Steering and Suspension Wear.

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astropa
Joined: Wed 19 Nov, 2008 20:09
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  Z3 roadster 3.0i
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Steering and Suspension Wear.

Post by astropa »

Hi Guys

With the nice warm summer we have been having I've been using my Z3 more than ever. But over the last month or so I've noticed that the handling is not all it once was. The Z3 has always been a little tail happy but mine is far too tail happy and ive also noticed the DSC light coming on when taking just average bends at less than break neck speed. Ive started to loose confidence although im still driving the car (how can you not with the roof down in this weather?) i tend to keep the speed down and take it easy around bends.

I had the rear tyres changed a couple of thousand miles ago, and had the tracking done last year too, so i dont think that either of those is the issue. (The new tyres did make the car feel different, but not dangerous).

Im beginning to feel that my issue is something either to do with steering or suspension, maybe bushes, shocks, springs etc. Although the car had only done 50000 miles it is 12 years old and i'm aware that all of these things need replacing at some point.

Any views on what the most likely cause is? Are there any tests that i can do that will lead to a likely diagnosis?

Many thanks
Paul.
gIzzE
Joined: Mon 06 Aug, 2007 21:32
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Re: Steering and Suspension Wear.

Post by gIzzE »

Sounds more like mis matched tyres, you running the same front and rear?
astropa
Joined: Wed 19 Nov, 2008 20:09
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Re: Steering and Suspension Wear.

Post by astropa »

No. Just changed the rears as the fronts have loads of tread left.

Continentals on the front, hancocks on the rear. Could that be a bad mix?
gIzzE
Joined: Mon 06 Aug, 2007 21:32
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Re: Steering and Suspension Wear.

Post by gIzzE »

I have had a few BMWs where running different treads on the front to back gave exactly the results you have said.

Back end becomes a twitchy mess.

Not always the case, but what you describe it would be my first guess.

I have just changed the shocks and two broken springs on my z along with roll bar bushes and new drop links all round and it now feels amazing, the shocks and bushes were absolutely shot to bits, but the it was more crashy than feeling loose at the back.

When did this start happening? after you changed the rear tyres?
astropa
Joined: Wed 19 Nov, 2008 20:09
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Re: Steering and Suspension Wear.

Post by astropa »

Yes it seemed to, maybe I should look at putting hancocks on the front too.

I might also get the suspension and steering checked too just to be on the safe side :-)
gIzzE
Joined: Mon 06 Aug, 2007 21:32
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Re: Steering and Suspension Wear.

Post by gIzzE »

I would do the tyres first.

The cheapest option.
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
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  Z3 roadster 1.9

Re: Steering and Suspension Wear.

Post by BladeRunner919 »

I'd start by just swapping the fronts and rears over (assuming they are the same size) and see what happens.
gIzzE
Joined: Mon 06 Aug, 2007 21:32
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Re: Steering and Suspension Wear.

Post by gIzzE »

Yeah good thinking.

If may not make a difference, they may not like being mixed on either axle, but often it is the combo one way round they don't like, but if it does you know for definitely the tyres.
astropa
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Re: Steering and Suspension Wear.

Post by astropa »

No the fronts and rears are different size wheels and hence have different size tyres.

Fronts are 225, rears 245
Del
Joined: Sat 19 Nov, 2011 18:35
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  Z3 roadster 1.9

Re: Steering and Suspension Wear.

Post by Del »

According to my handbook, if the car has 8.5J X 17 wheels on the rear and 7.5J X 17 wheels on the front, the BMW factory tyre recommendation is 225/45 X 17 on the front and 245/40 X 17 on the rear. From what you suggest, this is what you have. If the back end of your car is losing rear traction, during dry weather, on bends - even though you have new tyres, I would definitely suspect rear suspension components. I would closely check the springs to see if a typical bottom coil has broken away, the shock absorbers and ARB droplinks. The deterioration of the latter can be age related with the rubber bush holding it to the ARB shrinking and cracking with age. They have even been known to slip of the end of the ARB altogether.
astropa
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Re: Steering and Suspension Wear.

Post by astropa »

Hi for those interested in tyre choice and handling I thought I'd give an update on my tyre change issue.
Problemz started when I changed my worn rear continental tyres for new tyres by hankook. Handling although not dreadful was just not as good. Well before my mot is due at the end of this month I decided to swap the fronts and again chose hankook, the same model number but slightly different size to the rears. Result the car handles much better than it did with split tyres makes between front and back but not as good as it did with continentals at each corner.

Speaking to the chap doing the fitting, who seemed to know his stuff, he said that rear wheel drive cars drive better with non directional tyres, the hankooks being a directional tyre. I should have asked him if the contis were non directional but forgot. He mentioned that the car probably handled better with the contis as it was prob set up to run on them.

Anyway the car is handling much better and as some have mentioned on this thread, it's probaley always a good strategy to have all four tyres the same when it comes, to manufacture, model and age. :)

Paul.
gIzzE
Joined: Mon 06 Aug, 2007 21:32
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Re: Steering and Suspension Wear.

Post by gIzzE »

I have been banging on about this for years.
BMWs can become a complete twicthy mess on mixed tyres front and rear, if you have to mix at least keep them symmetrical or asymmetrical all round.

I wouldn't say that symmetrical tyres are necessarily worse than asymmetrical tyres, but probably the fact you have gone to a Hankook.

I find Michelin asymmetrical the best tyres on BMWs for handling and a nice progressive grip, the don't snap at the back when you press on, you can really feel as it starts to go.
Put a symmetrical tyre on and you loose that, they can actually grip at higher speeds, but when they do let go they can bite you and really go. :D


No point having a performance car or something sporty and then ruining it by mixing tyres imho, you may think it feels fine, but I have yet to be in a BMW with mixed tyres front and rear where the traction light doesn't at least come on more, and that shows it doesn't like it.
siwilson
Joined: Fri 19 Jun, 2009 09:54
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  M roadster S54
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Re: Steering and Suspension Wear.

Post by siwilson »

100% agree with the above statements regarding mixed tyres. I have just been through months of this and loads of mucking about trying to cure a handling issue. I would normally have looked at tyres first but didn't in my case since I was only moving the rears from Goodyear Asym 1 to Asym 2. This absolutely wax my issue. Asym 2 is a totally different tyre to Asym 1 so much so that Goodyear really should have called it something else. Not a bad tyre, just different and different is bad on a Z3.

I am not sayin mixed types is guaranteed to give you handling issues, but if you have a handling issue and you have mixed tyres then this is the first place to look.
2001 M roadster S54 Laguna Seca Blue
astropa
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Re: Steering and Suspension Wear.

Post by astropa »

Yes, my traction light was coming on with the mixed tyres when taking bends at even quite modest speeds. Does not come on now unless I really boot it. :)
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