View Full Version : master cylinder bore size.s10 rear disk swap.
bmx1112
03-11-2010, 06:14 PM
Im running power brakes on my 1980 camaro, the front brakes are stock calipers while i have changed the rear to a s10 disk setup, The front brake line with a T and the rear line running from the master to a adjustable prop valve. Anyone done this swap and can reccomend a mastercylinder to use. Rite now i have a 1 1/8 bore master from a disk disk 79 vette and the brake pedal is half way to the floor before it does anything. will switching to a 1inch bore help? any insite to this? Also the stock master from my car is also a 1 1/8 bore what is the difference between what the stock one and the corvette duel bail master does?
Skip Fix
03-12-2010, 04:13 PM
Your stock 80 should have had a 1 1/8 to begin with also, if it has a residual pressure valve in the rear you can just remove it and re use that MC. They are under the flair fitting that seals the brake line.Looks like a press in brass fitting. The Vette might have a deeper recess for the rod and not be getting full travel.
Even the factory 4WD Trans Ams used a 1 1/8" MC. the 79-80s a iron and the 81s a quick take up aluminum. The aluminum has a larger OD register so it will not fit the earlier power boosters for the cast iron MC.
With that setup you should have a very firm brake pedal. You have air in the lines. When I swapped to rear disc on my car I had a heck of a time getting the rear bleed out. I opened up the front bleeders to get enough pedal travel to move fluid to the rear.
bmx1112
03-12-2010, 05:58 PM
Your stock 80 should have had a 1 1/8 to begin with also, if it has a residual pressure valve in the rear you can just remove it and re use that MC. They are under the flair fitting that seals the brake line.Looks like a press in brass fitting. The Vette might have a deeper recess for the rod and not be getting full travel.
Even the factory 4WD Trans Ams used a 1 1/8" MC. the 79-80s a iron and the 81s a quick take up aluminum. The aluminum has a larger OD register so it will not fit the earlier power boosters for the cast iron MC.
on the vette master i put in it looks like there is a brass fitting to seal the lines. is that what your talking about? the stock master i took out doesnt have that.
bmx1112
03-12-2010, 06:00 PM
With that setup you should have a very firm brake pedal. You have air in the lines. When I swapped to rear disc on my car I had a heck of a time getting the rear bleed out. I opened up the front bleeders to get enough pedal travel to move fluid to the rear.
i have bled and bled some more,there is a firm pedal then when you bleed the front the firm pedal disapears, when you bleed the rear again without touching the front the pedal gets harder again. its baffeling me.
opnwide
12-23-2010, 06:06 PM
Anything new with this problem? I"m having the same problem. I put the s10 discs on the back of my '76 and can't get a hard pedal, even with a '79 master.
Skip Fix
12-28-2010, 03:39 PM
"on the vette master i put in it looks like there is a brass fitting to seal the lines. is that what your talking about? the stock master i took out doesnt have that."
Vette shouldn't have a residual pressure valve under the brass fitting as they were 4 WD since 1965.Could be some kind of insert to seal the flair.
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