To any and all,

My issue is that when I crank my steering wheel ALL the way over to the left or right (like backing into a parking spot or turning hard turns in a parking lot), my brake pedal depresses almost all the way down on the first attempt. After that initial attempt, the following 2/3 tries bring the pedal back to its original braking force like nothing happened (I can feel the pedal get more firm with those additional 2-3 pushes - almost like cadence braking).

Just curious as to why this would occur. To give some background, my car is:
-LS1 swapped 5.7L auto into 1989 Camaro
-LS1 swapped rotors/calipers on all 4 corners
-Just replaced power brake booster
-Stock 89 Master cylinder

I’ve had this issue since I had the car swapped over. Figured when I replaced brake booster that it would fix it but it didn’t. I’m assuming it’s the MC but just seeing if any of you guys have any other ideas. Going to replace the MC soon since it’s the only thing in the brake system that I haven’t replaced. But no leaks ever, brakes were always bled if any work was done... so just confused.

thanks!

 

Stupid question but is your ls1 cammed? Could be a insufficient vacuum especially at idle/low speed turning the wheel. Does the booster make any whooshing sounds when you first press the brake,is the vacuum line to the boost in good shape and makes a proper seal on the intake? If your not showing loss of fluid anywhere,I doubt the MC is at fault..though it wouldnt be a bad idea to replace for its age with a good quality unit. I dont think its MC though and lean towards the booster..even though its new. The only thing that does not add up is that the issue started after the swap. Recreating the situation and testing things should lead to the root problem. Turning the wheels slowly with a 2nd pair of eyes maybe might reveal something getting pinched,who knows.

 

Usually a bad master will result in a hard pedal, not a soft one.

 

Oh whoops! Sorry. Here I was thinking I was so detailed and forgot to mention that... the engine is cammed. Mild cam with stock converter.

Also, no problems at all with the brake booster or vacuum or even my MC really. My pedal has no swooshing sound. No leaks. No anything really. It’s practically perfect (except for this issue).

Honestly, I was just thinking that maybe it is what it is due to My cam at low vacuum at idle? Or maybe you’re right... maybe it is getting pinched somewhere? Out of curiosity, what would that be? Because even if it were brake lines, it wouldn’t cause my pedal to go all the way down right? Thanks for the reply guys.

 

My car did this after cutting off the steering stops for C6 Corvette brakes. It would happen after backing out of a parking spot (tight turn) and then I'd end up doing panic brake pedal pumping trying to stop at the parking lot exit.

I think it has something to do with the caliper slider pins getting pushed somehow. Never really took time to understand why, but I was warned about it when I bought the brakes. I probably should have cared a lot more (okay, it was pretty much idiotic to not care). Strangely it's never happened again since the last time I disassembled & reassembled the front suspension. I guess I'm still an idiot for not investigating.

 

If the act of locking the steering is somehow knocking the pads back then that would explain a dead pedal as it moves fluid back into the calipers and clamps down on the rotors.

I still am not sure how it would do it though. The calipers should float freely on the pins and be unaffected by steering angle. Unless there is some kind of play in the spindle bearing that's allowing the caliper to push outwards which forces the brake caliper pistons back. It doesn't take much for that to happen.

Its a common thing in Road Racing for the pads to 'knock back' and effectively push the brake pistons back into the caliper. So when you go to hit the brakes it drops to the floor.

https://nasaspeed.news/tech/brakes/p...o-do-about-it/

 

Thirdgen89GTA & QwkTrip,

Thanks for your responses! I honestly have no idea what a steering top is haha so I’ll have to look into that I guess. But if my car is doing that, I supposed I’d have to get under there while someone is turning the wheel to inspect for sure (which I will do soon).

I will say though, I did recently swap out my stock unpainted calipers with red powder coated ones and even though I disassembled that whole hub, issue still exists... so who knows! If I find out, I will let you guys know!

thanks a ton!

 

Change the MC. It's not hard, cheap, and will eliminate that as a source of trouble. In the failed MC's I've had, the pedal goes to the floor as the fluid leaks around the piston back up to the reservoir and very little stopping power.