Hey guys, I had a problem with brake overheating which was due to a caliper sticking. I rebuilt them and don't have the overheating problem, but the one side that was suspect still seems to be sticking a bit. The car is stored on a lift so I can spin the wheels and check for drag easily. The right side still feels like it's dragging. The left side is totally free. Any ideas on what would cause this? Should I get another kit for the caliper and take it all apart again? I completely cleaned the pistons and bores when I had it apart before. How about the caliper alignment .... would that 'cause some sticking? Maybe the drag when I'm turning the wheel on the lift is not really the caliper sticking and just "typical"? It seems like that wheel gets dirtier faster from brake dust than the other side which is why I do think something different is going on. New stainless brake lines also. Appreciate any input ... the old seals were all swelled up when I rebuilt the calipers a few months ago ... maybe the new seals are junk and started swelling up already. cheers
Interesting thread as I have the same problem exactly. My passenger rear caliper sticks (well, it's happened twice in two years). I now park the car in gear and avoid using the parking brake when possible. I also keep a rubber mallet with me as I was able to free the caliper with a few whacks. My brakes were completely replaced (new rotors, calipers, lines, pads, the works!) three years ago.
If the brake is grabbing the rotor, check rotor thickness and runout. Also, if the rotor has a lip edge and you changed pads, there may be an interference there. If you know the caliper is sticking, I recommend rebuilding and be sure to fully-clean and surface sand (1000+ grit) by hand all machined surfaces before installing the new parts. Be sure to clean/sand floating parts like sliding bolt holes, etc. Chase threads on the brake lines and look for rusting (water admittance). You know the drill...
Thanks everyone for the fast replies! Yes I'll give this a try for sure. The brake lines are probably 5 years old now ... stainless from Girodisc. Robz I'll knock off any lip that has formed on that side also. cheers! edit: It's the front right ... rebuilt the rears when I did the fronts and had no issues thus far.
Hi Im a new owner of just 2 weeks and am surprised to see this post. My mechanic warned me not to use the E-brake which doesnt work at all anyway.He didnt want to adjust them either and gave me a 4x4 block of wood which I thought was a joke.He has some nice porsche calipers and said a buddy is working on a brembo conversion,I will ask him about it today,he is installing the Retro-Air AC kit.
The usual culprit with those symptoms is the rubber flex hose going to the caliper. It can collapse and restrict the flow of fluid back from the caliper when you let off the brake, keeping pressure against the pads. It is embarassing at stop lights if the condition gets worse. I would start by pulling the pads out, making sure there is nothing keeping them from moving freely back and forth. If all is well there, then go to the flex hose and pull it and see if it is the problem. Since it is only affecting one side, seems highly unlikely that it has anything to do with the master cylinder. If your pads have a fair amount of wear, it would be wise to replace them now, particularly if the problem side has gotten hot. (Have you checked the front wheel for unusually high heat after driving a few miles? Be careful what you touch.) Putting new pads in will change the position of the pistons in the calipers, and will give you another shot at a cure. Good luck on it!
If the caliper seems to be sticking and the rotor is hard to turn, attach a hose to the bleeder valve and drop the other end into a container with some brake fluid in it. Open the bleeder valve. Does fluid run from the caliper to the container? If so, now try to turn the rotor. If it is easier to turn, this confirms that it's NOT the caliper. Most likely suspect is a bad flex hose. Disc brakes do not have "return springs" so when you release the brake pedal it's normal for the pads to rub slightly on the rotors ("kiss" the rotors as an old mechanic used to tell me). A bad flex hose will allow the pressure from the master cyl to apply the pads to the rotor for braking but it won't allow all the pressure to release from the caliper, thus holding the pads in a "partial braking" mode.
This makes excellent sense, especially if you have old flex hoses. Replacing them is a very quick fix. Personally, I have never experienced a loss of "brake off" in any of my cars...and all had flex lines somewhere in their systems. However, your "embarrassment" reveals the issue as pertinent here. Although caliper rebuild and a rotor check is still useful to you, a quick repmacement of all 4 of the flex lines (I used Goodrich and am satisfied) and a good, long, bleed until clear all around could fix the issue and give long life operation. BTW, luckdynes, I can't tell from your posts if your previous caliper work included new flex lines ("The brake lines are probably 5 years old now ... stainless from Girodisc" was that flex and or/hard line replacement?)....and, if you did this recently, well...back to square one then. Please let us know.
Popped the bleed screw open ... didn't change anything. The caliper that MIGHT be sticking does not seem like it's getting much hotter than the other side. As I stated in my original post, I just notice it dragging 'cause I'm able to turn the wheels by hand and check things since the car "sleeps" on a lift . The caliper WAS sticking which is what prompted a rebuild a few months ago. The rotor on that side definitely has more wear so in the name of science and understanding I'm going to swap the rotors and pads from the right to left. I'll take the lip off the corner off the rotor while I have it off too ... that's about all I could think would be causing any drag. If it still sticks I'll know something is going on with the caliper, even though I got real anal about cleaning the bores and pistons just a few months ago. The pistons are out quite a ways with the rotor wear and pad wear on that side also, but if everything is engineered and working correctly that shouldn't make them stick ... if they're poorly engineered (not enough bore area/length to really keep the piston straight) I can see that contributing to the problem but I'm assuming ATE got this right for a given pad, rotor spec . I tried manually pushing the pads back to completely free the wheel and it took a lot of force FWIW. The pistons were totally free when I rebuilt them so all I can think that would cause that is the lip on the rotor forcing the pads toward the center thus causing a bind on the retaining pins. Just removing the chamfer would test if this is what's going on but since I'm going to open the brake system I think I will go all the way and swap parts side to side. Hmm I could just knock the lip off by hand with a die grinder also to test that theory ... cheers edit: I never replaced the hard line but based on the bleed screw experiment don't think it's anything to do with that ...
I'm missing something here. You can't push the pads back on the rear calipers but they can be adjusted back using the adjustment screws. I would make sure that the hand brake lever is not hung up and then adjust the pad to rotor clearance using the adjustment screw. If it still hangs up then you would need to remove/rebuild the caliper.
Knocked the corner off the rotor in one area and rotated ... no difference. Took it apart ... uneven wear on the pads (edit: top to bottom ... not inside to outside with respect to the diameter) Pistons are orientated correctly. I had not been polishing the guide pins for the pads as suggested. I think the pads were hanging up on them. I gave them a good polish and coated them with dry lube. Years ago I think I use to put a bit of grease on them but stopped doing that thinking it was bad to have any grease so close to the pad ... I'll see how this dry lube holds up. cheers
That didn't do it. I'll take the caliper apart I guess. Should there be any taper on the seals? It didn't seem like there was much of one on these IIRC. cheers
If you can turn the wheel easily by hand then I don't think you have a problem. As was pointed out the fronts do not have a return mechanism. Taking your foot off the brake just reduces the hydraulic system pressure. The front pads float. If they scrap against the disk a little that's in not unusual. If the car rolls easily you should be fine.
yeah maybe I'm being hyper sensitive to it ..... The left side is just so nice and free in comparison. The right side is kinda grabbing right now. Yeah I can turn it, but on the driver's side it's like the pistons pulled back ever so slightly. Rotor run out and wheel bearing slop help "knock" the pads/pistons back just that little bit, but both of those are negligible. I thought the seal geometry helped with pulling the pistons back just a little? It sure seems like it on the left side. As I mentioned I didn't see a distinct inner lip or taper in the cross section of the seals ....
Yes. I had my car in the shop for some routine maintenance and had a look. The parking brake does not return to resting position when the brake handle is lowered.
Took the caliper apart. The seal is junk ... all swelled up and starting to rot. So much for this brand ... "made in USA since 1913" right on the box .... I honestly don't know anything about seal brands and didn't think I needed to but I guess it's like everything else nowadays. The real old ones I pulled out that had been in for almost 17 years of my ownership are less swollen. They also have none of the rot that these do. I guess I'll try Beck Arnley? These were Dorman. I was running Motul brake fluid that I had run for years with the old seals. Any other input on specific brands? These look like they were cut on a water jet or something. I have another size from them that are clearly molded ... the wrong size though. Oh well.
My mechanic hasnt a clue why theres so much bizness in that R/R caliper but he says they all drag.After some quality seat time I dont think there is any braking power in the rear at all.When you hit them hard the rear end stands up,a Porsche sits down.
It is real annoying to have **** show up in the parts bin...good work so far. I would try an OEM vendor.
Not the case with mine. In fact I feel more brake from the rears then the fronts. In fact I am thinking about installing an adjustable bias valve in the system.
"Not the case with mine. In fact I feel more brake from the rears then the fronts. In fact I am thinking about installing an adjustable bias valve in the system" It didn't need such a valve when it was new... Re dragging - under normal conditions, disc brakes drag. THey are not like drum brakes that had powerful springs to ensure they DIDN"T drag. Nothing pulls the brake pad away from the caliper and every caliper/pad can be slightly different as far as how much it drags. IOW, your right front may just exhibit a slight rubbing sound while the left front has noticeably more. Every time you apply/release the brake, the "rubbing" of each pad/caliper will change. After you roll down the road, they will all be equal in a few miles. As soon as you step on and release the brake, they will drag again. This process repeats itself constantly. If you were to drive the car for 5 miles and then pull over WITHOUT touching the brakes, lift the car and spin the wheels, you would find them to be essential the same - accounting, of course for the additional drag at the rear from the tranny. Now obviously if one caliper is causing the rotor to overheat or be nearly impossible to turn, there is a problem. But the fact that one wheel turns with less dragging than the other is just a matter of how much each individual pad "relaxed" from it's brakes-applied position.
None of these diagrams show any sort of spring return (my 328 has spring loading). Some possible actions: 1. adjust parking brake cable turnbuckle(s) to achieve symmetric tension; have someone operate parking brake and release while watching for slack (also wheel(s) #27 in top figure could be stuck) 2. replace parking brake cables 3. check that you got OEM rear caliper replacements (parts not compatable); parts 26-29 or the latch mechanism itself (bottom figure) may have something to do with the problem 4. remove, clean and lubricate handle mechanism 5. I can't tell if there is anything fluid-pressure related for parking mechanism itself; certainly, a sticking caliper would oppose parking brake return; your issue could be similar to luckydynes (bad seals), maybe flex lines. But, you did get new stuff, right? Apart from #3, I am pointing you to the actual parking brake system. Image Unavailable, Please Login Image Unavailable, Please Login
