[hazkirby]

Hi

Some assistance most appreciated here.

At speeds of 65 plus if I touch the brake pedal even lightly the whole middle to rear of the car vibrates.

I'm thinking probably warped rears but the brake pedal and steering wheel do not vibrate.

Any ideas ?

[Raahil]

If the vibration only comes when braking would have thought the problem would def be within the braking system.

Most likely would be warped discs

[Styvy]

Second that. I had warped disk's in front which resulted in vibration on heavy breaking but none on slow speed. Funny enough If I heated up disks with a lot of braking the problem was gone for a bit

[ChawenHalo]

Sometimes "warped disks" get confused with Wheel balancing and especially geometry. Could also be supension joints etc failling if the car is old.

In all my years of running cars hard I've never, not once had "warped" disks. It eventually occurs if you buy cheap disks or on OEM when well past their measured best on very hard braking (ie: on track).

Could be worth a look.

[Chappers 71]

I had shuddering under braking last year. I took it into my local STS for a free brake test & discovered my front right brake was out of balance.
I tried to re bed them but that made no difference so I changed the front discs & they've been fine since.
I was told that if you do high speed braking down to a stop not to hold the car on the brakes as this can cause heat sink in the discs leaving deposits or can 'distort' the discs.
Find a STS/Kwikfit etc that does free brake tests & take it from there.

[Raahil]

Originally Posted by ChawenHalo

Sometimes "warped disks" get confused with Wheel balancing and especially geometry. Could also be supension joints etc failling if the car is old.

In all my years of running cars hard I've never, not once had "warped" disks. It eventually occurs if you buy cheap disks or on OEM when well past their measured best on very hard braking (ie: on track).

Could be worth a look.

May well be the case but i would imagine imbalanced wheels or bad geometry would cause vibration when you are driving and should not only occur under braking.

Sometimes problems can be a right b***.
I had serious thumping/grinding sound from my dads e90. And i mean serious, couldn't go over 30mph without thinking something would break off. Jacked the car and checked the lot and everything was good. Spun all the wheels and everything was solid and no sounds or play in wheels.
Turned out to be front wheel bearing

[hazkirby]

Thanks guys

Managed to get it onto a brake tester today. You could see the rear left brake pressure fluctuating.

This issue got much worse after a recent track day. Now I've done my research prob my fault.. I kept the handbrake on after several 20 minute runs. Probably causes some serious problems right there.


Anyway new discs and yellowstuffs (should really have got these anyway) on order so I will update next week when they're fitted.

[ChawenHalo]

Originally Posted by hazkirby

Thanks guys

Managed to get it onto a brake tester today. You could see the rear left brake pressure fluctuating.

This issue got much worse after a recent track day. Now I've done my research prob my fault.. I kept the handbrake on after several 20 minute runs. Probably causes some serious problems right there.


Anyway new discs and yellowstuffs (should really have got these anyway) on order so I will update next week when they're fitted.

Absolutely, as Chappers71 said.

I used to do quite a few trackdays (not on my E91) on OEM and then track prepared brakes (ie: Goodridge braided lines, 5.1 DOT fluid and RS29 pads). Never leave the hand brake after a run. In fact thats why when you get the last round flag before pitting you should do a cooling lap.

The heat from the disks (which get to around 650°C if I remember correctly, especially on heavy BMWs with their single piston brakes) will transfer and boil your fluid (which is why cars for track use different pads and higher boiling point fluid).

Its also normal to cook your brakes when you start doing track days with your "road" car. They are heavy and we all tend to go too fast and have to brake harder and longer rather than carry enough controlled speed through the corners. Road cars are set up to understeer ( a good thing) to warn of appoaching limits. Sorry this is a different subject

Either way; when ever I get a new car st thing I do is to get new quality rubber on all 4 corners, get the wheels ballanced and full geometry done. BMW are soooo good when their chassis is setup as intended by the manufacturer. Find, it also cures or at the very least takes many potential problems OUT of the equation, letting me investigate elsewhere if there are problems. Second that with a full brake change and ESPECIALLY fluid.

I recently changed my wife Z3 2.8 Coupe brake fluid and it was BLACK The cars has a fantastic BMW service record with all the bills. I suspect its rarely, if ever been done by BMW in all its almost 20 yrs history and 90000 km.

Let us know how you get on.

[hero honda]

Im having the same issue with my e90 320d. I believe its deposits buit up on one/more of the discs.

My brake pedal judder did get very violent, especially when slowing down on motorways to leave off a junction. Then a very noticeable brake pedal pulse when driving locally and braking.

Reason why i believe its deposit build up on mine and possibly be same on yours is, after a night shift i really 'cooked' the brakes on a empty industrial estate. I Must have done hard, around 30 stops from 50mph down to 10mph. When i was done i noticed my front left was giving off ALOT of smoke, almost thought its on fire but i assume it was burning the deposit build up. After that the brake judder has improved/reduced by id say 75%. Theres still a very faint judder/ brake pedal pulse now.

For what its worth, il be replacing all discs and pads as theyre only cheap discs and pads on the car, will be replacing with good quality stuff.

[hazkirby]

Rears replaced.

No more vibration ! thanks all

[bayerischer]

i had it even though my wheels are slightly bent, but the major cause was my failed control arms.....then it reduced by about 70% after replacing them