86 3800 4spd. Recently put on Grand Am brakes on all 4 corners, paired with a 93 S10 Blazer 4.3 master cylinder, and braided steel lines. The brakes are really quite nice and are a huge upgrade over stock, but for some reason when going over ~30 the pedal hits a wall about halfway down, after I slow down under 30 it'll go down the rest of the way and lock the front tires.... it almost feels like ABS which would be impossible so clearly something is wrong. Did I get the wrong master? Prop valve acting up? Both?
Keep in mind this is a dedicated track car at this point, so if I need to get an adjustable valve or something, I'm fine with that.
EDIT: Forgot to mention, but the brake warning light comes on the dash after the wall goes away and I can lock the tires. Turns off when I let off the pedal and doesn't come back until I brake heavy again. Fluid is full and new in the reservoir.
[This message has been edited by Additivewalnut (edited 10-07-2024).]
The M/C should be from a 2 wheel drive, not a 4 wheel drive.
I got it off rockauto from a 93 S10 Blazer 4.3, I didn't see any mention of 4wd or 2wd in the options.... did I mess up and choose a year that was 4x4 only or something?
When I did the GA brakes on my 86 years ago, I used one from a 1991 S10 Blazer 2WD. But, I only buy my parts locally, from knowledgeable countermen who have been doing their jobs for a long time. My experience with Rock Auto was not worth the hassle of wrong parts and returns, let alone the wait.
The Master cylinder was changed therefore if not matched correctly to the wheel cylinder capacities the braking may feel strange. I just keep My stock Fiero system in good shape and it seems to work OK, Never had a problem stopping even from 90-100 MPH.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
The Master cylinder was changed therefore if not matched correctly to the wheel cylinder capacities the braking may feel strange. I just keep My stock Fiero system in good shape and it seems to work OK, Never had a problem stopping even from 90-100 MPH.
I'd agree that changing the master may have messed something up if it weren't a tried and true upgrade on this car. Im just not sure what, if anything, I did wrong to cause the pedal to act like this.
I'd agree that changing the master may have messed something up if it weren't a tried and true upgrade on this car. Im just not sure what, if anything, I did wrong to cause the pedal to act like this.
nope not you. ran into this on a white gt a few days ago. actually threw out the stock master since it was leaking and had the same thing going on. so a big bore (fiero store but it's just an s10 one) went in for the LeBaron brake upgrade kits needed fluid volume but the issue is almost like the reservoirs are swapped. it hits the fronts first then the rears which might be correct but tends to have that dead wall and act funny sometimes. the brake light is triggering due to the proportioning valve recentering since it feels like it's having a leak in the fronts due to the massive fluid volume needed for the brake pad clearance. I bet if you look you can wiggle the fronts a bit and they won't be touching the rotor
nope not you. ran into this on a white gt a few days ago. actually threw out the stock master since it was leaking and had the same thing going on. so a big bore (fiero store but it's just an s10 one) went in for the LeBaron brake upgrade kits needed fluid volume but the issue is almost like the reservoirs are swapped. it hits the fronts first then the rears which might be correct but tends to have that dead wall and act funny sometimes. the brake light is triggering due to the proportioning valve recentering since it feels like it's having a leak in the fronts due to the massive fluid volume needed for the brake pad clearance. I bet if you look you can wiggle the fronts a bit and they won't be touching the rotor
yeah that sounds about right. So I guess go get an adjustable proportioning valve and see if that takes the wall away?
I've done several of the GA upgrades my with the proper M/C.
Never had an issue.
Be sure you actually have the correct M/C before trying to reinvent the wheel.
Don't trust an online vendor because you like the price. Buy local.
I can try another MC, but buying local isn't gonna be much better. I have my choice of Autozone and Oreillys around here, both of which hire the dumbest possible people.
I've done several of the GA upgrades my with the proper M/C.
Never had an issue.
Be sure you actually have the correct M/C before trying to reinvent the wheel.
Don't trust an online vendor because you like the price. Buy local.
before we blame the master how about we take the 3 seconds and make sure the calipers are actually taking up the dead space that they sometimes cannot for whatever reason. sometimes you need to check a few things before going and saying immediately the master is bad. also like cmon man. "I never had an issue" and part quality has literally plummeted within the past 6 months even worse than before. I've gotten so many bad mahle gaskets and out of the box broken MC and bad axle seals that's its getting concerning.
before we blame the master how about we take the 3 seconds and make sure the calipers are actually taking up the dead space that they sometimes cannot for whatever reason. sometimes you need to check a few things before going and saying immediately the master is bad. also like cmon man. "I never had an issue" and part quality has literally plummeted within the past 6 months even worse than before. I've gotten so many bad mahle gaskets and out of the box broken MC and bad axle seals that's its getting concerning.
If the caliper are able to wiggle around, does that mean bad master? I can't check them right this second but I'd like to know what to make of my eventual findings
If the caliper are able to wiggle around, does that mean bad master? I can't check them right this second but I'd like to know what to make of my eventual findings
could mean alot of things. I do know I and some of the other members on the club had trouble with the LeBaron kit we put on which was the fronts being a 1/16th of an inch from the rotor at all times. they just would not stay pit and moved very notchy. turns out the calipers were remanufactured incorrectly and were somehow retracting after every hard stop. we kinda gave up since no combination of master, prop valve or calipers would resolve the issue so it's just put on the back burner until then.
but if yours wiggle and tighten up right as your hitting that wall with the engine off (you need a friend for this present or a stick) then you are facing the same issue and pretty much need to remove the calipers let them extend out to basically having to hammer them onto the pads and the brakes will be much much better. the proportioning valve may also not like the amount of fluid needed for the fronts compared to rear but I'm not 100 percent on why brake upgrades are getting harder to do
Calipers shouldn't wiggle, they slide freely on the slide pins.
The pads should have minimal spacing off of the caliper, to the point it looks like they are touching.
i am very aware of what they are supposed to do Joe. just sharing a recent experience of what I was having an issue with since my brakes feel the same way and I found a few things wrong.
i am very aware of what they are supposed to do Joe. just sharing a recent experience of what I was having an issue with since my brakes feel the same way and I found a few things wrong.
With the Grand Am calipers I believe that you must cut the hubs from the Fiero rotor discs for the Grand Am rotors to fit. This leaves the rear where you will fit new calipers and you will lose the parking brake. That's the part that was unacceptable to myself as I always like a backup . As for the OP's setup it sounds like something was mismatched.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
With the Grand Am calipers I believe that you must cut the hubs from the Fiero rotor discs for the Grand Am rotors to fit. This leaves the rear where you will fit new calipers and you will lose the parking brake. That's the part that was unacceptable to myself as I always like a backup . As for the OP's setup it sounds like something was mismatched.
Benefits outweigh the negatives for me. I can actually buy brake pads and rotors at a local parts store, vented rotors, more clamping force. Parking brake isn't a huge deal for me since 1st gear exists. It's not like you'd be ripping the ebrake in an emergency anyway unless you wanted to make it worse LOL
Benefits outweigh the negatives for me. I can actually buy brake pads and rotors at a local parts store, vented rotors, more clamping force. Parking brake isn't a huge deal for me since 1st gear exists. It's not like you'd be ripping the ebrake in an emergency anyway unless you wanted to make it worse LOL
definitely got a lead on what part of the problem might be. it seems our fiero proportioning valves are getting old now and sticking in places they shouldn't. I just had to replace mine to get the brakes working well since it was just as you were describing
definitely got a lead on what part of the problem might be. it seems our fiero proportioning valves are getting old now and sticking in places they shouldn't. I just had to replace mine to get the brakes working well since it was just as you were describing
I was kinda thinking prop valve since the brake light comes on under heavy braking. Can you even find prop valves anymore? How hard are adjustable ones to install?
I was kinda thinking prop valve since the brake light comes on under heavy braking. Can you even find prop valves anymore? How hard are adjustable ones to install?
yes and no. you can use wilwoods ones. you can rebuild the stock fiero ones but it's starting to seem like we might be flowing too much volume with how bad reman parts are getting to keep it happy
yes and no. you can use wilwoods ones. you can rebuild the stock fiero ones but it's starting to seem like we might be flowing too much volume with how bad reman parts are getting to keep it happy
Only thing that sucks is that I'd have to make new lines to get everything to fit into a Wilwood unit. Probably worth doing though.
