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Stock boosters are about 9 to 10 inches in diameter and look like this
I would need some more space so I am looking for a 6 to 7 inch booster, that would bolt on to a C4. I did find some universal 7" boosters but they were not bolt on, they for example had four attachment bolts.
For my 92 6 speed I discovered the manual trans boosters are slightly smaller to clear the manual trans clutch slave, but only slightly. Not a couple inches.An automatic trans booster hits the slave.
I thought the ZR1 booster was a smaller diameter tandem design. Might be tough to find one though. Scratch that, the ZR1 booster has 4 bolts, so not a bolt-on.
Last edited by tequilaboy; 03-02-2024 at 05:16 PM.
If you also race your car around circuits it's slow and sluggish to react. My friend tried it and he had to take it off. Brake feel accuracy is also not good. I also tried completely without a booster, but slowing down hard from high speed I noticed I do need some boost.
Originally Posted by tequilaboy
ZR1 booster has 4 bolts, so not a bolt-on.
Also I would bet, it's not 7 inches or smaller.
Originally Posted by WVZR-1
Years ago I believe that someone mentioned a Holden/PBR that was used for RHD.
That looks a bit smaller than stock, true, also it has two attachment bolts and a loop type attachement for the pedal. However I think it's still clearly too big, looks like 8.5" or so. Actually, now I found information it is 8".
Did you change the master cylinder when you went boost-less ? ... Also need to change the pushrod position on the pedal to increase the leverage .
No I didn't. It's true that smaller bore mastercylinder, and longer distance pedal travel would also help with the power. Both are needed or the pedal will bottom out with big brake calipers. However increased leverage usually means the pedal moving more and the master less which is not good since then volume will then run out.
I now ordered one 7" booster with four bolts, since it was not available with two, I will modify the car so that fits and then we will see how the brakes feel.
I thought the ZR1 booster was a smaller diameter tandem design. Might be tough to find one though. Scratch that, the ZR1 booster has 4 bolts, so not a bolt-on.
But isn't the firewall 'dimpled' and the pedal support already drilled to accommodate it?
03-02-2024, 05:54 AM
Smaller diameter brake booster for a C4?
