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Discussion Starter · #1 ·
A week ago I redid my brakes. New z-rated performance friction pads, new calipers, rotors turned, cleaned out resevoir, bled new fluid all through lines, speed bleeders, wheel bearings, took out & cleaned abs sensor. It brakes fine under regular & hard breaking.. But under high speed breaking or emergency like hard breaking the abs seems to kick in a bit too early, & the abs only seems to be activating on the drivers side wheel.. When the abs engages the pedal gets soft & goes kinda close to the floor.. I think I remember before break job that whenever the abs engaged the pedal just got really stiff. Theres no leaks whatso ever from the bleeders, hoses, or master cyclinder. Fluid level is remaining the same.. I also measured the amount of fluid that the drivers side is spewing out on 4 pumps compared to the passenger side & both were the same. The car isn't pulling to either side except when the abs engages, but even then it BARELY goes to the left. I haven't taking the calipers off in the last week, wanted them to break in real good.. I really dont know what else to check. Could the brake pad(s) on the right side be defective in some way? Thats why I was leaving them on there for a week to see what they look like when I take them off to see if the material looks right. I can check the pads but if everything looks good with them I dont know what else to check.. ALL SUGGESTIONS WILL BE GREATLY APPRECIATED.

Thanks, Justin
'94 DGGM Caprice SS Wagon
 
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Discussion Starter · #2 ·
Others with more knowledge should speak up here, but whenever the ABS engages, you should feel the pedal shuddering. I don't think it should ever go soft and get close to the floor. I know it can be hard to get all of the air out of the ABS and it may be time for you to take this into a dealer (not something I would recommend lightly) and have them bleed the system with their equipment. I believe they have equipment that is specially made for bleeding the ABS. They can also scan for ABS codes, which is something I think a regular scanner, such as an Autoxray, cannot do. The FSM would probably be helpful to you here, if you can get your hands on one.
 
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Discussion Starter · #3 ·
I drove about 150 miles today to the beach on congested highway( stop & go). The pedal does get stiff & starts shuddering, but it only feels & sounds like the drivers side is engaging abs, pass side just rolls to a stop. It pulls more to the left with more brake pressure. I was trying to engage the abs on both wheels where there was alot of sand on the road & the pass side SEEMED to enage better. Then bled again once I returned home. Still no air bubbles what-so-ever. I'm not getting any abs or brake warning lights.. I have a fsm & have read through alot of stuff. A brake maodulating valve, selonid, & a motor rely? Can the dealership or brake chain do somekind of test on it without having to go through piece by piece charging hour by hour? Thanks, Justin
 
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Discussion Starter · #4 ·
If you've got the FSM, you know as much about this as I do (more, since you read it recently). Anybody else? I will say that it sounds like for some reason your driver side caliper is grabbing more than the passenger side, and maybe too much. If true, that would suggest to me that your ABS is fine, but one or the other of your calipers may be screwed up. Not what you want to hear if you just replaced them. Also, if you're still having a problem with the pedal getting soft and going to the floor, that sounds scary.
 
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Discussion Starter · #5 ·
I just took the calipers back apart.. Pads look fine although the outside pads on both sides dont look fully broken in yet, 2 weeks now? Both calipers are expanding & contracting fine.. Is there a difference between the pass & drivers side rotors?? I switched them during the install but didn't look like it'd make a difference.. Going to go measure the amount of fluid that comes outta each side again.. Any other ideas?? If a seal or something like that blew or whatever in the master cyclinder that wouldn't make a difference from side to side right??? Could either of the rear drums be affecting the front discs in some way? ???
 
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Discussion Starter · #6 ·
I don't think there's any difference between the rotors unless they're directional. Even then, I don't think switching them would cause the problems you're having. I would expect you're right about the master cylinder. Plus, it just doesn't sound like there's anything wrong with it. On the drums, I don't see how they could affect the discs, but I suppose they could be causing it to feel like a disc problem somehow (hard to imaging how they'd create the symptoms you've described, though. I only have two other thoughts for you. First, check the position of your ABS sensors. Maybe something got knocked around during the brake job. Second, while you have everything apart, I'd try flushing the brake lines separately from the calipers, just to make sure they are clear and flushing the calipers separately to make sure you didn't accidentally get any crud in them when bleeding the brakes the first time. I don't know if it's possible to back-flush the calipers, but you might give that a try if you can.
 
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Discussion Starter · #7 ·
Thanks for all the suggestions Erik.. Still trying to track it down. I was kinda surprised that the outside performance friction pads still have lowspots where there doesn't seem to be alot of metalic material, more-so on the pass side. The ABS senors are in place & tight. I actually used a graduated cylinder like measuring cup & both sides bled exactly the same amount of fluid. It does seem to get better the more I drive it, maybe it'll all go away once those pads have a uniform surface? Going to go & get my alignment checked later on in the week, but I had it checked about 4 months ago & they said it was right on. Thanks
 
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Discussion Starter · #8 ·
Maybe you should try sanding the pads to an even surface (fine sandpaper on a piece of plate glass) and see if that helps. It makes sense that if you're not getting the same amount of contact area between the rotors and the pads on both sides that you'd have differences in the braking force generated by each side (i.e., the brakes would pull).
 
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Discussion Starter · #9 ·
Your rear caliper slide pins are hung up, and the caliper is not floating properly.

Replace the pins and get new bolts that hold the pins to the calipers. When you reinstall, use a generous amount of caliper slider lube (and yes, it is sold as "caliper slider lube".....do NOT use generic grease here!) on the new sliders.
 
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Discussion Starter · #10 ·
Ed, you've been much help to me in the past.. I should have stated that I have a Caprice Wagon. I have rear drums, which I replaced the pads on also.. That heavy-duty 11" drum was a PITA to replace the pads on.. When I was done cleaning everything & put the drum back on it was pretty snug sliding the drum back on. I'll check the rear drums tomorrow to make sure all springs & so on are still attached. Dunno... Thanks again Ed for all your help.. Justin
 
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Discussion Starter · #11 ·
Well I think I found my problem.. After I checked the rear drums for unhooked springs & other nonsense I took the calipers back off to look at the pads.. When I first installed the pads I noticed that the outside pad on the passenger side wasn't even in its compositional make-up, while the pad on the drivers side looked as it should new.. But I figured that during the break in that it would get smoothed down. Well after 2 weeks of driving & the initial break in, it still wasn't nice & smooth (low spots). Since there was low spots on the drivers side I started sanding it down lightly & found that while sanding it it was actually making the craters (lowspots) worse & spreading it out more. So I stopped. Put it all back together, bled the lines for like the 7th time & took for a test drive.. Warmed the pads up a bit then started with the testing.. The car now pulls to the right with the front right wheel engaging the abs now; totally opposite from before.. So I guess when I sanded the drivers side when it made it worse, that it made the drivers side braking worse thus making the right side brake better.. I was really confused when it first happened, but a few seconds later it all made since. I dont understand how they're not smooth yet after the brake-in & the 2 weeks of driving. Should I stick with them for another 2 weeks & wear them in real good, or try to get a replacement that all pads look like new in box?? Thanks for your help Erik, I was thinking myself about sanding it down but didn't think it'd really do that much, but when you suggested it I thought that it was a great idea.. Thanks Again, Justin
 
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Discussion Starter · #12 ·
I'd get a new set of pads, because it sure sounds like they are the problem. Tell them the problems you've been having. They should give them to you for free (they can just send them back as defective). Why f!ck around for another two weeks?
 
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Discussion Starter · #13 ·
Also, it sounds like you still have some hung calipers (not floating correctly) in front.

Check those caliper slide pins and bushings carefully! It'd get expensive quick to keep ruining brake pads :D
 
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Discussion Starter · #14 ·
This isn't entirely related, but are you guys aware that the PF pads have a lifetime warranty? I definately don't have the receipt for my pads, but can I possibly get new pads by bringing the old ones in as proof that I own them? I have a set of EBC Greenstuff pads that I will put on next, but I wouldn't mind getting my free set of PF pads for future use.
 
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Discussion Starter · #15 ·
I called autozone tonight & they said I could bring my pads back in & exchange them. So again tomorrow before work I get to take the pads off, put my old pads back on, go up to autozone & exchange, come back home, put new pads on, take a shower, & on the way to work break'em in again. But I'm very thankful that I figured it out without having to go to the dealership & spend $$$$. Thanks alot everyone, Justin
 
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