But for the fact you have replaced the suspension, I would say your symptoms are most likely thrust arm bushings. The light braking around 50 ish mph is typical of that. I personally use the X5 thrust armbushing (which have to be put in 180 degrees out of phase-- see old thead "Crevier sucks" for long discussion), but stock or other upgraded bushings are out there.

You can try to do some rebedding of the brakes, that might help if it is rotor related. Often brake shudder is an uneven coating of brake pad residue on the rotor creating high and low spots. It is pretty rare for a rotor to warp, but they can be measured (micrometer?) and there is a minimum thickness at which point they are replaced. The difference in thickness between new and replace is not that great. Swapping rotors yourself would not be very expensive.

Regards,
Jerry

 

I would say your symptoms are most likely thrust arm bushings. The light braking around 50 ish mph is typical of that.

I know right? Was my first thought, and immediately went under the car to wiggle/check the new thrust arms/bushings for signs of leaking/damage/etc. Nothing obvious, so I drove around some more and I *think* I remember that when I had bad thrust bushings in my 540 the side-to-side steering wheel shimmy was pretty prominent, and now in the M5 it seems more whole car shudder (including the wheel), but not so much steering right/left. Wish I could feel it in the pedal, but really can't, so as much as I want to, I'm not quite ruling out the thrust bushings yet, despite them being new. FWIW the new bushings had the orange-ish plastic inserts in the middle of them and the old ones that I removed from the car did not, though I seriously doubt this makes much difference for my current issue.

 

Been through this myself if you look through some of my previous postings.

Mine was terrible even after the suspension work - main issue turned it to be powdercoat on the wheel face. Removed this and it was 90% better. Next step I had discs skimmed on car - they removed 0.4mm of material and after that it was perfect, no judder at all.

Added a few hundred miles back on and it’s back at 50mph - I think my discs have an issue with heat treatment somehow, causing pad deposits to stick unevenly. Discs in UK are £600 a pair for front, I think US ones are simpler design so probably a lot cheaper.

Well worth an on-car skim if enough material is there.

Simon

 

Slightly more aggressive pads are what I’ll try next - however I need to get some advice on what makes are suitable - anyone got any experience of pads slightly harsher than oem?

Simon

 

monoballs I think are the best upgrade to the m5. dealt with exact issue of shudder and redid brakes but always would return, already had newer trw arms, then did the hd bushing also. just did bc coilover and monoballs and it made a definite difference right away, the brake pulsation was still a bit there but been working them hard and feel great now. they even make the lower arms with monoballs now.

 

100 miles is 100 miles and if you chose less than Lem they might have broken. Heck Lems have broken in less than 500 miles. You need to crawl under and look for signs of oil that has leaked out of the thrust bushing. That is an absolute must do because your symptoms scream thrust bushings. I think if bushing make it some miles they will last but clearly there is a failure rate that happens soon after installation.

 

100 miles is 100 miles and if you chose less than Lem they might have broken.

I did go with Lemforder parts but will double check today for any leaking; does it look similar to motor oil, or what sort of appearance other than cracking is indicative of a bad bushing?

 

A shimmy is strange but don't discount the rear suspension as a contributor to driving woes. Worth a look anyway. Have you inspected the wheels and tires? Standard mount and balance should be sufficient but sometimes minor wheel and tire variations can be minimized with indexed mounting and road force balancing.

 

Assuming that the suspension is ok (and center track rod is installed properly), curtissp321's advice would also be my next step. Make sure the back face of the wheel and the hub face the wheel mounts to are clean...perfectly clean.

Second, while moving very slowly (10mph or less), lightly apply brake pedal pressure...very lightly, just enough to barely allow pad to rotor contact and see the response you get. Windows down so you can listen also. If it is rhythmically pulsing either in brake force, pedal feel or sound, you know what's next.

FWIW, if you buy new rotors and pads from FCP Euro, you'll never need to pay for new ones again...for any reason. Just order a new set and then send back the prior parts for a full refund regardless of their wear level...makes worry about future rotor issues a lot less. Even if you track the car and smear brake pad material on the rotors that turns into cementite...order new ones, full refund once old are sent back.

 

Some good news, I took the girls to daycare this morning and paid really close attention, and I'm pretty convinced now it's definitely in the brakes, moreover I'm pretty sure it's in the rear brakes. Here is my reasoning:

- Definitely dependent on brake temperature, the warmer they get, the more pronounced it is.
- Once warm, I can feel it when slowly coming to a stop under light braking: rhythmic more/less/more/less stopping power with light braking. Not very pronounced at low speed/light braking, but definitely there.
- More of a forward/backward shudder than side to side.
- And lastly, almost forgot since this was on my to-do list already, but there is something genuinely off about my rear brakes, because the pads look like this, which CANNOT be good for consistent braking. Sorry, this is obviously a good smoking gun to start with, just with all the suspension work recently slipped my mind for a bit!

 

Well crap, did rear brake discs and pads and basically made zero difference. After driving it a bit and deciding things were exactly the same, I took another look back up front and was greeted with this sight on the drivers side. Guess it there are a few Lemforder Lemons out there after all. New part ordered from FCP, so they'll take the old one back under warranty once I swap them out. Only doing the drivers side for now as the passenger side still looks clean as a whistle at least.

 

I seriously thing lemforder is having QC issues these days. I've had 3 bushings fail withing 2 years under mixed driving.
I simply gave up and went with mooseheads. Harder ride, but by god no shakes!

haven't had the chance to get the car in the air yet but i've started noticing the exact same symptoms described by the OP. thing is, i've got moosehead engineering thrust arms and fairly new stoptech bbk all around so i'm assuming it's not thrust or brake related. could i just need to re-bed? what else could it possibly be?

I would measure rotor runout and rebed if needed, I think the limit of tolerance is 3 thousandths.

 

haven't had the chance to get the car in the air yet but i've started noticing the exact same symptoms described by the OP. thing is, i've got moosehead engineering thrust arms and fairly new stoptech bbk all around so i'm assuming it's not thrust or brake related. could i just need to re-bed? what else could it possibly be?

 

It’s a bit of a crap weak design isn’t it - don’t know why BMW lower themselves to quality like this that won’t last. All about the first owner I guess.

Only thing that made mine smooth was a disk skim and that only lasted a 100 miles - disks must be toast underneath the surface, heat treated or whatever causing pad deposits to return through use.

Need to try some harsher pads as the disks have loads of meat left on them. They are very expensive here in uk as two piece floating caliper design.

Simon

 

It’s a bit of a crap weak design isn’t it - don’t know why BMW lower themselves to quality like this that won’t last. All about the first owner I guess.

Only thing that made mine smooth was a disk skim and that only lasted a 100 miles - disks must be toast underneath the surface, heat treated or whatever causing pad deposits to return through use.

Need to try some harsher pads as the disks have loads of meat left on them. They are very expensive here in uk as two piece floating caliper design.

Simon

Try something like Hawk Blues. They are track pads. But without getting enough heat from street driving, they will be very abrasive and do a decent job of "skimming" your rotors. A few days should do the trick.

Remember to rebed brakes when switching back to stock pads.

Regards,
Jerry

 

Another idea here: is it possible that bad rear swing arm bushings can cause this? I ask since these are the only not-new bushings on the whole suspension, and also because I had to crank on those poor things pretty hard to get the swing arm down low enough to change the ball joint and swap out the rear struts. . . any history of this issue? If so, is it possible to press out/install new powerflex bushings with the swing arm in the car, or best just to take it (back) out again? Thanks all!

 

Thanks Jerry I’ll look into those pads.

I’m pretty light on the brakes and spend lot of time on the motorway so that probably doesn’t help.

Simon

 

If you can't find the Blues, check HT10.

Good luck!!

Regards,
Jerry

 

If you haven't balanced the wheels recently, try that as well. Surprisingly it resolved the issue in my Camaro 8 years back and my M5 last year..

 

Do you mean wheels alone or tires on wheels?

 

Wheel balancing with tires.

 

Subscribing to this because it sounds all too closely related to my issues which are documented in this thread https://www.m5board.com/vbulletin/e...discussion/602894-no-crank-no-start-problem-new-post.html#/topics/587762?page=3


I still haven't found out what's wrong with mine...

 

What color/viscosity is the thrust arm hydrobushing fluid? Want to make sure that's really what this dribble is and not some other fluid just coming down right there. Thanks!

 

Here's a post I did where I drilled a bushing...you can see a drop of the oil that came out.

 

Gents, I'm throwing my thoughts into the mix here. Or really just my frustrations.

My mechanic didn't believe the problem was anything other than me driving like a maniac. Replaced the rotors and then a second time... and the problem would go away briefly but come back quickly. Got in touch with a different shop that ended up first replacing my thrust arms. This made a dramatic difference but did not fix it. Next they did center tie rod and ends. All of this was still original on a 140k mile car. Again the problem was notably improved but not fixed. They noted some slight play in the steering gear, but suggested that is very unlikely to be the main culprit. Measured runout of 3 thousandths in the rotors. The spec according to them is 8, but that would be the next thing they intend to replace. The rotors are zimmerman. Not junk... not old... should not be warped but I don't know what is up and down anymore.

The shudder is felt in the steering, not in the pedal... tends to happen at light to moderate braking above 60 or 70 mph. Same situation as OP that it seems worst when i've been on a long drive and everything is warmed up. I will do some more digging and try to read up as I see I am not alone in this. But thought I'd throw out the story incase anything stood out to anyone.

 

My saga to date is here - I’d try disc skim or new discs if I were you next...

https://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/598828-wheel-bearing-brake-judder.html

Simon

 

I had an issue. A lot of noise and shaking, even a groaning sound during braking. Thought it was a wheel bearing for a long time.

In the meantime I cleaned and scuffed the rotors and pads, front and back and cleaned the calipers and replaced the slide pins. No difference. On a whim and hoping for a cheap fix I installed new Jurid pads and everything was fine after that. Don't know why.