Don Terrill’s Speed-Talk

Hi.
just a question of curriosity what happens if you enlarge rear slave cyl on the brakes?
lets say its one inch.. and you step it up to 1 1/8.
for discussion sake rest of system stays the same.
thanks
chevyfreak.

You loose some pressure when going larger, what are you trying to accomplish?

Gov

Hi. Its not me its my one buddy. He fitting a 12bolt diff into one of his cars and the slaves are totally ruined. He's got a set slaves he wants to use but its 1/8 bigger in the pistons.
i was thinking there was gonna be a bit of less pressure on the pedal but wasnt sure if someting else was gonna happen. System has no power assist and drums in front as well,
thanks for reply.
chevyfreak.

You mean the rear wheel Cyl, not the slave or master cyl. If you are talking axle wheel cyl larger then pressure should not change much.

I re-read your post and realized your term was a little different than what I was used to, LOL

Gov

Hi , im from south africa and the 'lingo' here is way different than anywhere else, sorry for the misunderstanding caused. If i start talking the american way of headers ,oil pans and stuff the petrol heads here think im weird,lol.
Thanks for the help.
chevyfreak.

Some sprint car racers I know from United States who are from Michigan have made trips to race in your area the last few years, did you happen to attend
any of those races?

Gov

Give me a reality check if need be.

Doesn't the pressure coming from the master say the same? And, doesn't that pressure on a wheel cyl [slave] with more piston area result in MORE force on the shoes?

The PSI would not change from the master cyl, but I believe the pedal would stroke a little farther to fill the added sq inch of the larger wheel cyl.

I very sure the pressure at the wheel cyl would not change, but maybe someone who has more Hyd pressure knowledge will chime in here.

Gov

dave brode wrote:Give me a reality check if need be.

Doesn't the pressure coming from the master say the same? And, doesn't that pressure on a wheel cyl [slave] with more piston area result in MORE force on the shoes?

You are correct, with a bigger bore wheel cylinder and everything else remains the same size bore you will have more pressure/force on the shoes or more clamping on pads if it is a disc brake system.

Governor is also correct.

governor wrote:Some sprint car racers I know from United States who are from Michigan have made trips to race in your area the last few years, did you happen to attend
any of those races?

Gov

Hi yes i did , was an experience seeing how their setup on sprints against ours. And i know our top driver also went over to your side to race.
over here there are few things that screams like a sprint ,only other would be the rotaries.
Thanks to all the replies i will forward it to my buddy and will see what happens but i still think he should be fine with it.
thanks
chevyfreak.

You will have a little longer stroke on the pedal. The master cyclinder will still put out the same pressure. You will have more force on the shoes.

I bored out the rear slave cylinders on my road racer to increase the rear bias -all other things kept the same.

Olefud wrote:I bored out the rear slave cylinders on my road racer to increase the rear bias -all other things kept the same.

In effect its exactly what my friend is doing buzy now helping him fitting cylinders and new brake shoes and all. This is all on a pontiac parisienne. Which here in south africa came out with chevy drivetrain. 327 powerglide and 12bolt c clip diff 3.07 ratio. Its a big car so i dont think there will be any issues with locking up the rear wheels.
thanks for all the input guys.
chevyfreak.