For the next month we will be taking a different route home on the new M8 where I am regularly doing over 70mph and there is something very wrong at the front.So much so that I was worried that perhaps Cooper's had left the wheel nuts loose on the front left wheel or there was some foreign body preventing the wheel seating on the hub properly!
Below about 40mph there is nothing, but I start to notice a vibration about 50 and by 75 it is a noisy drone and vibrating the steering wheel a bit as well. I'm pretty sure (but it's so hard to be certain!) that the noise is coming from the front. Braking hard at speed makes the vibration much worse.
So last night worried that I might have loose wheel nuts I whipped both front wheels off and did an inspection. I couldn't really find anything to be honest.
Wheel nuts were tight, both front discs seem to be spinning perfectly true on the faces, so aren't warped, (although they both look a bit glazed and seem to have some micro pitting) both calipers are releasing properly with no grabbing, although there is the tiniest bit of drag where the pad is touching the lip on the inside edge of the disc - and as the lip is not perfectly round it doesn't drag for the whole rotation, but I highly doubt this is the vibration I'm looking for.
I also checked for play in the drop-links and track rod ends but couldn't find any - however I'm notoriously bad at finding worn ball joints, and the drop-links were probably under tension as I'm pretty sure the right drop-link is worn from the clicking and rattling it does yet I couldn't detect any play in it...
I put everything back together and the problem is still there this morning.The front suspension is ultra simple on this car - McPherson strut, bottom A arm with rubber bushes, drop-link and track rod, that's it. No drive shafts etc as it's rear wheel drive.
Could it be a wheel bearing ? I don't hear or feel anything at all below 40mph, so that would tend to discount a wheel bearing ? I've only ever had one wheel bearing failure in all my cars so I'm not attuned to how they sound but I would have thought I'd hear it at lower speeds too as a droning noise.
Wheel balance ? Brand new "balanced" tyres on the front, but could they have made a mistake ? There was an imbalance at the front before on the old tyres but it actually seems worse now.
One thing I did notice in last nights inspection is that both front wheels especially the left one have a lot of balance weights on them. More than I have ever seen on a wheel before.
On the left wheel it literally has a continuous line of adhesive balance weights around about a 30 degree rotation of the wheel.
Then on the opposite side of the wheel about 20 degrees worth of continuous weights... That can't be right surely... The right wheel doesn't have as many but still has a lot, and has two opposing rows of weights as well. (Why ?)The worst vibration is around 70-80mph which would be typical of an imbalance, but if it was a wheel imbalance would braking hard cause the vibration to get much worse ? Perhaps due to throwing more weight onto the front tyres, which are normally lightly loaded as the car is rear heavy ?
I think the next step is to take it back to Cooper brothers and see if they will re-check the front wheel balance for free because I really don't think it can be right. I should not be noticing a vibration on the steering wheel and the excessive number of balance weights reminds me of the times that the Xantia wheels were incorrectly balanced - they (another company not coopers) were adding a lot more weights than they should have due to a wrong reading from the machine.
One other thing I noticed is that when I first picked up the car and took it for a test on the motorway I could have sworn that there was no vibration, and yet after a day of driving the vibration was there. I notice they put a lot of black lubricant on the bead of the tyre - it looks like unset black silicon sealer, and there is enough that it is spilling out of the gap between tyre and rim - is there any possibility that excessive braking or acceleration shortly after the tyre is fitted could cause the tyre to slip on the rim and lead to the wheel being unbalanced again ? (Assuming some of the imbalance is tyre and not just the rim)
While I was in there I also looked at the droplinks - tiny little things, but the nuts are quite badly rusted so I think they will definitely require the services of Mr A Grinder to change.
