How much horse power can be generated before the torque-steer becomes a
issue during spirted driving or autoX ? just a thought.

 

You can add an aftermarket intake. Maybe an exhaust too. That's about it. I'd say any more than 10 horses and torque steer becomes an issue. Add a 15% pulley and it becomes a serious issue. Go a step further with a 17% or 19% reduction pulley and you now have a torque steer problem. Add an ECU on top of that setup (any day now, right Eric?) and you've got a serious torque steer problem! :smile:

 

What torque steer? Just hold on tight, with it's equal lenght half shafts, torque steer is minimal on the MINI, on the other hand wheel spin and now with my 19% wheel hop too, can be a problem.

X2

 

I agree, ... the torque steer on the MINI is MINImal due to the
equal length half shafts and confirmed by the seatofthepants sensor.

 

I have Webb Motorsports 200HP package, and the torque-steer is only marginally increased from stock, which is negligible compared to any of my previous front-drive cars.

I'd guess 220-230HP is the area where the MINI will start to get a case of "stiff [steering] wheel" during on-power cornering.

$0.02

 

I have yet to hear a persuasive explanation as to what causes torque steer and, more specifically, why having equal length drive shafts is the cure.

Granted, if one shaft is longer than the other than it will twist more than the other while transferring power. But this would occur during steady state speed as well as during acceleration. Yet torque steer is generally considered an acceleration phenomenon. Besides, how much twist can there be in a fairly beefy appearing drive shaft...

Any automotive engineers out there???

 

Add a 19% pulley and you'll be fighting with the wheel to keep your MINI straight - I guarantee it! The reason why the stock MCS has very little torque steer really isn't because of the "equal length driveshafts" as MINI would like us to believe. It has much more to do with the fact that the MCS is fairly low on low-end torque and that's what creates torque steer. So this brings us to another question I guess - how much torque can one add before torque steet becomes a problem. I say it probably starts with the 17% pulley and there's heavy torque steer with a 19%.

 

>>Add a 19% pulley and you'll be fighting with the wheel to keep your MINI straight - I guarantee it! The reason why the stock MCS has very little torque steer really isn't because of the "equal length driveshafts" as MINI would like us to believe. It has much more to do with the fact that the MCS is fairly low on low-end torque and that's what creates torque steer. So this brings us to another question I guess - how much torque can one add before torque steet becomes a problem. I say it probably starts with the 17% pulley and there's heavy torque steer with a 19%.
>>
>
I have to disagree with you on this one, torque steer is caused by unequal power distirbution, with equal lenght shafts, this is not a problem with the MINI, my old Pontiac Bonneville was a torque steer monster, with only 170hp at the crank. If I launch my car just right, with minimal wheel spin, I have no problem maintaining a straight line in flat out acceleration.

X2


_________________
Men that drive MINIs have no shortcomings to make up for.

 

that's what i'm talking about, put a good question out there and get some
people thinking about it.It's all about making the driving experience something
to talk about

 

All,
Am confused about what it is, exactly, that people have experienced as torque steer. I will explain:

I could once provoke a small amount of directional change while going exactly straight ahead when ever I would very abruptly get on and off the throttle in 2nd or 3rd gear at 3500 to 4000 RPM. The most violent directional changes would come if when turning a corner, I would do the same thing with the throttle. Sometimes, these changes would be down right frightening. On the skid pad, in a steady state condition near the limit of adhesion at about 50 MPH, I could get the chassis to oscillate from side to side, "yaw instability", as I gently changed throttle settings.
My friends tell me that they are surprised to see just how much their MINI engines move in all directions in the engine compartment and how much the drive wheels move from side to side while observing their MINI's on a rolling road dyno.

The above experiences suggest that there is considerable compliance in the motor mounts and engine stabilizers, the front compliance bushes, and the rear control arms and rear compliance bushes. As a result, there are probably a number of different torque steer modes with MINI, not just the plain old straight ahead torque steer mode.

Went on an anti-torque steer crusade to stabilize my chassis. I replaced both engine stabilizers and the driver's side engine mount with a combination of Delrin bushes and the yellow PowerFlex poly inserts. In the rear, I installed heim jointed lower rear stabilizer bars and, for the front, the M-7 Delrin/bronze compliance bushes for the front "A" arms.

Now, I can no longer provoke much if any torque related directional changes no matter if I'm going straight ahead, turning a corner or on the skid pad, 15% or 19% pulley. Am very pleased. The predictable handling inspires confidence and I am no longer afraid of my car the way I once was.

Any comments from those of you with thoughts on torque steer?

Regards,
John Petrich in Seattle

 

I'm kind of surprised at your reply greatgro, for I have exhaust, intake and pulley and torque steer isn't an issue, let alone a problem. The only time I can have the tires lose its track is in the 1-2-3 shifts, and that is shifting very hard, but it's still not an issue. If you got bad tires, or in the rain, of course it's going to be worse but overall, I have to say the power is not a problem at all at this point. I suspect when I get the ECU upgrade which should add as much power as all these 3 mods combined, then it may become an issue of some sort. :smile:

 

Petrich has it right on. I have changed out all my front end rubbers to stiffies: control arm bushes, steering rack, engine and trans mounts, top strut bearings carriers,and it is a huge improvement. I especially noticed the front wheel hop at hard launches which sems to have been improved.

I am waiting to do the rear.

Another factor is the LSD which will tend to equalize traction.

I have never noticed a tendency for my car to try and steer under hard throttle when aimed straight; that would be traditional torque steer.
Turning and using power is another matter. More hp will increase the effect, which is for the car to try and straighten out the front wheels, so you have to hold on to the steering wheel. In this case, the LSD increases the effect (imagine trying to turn with a locked differential and limited wheelspin). Without the LSD, the inside wheel will typically just spin and take power from the outside wheel, the car will slow down (and understeer), you let off on the gas, get traction and some steering wheel pull, give it the gas and it repeats. While this would be the extreme case, it is what you are fighting with at the traction limit.

 

Jim and all,

Very interesting on the modifications that you have made and your thoughts on the LSD. A few questions.

Those top strut bearing carriers: just what modifications did you make? Did you perform the modifications incrementally and can you point out to a specific stability improvement just from the modified strut bearing carriers? Also, I'm a little afraid to modify those carriers out of concern that I will pick up a ton of road vibration and noise. Those strut carriers are about the only stock compliance component left on my MINI front end. What about the ride/noise quality with the strut modification?

My chassis modifications have resulted in a certain amount of low frequency engine buzz noticeable in the driver's seat, especially when the engine is cold, and a little more awareness of road roughness, especially at low speeds. Overall, noticeable but not bad at all. I replaced the runflats with the Bridgestone SO3's resulting in a marked improvement in the traction and ride quality and noise reduction.

Regards,
John Petrich in Seattle

 

Sites discussing "What is torque steer" for your enjoyment.
Site #1
PDF from Ford research giving good descriptions
Struts and torque steer
I like this one

This image pretty much sums it up:


The center of the tire is farther from the center of the car than the line
along the rotation of the turning-axis of the front wheel, so when you
whomp on it, the tire tries to turn towards the centerline of the car.

We don't have kingpin suspention, but anytime the centerline of the
steering axis does nto go straight into the center of the contact patch
of the tire, this will happen.

This is helped if you don't let the front-end geometry mush around
by replacing the rubber bushings with something stiffer.

_________________

 

I believe Trippy is referring to Ackerman, a problem that first surfaced with solid wagon wheels that had inboard kingpins. With offset wheels, camber and McPherson struts, a properly set up car has the steering axis project into the contact patch. Of course, wider tires and wheels, more wheel offset (to clear struts), changing camber, can all affect this.

Petrich:
I have my own custom spherical strut bearings and camber plates with no compliant elements. I get a fair amount of road noise; it comes from a variety of sources and was not significantly increased from the strut bearings (this was a surprise). I also get the cab vibrations at idle from the stiffer motor mounts.

 

>>Add a 19% pulley and you'll be fighting with the wheel to keep your MINI straight - I guarantee it! <<

Gro -

My best friend (who is an attorney) always told me "Never guarantee anything!". I have had a 15% and a 19% pulley. I did see some torque steer when changing to the 15% which went away when I upgraded the bushings on the upper engine mount. The change to the 19% did not change this significantly. No problem with autocrossing just a slightly firmer hand is required. The recent addition of a Quaife requires a firm hand while turning under power but straight line torque steer is the same. I don't think it will affect autocrossing. The season starts here in 2 weeks. I'll let you know.

 

Trippy,

Thanks for the links.

I think the Ford paper has the best explanation.

Assuming equal length drive shafts and symmetrical suspension geometry (L/R), there should be no torque steer.

But the fact remains that torque steer can be induced if torque is increased. I think the real culprit is differential friction. The tire with more friction will force the car to veer in the opposite direction.

I think the electronic stability stuff complicates the dynamics because it tries to intervene but can never quite cancel out the differential-friction-induced transients because of the inherent delays involved. It may even make matters worse by over-compensating.

My guess is that torque steer in the MINI decreases when the stability control system is disabled.

I'd put this to the test if I only had some more torque...

 

Hmm...after re-reading this thread, I think I was unclear with my post. By problem, I really meant it is there. It's really isn't a problem. But it is verynoticeable versus when my MINI was in stock form. In stock form it was hardly there - nothing like a front wheel drive car. But with my mods now, there's more torque steer than any front wheel drive car I've driven, even my old '97 110hp Escort.

Even when I say "serious problem", I really don't mean a problem. I mean it's so noticeable that it can't be ignored. There's no way you can't notice it.

My brother got the 19% pulley the same time I "upgraded". I had to leave Helix first so we didn't drive back together. But the next time I saw him, he commented to me about the torque steer and how hard it was to keep the MINI straight under hard throttle. He went from intake only to 19% and Borla Race exhaust. That's a big change and probably why he noticed it.

 

Torque Steer has nothing to do with how much torque your motor induces.


... it does have to do with the amount of twist in the drive shafts; some companies have tried to equalize the twist (or Torque transmitted from the inner end of the shaft to the outter end of the shaft) by making the shafts equal lengths, or by making the shafts different diameters, or by making one solid and one hollow ... but that's all it is: one wheel spinning before the other because the shaft twists less than the other.
The MINI (as has been stated) has (essentially) Equal Length Shafts - and therefore has MINImal torque steer.
Please don't go any further into discussing how your pulley swap gives you more torque and more torque steer ... it just sounds silly ...

 

t140v:

"Torque Steer has nothing to do with how much torque your motor induces."

How can you claim that when the unequal transmission of torque is the very basis for your explanation?

Besides, if your explanation is correct, the MINI should have ZERO torque steer because it supposedly has the requisite equal length drive shafts. Yet the "torque steer" phenomenon persists and gets worse when the torque is increased.

Please explain...

 

Hey Guys...although the Mini design does reduce torque steer with it's equal length drive shafts heres something I know from my knowledge of helicopter dynamics. Even though the wheels are spinning vertically, anything spinning clockwise will tend to pull to the right which is a little different than torque steer but has the same effect as the front tires will "walk" to the right, people who ride motorcycles will verify this because it's effect is even more noticible on a bike.

 

SCCA:

Nice try, but rwd cars have the same rotational dynamics yet they don't exhibit torque steer!

Anyway, the gyroscopic effect you describe only occurs when you attempt to change the plane of rotation.

 

>>SCCA:
>>
>>Nice try, but rwd cars have the same rotational dynamics yet they don't exhibit torque steer!
>>
>>Anyway, the gyroscopic effect you describe only occurs when you attempt to change the plane of rotation.
>>
>>
Correctomundo!!

 

More than likely the problem is amplified by how you are holding the wheel. With the increase in horsepower, the front end lifts quite a bit when compared to stock. The steering wheel gets very, very light. Use a very gently touch on the wheel and you will find the car tacking much straighter when you apply the power. If you have an input in the wheel or one hand is "heavier" on the wheel that the other you will, and I have, induced "torque steer".

Either way, the car has extremely neutral steering and I do 3500 rpm drop clutch starts (autox) with one hand on the steering wheel (other is on the e-brake) and the car tracks perfectly straight.

Uber

_________________
Always yield to temptation it may not pass your way again. -RAH