Rear disk help or hurt building boost at the line?

[22lbChevelle]

I've done a search but for whatever reason I haven't found a straight answer on whether a rear disk swap such as from a 4th gen camaro would help or hurt building boost at the line.

 

[scot w.]

I've done a search but for whatever reason I haven't found a straight answer on whether a rear disk swap such as from a 4th gen camaro would help or hurt building boost at the line.

How much do you consider hurting? I can hold at least 5 lbs of boost at the line with my BAER disc brakes and street tires and cut 1.8 sixty times. I personally think any more boost than that at the line should be done with a trans brake.

 

[22lbChevelle]

Well I to some extent agree with your last statement but thats not really part of the question. 5psi is a decent number. I can currently build 8psi pretty quick with my drum brakes with barely any effort. I just want to make sure people haven't gone from holding 12psi with drum brakes to 2psi with a disk swap.

 

[forcefed3.8's]

Disc brakes will hold less than drums.

 

[bishir]

Also not all psi is the same.

 

[Hot Air]

I have rear discs and could not hold car on the line with vacuum booster. I switched back to hydroboost and have no problem at the line now! HOWEVER, vacuum worked fine everywhere else!
Conrad

 

[tbone87]

Mine held 15 lbs footbreak. Vacuum breaks with aluminum drums with my little 49 on a full radial tire

 

[nonosv6]

Mine held 15 lbs footbreak. Vacuum breaks with aluminum drums with my little 49 on a full radial tire

He is asking about disk brakes holding boost.

 

[nonosv6]

I have found that my rear 4th gen disk upgrade will not hold much boost but I also haven't messed with the prop valve should prob try an adjustable one at that. Or try and connect the parking brake and use that to build some boost.

 

[Slow91z]

Disc take more pressure so the stock proportioning valve needs to be gutted or removed to even get close to drums.

If someone was looking for maximum holding power think about this, one of the reasons why discs are better than drums is they don't lock up as easily, but if we are talking holding power we want them to be locked up.

Ps I can hold 8, sometimes 10 psi (depending on the heat in the brakes) with s10 wheel cylinders, long shoes, and manual brakes...many years ago on my last car with the power master and the same brake mods I could put it to the floor and hold whatever it could make.