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Is the suspension shot, or is it the run-flats...?

Discuss problems you have had or are having with your Z4
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Ala5dair
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Is the suspension shot, or is it the run-flats...?

Post by Ala5dair » Thu Nov 23, 2017 12:06 am

I am gradually falling for my Z, despite the niggles, but I am a little concerned about the harshness of the ride, which is severe at best, especially at very low speed. The front may be worse than the rear, but it’s not clear, and there is a weird rasping sound from the rear wheel area, which sounds like metal on metal, as I get out of the car.
I’ve read in other posts, that the std run-flats are awful, and I plan to replace these when necessary, but they all have over 4mm, and so I am reluctant to do this immediately.
There were no advisories on the most recent MOT, but I feel something isn’t right, and so will visit my Malvern Tyre site again, but I’d welcome any suggestion or description of what sort of ride I should be expecting?
Should I ditch the run flats immediately, given that winter is on the way?
2004 3.0i SE in titanium silver with clear third brake and side lights. Black interior.
M-Sport suspension, 18” 107 mag ellipsoids, ZHP, xenons, cruise control and stubby

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Is the suspension shot, or is it the run-flats...?

Post by Marlon » Thu Nov 23, 2017 12:09 am

The SE suspension should be quite forgiving, could be the rear springs have gone - do you know if they have been replaced?
Ditching the run-flats should improve the driving experience but more in the area of feel through the steering
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Is the suspension shot, or is it the run-flats...?

Post by Mr Tidy » Thu Nov 23, 2017 12:14 am

You can't help falling for a Z, especially a 3 litre one!

But as you say, the ride isn't great! At least you have an SE, it's worse on a Sport!

I've read so much about ditching the run-flats that I am about to do just that as I bought a set of wheels with non-RFT winters on.

It must be the first time I've been looking forward to it getting colder, so I can find out what the difference is! :)

Just a thought, but you could always get another set of wheels with non-RFTs (or no tyres) then sell your wheels with RFTs while they still have decent tread left.

My RFTs are the OEM Bridgestones by the way - I never had any problems with poor ride on my 1 Series that had Pirelli RFTs and M-Sport suspension.
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Ala5dair
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Is the suspension shot, or is it the run-flats...?

Post by Ala5dair » Thu Nov 23, 2017 8:45 pm

Thanks, both, for your comments.
My zed has had 2 health checks today, and it turns out that it has the M-Sport suspension which, when coupled with the 18” wheels and the run-flats results in the ride I’m experiencing. There is some play in both front lower arm ball joints / bushes which comes into play at low speed, so these will need to be replaced, but the suspension is generally fine and replacing the bushes is a relatively low cost job. There is about 6mm of tread on the tyres, and cash is now tight, so I’ll live with the ride until they run low, and I’ll then consider std tyres.
The noise I’m hearing when exiting is the crappy handbrake finally biting, but I’ve read other posts which suggest applying it twice, so I’m following this practise for now...
Unfortunately, the health checks exposed a longstanding rocker valve cover leak. Oil loss is minimal, and I have no stains on the driveway, so I think the leak is minor, but I have to add this to the (growing) list of things that need doing before I have 100% confidence in the car...
2004 3.0i SE in titanium silver with clear third brake and side lights. Black interior.
M-Sport suspension, 18” 107 mag ellipsoids, ZHP, xenons, cruise control and stubby

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Is the suspension shot, or is it the run-flats...?

Post by buzyg » Thu Nov 23, 2017 9:00 pm

Good to read you have your jobs in order and know biggy problems. Falling for your Zed is par for the course, I'm afraid. Personalty I know of no cure. :D
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Is the suspension shot, or is it the run-flats...?

Post by Marlon » Thu Nov 23, 2017 10:06 pm

Health check seems to have accounted for all your issues - as mentioned the Sports suspension is harder than the SE.
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Is the suspension shot, or is it the run-flats...?

Post by MACK » Sat Dec 02, 2017 7:40 am

The chances are its a combination of both. Runflats and worn shocks. Which one to do first is up to you. Both will likely make a noticable difference. A decent wheel alignment won't hurt either, just don't go to kwik fit for that.
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Is the suspension shot, or is it the run-flats...?

Post by Silverzedtom » Sat Dec 02, 2017 8:19 am

Echoing the above the runflats and sport suspension is a harsh combo. I ditched my 18” runflats at the same time as getting 19’s. Even with an extra inch of metal and a thinner tyre wall the car is so much better to drive, no more pulling to the nearest ditch and a lot less skipping at the back.

Coilovers would dampen the ride a hell of a lot better than the oem set up, but at a cost of course.
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Is the suspension shot, or is it the run-flats...?

Post by jack07 » Sat Dec 02, 2017 9:05 am

The ride quality versus handling and roadholding equation has been THE toughy for chassis designers since drivers first wanted to go faster.
Most road cars will give a reasonably soft ,quiet and cosseting ride these days,but they are mostly aimed at A to B motorists pottering about at sedate speed.Our cars are towards the higher end of the speed and capability range,so you have to forgive them the relatively harsh ride at low speed. Personally,I marvel at the trade off given by my car's ability to gobble up hundreds of miles of twisting roads at higher speedsin a day,then allow me to step out without a bad back.
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Is the suspension shot, or is it the run-flats...?

Post by Ala5dair » Sun Dec 03, 2017 9:40 pm

Thanks, all for the further comments.
I’ve now called the supplying dealer, and the car is due to go into his engineer on Weds to determine which faults should have been noticed pre-sale. I’m then expecting an offer to replace, or help with the cost of replacing, both front suspension wishbones and bushes (I’ve been quoted £375+ for OE parts by a local indie) and the rocker gasket.
Once these are done, I’m sure the ride will improve, but the indie (who’s previously had zeds) has recommended ditching the runflats, so that will be my next purchase....
2004 3.0i SE in titanium silver with clear third brake and side lights. Black interior.
M-Sport suspension, 18” 107 mag ellipsoids, ZHP, xenons, cruise control and stubby

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