Rear wheel excessive wear

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chris1984_99_99
Joined: Sat 01 May, 2010 17:24
Posts: 200

  Z3 roadster 2.0
Location: Troon

Rear wheel excessive wear

Post by chris1984_99_99 »

Hi all, I seem to be having a real problem with the Z3. The rear tyres are wearing out at an extremely excessive rate, after about 5000 miles the tyres are bald...and I mean bald!

The other day I was getting the car sprayed with Waxoyl for the winter when the guy doing it said the rear tyres were completely flat. I never thought of checking them so soon as they were only fitted about 5000 miles ago, but when I looked I was shocked to see how far gone they were, one was through to the wire mesh! Wearing out faster on the inside.

Ive had this problem for a while with the car, but it actually seems to be getting worse and im at a wits end at to what it could be! The only way I can manage it at the minute it by sticking a pair of cheap tyres on the back every so often.

My question is has anyone ever had this problem before themselves and what was the solution? My fear is the car has maybe had a jolt, been involved in an accident in the past and or hit a big pot hole and some damage has been caused.

As far as im aware there is no adjustment on the back wheels of the Z3's and every garage ive been to has been stumped as to what it could be!

Any help would be much appreciated guys!
Thanks
Chris
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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Rear wheel excessive wear

Post by Del »

Very worn rear shock absorbers can cause excessive wear as well as uneven wear as the wheels will tend to "bounce, skip and scuff". Lowering the suspension can cause more wear on the inner section of the rear tyres as well. Shock absorbers will be on the way out after 70,000 miles and for a standard Z3 a new rear pair (e.g. Sachs) can be bought for under £100.
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Deano1712
Z Register organiser
Joined: Sat 05 Aug, 2006 12:56
Posts: 1396

  M roadster S50
Location: Leeds

Re: Rear wheel excessive wear

Post by Deano1712 »

Is it both tyres wearing at the same rate, in the same place? What tyre pressure do you use? Is the car lowered?

Its worth having an alignment check done to see if the rear toe in is right. You could always try a course check with a string from the front tyres to the rear, to see if both rear wheels are pointing in the same direction. You can also check the camber angle with a spirit level and rule, to see if both side have similar camber. If there is something out far enough to wear the tyres out quickly I think it should be easily spotted.
Z3M with a few mods...and a little bit more power
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chris1984_99_99
Joined: Sat 01 May, 2010 17:24
Posts: 200

  Z3 roadster 2.0
Location: Troon

Re: Rear wheel excessive wear

Post by chris1984_99_99 »

Thanks for the reply guys and apologies for me taking so long to get back!

I think the shock absorbers and or springs may be one road to take to trying to sort this out. Am I correct in assuming its best to replace the springs if the shock absorbers are to be replaced? Also a little nagging thing I might get sorted aswell is a slight whinning noise coming from the rear, im guessing it could be the bearings?

Can anyone suggest a retailer to get the parts from? So far ive looked on ebay and euro car parts and the best I can get the shock absorbers for is £88 posted for the pair. I think however I will wait for the winter (and salt on the roads) to pass before fitting new parts to the underside of the Z!

Thanks again for the advice and help guys! Its really appreciated!!
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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Rear wheel excessive wear

Post by Del »

It is not necessary to automatically change the coil springs when changing the shocks. If the springs are in good condition i.e. not broken or damaged and still have most of their black coating, then they can be safely retained.

Assuming you are happy with OE equivalent shocks then Carparts4less offer a rear pair of Sachs for around £70, after their discount, for your car.

http://www.carparts4less.co.uk/?gclid=C ... tAodpB8AEw

It’s good practice to change the shock top mounts at the same time and many Z3 forum members (including me) have used the Meyle ones.

http://www.ebay.co.uk/itm/BMW-3-E36-E46 ... 565cac3797

Difficult to gauge what a whining noise at the back might be. A wheel bearing makes a pronounced rumbling noise that gradually gets worse over time and it is generally possible to make out what corner it is coming from. On the other hand the noise you are hearing might just be the usual, slight mechanical “whirring noise” coming from the differential at the rear. Like some owners, I can hear this slight differential noise, at higher speeds with the roof up, other owners say they are not conscious of any such noise. :shrug
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: Rear wheel excessive wear

Post by Southernboy »

The "whining" from the rear is likely to be the differential. If you consider your normal seated position in z3, the diff is quite literally about 2 feet behind you under the car. I have had an issue with the BMW diff whine, and if you google the issue, you will gather it is a universal problem. The fact that some people don't seem to hear it as much as others may be due to their hearing being not being sensitive to the pitch of the whine or they are simply blessed with quiet diffs (quite unusual according to the numbers of "complaints" about the BMW diff). The solution to the problem is sound proofing. I have known guys that have spent thousands here in SA in attempting to have the diff machined, mechanically doctored etc etc in an effort to silence it...and to not much avail. Most of the sound is able to be elliminated by sound proofing the boot, especially the metal body wall directly behind the seat. I have lined the entire boot interior with "builder's flashing". Flashing is a thin membrane of aluminium which has been coated with aprox 2mm of Butyl. It generally comes in rolls and is easy to apply, shape and trim to your requirements. It provides a value for money and reasonably effective soundproofing solution, although not 100%. I did this, and undoubtedly it improved matters. Ultimately, I also replaced the OEM boot carpet trim with "real" carpeting vs the almost cardboard-like stuff which comes as standard. This has practically elliminated not only the diff whine, but also general road / tyre noise from the rear.
A pleasant side effect is the improved quality of the volume / clarity of music from the headunit / speakers. A worthwhile effort IMO... :wink:
"Normal is overrated"
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