Brakes, and what to do if you mistakenly use them

[brian99997]

I had the impression I could get one track weekend out of the brakes without trouble but I seem to have been mistaken and now my car has a really wicked vibration under braking at all speeds but especially slow although I am finding new rattles. Obviously the dealer will have nothing to do with the car while the tires look feathered.

The rotors are clearly not warped, but they are not true either. Stoptech has an interesting article at http://www.stoptech.com/technical-su...nd-other-myths that says you can either true them or try to grind them with garnet paper.

Has anybody had luck with sanding them? I tried last night with the wheels off but rotors attached for about 15min per rotor and while its better, its not great although I still have the stock pads on the car waiting for some rs29's to show up.

[pikkagtr]

Not sure if the M rotors can be resurfaced on a lathe by any machine shop with one. As long as it is within minimum thickness you can have most brake shops perform this for about $20 per side. Just be sure to sand down the pads before install in case there are foreign materials imbedded in them that can score the surface of the rotors you just had redone.

[CanAutM3]

Just run them on the street normally, the shudder should eventually go away.

[thebishman]

This is not a problem with your rotors but rather uneven deposition of brake pad material, especially common if you ran with the OEM brake pads. Go out and (safely) do some high speed decelerations from say 60 mph down to 5 mph. Really hammer on the brakes but do NOT allow the ABS to kick in. A couple of stops like this should even up things again.

[brian99997]

Originally Posted by thebishman

This is not a problem with your rotors but rather uneven deposition of brake pad material, especially common if you ran with the OEM brake pads. Go out and (safely) do some high speed decelerations from say 60 mph down to 5 mph. Really hammer on the brakes but do NOT allow the ABS to kick in. A couple of stops like this should even up things again.

Tried it on my way into work but could only get 3 with a few minutes between. Could have helped a little bit, but clearly needs more attention.

[nicknaz]

Originally Posted by brian99997

Obviously the dealer will have nothing to do with the car while the tires look feathered.

Time for a new dealer then....

[MaynardZed]

Originally Posted by nicknaz

Time for a new dealer then....

x2, I don't understand why dealer would care what the tires look like?

When you get those RS29's in, they'll scrape those deposits right off.

[Merli]

Originally Posted by thebishman

This is not a problem with your rotors but rather uneven deposition of brake pad material, especially common if you ran with the OEM brake pads. Go out and (safely) do some high speed decelerations from say 60 mph down to 5 mph. Really hammer on the brakes but do NOT allow the ABS to kick in. A couple of stops like this should even up things again.

I agree with this man

[brian99997]

Southbay BMW (LA) is considering the car to be driven past what is reasonable for an M car. The initial suggestion was new pads and rotors all around on my tab, something in the 2 grand area.

I recently joined BMW land from Porscheville and the GT3 was just more up to the task from the beginning although even it required RS29's and rotors after multiple days. I have some new pads and tires coming for next weekend though, the rest of this chassis is amazing but those two points really hurt the car.

[thebishman]

Find a new dealership to service your car. These guys are idiots. I fear that the whole of BMW is moving quickly away from the whole essence of what an 'M' meant; from the designers, engineers, sales and service. Very depressing.
Bish

[MaynardZed]

Originally Posted by brian99997

Southbay BMW (LA) is considering the car to be driven past what is reasonable for an M car. The initial suggestion was new pads and rotors all around on my tab, something in the 2 grand area.

I recently joined BMW land from Porscheville and the GT3 was just more up to the task from the beginning although even it required RS29's and rotors after multiple days. I have some new pads and tires coming for next weekend though, the rest of this chassis is amazing but those two points really hurt the car.

That's BS! Get a new dealer. My dealer knows I track my car aggressively and says go for it because "M stands for Motorsports". Maybe helps that my dealer is owned by Penske and right next to the Penske Racing Museum.

FWIW the brakes on the M4 were giving me some grief at the track initially, but I've finally got them sorted. My advanced instructor drove it on the track this past weekend and said the brakes were "amazing". My brake setup is:

SRF fluid
SS brake lines
Carbotech XP12 front / XP10 rear

[MasterP]

OP. Get a Rotor Hone.

I grabbed three In Course, Medium, and Fine. They're about $30 each.

You may only need Coarse and Medium.

They'll knock those deposits off.

Then take the pads off and Scuff them up with some 220 Sand paper. I had this happen on my GTR, and this is the best fix if you can't replace your hardware.

Also happened on my F80, but I have bad ass tech and SA at my dealership that got me all new pads and rotors all around.

[brian99997]

Originally Posted by TrakBch

OP. Get a Rotor Hone.

I grabbed three In Course, Medium, and Fine. They're about $30 each.

You may only need Coarse and Medium.

They'll knock those deposits off.

Then take the pads off and Scuff them up with some 220 Sand paper. I had this happen on my GTR, and this is the best fix if you can't replace your hardware.

Also happened on my F80, but I have bad ass tech and SA at my dealership that got me all new pads and rotors all around.

ah yes this is perfect! I am going to try to find one local, amazon seems to be a bit slower than I would like.

I will deal with the dealership issue later.. In Houston, Porsche of North Houston had no trouble what so ever with the fact that I damaged a differential while I was at the track or the fact that the car came in for service with Hoosiers every time. I even took their loaner cayman to the track while the GT3 was in the shop with no complaints afterwards.

Any recommendations around Los Angeles?

[brian99997]

Originally Posted by MaynardZed

FWIW the brakes on the M4 were giving me some grief at the track initially, but I've finally got them sorted. My advanced instructor drove it on the track this past weekend and said the brakes were "amazing". My brake setup is:

SRF fluid
SS brake lines
Carbotech XP12 front / XP10 rear

I may have to give the carbotechs another shot after the pagids, I wasn't a big fan of them in my spec miata because of the lack of bite on release but this is a drastically different car.

[brian99997]

Originally Posted by MaynardZed

x2, I don't understand why dealer would care what the tires look like?

When you get those RS29's in, they'll scrape those deposits right off.

More or less, this was the solution without much labor involved. the rs29's removed the shudder after 8-9 100-30 stops.

All is well again

[CanAutM3]

Originally Posted by brian99997

More or less, this was the solution without much labor involved. the rs29's removed the shudder after 8-9 100-30 stops.

All is well again

As I posted in post #3, the pad deposit would have eventually scrubbed off with normal street driving. It just takes longer (a few weeks) with street pads. The abrasive Pagids accelerated the process .

[Brosef]

Originally Posted by CanAutM3

As I posted in post #3, the pad deposit would have eventually scrubbed off with normal street driving. It just takes longer (a few weeks) with street pads. The abrasive Pagids accelerated the process .

+1

just throw some more aggressive semi-metallic track pads on there (the RS29's will work) and that should take care of it. I did the same thing after my first track day in my e92 at Road America. felt like the car was limping home with the brake shudder, but totally worth it.

[Swancoat]

Regarding your dealer: The first time this happened to me (and I thought the rotors were warped). I just dropped it off with a dumb "I dunno - there's a weird vibration on braking".

The dealer immediately called me and said "Were you tracking this thing?" before I could answer he said, "we know you did - we can tell by the tires". So I admitted I did (heck I thought he could tell because I removed the numbers and didn't wash the car - totally visible on the doors).

Anyway, I thought they were going to tell me to shove it. He said "No worries - we just wanted to ensure that was what happened. Brakes are covered though, the rotors are warped and we're putting on new ones".

When I picked it up they totally said something to the effect of, "it's an M car, should be able to do that". And they also replaced them twice more at BMW's expense. Same thing.

So, 1: your dealer sucks. "Driven beyond what is reasonable for an M car" is basically in direct contradiction to all of the marketing materials and what the salesman eagerly tells you when you're buying it, "This thing is basically a race car!"

2: I also agree with the rest of the thread here, in that my dealer was wrong, and it is just pad deposits, and they do go back smooth after some time. Happened to me after the car went out of the warranty/maint period and eventually it went back to normal.

[bigjae1976]

Stop crying about the dealer...hose down your wheels and rotors with water in the evening and then let the surface rust up a little. Drive it. Fixed.