HELP!!! Best test for stuck caliper?
 

My brakes were working just fine prior to me changing the pads and rotors. I have maybe 150mi on the new pads and rotors. Shortly after I noticed the wheel jerks to the right when I brake reasonably hard. Everything seems even and fine when I apply the brakes lightly.

I think I have stuck caliper but want to be absolutely sure, some are saying it could be thrust arm / tension strut / front control arm bushing or ball joint. I have already done the basic stuff: re-checking that all the hardware is torqued properly, rotors are straight and true, no pad material visible on rotors, inboard & outboard pads are sitting flush on the rotors, brake lines not kinked.

I would like to prove this out with a high degree of certainty before buying a replacement reman caliper and swapping it out. I am reading bad things about bleeding the brake system. These are all methods I have heard for determining stuck caliper - trying to determine what is the best:

Driving tests:

1) Temperature - compare by putting hand near each rotor on each side to see if one is hotter then the other. Perhaps use thermometer to be more scientific.

2) Rotor blueing - may occur on the rotor that is compensating for the other side with the seized caliper.

3) Dust - Clean wheels, more brake dust should accumulate on the good side.

4) Smell - stronger caliper is working harder may overheat and smell asbestos from brake pads

5) Steering wheel jerk/shudder/vibration (mine jerks to the right quickly upon hard braking then stops) - wheel should move to the stronger side and vehicle will also veer in this direction.

6) Measure rotor thickness with digial caliper and compare each rotor thickness (prob too close with low mileage). Try measuring at different points on rotor to see if even.

Other Tests:

QUESTION - can the piston seize in any position? Is it usually compressed (open or pads spread wider) or uncomressed (closed or pads spread narrower)????

7) Jack up front end - apply brakes to build up pressure then release and rotate each wheel.

QUESTION - Is it also worth trying to do this while keeping the pressure applied to the brake pedal? Either with a buddy putting his foot on it or with a brick or something?

8) Remove wheels and use c-clamp to compress the calipers. A seized caliper should not move from its stuck position. Also then apply pressure to brake pedal and see if they uncompress.

Lastly - being that i have only 150mi on the new rotors, is it likely they will be OK once i replace seized caliper or will I need to machine or replace the fronts (or possibly just the pass side if it warped?) I can't imagine they would be toast with such low mileage.

Any other suggestions? Thanks guys!!!!!

All of the symptoms you list for finding a stuck caliper are valid. To your question about which position a caliper would stick, usually they stick compressed (contacting the pad) and fail to retract. Test 7 should indicate if a caliper is sticking. Another thought, the caliper on the left may have an air bubble causing it not to compress properly, making the caliper on the right do all of the work. Good luck

How can I get an air bubble without opening the system?

Cool - it seemed like almost everyone I read about having this problem the caliper compressed where the pad is contacting the rotor. So it seems to me like that should cause that brake to be applied until the pad/rotor wears away enough. This is why most say they can smell the asbestos from the pads.

I wanted to correct myself in my question below #7. Applying the breaks while turning the wheel would not help because the good break would hold and you would not be able to turn the wheel on the other side. You could, however perhaps remove the caliper on the assumed good side and do this test.

Well looks like I won't have time to mess with this until the weekend. Anyway i should be able to figure out what's what.

You need to bleed the brakes.

Am i missing something? Is bleeding the brake system part of a standard brake job? It was not suggested in the DIY. Is this what BMW mechanics do? It's worth a try I guess. I am a little confused here... please explain. Does compressing the piston with the c-clamp introduce air bubbles? How did I get air bubbles!!!! Is this why the DIY suggested optiional step of opening the Master Cylinder Brake Resovier cap?!!!

I am just a little hesitant because I am reading horror stories about brake bleeding on the X5. Also I read somewhere that you need some sort of computer to do this to cycle the ABS unit but maybe that was just if you get air in the abs valve. I guess for normal bleeding air cannot enter the nipple on the caliper and you never let the fluid level go below the minimum level so any air bubbles are just pushed out?

Any tips or links to procedures for this? I really don't want to f it up worse :) Is this something I should not attempt myself and just take it to an indy mechanic?

Someone please set the record straight on bleeding and if it is needed in my situation...

You should take it to a shop and let them fix it. Tell them what you have done so far, and let them take it from there.

Whereas your brakes may benefit from bleeding, you should not do it IMO.

I should not do it because it's a bitch on this car or i am not qualified or what? I need to do it on my Z since I am installing a BBK, no one seems to mention anything about it being difficult to do on that vehicle? Aren't they all the same!!!

1) Start Car
2) Enter Freeway
3) Drive for a bit
If its smoking and shuddering, its hung. If not, its fine ;)
JK, don't do this. It happened to me once, I think that if you really had a stuck caliper, you'd really know it.

Yea - I agree with you and the vehicle is NOT exhibiting smoking/shuddering behavour. IN FACT steering wheel is perfectly straight and normal and ride is smoothe. No noise coming from brakes, no burning smell, no smoking. WTF. Not sure how likely a candidate for seizure a caliper with 69Kmi is on it either.

I agree with you 100% that I would really know i have a stuck caliper too lol. This still doesn't explain why the hell my steering wheel jerks to the right upon applying a decent amount of brake pressure.

Enough speculation. I will do the damn tests. It may very well be the stupid bushings. UGH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!

My suggestion to take it to a shop was based on your diagnostic skills (no slam, just noticing) and the fact that brakes are a safety item. Bleeding brakes is fairly straightforward, but not if you haven't done it before. Yes, you can get air in the bleed nipple, just let the pedal rise while the bleeder is open. The X5 has some complexity to the brake system due to the ABS module, which can trap and hold air bubbles. Thus, all cars are not the same. If you get air in the system, and it gets into the ABS module, you may not be able to repair it without taking it to a shop that has a BMW computer to cycle the ABS controller. $$$$.

Your other question was about a vehicle with low miles having a stuck caliper. The failure of a caliper isn't related to miles, it is related to time, and more specifically, not changing the brake fluid every two years. That lets water collect in the system, it goes to the low point (the caliper), and corrodes around the piston. When you push the piston back while changing pads, the piston can can hang up on the corroded area.

All that said, I don't think you have a caliper problem, I think you have a suspension problem. That is because of the problem description, but it is just a judgement call without more info.

I'm having similar issues. I just did a brake job and after doing so I noticed that when I get up to around 80 mph and start applying brakes hard it will shudder but then it clears up if i apply more.
It doesn't happen much at inital application only when i apply it harder.

I tried slamming the brakes a couple of times to see if it was build up on the rotor from the pads and it seemed to have lessened the shuddering affect.

I was thinking this is more of a pad and maybe some warping of the rotor or material stuck.

I'm using EBC Red and Brembo slotted. I don't see any blueing on any of the rotors and the car drives without shudder or vibration until i perform this around 80 mph.

I also happened to notice this after swapping to my style 87's so I'm not sure if there's some wheel imbalance in the equation as well..

Please keep us posted on your findings!

You are right. I am jumping to conclusions and speculating too much without a proper diagnosis. It only seems like it would be the brakes since i just changed them. It may very well be a suspension problem. I just wish there was a more conclusive test to verify the operation of the calipers so that I could certifiably rule them out.

I am very systematic about the way I do things lol. I can't help it I am a programmer so I try to think about all the possible things it could be :) It's just killing me because I won't have time to take a look at it until this weekend.

I will heed your advice and if the problem doesn't become obvious I will discuss it with my local indy mechanic. If the caliper need replacing or the system otherwise needs to be bled I will let them handle it. Don't want to make matters worse.

So I am not the only one with phantom brake problems haha. Good to know that I am not alone. I really need to dink around with it a bit and do the tests. I'll keep you updated on what i find if you promise to do the same.

I too still think that it may be possible that mine are just not bedded in yet. I'm afraid to do the bedding procedure again though if i really do have a stuck caliper. I feel that might just make things worse, who knows maybe it will straighten it out.

Could be anything mentioned in this thread so far:

- Stuck Caliper
- Air bubble in system
- Bad suspension part (i.e. thrust arm bushing, etc...)

Is yours a shudder or jerk? One thing I can say is that mine jerks at almost any speed but only if I apply a good amount of brake pressue. It is hower I beleive more pronouned at higher speeds. Its just one quick jerk and then that's it. I didn't really notice if the car veered but then again the first time it happened i was startled and grabbed the wheel.

I should do a slow breaking test to see if it veers.

I talked to my buddy about brake bleeding who may help me out and this is what he said:
What do you think?

He also added:

So screw it, if it comes down to it I will attempt this myself. Can't be that hard. If I can change my fuel rails and injectors, replace cv boots, do coolant flushes this can't be THAT hard. I need some practice for my other car anyway.

What's the worst that can happen? If i F it up i have AAA.

I agree with your mechanic's comments.

I don't think it is a stuck caliper only because if it was stuck it wouldn't unstick so regularly.

First, resolve the sticking caliper concern. This isn't anything specific to the X5, more just a general procedure. Keep the wheels on. Get someone to sit in the driver's seat. Jack up the car, both sides. Use jackstands. Make sure the wheels spin freely. Have someone apply the brakes slowly, until one wheel is dragging. Freeze the pedal there. Spin the other side and see if the drag is similar. Now do it in reverse, starting on the other side of the car. Push the brake on hard, and make sure both wheels lock up. Release the brake pedal, and make sure both wheels spin freely. End of test.

If that doesn't point to a problem, move to bleeding. First lesson is to always keep the reserve topped up. Check it regularly during the bleeding process. You want to avoid getting air in the system.

Work on one wheel at a time. I would use a hose from the bleeder nipple and a clean pop bottle with several inches of brake fluid in it, with the hose end below the fluid level, but you can do it without that if you open and close the bleeder with every stroke of the brake pedal. Have a cooperative, attentive, helper in the driver seat. Call out your request for pedal up, pedal down, etc, and have them confirm each pedal stroke. It is slow and boring, but attention to detail pays off.

After all this, test drive the car. Make sure it is all buttoned back up, the brake reservoir cap is on, etc. Test the brakes before getting to the street. Once you determine everything is working, test them with a slow application, a hard application, and a so on. Bed them in if you like, but bedding in won't have much to do with your clunk, just with brake pedal feel.

Hope all that helps. I admire your determination. You do want to make sure that you don't let air get in the ABS controller. If you do, no handheld checker will help you, save your money. You would actually need the BMW computer that actively cycles the ABS valves to purge the air, you are not just clearing codes out to resolve that problem. Last price I saw posted on here was in the order of $500 to fix that problem, IIRC.

Good luck, and let us know how it works out.

Jeff

Thanks JCL - I really appreciate the additional advice. I actually haven't talked to the mechanic yet this guy is just a friend who wrenches.

I have learned from prior mistakes that it pays to do your homework :) I think it probably isn't a stuck caliper either. As for how an air bubble could have been introduced I have no idea either.

I need to look at the service records to see the last time the brakes were bled. I have had the car for almost a year and a half and I know that I haven't done it. I beleive the service intervals call for bleeding every 2 years. So it sounds like they need to bled one way or another.

Your procedure for checking for a stuck caliper sounds like the best one so far. Couple questions though:

0) Should I do this with the car started or at least with the key on?

1) If caliper grips the rotor on one side, even if the other side is not gripping completely - won't that still prevent the other side from turning? I know without engaging the brakes when I turn one wheel the other side turns as well. Aren't the hubs linked via the diff on AWD, or are they independant? Or are you just saying to compare the drag with the brakes applied lightly to see if the wheels turn with the same resistance?

I have noted your bleeding instructions. So if I get the kit with the little bottle just use the apparatus except with a clean coke can instead of the little shot glass bottle? Are you suppsoed to put a little fluid in the can with the hose submerged before you start bleeding?

What you say about the diag unit makes sense. I get the fact that if air gets in the ABS valve that a specialized BMW service computer is required to cycle the valve to purge the air out.

Again - thanks for the tips. You da man!

Engine off.

No regular bleeding required. The brake fluid is to be changed every 2 years, and that involves bleeding, but if you didn't change the fluid no bleeding would be required.

Correct, you are just comparing the drag.

Use a clean glass bottle, or the bottle that comes in the kit. You have to have the free end of the hose submerged in brake fluid.

Makes sense. I guess the idea is to change the fluid by forcing out exsiting fluid in each segment "run" to each of the calipers which in turn shoild expell any trapped air bubbles that might be in there. So by attaching a hose to the end of the bleeder nipple and submerging the other end in the fluid within the bottle itself this should prevent or greatly reduce the likelihood of air coming back into the line via the bleeder nipple? What about the air in the kit hose between the bleeder nipple and the and fluid in the bottle when you first start bleeding?

As far as the bottle that comes with the kit. Since it is so small, when you need to dump it's contents - I assume you just close the bleeder valve on the current caliper you are working on and then repeat the process, correct? It sounds like the glass soda bottle would prob do it in one shot.

Brake fluid reservoir should be open during this entire procedure to monitor it's level and add more fluid as necessary right? Never let it go below the MIN level right? How many pumps can you typically safely go before needing to add more?

What is the best brake fluid to use and how much will I need? BMW? Motul? What do you reccomend? I have 3 bottles of AP Racing brake/clutch fluid. Does it really matter?

Could my problem then be just that I have old brake fluid in the system? Is it more susceptable to getting air bubbles?

If you are using the bleeding kit with the bottle do you absolutely need to have an assistant? Just to make sure:

After hooking up bleeding kit to caliper bleeder nipple and opening the caliper bleeder valve:

1) Push pedal all the way down
2) Release pedal so it is all the way up.
3) Repeat until bottle is full, ? number of times

So you are saying with the bottle you can leave the bleeder valve open until you fill the bottle instead of opening and closing it with each stroke of the pedal? Is this the main benefit of the bottle - to speed up the process or does it also reduce the risk of introducing air into the system as well?

Lastly, like my friend suggested how important is it to have the bleeder bottle above the caliper?

Is this procedure similar for the clutch in my manual transmission car? Should it too be changed every 2 years?

I sat in on the installation of my street clutch and I remember assisting the mechanic by pumping the clutch pedal. I don't recall him adding fluid tho, just release air pressure via some valve in the engine compartment...

Sorry for the barage of questions, they just keep coming to me lol.

I should have just looked at the home page:

http://www.xoutpost.com/articles/x5/b...flush-diy.html

Im may just get the motive universal power bleeder since It seems easy and I can use it on my bmw and nissan. Also supports one man operation.

Is it OK to use this AP Racing Formula DOT 5.1 fluid? Says it mixes safely with DOT 3, DOT 4, DOT 5.1 fluids.

I think I want to upgrade to Motu RBF 600 Full Synthetic for my Z anyway.

DIY Says to USE ATE DOT 4 (OEM) fluid. It says 1L for full 4 caliper flush. So even if I end up having to replace a caliper after doing 1 flush I should have enough.

I checked the service records I had. 3 brake services in there for pads and rotors front and rear with sensors. NO mention of changing the brake fluid anywhere.

I don't think I have the service records during the warranty period when the car was taken to the BMW dealership. Perhaps they did a brake bleed but that means 2003-2004 may have been the last time it was done - IF EVER.

I shook the front wheels at 3 and 9 o'clock to test for play in the suspension as prescribed in my original thread. Everything seem fine, thought the pass side wheel seemed to have a tiny bit more play. I do notice some squeaking sounds when drive the passenger side over speed bumps. I don' think the driver side is doing this.

Also checked fluid level in reservoir is good. Looks like a sensor should come on anyway if it were low since there is some sort of wiring apparatus hooked up to the level mechanism.

I am going to do the drag test now and then try retracting the pads on each side with the c-clamp to see if they contract when I hit the pedal.

It's probably a good idea to do the brake bleed anyway. I think I will be ordering the Motive Power Bleeder on monday and doing a full flush using the AP Racing Forumla DOT 5.1 brake fluid I have laying around.

I'm really starting to think that a flush will indeed solve my problems. I randomly found this post on acuraworld by x5world's very own hayaku (who also wrote the brake flush DIY). It sounds almost exactly like the issue I am experiencing.

I am ordering the Motive Power Bleeder tomorrow. I just need to confirm with them that an extra adapter I am buying will fit my 300ZX.

DOT 5 needs to be changed every year. Unless the X5 is going to get tracked, use DOT 3 and change it every two years.

No plans on tracking, and I guess it's really pointless to use this good of stuff for OEM brakes. What can I go get in a store locally that's good without breaking (haha) the bank?

Is Dot 5 synthetic? Actually I heard someone saying it last longer than the DOT 3 stuf...

Will I get better brake performance on the street with DOT 5.1? It doesn't sound like the AP Formula stuff is synthetic. I don't want to waste this stuff if I won't benefit from it.

So will any DOT3 fluid do? Does it have to be this ATE stuff? Isn't it all the same really?

What about this?

talked to indy mechanic, he confirmed the next thing he would do is a brake bleed.

i did the caliper drag test by wedging a stick between the brake pedal and the seat then adjusting the seat forward. I tried applyinh various brake pressures and I didn't notice any difference when rotating either wheel. They both made scraping sounds on the rotors.

I dunno hopefully the bleeding does the trick.

Got a liter of the Valvoline Synthetic DOT 3/4 fluid, just need a turkey baster now and I am ready to flush :)

Well OK i completed the flush. Took longer to jack the car up on all fours almost than it took to flush. This power bleeder really is handy dandy, works like a charm. The shit that came out is definately tea/cola colored. It is some nasty stuff for sure. I was careful not to get it on the car but i did knock my catch bottle over. Good thing I have epoxy floor paint covering. I am too tired and lazy to put the wheels back on and put it on the ground to take it for a test drive tonight. Though I did push the brake pedal in a couple times and it feels really firm. More so than it was before. We'll see - I hope this did the trick. Let you all know tomorrow.

Bump..

Fix your issue?

Well I took it out today and test drove it a little. It doesn't seem as bad now but I still think there is some shudder. Actually seems like it goes to the left now.... WTF? Some of the roads i tested on weren't quite perfectly flat. So I want to try this on a stretch of nice even flat road. I also am contempating re-doing the bedding procedure.

I am puzzled. Maybe it just isn't broke in yet. There is no explanation for this that i see. I think I will test drive it again after i do the CV boot and if it's still messed up I will let the indy mechanic deal with it.

ne1?

OK I did another road test, did a bunch of laps in the church parking lot next store and on a newly paved stretch of straight road. Shudder is definately still present. I don't think it's as bad as before but hard to say.

I did the finger touch test. All 4 rotors were hot, especially the fronts. The driver side and passenger side both felt like they would burn my finger had i left it there longer than a split second. I tried to get scientific with my radio shack digital indoor/outdoor temperature guage. I hovered the probe inbetween each side of the rotors. Both sides hit 157 degress than the reading went to HH.H since It was too hot for the thing to read.

That being said. I guess I have a suspension problem. Go figure. Oh well brakes needed bleeding anyway and was good learning experience for me. I am debating on whether or not I am going to do the pass cv boot or not since its a pain in the ass. I might just let the indy handle it and ask them to take a look at the suspension while they are at it.

So I just came back from the dealer today and had a brake flush and my CV swapped due to a ripped boot.
And to my suprise my shudder is gone.

So I'm not quite sure if it was something related to the CV or the brake flush.
I'm leaning towards the brake flush.

Fluid doesn't shudder. Rotating components do.

Bet on the CV, not the brake fluid flush.

i still seems to be doing this very slightly, and also now i have notices a steering wheel vibration on the highway. Another thing is a thud sound on the driver side when i enter driveways and stuff. I took it back to the shop they are shaking it down.

Bushings are still dead on center. We'll see they thing it could be one of the ball joints or tie rod or something...

did you get the whole axle replaced or just replace the cv boot?? if it's just the boot, I don't think the new brake fluid and the cv boot would fix the shudder. I guess maybe some suspension components were out of torque spec and getting loose a bit. in the process of putting things back on, your mechanic torque everything to spec. so, the problem is fixed.

Well when they installed the bushings recently everything should have been torqued properly by them. So my guess is I have some other bad suspension component. I should know shortly.

I had the axle replaced instead of just replacing the boot.
Extended warranty covered the entire job except for my $50 deductible.

I don't think they take off the rotor when they swap the axle, they just slip the caliper off and so they can drop the spindle. So the only thing that could have been torqued out of speck was the caliper bolts

Then I would guess the shudder was from bad CV joint. But glad you got it fixed for just $50. If you're paying it out of your pocket, it's probably $1K something. Did the warranty also cover the alignment? I assumed they also performed an alignment after the axle replaced, right?

Didn't see anything about an alignment in the work order.
Car tracks perfectly straight

BUMP an old thread, OP did you confirm your problem? Its been alllong time. thnx