I've got a 09 JCW. I got this after retiring my 05 base cooper. The torque steer in the JCW is completely manageable. What gets me down, however, is the way it really side kicks when I hit a bump while cornering. I put 80K on my Cooper and never noticed such a problem. Why does it happen so much on the JCW? Why didnt it happen on the Cooper? Any ideas on how I could remedy this?

 

I also come from an R50 Cooper, my new MCS has plenty of "bump steer", and I would like to mitigate it.
I will likely try the TSW X-brace in the near future.
The Alta PSRS is touted as a means of improving the steering response, not sure if that includes reducing the bump steer.
While the X-brace is an easy DIY, the PSRS is anything but...

 

i think its just the torque you now have in those corners that you didnt with a base cooper..
i know what you mean.. i have an 07 MCS.
for now, just hang on tight on the turns. i'll follow the post for tips.

 

I changed my tires to Non RFT and it helped. Also I brought the tire pressures down a little from the recommended 38 psi F and R to 36 psi F and 37 psi R and that helped a bit too. Then lastly, I adjusted front camber from 0 to -1.4 and that helped (you need camber plates for this).

 

I'm pretty sure it's not solely related to me having more torque to manage... I took corners pretty hard and bast in my old mini... I never felt it hopping like this one does...

 

The run flats seem a bit suspicious to me... why do you believe switching off them would help? Is there any testing info you know of?

 

Not sure what is suspicious? Basically, RFTs are hard, heavy and not as grippy. When you hit a bump with hard, heavy and not grippy tires, what do you think would happen? If you still do not believe it, look through the volumes of posts in NAM.

I would like to find someone with so much time and money that they will scientifically test bump hops.

 

Sorry for the misleading wording... I meant that I'm suspicious or runflats because they are hard, heavy and not very grippy... not your matching belief... I was asking if you knew of any review/comparison of runflats vs. regular tires... not bump hops...

relax man!

 

The DSC will also kick in and can feel like torque steer or bump steer because it is applying the breaks to try to control the car for you. I noticed it a lot at first, so at an autocross I experimented with the DTC and noticed that when you turn DTC on (push the button once) the torque/bump steer is not nearly as bad. If I tuned everything off (hold the DTC button down for a few seconds), even when your wheels loose traction you don't get any torque steer, you just spin one wheel or the other.

 

Do some work yourself and search NAM.

 

bump steer or Torque steer... one way or another the car has a lot of character.

 

Yeah, I think this is the real culprit here.

 

is a geometric effect that when the suspension is compressed it actually increases or decreases the steering angle of the side that compresses or extends. Sorry for the techno-speak. It's not a significant contributor to the handling issues on our cars (unless you put parts on that increase it).

Torque steer is more than just having more torque. It's also affected by what is known as the "scrub radius" or where the effective contact patch center is relative to the rotational axis of the strut. Anything that changes this distance will effect torque steer. Increasing negative camber tends to shorten this, hence the reduction in lever-arm and torque effects. A larger offset wheel of the same width would help as well. Wheel spacers would tend to increase the effect.

But for sure this is something that you don't have to live with (at least as much as you feel it with a stock set up). Like others here have stated, what you do with your tires, wheels and suspension can "tone it down" a lot.

Matt

 

... I have replaced OEM wheels with sub-16 lb. items and gone with sticky performance tires, and find the bump steer to be a real problem - turning + bump or pothole upsets the car something fierce, and this at steady state speed, no acceleration...

 

Was it the same with your OEM wheels? What you are seeing seems to be more pronounced than others. I don't notice any bump steer and torque steer is only noticable with hard acceleration and then its only minor. Have you tried turning DTC on and DSC off to see if it makes any difference? I guess its possible that your alignment could effect it. It is also possible that you have a broken part somewhere in the front end.

 

You know, I was just thinking about this... I never did try the OEM S-Winders and Conti all-season runflats, they were only on the car 2 days before putting the Enkeis on. (I don't much like runflats)
I will try this out, and also, if I take it to the dealer to have them diagnose if there is a problem, my feeling is with the non-OEM wheels and tires on the car, that would be an easy blame so they would not spend any time on checking out the suspension, etc.
And, one of these days I must try turning off DSC (mine has the LSD, not the DTC), although I have never noticed the light flashing, unlike my Wife's 3-series which flashes all the time when you are hard on the throttle...

 

I posted about this issue some time ago, and I think I understand the OP's experience, which is not torque steer at all. My wife's car still has that issue, and it a justacoop, no power adder of any kind. I have driven numerous loaner cars, first and second gen (I have a 1st gen cabrio myself), and the issue is there, mostly on the 2nd gen cars, both S and non S... I'd say about 1/3 of the one's I've driven had that issue, some bad enough to make them dangerous on the road.

My wife's car had it really bad at the beginning. Following a dealer realignment it was better, but still present. Bought non runflats for her last year and the problem got better still, but still there.

I could believe the DSC may be mucking with the steering on bumps, but why is it just some cars and not others? I've driven nearly identical cars, one had the problem, the other didn't. And the "bunny hop" as she calls it, feels like it's coming from the front wheels, it actually launches the car sideways a bit. It was pretty scary when she first got the car.

Daniel

 

Bump steer or suspension hop seems to be a rather common problem in the R56. It is a product of the short wheelbase and suspension geometry including unsprung weight.

I find that there are few real solutions that work well. These are a few:

1. The one that seems OK is to reduce the tire pressures especially for the fronts. I find that 36 psi is OK for me with 17" crown spokes. You could go a little lower if the problem persists (perhaps 34 psi). Remember 38 psi is what Mini recommends.

2. Reducing the weight of the tire/wheels can help the suspension react faster to bumps. I did not do this as I do not have lightweight rims/tires. Mini rims are just plain heavy.

3. The last is to increase negative camber to make sure the tire contact patch is optimized in turns. This seems to work OK for camber around -1.4 (with adjustable camber plates). I think the pin removal method to get -0.5 may help.

Anyone else try these solutions? Are there anymore that others have tried?

 

bump steer is defined as a change in toe with suspension compression or extension. It happens when the steering rack/tie rod geometry is a very different length and isn't parallel to the control arm. It has nothing to do with wheel base, weight distribution, contact patch or anything else.

there are lots of things that can result in poor steering dynamics when going over bumps in turn that are not bump steer.

Matt

Here's a good explanation, even though it's about Mustang suspenensions, it's got some graphics to help with the explanation.

 

had same thing happen w/yokohama prada spec 2's 205/45/17 just a cooper . i think its stiffer side walls. i now have s drives ,does't happen anymore !

 

I seem to find that I encounter torque steer when I give'er hard in 1st and second gears only, you just need to hold on the wheel with 2 hands. I am use to it. The bump steer does not seem to be a problem. I have a JCW with 4000 miles.

 

Not matter what you call it and may not call it, it still exists. What do you suggest to help it?

 

there are lots of things that can contribute to poor handling over bumps. There is no one sized fits all solution, that's for sure. The fact that some cars have it and some don't makes me think that starting with a good alignment is a good place to start.

But really, the best way to sort a suspension is to work with a shop that knows what they are doing. Most times, this is not the dealer, and for sure, it's not one of the cheap alignment shops.

Matt

 

I forgot the link before..

http://home.bresnan.net/~dazed/bump

Matt

 

This happens to an almost dangerous degree on my JCW clubman. If I hit a bump on a sweeper at a steady speed, i.e. no acceleration, causes the car to jump sideways and pulls the wheel from my grip. Part of my commute (287 Westchester, NY) is a white knuckle ride. I guess I will try to reduce the front tire pressure and see if that helps. I won't let my wife drive the car on the highway for this reason.