7 Series 2008 Vibration

[996Type]

Looking for advice ahead of booking car in.

Recently had discs and pads changed at front as was getting vibration under braking due to warping. These were switched under warranty as the previous set were only on 2 months before these warped badly.

Car had run the previous discs and pads for three years before this. But these were also replacements for the same issue back then.

So whatever warped the discs "went away" for 3 years.

Bottom steering arms were switched this time also (as they had developed play) and the car fully geo'd and found to be in tolerance after all work done with minor adjustments.

The car has never felt razor sharp steering wise but now it feels a little vague and there is some vibration over 60MPH (not under braking though).

Anyone any idea what could be warping the discs that might be related to the steering system or suspension set up?

The disc supplier has replaced under warranty but suggested the hubs may need to be checked for play, this could be creating eccentric rotation that may be grabbing the discs wrong and creating the warping through heat.

It's going to BMW for a service check but they are a franchise and could swallow thousands to no effect from experience.

Thanks,

996T

[Davie_GLA]

I also have a 2008 7. 730d and had wool steering.

After some investigation I had a broken spring and the bottom arm and drop links were shot. Replace at eye watering cost and feels a lot better.

They are heavy big things and eat bushes like nothing. My previous E65 had the very same issues as yours. Replaced discs and nothing. Again turned out to be some suspension items that were done in.

[996Type]

Thanks for this, same model I beleive.
I get the car checked at BM then get an indy to deal with the work.

[Davie_GLA]

I really wish I had gone Indy. £1100 it cost at BM.

[anonymous-user]

Not wishing to have the same old discussion again but discs rarely ‘warp’.

More likely pick up, uneven corrosion or something else entirely.

[996Type]

3 sets, as observed by BMW main dealer and 2 independents, “warped due to heat”. Clean with no build up no longer concentric. Also confirmed by Mintex and Andrew Page who supplied.

[Davie_GLA]

He did say rarely to be fair but I have had it. Checked with run out gauge and beyond skimming.

Willing to bet a shiny pound it’s suspension related.

[anonymous-user]

996Type said:

3 sets, as observed by BMW main dealer and 2 independents, “warped due to heat”. Clean with no build up no longer concentric. Also confirmed by Mintex and Andrew Page who supplied.

You’ve been amazingly unlucky, if that the and I’m still not convinced.

Search for the warped disc myth. You’ll see what many brake manufacturers say about it.

What has concentricity to do with it anyway? A disc that wasn’t concentric wouldn’t cause your problem.

[anonymous-user]

Davie_GLA said:

He did say rarely to be fair but I have had it. Checked with run out gauge and beyond skimming.

Willing to bet a shiny pound it’s suspension related.

Lateral runout has several causes. So called warping the least likely.

I wouldn’t take your bet; you’re likely right.

[996Type]

Just out of interest, was an issue with discs and pads at the front of these a known issue?

Inclined to believe that something in the suspension is causing this but its also inconsistent which means difficult to trace without me literally burning through pads / discs to find out!

Thanks for all the replies, I'll report back how I get on,

[Davie_GLA]

996Type said:

Just out of interest, was an issue with discs and pads at the front of these a known issue?

Inclined to believe that something in the suspension is causing this but its also inconsistent which means difficult to trace without me literally burning through pads / discs to find out!

Thanks for all the replies, I'll report back how I get on,

no directly caused by discs, but if the suspension is worn then it's putting all sorts of foces to places it shoulldn't. The car should track true and traight with that characteristic big BMW feel.

mine was tramlining a lot and had a pull to one side. Bottom arm, droplink and spring was shot. All replaced and much better.

[996Type]

So the saga continues.
Wheels all balanced at Kwik Fit (which were all well out, surprising as car was recently geo'd).

At which point they noticed play in the brand new NS lower steering arm (which won't tighten out).

So back to garage to switch these out for new items under warranty.

So all the recently replaced suspension and brakes will have been switched in under 2 months......

[Wills2]

I've always held the view that your brake fluid will give up before your discs suffer from warping, what kind of driving (bearing in mind it's a 7 series not a sports car) would you have to do to warp the discs?

I've had my brakes fade badly many times in my M cars but never suffered from warping.

[naturalaspiration]

The discs do not warp as they are made of cast iron. It more the case of excessive/uneven.brake pad material transfer. I would just change pads for a set which is harder and it should, albeit slowly wear off the old pads deposits. Give it a few thousand miles. That's how I had finally cured my reoccurring brake wobble issue. Offender in my case were Pagid brake pads. Can't recall what I ultimately replaced them with. Now mostly sticking with Textar and have no issues.

[bigdom]

996Type said:

So the saga continues.
Wheels all balanced at Kwik Fit (which were all well out, surprising as car was recently geo'd).

At which point they noticed play in the brand new NS lower steering arm (which won't tighten out).

So back to garage to switch these out for new items under warranty.

So all the recently replaced suspension and brakes will have been switched in under 2 months......

If you can send the current discs back under warranty, you can buy original specification from here - https://www.c3bmw.co.uk/front-brake-disc-324x30-e6...

I’ve found over the years, they can be quite fussy with makes of tyres, suspension, brake parts. Meyle, Behr, Lemforder etc are all oem suppliers.

[996Type]

So.....

Another lower arm switched, 2 rear alloy cracks repaired, wheels rebalanced and MOT passed again.

Still a slight vagueness to steering above 70 (not that that will ever be an issue...) and slight rolling vibration.

BMW can’t find anything (but only did a static check of bushes etc).

I’ll book it in with an independent garage and see if they can determine anything as next step....

[996Type]

naturalaspiration said:

The discs do not warp as they are made of cast iron. It more the case of excessive/uneven.brake pad material transfer. I would just change pads for a set which is harder and it should, albeit slowly wear off the old pads deposits. Give it a few thousand miles. That's how I had finally cured my reoccurring brake wobble issue. Offender in my case were Pagid brake pads. Can't recall what I ultimately replaced them with. Now mostly sticking with Textar and have no issues.

Thanks but the vibration was so violent it was kicking the wheel out of my hands, I tried the burn off technique on the motorway and feared for the rest of the system so gave up and had them switched. Independent said same, they are fussy about parts.....I’ll get approved or known brands in the future (although my local garage but non specialist for a well known brand so not the real basic stuff....)

[996Type]

naturalaspiration said:

The discs do not warp as they are made of cast iron. It more the case of excessive/uneven.brake pad material transfer. I would just change pads for a set which is harder and it should, albeit slowly wear off the old pads deposits. Give it a few thousand miles. That's how I had finally cured my reoccurring brake wobble issue. Offender in my case were Pagid brake pads. Can't recall what I ultimately replaced them with. Now mostly sticking with Textar and have no issues.

Thanks for this, but the supplying main dealer, my current main dealer service centre and the brake disc manufacturer all reported that the discs had warped and switched them under warranty, their words. They did state hub float can allow the disc to be grabbed unevenly which can wear the disc unevenly and didn’t specify how they’d reach that position. They also said last set they would provide and if it does it again it’s not their issue, which is not particularly helpful.

[996Type]

Wills2 said:

I've always held the view that your brake fluid will give up before your discs suffer from warping, what kind of driving (bearing in mind it's a 7 series not a sports car) would you have to do to warp the discs?

I've had my brakes fade badly many times in my M cars but never suffered from warping.

I drive it like a pensioner as it’s a floaty old boat which tbf is why I bought it.

Definitely not getting loads of driving stress, an annoying issue that seems to have several contributing factors, disc, pads, bottom links, wheels going quickly out of balance, cycle around again.

It’s almost back to how I remember now before the issue crept in before Christmas, BMW states nothing looks amiss on the suspension front / good condition (but they don’t actually test drive them and wouldn’t exceed 70 even if i insisted which is fair enough).

Next step now everything is as good as it can be is to get the car to an independent to drive it and see if they can tweak the last 3%.

[996Type]

Added note, the tyres cause wear which throws the wheels out of balance so suggested balance schedule is every 5K miles! Free if no weights needed or 15 pound per wheel of work needed.....