650i (F06) brake judder/disc replacement

[MDMetal]

My 650i has been getting a vibration when braking in the front right (drivers), I figured it was balance from the new tyres but a re-balance doesn't help and it's now very slightly noticeable when driving at certain speeds. I've checked the wheel and it seems stable so it's not a wheel bearing and given it's noticable under braking I assume it's a warped disc or some sort of runout. Car only has 27k on but the discs do seem lipped which seems a bit odd.

I'll try taking the wheel off and seeing how the disc spins in the caliper before anything else but assuming it's the disc is there anything stopping me swapping the discs and pads out. As I understand it you can reset the service indicators for the pads through the menu system and there's nothing "coded" so no reason not to do it all myself? Done it before on all my older cars but nothing that actually cared about codes or registering rubbish!

[Chamon_Lee]

It could be the discs but I have to say its unlikely.

1) Where did you get the wheels balanced and did they check the alloy to see if it has a buckle (BMW alloys are made of chocolate). plenty of posts from 6 series owners complaining about 6 series alloys buckled.

2) Have you given the car a strong run and hard stops - do this 6 or 7 times from a high speed (safely!). It could be deposits on the discs. If it is deposits on the disc each time you brake the vibration will reduce not get worse.

3) Could be the tyres are out of round

I would bet money its your alloys or tyres
To give you an example I had a vibration from 100+. It would happen quite a bit when braking hard and you would assume it was discs but I knew it is a good chance it was balancing. Had the wheels road force balanced and smooth as silk now at all speeds and all braking.

Edited by Chamon_Lee on Wednesday 22 August 13:28

[Ninja59]

Could also be the mating face of the wheel if for example the wheels have been refurbed and not being kept bare of paint (and yes I know of owners that have had those problems).

It could also be from the diff bushes and around that area as I know some issues have been tracked down to those areas.

[MDMetal]

Chamon_Lee said:

It could be the discs but I have to say its unlikely.

1) Where did you get the wheels balanced and did they check the alloy to see if it has a buckle (BMW alloys are made of chocolate). plenty of posts from 6 series owners complaining about 6 series alloys buckled.

2) Have you given the car a strong run and hard stops - do this 6 or 7 times from a high speed (safely!). It could be deposits on the discs. If it is deposits on the disc each time you brake the vibration will reduce not get worse.

3) Could be the tyres are out of round

I would bet money its your alloys or tyres
To give you an example I had a vibration from 100+. It would happen quite a bit when braking hard and you would assume it was discs but I knew it is a good chance it was balancing. Had the wheels road force balanced and smooth as silk now at all speeds and all braking.

Edited by Chamon_Lee on Wednesday 22 August 13:28

Next time I have it out when it's quiet I'll re-bed the discs/pads, it's odd that it's started to increase drastically.

I had them rebalanced by a different company just to see, I watched them clean the hub surface prior to mounting and asked how the balance came out vs how it was and the guy said it was pretty much the same. I'll give the wheel a good inspection it looks fine from the outside but there maybe nearside damage I guess.

Is road force balancing a wide spread thing?

[MDMetal]

Ninja59 said:

Could also be the mating face of the wheel if for example the wheels have been refurbed and not being kept bare of paint (and yes I know of owners that have had those problems).

It could also be from the diff bushes and around that area as I know some issues have been tracked down to those areas.

Surely no diff bushes on the front wheels? It's not an Xdrive or whatever they call it so just rear wheels although the fronts have regenerative breaking but I assume that's just mounted on the inside of the hub/wheel bearing?

[anonymous-user]

I wouldn’t get too hung up with all the advice. Start with the simple things.

Do you leave the car outside much? I had this issue with my 5 series after it was parked outside, unused, for a month in Feb/March the other year.

I knew the wheels were fine and balanced (you’d feel that at other times than just under braking anyway) and was planning to have the discs, which appeared quite true, skimmed.

I tried the heavy braking lark which seemed to improve things a bit, then I just left it. Within a month or so it had disappeared, never to return!


I’m convinced it was uneven corrosion on the discs.

Distorted discs are very rare. BMW wheels are no ‘softer’ than any other.
Pad pick up and uneven corrosion are not uncommon.

[Chamon_Lee]

MDMetal said:

Chamon_Lee said:

It could be the discs but I have to say its unlikely.

1) Where did you get the wheels balanced and did they check the alloy to see if it has a buckle (BMW alloys are made of chocolate). plenty of posts from 6 series owners complaining about 6 series alloys buckled.

2) Have you given the car a strong run and hard stops - do this 6 or 7 times from a high speed (safely!). It could be deposits on the discs. If it is deposits on the disc each time you brake the vibration will reduce not get worse.

3) Could be the tyres are out of round

I would bet money its your alloys or tyres
To give you an example I had a vibration from 100+. It would happen quite a bit when braking hard and you would assume it was discs but I knew it is a good chance it was balancing. Had the wheels road force balanced and smooth as silk now at all speeds and all braking.

Edited by Chamon_Lee on Wednesday 22 August 13:28

Next time I have it out when it's quiet I'll re-bed the discs/pads, it's odd that it's started to increase drastically.

I had them rebalanced by a different company just to see, I watched them clean the hub surface prior to mounting and asked how the balance came out vs how it was and the guy said it was pretty much the same. I'll give the wheel a good inspection it looks fine from the outside but there maybe nearside damage I guess.

Is road force balancing a wide spread thing?

You won't be able to see a buckle kink while the wheel is stationary unless its drastic.
You are you dont have a sticky caliper?

The road force balancer will be all over the country. have a search online to find your nearest one but are not that common either. Good thing about that is they will establish if you have an out of round rim, out of round tyre and if you have a high spot on the tyre it will match it with the alloy.

If you get it done atleast you will know it is NOT the alloy or tyres. That leaves the discs and its related components.

I think you need to give us more symptons to get a more detailed diagnosis.
Is the vibration just as bad from when the car is cold or does it get worse or better once the tyres/car is warmed up after a 20-30mile run etc.

I am very very very pernickety when it comes to these sorts of things.

[MDMetal]

Chamon_Lee said:

MDMetal said:

Chamon_Lee said:

It could be the discs but I have to say its unlikely.

1) Where did you get the wheels balanced and did they check the alloy to see if it has a buckle (BMW alloys are made of chocolate). plenty of posts from 6 series owners complaining about 6 series alloys buckled.

2) Have you given the car a strong run and hard stops - do this 6 or 7 times from a high speed (safely!). It could be deposits on the discs. If it is deposits on the disc each time you brake the vibration will reduce not get worse.

3) Could be the tyres are out of round

I would bet money its your alloys or tyres
To give you an example I had a vibration from 100+. It would happen quite a bit when braking hard and you would assume it was discs but I knew it is a good chance it was balancing. Had the wheels road force balanced and smooth as silk now at all speeds and all braking.

Edited by Chamon_Lee on Wednesday 22 August 13:28

Next time I have it out when it's quiet I'll re-bed the discs/pads, it's odd that it's started to increase drastically.

I had them rebalanced by a different company just to see, I watched them clean the hub surface prior to mounting and asked how the balance came out vs how it was and the guy said it was pretty much the same. I'll give the wheel a good inspection it looks fine from the outside but there maybe nearside damage I guess.

Is road force balancing a wide spread thing?

You won't be able to see a buckle kink while the wheel is stationary unless its drastic.
You are you dont have a sticky caliper?

The road force balancer will be all over the country. have a search online to find your nearest one but are not that common either. Good thing about that is they will establish if you have an out of round rim, out of round tyre and if you have a high spot on the tyre it will match it with the alloy.

If you get it done atleast you will know it is NOT the alloy or tyres. That leaves the discs and its related components.

I think you need to give us more symptons to get a more detailed diagnosis.
Is the vibration just as bad from when the car is cold or does it get worse or better once the tyres/car is warmed up after a 20-30mile run etc.

I am very very very pernickety when it comes to these sorts of things.

There's a very subtle vibration at motorway speeds very very soft just an inkling that the steering wheel has some slight vibration and the car at the drivers front is the centre, if you go to sport mode and firm up the dampers it's slightly more noticeable. If you brake the mid phase (when the pedal is semi depressed) is noticeable in terms of judder, a firmer application and it's gone (firm but not standing on the brakes) The fact that it's always present to some degree I guess means the discs aren't warped they'd need to be uneven (assuming a warped disc had the same weight distribution anyways)

It's steadily got worse over the past few months which maybe indicates build up? I'd assume a buckle would stay constant and a warp/odd wear would take much longer to exaggerate itself

[anonymous-user]

Bet you a tenner a) buckled wheel plus b) brake disc DTV. Both v common in your car at your mileage. I would start with Road Force balance to identify wheel issue. And then fit new discs and pads.

[MDMetal]

Not sure age is an issue for buckled wheels! Or the discs tbh, the service indicator thinks the pads have another 70,000 in them so the discs should be fine even if they are looking a bit worn.

I'll give the re-bedding a try next time I have it out

[Chamon_Lee]

I honestly think its alloys/tyres related.
Get to a shop that has a road force balancer. Tell them you feel a vibration and if they can asses the alloys for buckles and any issues with the tyres. They will pay close attention to any kinks/buckles as its spinning round on the balancer and it will be clear to see the wobble/kink.
As you have had new tyres it could be a defect in one of the tyres - It happens more often than you think. Again the Hunter RFB will pick this up

Rule that out then move onto the disks calipers.

[MDMetal]

Chamon_Lee said:

I honestly think its alloys/tyres related.
Get to a shop that has a road force balancer. Tell them you feel a vibration and if they can asses the alloys for buckles and any issues with the tyres. They will pay close attention to any kinks/buckles as its spinning round on the balancer and it will be clear to see the wobble/kink.
As you have had new tyres it could be a defect in one of the tyres - It happens more often than you think. Again the Hunter RFB will pick this up

Rule that out then move onto the disks calipers.

Having had the car up last night it feels like a low spot on the disc, I'd driven it hard with lots of braking but no change the previous day, then lifted the car up to spin both fronts by hand and see how they felt, they both have the general "swosh" of pads on discs but the side with a slight wobble has a definite area of no swosh, it's not that there's resistance in other areas just a spot of less resistance. Not sure what causes a low spot though unless it's runout?