5p / 50p moment.

V

Voodoo

Member
 SE Kent
Hi all,

On a private test track today at circa 140mph I had one of the above moments.

I was taking a very fast, long left sweeping bend and had the misfortune to hit a bump and dip.

I moved at least 6-8ft to the right because I hit the bump and dip. :o

WTF is that all about? Maybe I would have moved a couple of feet in my old Impreza, but this was a looooong way.

Is there some camber / rear steer issue I need to know about? How do I remedy the issue?

Cheers,
Nige.
 
Blimey, 20 views and no one's experienced the same? :tumbleweed:

Does that mean I've got a problem with my car? :?
 
WLH, true, I just about managed to hang on to it, but the air was rather blue in the car just afterwards. I really wasn't impressed.

The last time I had bump steer like that was in an old hot rod with a badly designed and built drop tube front end with a rack.

Anyone else had this rear steer issue and lived to tell the tale? :cry:
 
I was testing mine at Longcross today - hit a few bumps and well the car just rode them out fine. Fun at 120+! Sorry to hear you had a moment out there...
 
Ok, I'm thinking I have an issue here then. Anyone else experienced similar? Any ideas how I can show a tech what I mean when it has to be at rather high speed and involves frightening the beejaysus out of myself, let alone a passenger....

Maybe I just need the back end checking over...?
 
Just because it was the back end which stepped out doesn't mean the problem is there. You do have a problem though. One of the charachteristics which is most impressive about the Z4M is its neutral handling which then goes to progressive oversteer - very easy to control and fun to drive.

I have had similar issues with other cars and a 4 wheel alignment has always fixed it. I suggest you get this done ASAP.
 
So when did you move, after the bump, or in the dip, or all the way through!?

I guess at 140bhp in a bend there is lots of lateral acceleration going on, so any reduced grip which will be evident after suspension is compressed and the car pushed upwards on the bumo, and then left with upwards momentum and suspension drooping to fill the gap of the dip, will leave you with lots of time to slide wide.

It seems the Z4M is fairly stiff, so it'll pay dividends on the smooth stuff, but a bump and dip clearly are not it's forte at such speeds. The Impreza setup more for rallying and fast road use, will likely have taken that sort of thing more in it's stride.


Always worth an alignment check though I suppose :)

Hope all is ok!

Dave
 
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