We have a problem!

[mLuMaN83]

So I just had my front end stuff done, tie rods, bushings, all that. My problem still exists.

It does this on and off every few minutes while driving. It gets bad for a minute, then goes away a little, then comes back, then goes away. It will be ok for a few minutes, then it starts to bump bump bump bump. Bump in the steering wheel, car, everything. Bumping. When this bumping gets bad, and I hit the brakes, the car feels like it's floating and can pull to one side or the other. This is scary. It also tends to "hold back". It's like something is stuck and not allowing the car to roll freely. You can feel something "holding the car back". Almost like if the e-brake was on just slightly and you get the feel of something holding the free motion of the car back.

I'm freaking out.

I just dropped some good cash and turns out it's not the main problem. Could this be failed rear bushings? Anything specific? The car is parked once again.

[LivesNearCostco]

Did you have front control arm bushings done, and/or control arms replaced? Could it be sticky brake caliper? When is last time you bled the brakes?
Failed shocks could cause floaty feeling, but not normally bumppity-bump.

Failed FCABs can cause weird feelings or clunks on braking
Failed RTABs can cause rear end to behave weird under hard cornering, acceleration, or braking (because rear toe-in is changing)
Failed shocks can cause oscillations or floaty feeling

[mLuMaN83]

Control arms and bushings were also done. It's scary because it's a lot of things all at once. It will feel ok for a seconds, then it starts bumping and I feel that "e-brake" feeling, and it floats around. I'm pretty sure the floating if coming from the rear end but I could be wrong. I know the rear has issues because when you put on the e-brake on a hill, the car will settle to one side along with the classic clunk when shifting. But, all this craziness I am talking about started last week.

[mLuMaN83]

I think this may be it...

http://www.e46zone.com/forum/topic/29608-sticky-brake-calipers/

[Hornung418]

When the subs hit dat ass go bump bump bump bump.

Verbiage on point, dawg!

Sent from my GS3.

[mbeckel]

When the subs hit dat ass go bump bump bump bump.

Verbiage on point, dawg!

Sent from my GS3.
Lmao

[Oli77]

Feel all the wheels and see if one is hotter than the others (after you drive a couple of minutes).

[alexandre]

Was gonna say sticky caliper too. Definitely something to look into.

[mLuMaN83]

I'll test the heat situation tomorrow. I went out earlier to see if the rotors looked different than each other and figured this could tell me something. The fronts definitely look different than each other so I think that might be it.

[mbeckel]

I'll test the heat situation tomorrow. I went out earlier to see if the rotors looked different than each other and figured this could tell me something. The fronts definitely look different than each other so I think that might be it.
It sounds like a caliper issue. Might be best to replace in pairs. If it were me, that's what I'd do.

[mLuMaN83]

It sounds like a caliper issue. Might be best to replace in pairs. If it were me, that's what I'd do.

Yeah thats usually how I do things. I think I might look at two reconditioned calipers and slap them on. Gotta make sure this is the issue but I'm pretty sure this is it. I was freaking worried. It feels CRAZY!

[mbeckel]

Yeah thats usually how I do things. I think I might look at two reconditioned calipers and slap them on. Gotta make sure this is the issue but I'm pretty sure this is it. I was freaking worried. It feels CRAZY!
Might want to make sure the rotors aren't damaged from this as well. Might be able to get by getting them surfaced.

[3ZHP]

A quick way to check the caliper, is to get the wheel off the ground with a jack and see if it rotates freely. The fronts will rotate more freely then the rears "because of the transmission drag" but they should have the same resistance on each axle. Remember to put the car in neutral.

FYI on the turning of rotors; that is A BIG NO-NO on Bimmers. They need that mass to dissipate heat and turning them reduces the mass and causes them to warp even faster. As nice as the cross drilled ones look, they actually dissipate heat less due to the reduced mass. So, always replace the rotors with new solids when doing a pad replacement. Both the roter and the pads wear with the heat and friction that are a result of breaking.

[mbeckel]

A quick way to check the caliper, is to get the wheel off the ground with a jack and see if it rotates freely. The fronts will rotate more freely then the rears "because of the transmission drag" but they should have the same resistance on each axle. Remember to put the car in neutral.

FYI on the turning of rotors; that is A BIG NO-NO on Bimmers. They need that mass to dissipate heat and turning them reduces the mass and causes them to warp even faster. As nice as the cross drilled ones look, they actually dissipate heat less due to the reduced mass. So, always replace the rotors with new solids when doing a pad replacement. Both the roter and the pads wear with the heat and friction that are a result of breaking.
Are you saying the solids dissipate heat better than my drilled and slotted rotors? I can't hardly believe that fact. I am requesting proof on this please.

[3ZHP]

Are you saying the solids dissipate heat better than my drilled and slotted rotors? I can't hardly believe that fact. I am requesting proof on this please.

I thought the same about the cross drilled until my first BMWCCA HPDS (High Performance Driving School @ Mid-Ohio) when I was told differently in the class room, by my instructor and many old time participants. And, to conform my thoughts, I started checking out the roters on the cars at the track that day and found very few cross drilled, unless the were over size kits.

[mbeckel]

I thought the same about the cross drilled until my first BMWCCA HPDS (High Performance Driving School @ Mid-Ohio) when I was told differently in the class room, by my instructor and many old time participants. And, to conform my thoughts, I started checking out the roters on the cars at the track that day and found very few cross drilled, unless the were over size kits.
The performance of the rotors I have now compared to the flats is night and day. I just don't get how that's possible for the flats to outperform the cross drilled and slotted rotors.

[3ZHP]

For the street, that may be the case but, at the track you are at the extreme limits of the brakes. That's like I never knew the significant differences you can get in pads and with track pads, that even takes you in to a whole nother world of stopping power and cost. Check out Hawk, the pad choice of many instructors and BMWCCA Club Racers. http://www.hawkperformance.com/motorsports/compounds

[mbeckel]

For the street, that may be the case but, at the track you are at the extreme limits of the brakes. That's like I never knew the significant differences you can get in pads and with track pads, that even takes you in to a whole nother world of stopping power and cost. Check out Hawk, the pad choice of many instructors and BMWCCA Club Racers. http://www.hawkperformance.com/motorsports/compounds
I have hawk pads on my zhp! :thumbsup

[tkundhi]

Let's start from the beginning. What was the original issue you were trying to fix?

There really isn't a need to throw parts at most problems. Suspension problems and brake issues are generally pretty easy to diagnosis by properly inspecting the car. For suspension parts basically make sure there are no cracks and no play. For example on a control arm ball joint, try to compress it. If you can then it is bad and needs to be replaced. I have yet to see a suspension part that has failed and passed visual inspection. You just need to know what to look for. Cracks in rubber, bad.

Regarding a sticky caliper. It will usually stick after you apply the brakes and then pull to one side. Also as someone else mentioned it will heat things up. But, I wouldn't check with your bare hand. You can easily get burned. Brake parts get hot. BTDT.

Now on to some of the brake comments. Sorry but I disagree with several comments about brakes. They are internet lore and misconception. Generally speaking people will say don't turn a BMW rotor. This is because they aren't usually warped. Unless it is a cheapo rotor from China or something similar. Simple comment, OEM does not mean the same as BMW or OE. Be sure to buy OE or BMW quality parts. Now back to the brake rotors. There is a thickness spec. You can turn a rotor if it is warped but still within the thickness spec. But most places won't do that because it is cheaper and easier to simply replace. Plus modern quality rotors are difficult to warp. Ridges, lips and cracks in rotors are bad and generally signs that the parts should be replaced. BTW, some warped rotor claims are nothing more than pad build up.

As far as cross drilled rotors go. Most are simply for show and don't perform as well as a solid vented rotor. Look closely at the cross drilled rotors and you will often find small cracks between the holes. I'm not talking about the expensive ones found on exotics but the stuff most people put on their BMWs. Unless you drive roads like the Tail of the Dragon or CA canyon roads really aggressively it is highly unlikely you are heating up your brake system to the point where brake disc heat dissipation is really an issue. And if you are I can almost guarantee the problem is your fluid and braking technique not the rotor. Plus you should NOT be driving like that on public roads.

All that said you can experience strange brake issues under extreme conditions that are very difficult to isolate. For example a buddy had vibrations coming from the rear of his E36 M3 track car once everything got warm. We replaced the rear rotors. He had OE rotors which where replaced with expensive BMW rotors. He didn't want to waste a whole weekend at the track. But the problem still existed. Turns out there was even a technical term for this symptom, "hot roughness in the rear." One of the guys driving the car was key automotive engineer/racer and mentors the BMW Performance Driving School instructors. Sometimes the mix of parts just doesn't work right together. The expert's words not mine. These guys were running the M3 hard. It was fine for a few laps and then when the pads were up to temp the problem manifested. Slow down for a lap and the problem was gone. Pick the pace back up and it reappeared. For these guys slowing down meant backing off so the car was only a couple seconds a lap slower. Still really fast. This car was on R comp tire, solid rotors and Hawk HT10s. The car never experience the problem again after that weekend.

I run Hawk HT10s on my car with OE rotors and ATE brake fluid. I have yet to boil the fluid. Same setup on my E36 M3. My E30 M3 is also similar with Pagid Orange pads. Point being, buy quality OE rotors and skip the bling if you are really after the performance and durability. If you want cross drilled rotors for the looks, that is fine but don't kid yourself into thinking you have better performance. All you are doing is going through rotors and pads faster. Think cheese grater.

FWIW, our "new" ZHP has slotted rotors and the pedal feel is not as good as the "old" car with solid rotors. These slotted rotors will come off soon. I am going to do an event next month with these rotors as the have a lot of life left. Then they will become spares for the wife's car (old car).

OK back to the OP's issue. If you did all the work yourself the first thing to do is reinspect everything. Make sure all the bolts are tight and properly torqued. Start with the lug bolts. Verify the suspension components are not damaged. If you paid someone to do the work, take the car back to them.

t.

[Newjack]

^^^ Solid points.

However running slotted rotors instead of blanks wont have any difference on pedal feel. They will wear faster as you said, but unless you run stainless steel lines or change pads, pedal feel should be the same.

Luman if you take your car for a drive for a bit just see which wheel is hottest like everyone above me has said. It sounds like a sticky caliper. You should be able to smell which wheel is stuck by the brake dust right after a drive.

[3ZHP]

Let's start from the beginning. What was the original issue you were trying to fix?

There really isn't a need to throw parts at most problems. Suspension problems and brake issues are generally pretty easy to diagnosis by properly inspecting the car. For suspension parts basically make sure there are no cracks and no play. For example on a control arm ball joint, try to compress it. If you can then it is bad and needs to be replaced. I have yet to see a suspension part that has failed and passed visual inspection. You just need to know what to look for. Cracks in rubber, bad.

Regarding a sticky caliper. It will usually stick after you apply the brakes and then pull to one side. Also as someone else mentioned it will heat things up. But, I wouldn't check with your bare hand. You can easily get burned. Brake parts get hot. BTDT.

Now on to some of the brake comments. Sorry but I disagree with several comments about brakes. They are internet lore and misconception. Generally speaking people will say don't turn a BMW rotor. This is because they aren't usually warped. Unless it is a cheapo rotor from China or something similar. Simple comment, OEM does not mean the same as BMW or OE. Be sure to buy OE or BMW quality parts. Now back to the brake rotors. There is a thickness spec. You can turn a rotor if it is warped but still within the thickness spec. But most places won't do that because it is cheaper and easier to simply replace. Plus modern quality rotors are difficult to warp. Ridges, lips and cracks in rotors are bad and generally signs that the parts should be replaced. BTW, some warped rotor claims are nothing more than pad build up.

As far as cross drilled rotors go. Most are simply for show and don't perform as well as a solid vented rotor. Look closely at the cross drilled rotors and you will often find small cracks between the holes. I'm not talking about the expensive ones found on exotics but the stuff most people put on their BMWs. Unless you drive roads like the Tail of the Dragon or CA canyon roads really aggressively it is highly unlikely you are heating up your brake system to the point where brake disc heat dissipation is really an issue. And if you are I can almost guarantee the problem is your fluid and braking technique not the rotor. Plus you should NOT be driving like that on public roads.

All that said you can experience strange brake issues under extreme conditions that are very difficult to isolate. For example a buddy had vibrations coming from the rear of his E36 M3 track car once everything got warm. We replaced the rear rotors. He had OE rotors which where replaced with expensive BMW rotors. He didn't want to waste a whole weekend at the track. But the problem still existed. Turns out there was even a technical term for this symptom, "hot roughness in the rear." One of the guys driving the car was key automotive engineer/racer and mentors the BMW Performance Driving School instructors. Sometimes the mix of parts just doesn't work right together. The expert's words not mine. These guys were running the M3 hard. It was fine for a few laps and then when the pads were up to temp the problem manifested. Slow down for a lap and the problem was gone. Pick the pace back up and it reappeared. For these guys slowing down meant backing off so the car was only a couple seconds a lap slower. Still really fast. This car was on R comp tire, solid rotors and Hawk HT10s. The car never experience the problem again after that weekend.

I run Hawk HT10s on my car with OE rotors and ATE brake fluid. I have yet to boil the fluid. Same setup on my E36 M3. My E30 M3 is also similar with Pagid Orange pads. Point being, buy quality OE rotors and skip the bling if you are really after the performance and durability. If you want cross drilled rotors for the looks, that is fine but don't kid yourself into thinking you have better performance. All you are doing is going through rotors and pads faster. Think cheese grater.

FWIW, our "new" ZHP has slotted rotors and the pedal feel is not as good as the "old" car with solid rotors. These slotted rotors will come off soon. I am going to do an event next month with these rotors as the have a lot of life left. Then they will become spares for the wife's car (old car).

OK back to the OP's issue. If you did all the work yourself the first thing to do is reinspect everything. Make sure all the bolts are tight and properly torqued. Start with the lug bolts. Verify the suspension components are not damaged. If you paid someone to do the work, take the car back to them.

t.

Great points, thanks for taking the time in your detailed response.


Sent from my iPhone using Tapatalk

[Oli77]

Yes but "hot roughness in the rear" was a bit distracting.

[Newjack]

Yes but "hot roughness in the rear" was a bit distracting.

I'm glad I wasn't the only one.

[iZHP]

I'm glad I wasn't the only one.

Lmao.

I'm in for sticking caliper as well. Had that issue before on a rear caliper, "holding the car back".

If it's the fronts, it would make sense that it pulls to one side.

[tkundhi]

I'm glad I wasn't the only one.

Yes. That is still an ongoing joke. 4 years later.

t.

[tkundhi]

^^^ Solid points.

However running slotted rotors instead of blanks wont have any difference on pedal feel. They will wear faster as you said, but unless you run stainless steel lines or change pads, pedal feel should be the same.



I agree. The new car has SS brake lines too. Honestly don't know about the pads as I haven't pulled them off to check. I'll know more in a few weeks after first track event with the new car.

t.

[mLuMaN83]

I went for a short drive the other night around the neighborhood and it seemed that the passenger side was warmer and was a bit burny smelly.

Gonna give it one more drive test.

I'm 98% positive that this is the issue. This is quite a relief. I was not connecting those symptoms to the brakes other than that grabbing sensation. This is quite an easy fix and I can replace both front calipers with rebuilt ones for $60 a piece from Turner. Now I have to wait another week once again for the parts to come in and find a day off where I can knock this job out. My car has been out of commission for two weeks. It's killing me! Especially since I got all the front end suspension work done and I have yet to enjoy it.

[Rovert]

You can also diagnose by having the car on a slight incline and in neutral. If you're supposed to roll back or forward but don't then that's a sign. If you are good with doing your own brake work you can buy caliper seals for $10 and fix the caliper yourself. That's what I did when the front caliper stuck on my car. All has been good after a full brake fluid flush.

Edit: refer to http://www.zhpmafia.com/forums/showthread.php?t=13069

[mLuMaN83]

Most likely a stupid question, but as far as bleeding goes, I would like to bleed the system with fresh fluid while I am at it. Do I just bleed each side one at a time? Or can I bleed the whole system once finished replacing the calipers from say the right rear? I'm not to keen on brake jobs.

Question is, should I spend the money on a pressure bleeder kit and how would I go about flushing the entire system? I'm confused from all the videos I have watched and I'm quite tired. After watching the videos, I am under the impression that in order to do a full system flush, I would need to bleed from all 4 calipers?

PS, the brake fluid atm looks great. Looks like fresh cooking oil. I changed it awhile back and I also had the brakes done by a friend of my brother in-law like 6 months ago. I honestly don't know if he flushed the system or not but the fluid looks clean!

[tkundhi]

You must bleed the system if you are going to open it up by replacing calipers. After replacing the calipers, bleed in the following order: RR, LR, RF, LF. You want to go from the furthest to the closest.

IMO, a pressure bleeder is a helpful tool. It doesn't need a lot of pressure, maybe 20 psi. Keep it above the reservoir while bleeding and then below when you disconnect. You can also suck most of the old fluid out of the reservoir to speed things along. Just don't let the reservoir run dry.

t.

[Rovert]

I did it myself with a clear piping tube from an old camelbak going down into a large cup. It fit and sealed perfectly over the caliper. The thing was that my fluid was totally nasty so I could easily see the difference. I went from furthest away to closest from where the brake fluid reservoir is located. I turned on my car and pumped the brake pedal easily instead of pump a hard unpower assisted system. I just had to make sure every few pumps that I added new fluid to the reservoir and keep it at the very top while checking the corner I was bleeding until I saw clean fluid.

All in all it's easy to do when the engine is started!

[mLuMaN83]

Thanks guys.