instability at speed
- Thread starter gonads
- Start date
I can't really compare mine as it's sat far from standard geometry wise, but as you suggest it's at speed on motorways. It could be the road surface, the z4 can be very sensitive to grooves etc and they skit about.
I've had mine upto 140 ish (private road/strip) and it felt very stable, but I think that could have easily different depending on road surface condition
I've had mine upto 140 ish (private road/strip) and it felt very stable, but I think that could have easily different depending on road surface condition
Thanks for all the ideas above, they give me more to go at. The wheels are as they came from the factory, the tyres were fitted as a set and all appear to be wearing evenly although I will measure the tread depth. Above the speeds in question (not in this country), the car reverts to its normal planted solid self also, if you apply some lock (motorway bend, slip road etc.) the oscillation stops. This does make me wonder if some aero/loading combination is inducing the steering to overreact in some way. Is the steering's input sensitivity adjustable? Either way it's niggling in the extreme.
There is a lot of trial & error regarding Z4s & this "twitching + tramlining " issueFast3000 said:
i pxd a set of 17inch alloys today with a Z4 fella who described the exact same tendencies as OP before we did the switch , both sets OEM 17s his current tyres were Firestone almost new fronts & Dunlop 6mm rears
I suggested trying the Firestone runflats on the rear & the Dunlop runflats on the front
A PM within a hour to say the problem had disappeared , its pure trial & error with no definitive answer .
He had visited a garage earlier in the week regarding the problem who had said to switch all the bushes for polybushes & this would cure it :wink:
BranNubian said:
+1 Mine was like this for a while when i first got it (Twitchy on high speed turns).Turned out to be a broken spring.
Only the top coil had broken so it still sat right visually.
Changed both Springs, which took a couple of hours and BINGO problem was solved .
Have you had the front wheel balances checked ? I had mine done when I had an alignment recently and they both required 20g weights. Chap said that a lack of 20g would definitely be noticeable and sure enough my own wheel wobble at speed is all but gone. Wheels can lose a weight of course, but what I didn't know is that balance can also change as tyres change shape and weight with use. Probably what happened to mine as I needed the same on each side.
I had all wheel weights removed and then re balanced to no effect. I have been wondering if this may be a bit of strut flutter as used to affect some fords at certain speeds in the 1960s, when all else (suspension/steering wise) was in good condition the remedy was to replace the front struts.
The oscillation was present prior to the fitting of the poly bushes and was unchanged. I had them fitted mainly because turn in was always too soft (rubbish compared to my previous s2000). they gave an excellent result with no deterioration in ride or noise. They've been on for about 10,000 miles now.
gordongecko500
Member
Hi
Sorry I can't help much but I am reading this thread with interest - I have a 3.0Si coupe 2008 with 49k miles - I have had the oscillating problem on and off from the day I bought it. It's irritating but I still have RFTs which I will be swapping out next year. I've driven a number of bmw over the years but the zed is very twitchy. it may have a top speed of 155mph but I'm not sure I'd want to ever go there due to its unpredictability.
Still love it though!!
Sorry I can't help much but I am reading this thread with interest - I have a 3.0Si coupe 2008 with 49k miles - I have had the oscillating problem on and off from the day I bought it. It's irritating but I still have RFTs which I will be swapping out next year. I've driven a number of bmw over the years but the zed is very twitchy. it may have a top speed of 155mph but I'm not sure I'd want to ever go there due to its unpredictability.
Still love it though!!
Hi,
Just another thing to try, have you had the wheel/tyre assemblies road force balanced?, I had a similar issue on an X type I had (65-75 mph oscillation thru steering wheel and a feeling of instability, gone again at 80+). Normal balancing showed no problem, after the RFB all was good again.
Stu.
Just another thing to try, have you had the wheel/tyre assemblies road force balanced?, I had a similar issue on an X type I had (65-75 mph oscillation thru steering wheel and a feeling of instability, gone again at 80+). Normal balancing showed no problem, after the RFB all was good again.
Stu.
I had similar symptoms at motorway speeds with the steering feeling very vague with a tendency to wander. I've just had my e86 aligned on a hunter setup and its very much improved. Would recommend you look into a reputable place as most don't charge for the alignment check and then have set pricing per adjustment.
If you are anywhere near Leeds/York/Wakefield then I'd recommend Bram Racing in featherstone.
If you do get it done, make sure they weight the car correctly before checking/setting up.
If you are anywhere near Leeds/York/Wakefield then I'd recommend Bram Racing in featherstone.
If you do get it done, make sure they weight the car correctly before checking/setting up.
Gonzo said:
Cheers for that but I've tried that, it did cure a bit of back end wander in high speed bends but had no effect on the steering oscillation. I'm beginning to think that I'll just have to start replacing the front end one bit (or pair of components) at a time to see what works.