G.M standardized all their cars with power brakes in 1973. They eliminated the "deep" hole in the master piston, and made the push rod non adjustable. The purpose of the deep hole was to prevent the pedal rod from falling out when you release the pedal, or under acceleration. If the push rod falls out you know what will happen!!?? Total brake failure. That master does not have the deep hole for the push rod!

 

[turbofabricator]

That pedal must be really stiff to push. That master is a "2 stage" piston. It has a large piston to push out a large volume fo fluid, and then goes into bypass at 100psi. It's o.k., if you can hold the car. In the 60's most fast cars had 4 speeds and drum brakes. Kick it out of gear, and lock up those drums. Not so with an automatic trans and disc brakes. Be very careful about the depth of the push rod hole. G.M standardized all their cars with power brakes in 1973. They eliminated the "deep" hole in the master piston, and made the push rod non adjustable. The purpose of the deep hole was to prevent the pedal rod from falling out when you release the pedal, or under acceleration. If the push rod falls out you know what will happen!!?? Total brake failure. That master does not have the deep hole for the push rod!

Yes.....all true. I adjusted the rod, to be at the pedal stop. No way for the rod to drop out. (unless the piston freezes half way.) It already has a few thousand miles on this set-up. It works great! Not power brakes for sure, but not a big deal, at least not for me. I was VERY concerned about the recess depth, and had to use a slight pre-load on the rod. I also use Wilwood front brakes and S-10 wheel cylinders in the rear.
One mod I AM planning for the spring, is to install a Wilwood M/C. I didn't use one at the time, because I didn't know how the brakes would feel. It currently stops the car at 128 mph.NO problem.
I have ALOT of brake experience both OEM and aftemarket, so I wasn't concerned with the details. Posting your info was a great idea. For those considering this mod, read the above info CAREFULLY!