I just had StopTech's Big Brake kit professionally installed (by a BMW performance shop) on my Cooper S, along with SSR Comps and Michelin pilots.

Now, I get pretty severe torque steer (alternating left and right) under acceleration, especially in 1st and 2nd gear. It's particularly bad if the wheel is slightly turned on takeoff. I took it back to the shop and they checked all the obvious things: alignment, tire pressure, etc. and everything looks ok. The suspension is stock. They have performed the same setup on 10 other cars with no negative results. They are at a loss to explain it.

Before I added the brake kit, there was absolutely no torque steer.

Any ideas?

 

Did you have the SSRs and tires on the car prior to the BBK install? There is a chance that the new wheel/tire combo could be the cause if you didnt have them on prior. I went from s-lites/runflats to SSR Comps and 215/45-17 GS-D3s with no ill effects in torque steer, though there is a new (and to me preferred) "lightness" in the steering due to the reduction in unsprung weight.

 

simple answer... your rims are very light, so you will spin tires alot easier. putting such light rims on is like adding HP to your motor...

i have light wieght 17s and man my car dances all the time when i gun it hard in first and second. keep in mind my rims arent anywhere as light as the SSR comp.

 

I think it's got nothing to do with the brakes. But I do have a guess.

It could be a deflection in the front suspension allowing the alignment to change under load. If the toe changes, it will pull to one side. You said it sometimes pulls to one side and sometimes to the other. I think you're experiencing it now as a result of greatly reducing the rotating mass by lightening the tires and wheels. The additional effective torque to the ground may be enough to expose a weakness in a bushing or other suspension link.

If the static alignment really is OK, then it's changing under load. Lighter tires and wheels are allowing you to place additional load on these components.

Let us know what you find out.

 

Another thought just occurred to me. I feel something under hard acceleration while steering that could be described the same way. When I first read this post I was thinking of relatively straight line acceleration. But if we're talking about accelerating and turning at the same time, that may be different.

Since I changed to SSR's and GSD3's after 100 miles, it's been this way from the beginning for me. I've just always thought it was a normal behavior for a powerful FWD car accelerating and turning at the same time. It kind of hunts and pulls. You gotta be careful with the steering.

Now I gotta know, too. Is this something that's common to powerful FWD cars?

 

You mean to say, before you added the brake kit, wheels, and tires, you didn't notice any torque steer. Scrub radius, camber, caster, and tire tread shape play the biggest roles in adding "torque steer" and "tramlining" to otherwise well-designed front suspensions on FWD vehicles (i.e. the MINI). The brakes didn't change a damn thing.

 

I do have SSR and Stoptech BBK and I do have torque steer but since my first mod ( coilovers ) not affiliate with the SSRs and BBK.

 

How much torque steer can be expected as we make mods to our MINI's?

 

Whats your tire inflation pressure set at?

Alex

 

jwilson1,

Torque steer is minimized in a stock MINI but does exist.
Your big brake kit upgrade is not the main cause. The much lighter than stock SSR comps are. The Michelin Pilots are average for tire weight.

What size wheels do you have with the SSR comps? What wheels did you have before? Stock 17" S-lytes? If so, put the stock wheels back on and see how the torque steer feels.

Wheels need to be straight when launching your car with lighter rims. The MINI has equal length shafts to minimize torque steer but it can be revealed.

When I added the Quaife differential to my MCS I could tell that there was much more pull on hard acceleration. You get used to it; firmly hold the steering wheel and apply throttle more smoothly. I hardly notice anything now whether on the street, at autocross or at the track.

Do you also have a reduction pulley upgrade? ECU upgrade? These would add more torque and power and reveal more torque steer.

 

Yep, I have a factory LSD as well. It's beginning to sound like a bit of torque steer/feedback through the steering wheel is normal operation especially as we do things to add to the power we can put to the road. You definitely want to have a firm grip on the wheel when accelerating and turning in the lower gears, but as minihune said, I think you get used to it.

I'm still hoping to hear from some of the owners of more heavily modded cars to see if there comes a point when this behavior becomes objectionable.

 

[QUOTE=minihune]jwilson1,


What size wheels do you have with the SSR comps? What wheels did you have before? Stock 17" S-lytes? If so, put the stock wheels back on and see how the torque steer feels.

Do you also have a reduction pulley upgrade? ECU upgrade? These would add more torque and power and reveal more torque steer

The previous wheels were stock 17" but I can't put them back on without removing the StopTechs. The engine has several mods, pulley, ECU, head, exhaust, and cam, so I'm sure that's contributing to the problem. It's just that the BMW performance shop has done at least 10 other cars without anything this severe. Applying the throttle more smoothly helps but I'm not sure I want to take the car on the track until this is figured out. And that was the whole reason for doing it in the first place.

 

[QUOTE=jwilson1]You haven't mentioned anything about suspension mods. Have you installed new springs? Lowering without adjusting the camber setting will introduce torque steer because of the altered alignment.

Wider tires will also induce more tramlining which can feel like torque steer as you motor over uneven pavement. The pavement near intersections can develop ruts for each lane of travel and as you cross them the car will shift or pull from side to side. This would be where you are in first, second and possibly third gear.

Changes in tire construction can change the amount of tramlining that is transmitted to the steering wheel.

 

I have sub 11 pound wheels, and I noticed this "lightness" and tugging immediately. As someone said earlier, tire pressure, even with just a little of a delta will make for a bigger difference now. And yes, as mentioned above, an alignment that is slightly off will be magnified. Other than that, more torque does make for the possibility of more torque steer...

 

Quote:

Originally Posted by TonyB

I have sub 11 pound wheels, and I noticed this "lightness" and tugging immediately. As someone said earlier, tire pressure, even with just a little of a delta will make for a bigger difference now. And yes, as mentioned above, an alignment that is slightly off will be magnified. Other than that, more torque does make for the possibility of more torque steer...

I copied this from mini-madness.com.



Under its stubby hood, the Madness Mini had a supercharger drive pulley that upped the blower speed by 15 percent, raising boost from 11.6 to 15.0 psi. Further mods include a ported and polished Madness Stage 3 head with big valves and a Schrick cam, a throttle body bored out from 58 millimeters to 63, a header, and a Borla exhaust system. Larger injectors and a modified ECU added fuel to match the engine's deeper breathing.

Mehallick credits the modified engine with 245 horsepower at 7100 rpm and 198 pound-feet of torque at 4000 rpm. To transmit this big twist to the wheels, the Madness Mini came with a modified flywheel and clutch, as well as a Quaife limited-slip differential.

The extra power comes with a comprehensively reworked suspension, including KW adjustable coil-over shocks at each corner that increase ride rates and lower the car nearly two inches. Several major components are adjustable, including the rear anti-roll bar, the rear lower-control arms, and the front camber plates. Big StopTech front brakes and upgraded rear discs shed speed when necessary. On the street, this muscular Mini's powertrain felt solid and robust. The clutch engagement was smooth and progressive, the power curve was glitch-free, and the car suffered amazingly little torque steer, even at full throttle in first gear

 

I think what you are experiencing is one or the other front wheels getting more or less traction under load. that can cause the rubber suspension bushing to compress differently, side to side and moment to moment as traction conditions change increasing the problem by fiddling with toe. I observed on my own car and a few others that under a hard launch, the wheel will hop front and back as the control arm bushes and strut tower bushes compress and relax. I addressed this by beefing up the bushings and adding nylon ball camber plates.
torque steer is typically caused by wind-up in the driveshafts under applied power and torque; if one side is longer due to the location of the trans axle, it will wind-up more and cause TS. Mini deals with it by adding a make up shaft of thicker material on the long side so the articulated portions of the driveshafts are equal length. Anything that loads one side differently than the other can cause the same steering symptoms.

Bump steer is even nastier; with this condition, the toe changes under up and down suspension travel. bump steer can not be tuned out with bushings, only tie-rod location and hub/strut geometry, fortunately, I measured this to be near-zero in the front (under the full range of shock travel, toe did not change significantly). in the rear though, there is some toe change with travel. (info buried somewhere in Mini2).

from jan '03:
http://www.mini2.com/forum/showthrea...ght=bump+steer

 

Oneother thing to look at is wheel offset. This will change scrub radius. Any other effect will be due to decreased mass and moment of intertia, especially if you didn't change anything else when the install was done.

I think Motor Trend actually had a usefull article in the current issue (the one that has the comparison of the Mustang and Nissan 350, the Corvette and Maserati and one other.....) looking at front, rear and all wheel drive, slip angle etc. There is a trade off in scrub radius (higher increases both steering wheel feedback and torque steer), so most font drivers use the equal lenght half-shafts like JLM mentioned, along with a slight amount of scrup radius to maintain tactile feedback.

Matt