I've now switched away from the run flat scam... the 'tires' are like driving on iron rims... my problem is now gone. Thank you BMW for ripping me off...

 

You really think that people who just paid 30K+ for a new car should be expected to 'work with a shop' to fix the problem???

 

pretty much every high torque front driver had torque steer issues. Really stiff chassis set-ups get upset when going over bumps in turns. That's just the nature of the beast.

Every car I've ever owned has some design compramises that I didn't like. I had a couple of choices: Live with it, work on it, sell the car and move on.

Pretty much every review of the R56 turbo has mentioned that torque steer is an issue, and only gets worse with the JCW. Sure it sucks, but it souldn't have been a surprise.

Matt

 

What's unknown is what the roads are like that people drive on when they notice this. Some people drive the same routes every day and it happens a lot. There's one curvy road that I have driven that results in bumpy instablity and I remember it well. But not many roads do it to me or bother me. I probably have the same car as others (factory rims, non-RF tires) and have done nothing except a swaybar to the suspension. I do 38 psi pressure front and rear. I think it really boils down to the roads you drive on. If they are bad the car is rough.

 

Dude... Have you read the thread??? This is not torque steer! This problem happens at 40mph while coasting around a corner. This has nothing to do with torque steer... really.

 

Until changing my tires, this happend on every road. If the road was smooth, and I was on a corner, and I hit a bit of a bump, the car jumped violently to the side...

 

I guess you missed the part about stiff chassis and how they react.

Look, the run-flats make it worse. Are you still driving on them? Getting rid of them will help, as others have mentioned.

The allignment specs from the factory aren't great, and the dealers are more sloppy than performance alignment houses, one shouldn't have to go to fancy aftermarket places to fix issues on cars out of the box, but remember that what is delivered from the factory is quite the compramise. Is it the compramise you want to live with?

I've found that bitchinng at the dealers rarely gets the satisifaction that I'm looking for, and I have to take it upon myself to get the results I want. Shouldn't be that way, but in my experience it is.

So, you're back to the same three choices: Live with it, do something about it, sell the car. This is true whether I understand what the thread is about or not.

I've also found that by working with a performance suspension/allignement house (I use Custom Alignment in Mountain View, CA), I pay more but get much better results and an education every time I go there and talk with my tech. For anyone with anything remotly resembling a sports car, I really reccomend starting a relationship with some experts in handling. Yes, it costs more, but every car I take there becomes a more pleasurable drive as a result.

Let's assume for a moment that I'm the idiot that you think I am (no big deal, I've been called worse by many). What are you left with?

1) A couple of suggestions of things to try.
2) A suggestion to work with experts on handling and suspension.


Matt

 

Slinger688:

• 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).

COKen:

• 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.

Slinger688 (again):

• I think the pin removal method to get -0.5 (front camber) may help.

ricbow:

• 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 !

jrs66:

• I've now switched away from the run flat scam... the 'tires' are like driving on iron rims... my problem is now gone.

So what's this all mean? Seems to be the consensus is chassis dynamics (and fwiw, this is NOT bump steer):

Things to do without aftermarket parts:

1. Alignment
2. Lower Tire Pressures
3. Pull pin and get a bit more negative camber. (if you're gonna do this, do it before getting your allignement)

Things to do with aftermarket parts:

1. Softer sidewall tires.
2. Camber plates and custom alignments.

There you go!

Matt

 

Matt,

Thanks for the well constructed synopsis... Lot of valuable info that people will undoubtedly will google for...

I've dropped the run flats... interested in what 'Pull pin and get a bit more negative camber.' means... does this mean i have to install some aftermarket camber plate? Will it violate my warranty? Dont mind paying for an aligment if it will help stabalize a bit.

thanks

ps... my pretty R112 JCW wheels are all stacked with balancing weights...

 

that locates the top of the strut guide to the strut tower. You can pull this out with some pliers, looseing the three bolts, and move the strut guide plate in a bit. Basically, you're moving all the slop over to one side to get the top of the struts a bit more inward.

I honestly don't know how much of a difference it will make, but if you're going to get an alignement, might as well do that first.

Personally, I'm a very big fan of camber plates. It was my very first mod on my car long long ago. I do live in hills so a lot of my driving is on curvy roads, so more camber didn't increase my tire wear, it actually almost doubled tire life...

Matt

 

I changed my Tires from Bridgestone Potenza to Yokohama A048 and lowered the tirepressure to 1.8 with cold tires and *shazaam* the bumpsteer was gone !

 

As in 1.8 bar = 26psi? Seems like low tire pressure, MINI recommends anywhere from 33 - 37 psi.

 

yea - but the warm pressure rises up to 2,4 bar with warm tyres on track. but I have also increased it now to 2.0 bar with cold tyres and its still not so much bumop steer as it was before I changed the tyres.

 

Basically RFTs ability to run flat is contributed to its very stiff sidewall design, needed to keep the overall tire structure maintained when flat. The plus side of stiff side wall is sensitive steering response and sharp turn-in, unfortunately the opposite applies ie: potholes are felt through the wheel, instead of being absorbed like non-runflats. In "rough" corners the stiff side wall design contributes to the bump steer. Even the stiffest side wall structure in todays NON-runflat "auto-x" type tires is more flexible that RFT. RFTS are not the culprit of the "bump steer" but changing to non-runflats will help mitigate effects of bump steer. Bridgestone and BMW just announced a 3rd generation rft to address these issues, and several car magazines praised the improved technology, but said they still got a ways to go. This is not much of an issue for me anymore since I'm in CA but when I lived in NY and Philly near NJ it was BAD. Coming off exits road has som expansion joints/ribbed design (not for my pleasure) that nearly would take me off the road.

 

opps