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RB, thanks for your post. Good info and contribution to the conversation. Hopefully others like me who are trying to learn, study, and ask for help when needed, will find the golden nuggets in this thread useful.Originally Posted by RBNetEngr
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A few things.
- I have no idea what your current brake problem is.
- Bentley spec for rotor runout while on car, is 0.008". Off car is 0.002".
- Rotors don't warp from moderately (or grossly) miss-torqued wheel procedure.
- Rotors don't warp. (It's rare enough, that 1 person will likely never see it in their lifetime.)
- Basic debug procedure. 1) I changed something on car. 2) Car started doing xyz funny. 3) Most likely fix: undo the change I did.
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When people claim rotors are warped they often didn't clean the hub surface properly.
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Or incorrectly bedded the pads resulting in spotty or inconsistent layer of a ‘smeared’ pad material
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This is one thing I did very thoroughly - removed every bit of rust I could find. The only bit I couldn't get to was some in a few vanes of the rotor itself, including the brand news ones I've had for only a few weeks.
Short of going with better rotors, such as those Brembo UV coated ones that according to them, offers superior rust protection, I don't know of a way to remove that rust. Question in my mind is, does rust in the vanes create a weight imbalance?
I already read that resurfacing a rotor in the long run will not fix excessive runout because it doesn't correct the loose manufacturing tolerances.
Last edited by trading10; 10-12-2021 at 01:04 AM.
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Attachment 696991
Like this?
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I don't get what you mean, but I'm talking about rust and dirt on the wheel hub which you must remove with a power tool wire brush. That wheel hub cleaning must be done when you put on new brake discs. In that scenario your brake disc is new and has no rust on it.This is one thing I did very thoroughly - removed every bit of rust I could find. The only bit I couldn't get to was some in a few vanes of the rotor itself, including the brand news ones I've had for only a few weeks.
Short of going with better rotors, such as those Brembo UV coated ones that according to them, offers superior rust protection, I don't know of a way to remove that rust. Question in my mind is, does rust in the vanes create a weight imbalance?
I already read that resurfacing a rotor in the long run will not fix excessive runout because it doesn't correct the loose manufacturing tolerances.
No, rust in or on brake discs usually doesn't create noticeable weight imbalance.
Last edited by importbanana; 10-12-2021 at 12:06 PM.
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I have read more and more about this in recent years. In the old days there was more metal and probably toxic material in pads that kept the rotor surface cleaner. I have suffered these deposits also and find that regularly “standing on” the brakes helps keep them clean.
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When I look down at the vents of the rotor, not the rotor surface, rust has formed there in just a few weeks since I purchased them. The zinc coating the manufacturer put on there is supposed to inhibit rust. The rust formation is not in every vane, and that is what made me question whether or not it could affect the balance of the rotor.
That, and the runout causing the pads to make contact with the rotor something like 30-40% of the surface. So for example, with the front end off the ground and the wheel still on, I can rotate the wheel by hand and it will spin maybe one full rotation. The pads grab just enough to prevent it from spinning more than that. I can hear and feel the drag when I rotate the wheel slowly. So the real question is, should it be doing this? Or is this an indicator of warpage requiring replacement?
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What I noticed with the Powerstop ceramic pads was that the rotor surface developed a brown hue to it. Not rust, but more like burnt metal. Before using their rotors/pads, the bmw rotors and pads left the surface silver like you'd expect. I just don't know what the brown coloring is or what it means.
I mentioned earlier in this thread that I just put in Akebono ceramic pads, and have yet to do their recommended bedding procedure. When I compared the properties of both pads, these were rated as having much greater initial bite. I figured that they might be like the bmw oem pads as far as leaving the rotor shiny silver.
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No.
Indicates that your brakes drag. Says nothing about why. Why don't you just measure the disc runout if you think they could be warped?
Last edited by importbanana; 10-13-2021 at 07:59 PM.
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I don't have a dial gauge to measure the runout unfortunately. I have micrometer to measure thickness, but I'm assuming that is not the tool you're saying to use in this case. Correct me though if I have that wrong. I had to replace the rears with identical rotors (Powerstop) when the left rear developed multiple heat cracks from the hat on up into the vanes, and those new ones have the same dragging issue. I can rotate them with two hands, but they drag the same way. Front rotors are not new. It seems unlikely that all four calipers pistons would be sticking the same way, so it sounds like you are saying the guide pins are not aligned or are sticking somehow. When the calipers are not mounted, they glide on the pins like butter. These are the bronze ECS Tuning bushing set mentioned earlier in the thread if by chance you didn't see that already. I could put the powerstop pads back in as a test to see if maybe the new Akebono pads are too thick. Is that a variable here in your mind? So far, no one has mentioned that as a possibility.
I should add here that the left rear rotor that developed heat cracks happened long before the bronze bushings were installed. Stock guide pins and bushings.
Last edited by trading10; 10-13-2021 at 08:34 PM.
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What did you do by now to diagnose the problem?
Last edited by importbanana; 10-14-2021 at 10:46 AM.
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it would be faster to list what I haven't troubleshooted so far. I just reached out to ECS to ask for their help with the bronze bushings with the thought that if they are not seated perfectly, the pins could be out of alignment with each other. I haven't been able to prove or disprove that theory, so I'm hoping they can. I had one other thought that maybe the new pads are thicker than they should be - perhaps the wrong ones for these calipers. I'm trying to remain open minded with all of the suggestions made here. I guess one other thing is the rotors themselves. I asked ECS today about their own rotors and tolerances, which compared to powerslops, sounds much better. I just received new pistons/seals for front and rear, but I'm trying to take one troubleshooting step at a time to pinpoint exactly what is wrong.
UPDATE 10/15: with pads removed, caliper will slide back and forth, but the bronze bushings have a very tight tolerance. Waiting for ECS's response to that now. They glide like butter, but any pressure on the caliper that isn't 100% in line causes it to bind. The person who mentioned he had to sand out the bore on his bushings could be right with this design, but I wonder how much slop is acceptable. I have to think ECS designed these this way for a reason. We'll see... Right now, I'm on the fence.
Last edited by trading10; 10-15-2021 at 09:54 AM.
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BMW CCA Member
Did you follow ECS installation instructions:
http://bd8ba3c866c8cbc330ab-7b26c6f3...stallation.pdf
They also say it is highly recommended to purchase their bushing installation kit ES#3154107:
https://www.ecstuning.com/b-ecs-part...t/003326ecs03/
-rb
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Thank you, and yes. I used that pdf guide to the letter, especially the part about not smashing the rim, causing it to deform. I purchased and used the special install tool, which is clumsy at best, but it does work.
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bluptgm3,
More and more I'm leaning toward what you are saying here as being the correct answer. With the pads out, and the guide pins slightly loosened, the caliper will glide easily. As soon as I snug them up, they bind unless I press exactly right on them. I didn't get a response from ECS on Friday about binding. If I do sand out the bore and it gets too sloppy, then I'd have to find a way to get the guide out of the hole. I'm not sure if the special install tool can be used to do that or not. So, my question is, how would I know how much material to take out and how can that be done evenly? Is it that the sandpaper runs the full length of the bore and does not have a solid backing like a dremel tool would?
Thanks
Last edited by trading10; 10-17-2021 at 07:50 AM.
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I think a little loose is better than binding.
I question the O-Ring seal in the ECS design.
The flapper I ‘created’ did not ‘address’ the full length of the bore. I ‘floated’ the ‘tool’ in and out of the bore until I got the fit I was happy with. The caliper slides easily on the torqued Guide Pins.
My kit was from BW.
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Why not simply go back to properly working OEM parts?
Last edited by importbanana; 10-17-2021 at 08:33 PM.
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One of my closest friends owns a machine shop and has 35 yrs experience, so I am reaching out to him too for his thoughts. I like your idea.
As for the o-ring design, it seems to work well. It keeps the insides clean. What are your concerns?
Member
I just might do that depending on how things work out with opening up these bushings. ECS should be an authority on this (not THE authority, mind you), since it is after all their own design.
My goal for this car is to make performance upgrades where possible while maintaining a stock appearance. For example, I'm not going to lower the car or otherwise change any suspension geometry, but I might upgrade the struts and shocks. Another example is back in 2005, I put in ZKW headlight assemblies with HID bulbs, which provides much better lighting. A simple upgrade that still continues to pay off.
|m| (-.-) |m|
BMW E36 M3 Expert
ECS is a parts reseller ... I would not trust them to be an authority on anything except making $$.
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I think you've found out several things. Remote diagnostics, changing more than one part(s) at a time and not having the proper tools make whole operation nothing more than a guessing game. Resolve one issue at a time or by the end of one of these threads the last recommendation will be to replace the car. Your brake pro recommendation was correct - don't concentrate on the booster. They're easy to check and diagnose. Master cylinders are a whole other story. They don't just leak. They can leak internally, externally, leaks to reservoir, leaks between chambers, clogged or covered compensation and replenishing ports all cause problems. Soft lines don't just swell up and pop, they swell internally and allow pressure to pass in only in one direction and won't release the pads. If you just throw a bunch of parts at the problem and still have that problem, where you gonna start the diagnosis? At this point, going back to stock might help if you know those parts weren't part of the original issues.
See ya later,
tony
'98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T
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I got a reply to my email from ECS about the binding, and the response from Matt was to make sure they are lubricated. As I've said here multiple times, yes, they are lubricated. I emailed him back stating this, and never heard back. So, I called and asked they said they'd connect me with Dillon in tech support, but the call dropped or they hung up. I retried calling 5 more times, each time getting hung up on. Long hold time to speak with a customer service rep and they then disconnect the call when they say they are transferring the call to Dillon. The first person I spoke with was helpful as far as looking through my previous unrelated orders, and informed me that for some parts, the supply chain problems many of us are aware of are delaying part arrivals clear out to February next year. They are the only place I've been able to order a Centric master cylinder from, and they keep pushing the date out further and further. So, if you're going to order parts from them, you might call to ask if they are actually in stock - forget what the website says.
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Well, my troubleshooting efforts have been as sequential as I could make them. For anyone interested in knowing the sequence to help troubleshoot their own brake problems, mine went like this:
1. two years ago, replaced the worn out original rotors and pads with Powerstops from Rock Auto. Mushy pedal after that install, which was done by a racer friend of mine who is the chief of the safety crew who handles the radios at Portland International Raceway, and has his own business repairing older BMWs. I later took the M3 to an Indy shop nearby that is a bunch of BMW certified mechanics, who bled the system as much as possible, but could not get the pedal travel mush fixed. They said over time it would improve, and it did. Just not like it was prior to changing out the OE rotors/pads.
2. After much research, I ended up replacing the pedal travel sensor on the brake booster, which helped somewhat. Still not the pedal feel I was used to, so I chalked that up the the change in pads from OE to a ceramic that required a bit more heating up before it developed it's full friction.
3. Two months ago, no parts had been changed since the Powerstop rotor/pads were installed, but suddenly the pedal travel became excessive and mushy. I chalked that up to spraying water under the hood to clean off some degreaser I was using, thinking I somehow got water into the booster. After troubleshooting the booster, and talking with a local rebuilder that specializes in restoring boosters for classic car restoration, I ruled out the booster. He suggested the problem was much more likely to be the master cylinder considering the system had already been bled thoroughly. Damage internally to one or both internal seals.
4. I bled the system again, multiple times to be sure the lines were clean with no corrosion coming out. I got a slight amount of black colored debris when bleeding the right rear. No other corner had this - just clean fluid. So, where did that come from, I asked myself. Perhaps when I bled the system and pressed the pedal down as far as it would go - farther than the pedal would normally travel when in use (80%). The possibility of damage to the master cylinder seemed more likely at that point. Corrosion in the tip end of the cylinder pushed in around the seal, damaging it, and causing internal leaking. (Tying into what you are saying here, Tony). I did not pursue buying a new master cylinder at that time because I could not determine for sure if this was what happened.
5. A month later (30 days ago or so), I discovered the left rear rotor had been overheating for some time, and developed multiple cracks starting from the hat to the rotor vanes. I discovered one of the two springs for the e-brake was not seated correctly, and the shoes were dragging all the time causing the excessive heat. The right rear did was not overheating and had been operating normally. I reseated the spring and adjusted the tension so the rotor would spin freely. Because the rotor was cracked so badly, I could not continue using it, and had to order exact replacements for both rear corners. Since the e-brake problem was solved, I decided that was the time to change pads to some that had better initial bite - Akebono ceramics - addressing the statement made by the Indy shop that pointed out the Powerstop pads required more heat, and the pedal would feel better then. No other parts were changed at that time. I test drove the car a very short distance to see if both rears heated up evenly and it seemed like maybe they did, but I was only 90% sure.
6. I started troubleshooting to find out if the calipers were sticking, purchase two new pistons and seals just in case, but did not install them at that time. I did not do anything else. I took it for another drive to double check to see if the front pistons might be working ok because they still did not heat up as much as the rears did on the first test drive. This seemed very strange to me, and I put my troubleshooting hat back on to figure out what was happening. Something had to be wrong with the rears, but what could it be that suddenly affected both sides I asked myself. Hm, not sure. When I compressed the pistons, they went back inside, and I put the pads back in to test drive a third time, thinking maybe the new pads and cheap rotors were just tight enough to drag on the high spot of the rotors and heat up a bit. I did the Akebono breaking procedure. Still no answers, except maybe the pistons sticking, but again, how could both suddenly start sticking I asked myself. Hmm... Was there corrosion in the back of the piston's normal travel area that got lodged between the piston and cylinder and they started sticking. This seemed logical to me at the time, but I did not rebuild the calipers. It was at this point that replacing the brake lines with stainless ones from Turner would be ok to do, and another brake flush might get any corrosion out of the rear calipers. Fluid was still clean, so I wasn't sure if my theory of another flush would tell me the piston and bore were damaged. However, it seemed more likely.
7. I probably should have replaced those pistons at that time, and I consider this to be a mistake in judgement on my part. Instead, I went ahead with replacing the guide pins and bushings, thinking maybe the calipers were binding on the 22 year old OE ones. No difference - rears still heated up on a test drive with minimal braking. Back to the drawing board, thinking again, this had to be the pistons. When I replaced the bushing/pins on the fronts and test drove it, the fronts now heated up too. So, my focus shifted from sticking pistons to the new bronze bushings.
8. I took a close look at those new bushings/pins and relubricated them, and tried to spin all four wheels by hand. They were dragging. At that point, I posted this thread asking for some bigger brains to help troubleshoot the problem.
9. After a lot of reading and listening to everyone who had contributed to this thread, I decided to pull the front pads out, and check to see if the calipers moved freely. I discovered that while the pins glided like butter before the pins were tightened down, and bind when I snugged them up, my conclusion was that there was some kind of alignment problem with the bushings and pins themselves. This was not supposed to happen because I followed the ECS instructions using their own special tool to install the bushings. I rechecked to make sure they were pressed in as far as they would go, and rechecked to see if they would glide with the pins loose and with them tight. Same outcome - when tight, they bind.
10. So, I am at the point of asking ECS for advice, and considering seriously sanding one of them out as a previous poster suggested in this thread. To date, I have not done that because ECS tech support kept dropping my calls, and I could not get through to Dillon to ask for help. That was today.
So there you have it. The full sequential steps I took. This may be a longer read that one previous poster can tolerate, but that's his problem. I'm putting this information here in case it is helpful to a future reader, and for those that have contributed their expertise in this thread already.
So, since I can't get help from ECS so far, is it logical to try sanding out a little material to see if they still bind? I can't think of another troubleshooting step to take other than finding a way to remove them in favor of rubber OE bushings. My hope is that these bronze guides will eventually work the way they are supposed to, and I'll have some marginal benefit in pedal feel and more even pad wear.
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