rear brakes

TIMINATOR

Active Member
IMHO disk brakes stop well, but have less holding power. Footbrake stall and launch boost drop. It does make burnouts easier without a line lock though. But then again with less spool, stall, and boost you wouldn't need as much traction anyway!
The opposite of this is using S-10 larger rear wheel cylinders to increase rear brake bias and holding power to raise footbrake stall and launch boost with your stock brakes. Soft linings, along with lengthened shoe area helps a bunch too.
This is one more reason that a bolt in 9" has another advantage that I haven't seen mentioned here, but I am a noob, just here, not in life or turbo cars. The ability to run any interchangeable wheel cylinder size from about 7/8" to I think, 1 3/16"!!!!!
Not to mention stock GN rear brakes are 10"× 2", and the most common, but still not the largest, ford car brakes are 11"× 2 1/4"! That raises the footbrake stall and launch boost quite a bit, and allows for higher boost/ spool street launches with a tighter convertor.
The other deal is with the taller 9" housing, the upper control arm mounts are raised in relation to axle center line, that reduces the traction killing "squat on launch" characteristic that you have to add stiff shocks and airbags to counteract. On my H.P. g bodies, old chevelles, and ford cars, I lower the upper front control arm mounts with several holes from 1 1/4" to 2 1/2" lower to allow for instant center changes.
Whenever I have time to have Chuck walk me thru pic uploading, I will post before and after launch pics. Until then, think about my 1972 Big Block Chevelle street car running high 9s in 1990, on 295/50 street tires (garbage compared to today's tires) with the front wheels up a foot!
TIMINATOR
 

hensleyt

Well-Known Member
IMHO disk brakes stop well, but have less holding power. Footbrake stall and launch boost drop. It does make burnouts easier without a line lock though. But then again with less spool, stall, and boost you wouldn't need as much traction anyway!
The opposite of this is using S-10 larger rear wheel cylinders to increase rear brake bias and holding power to raise footbrake stall and launch boost with your stock brakes. Soft linings, along with lengthened shoe area helps a bunch too.
This is one more reason that a bolt in 9" has another advantage that I haven't seen mentioned here, but I am a noob, just here, not in life or turbo cars. The ability to run any interchangeable wheel cylinder size from about 7/8" to I think, 1 3/16"!!!!!
Not to mention stock GN rear brakes are 10"× 2", and the most common, but still not the largest, ford car brakes are 11"× 2 1/4"! That raises the footbrake stall and launch boost quite a bit, and allows for higher boost/ spool street launches with a tighter convertor.
The other deal is with the taller 9" housing, the upper control arm mounts are raised in relation to axle center line, that reduces the traction killing "squat on launch" characteristic that you have to add stiff shocks and airbags to counteract. On my H.P. g bodies, old chevelles, and ford cars, I lower the upper front control arm mounts with several holes from 1 1/4" to 2 1/2" lower to allow for instant center changes.
Whenever I have time to have Chuck walk me thru pic uploading, I will post before and after launch pics. Until then, think about my 1972 Big Block Chevelle street car running high 9s in 1990, on 295/50 street tires (garbage compared to today's tires) with the front wheels up a foot!
TIMINATOR
I do agree about drum for drag racing and a sham we don't have a bigger back brake, but the S10 wheel cylinder is big enough to get you in trouble with brake balance front to rear
80 TA WS6 is a 8.5 the backing plate bolt pattern I have no clue. My old Turbo 80 TA I could drive through the back brakes with all 200 hp it had.
I can hold 20 psi with my S10 wheel cylinder 4 primary shoes.
If I was to stop drag racing my car and drive it more often I might look to doing a 4 wheel disc brake setup.
 

TIMINATOR

Active Member
I do agree about drum for drag racing and a sham we don't have a bigger back brake, but the S10 wheel cylinder is big enough to get you in trouble with brake balance front to rear
80 TA WS6 is a 8.5 the backing plate bolt pattern I have no clue. My old Turbo 80 TA I could drive through the back brakes with all 200 hp it had.
I can hold 20 psi with my S10 wheel cylinder 4 primary shoes.
If I was to stop drag racing my car and drive it more often I might look to doing a 4 wheel disc brake setup.
I'm doing this my way because I will be driving mine extensively in the mountains surrounding Phoenix,AZ on the weekends. I am also lowering it and doing handling mods too for the same reason. I have run a bunch of high 8, 9, and 10 second street/strip cars before (all had stalls from 3000 to 4500), but I don't have any Vettes anymore for the mountains, so this is the hi perf cruiser..
TIMINATOR
 

TIMINATOR

Active Member
I have decided that I may need to add bigger disc's on the front to keep the bias in check. I really hate to do that since one of my employees has added front disc's to his hotrod 55 chebbie, then since that company went out of business, he had a different brand of rear disc's, as recommended by a "reliable, old school" company installed, had more problems than he had before, now has spent almost $3000.00 on another complete kit from someone else, including, not included parts and machine work to make his "bolt on" kit, actually bolt on.
In about two years, he has replaced 3 vacuum pumps, and has just ordered a 4th, since the car has a ROCK HARD pedal and will BARELY stop without the pump. I convinced him to install two Cadillac/Delco pumps, next to each other, in case of failure he can plug in the new one and swap over the hose. He is a small old guy, and I am not, so I think I will play with rear cylinder sizes to try and make my bolt in 9" deal work.
TIMINATOR
 

Chuck Leeper

Toxic old bastard
Staff member
My 55 has the C4 13" fts and Ford 8.8 rear with the 11+" discs.
We've done several of these combos, all without the booster.
We use either the Wilwood 7/8" or 15/16" mc and a Wilwood adj prop valve.
I have also done 2 HB units, and a couple of the elec units on various cars. Both worked well.
The HB on my last 55 worked so well, that during a panic stop, my dog ended up with a brown ring around his neck....
 

TurboTGuy

Gray Beard Member
I have S10 cylinders, use a primary shoe (the larger of the two in the box) for both and aluminum drums.

I haven't pushed thru the brakes doing 6-7lb launches yet. I know some of you guys launch way higher, but that's where I'm comfortable.

I already sheared one ring and pinion. Don't want to do that again. Differential oil stinks!
 
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