I did the LS1 brake conversion about a week ago and under normal braking it stops fine and doesn't pull. But when I get on the brakes hard, the passenger side front will lock. What would cause this? I would think that both should lock at the same time. The pedal is nice and firm, but would improper bleeding of the lines cause this to happen? I just need a point in the right direction before I start pulling things apart again...

 

were the discs new? did you change the rubber hoses?

 

Oh yeah, forgot to mention It's new everything. Pads, rotors, calipers, and stainless lines.

 

what about the proportioning valve, are you using the correct one?

the only thing I can think off is maybe debris in the caliper or hose..

 

It's the proportioning valve for PBR rear discs. You're not supposed to use a different one if you swap in LS1 fronts, are you?

 

I have drum rear, LS1 fronts, with the stock prop valve... Got it all from EbMiller on here works great.

 

If the caliper is OK, then I would tend toward a pressure difference between the two sides. Look at the hard lines for a dent or slight crimp in the line.

If the lines are OK then I'd go back to the calipers. Many years ago I had the same issue with a car. Normal to medium braking was great. Under heavy braking the left front wanted to lock and even made the car pull heavy to that side.

Found the piston seal in that caliper had folded over for about an inch of length. This was due to improper assembly of the caliper. What I mean by folded over, is that a portion of the seal had twisted 90*, then about a inch further along the seal then un-twisted 90* back to the correct orientation.

Note that the seals are a square cross section o-ring.

I was surprised that it never leaked.

RBob.

 

-Update-

I ended up re-bleeding the lines and now everything works as it should.