Torque steer and limited slip...
 

I was considering getting some kind of tuning kit for my '07 Cooper S, but even in stock form, when I really get on the gas, the torque steer is pretty wicked. I was wondering if a limited slip or a locker would cure this issue...? I don't want to get more power just to have it be totally uncontrollable. I would have gotten limited slip from the factory, but they didn't offer it for the automatic. :sad:

LSD's will reduce torque steer in FWD cars. There are no replacement LSD's for the R56 at this time, and i have never seen a LSD for a FWD automatic.

What about a custom diff? What about the diff from the manual, would that fit in the automatic?

What about limited slip vs. a locker? Would a locker get rid of torque steer completely?

Thanks!

A locker, like the Detroit Locker was used in drag cars on RWD cars to give both wheel equal torque and spin to go as fast as possible..in a straight line. They were useless for cornering, which is why they could be unlocked for normal driving, ie street use.

You need a diff that unlocks, or that allows the wheels to spin at different speeds since the outside wheels needs to spin faster then the inside wheel to get around the same radius curve.

in RWD cars the differential is in a housing at the rear axle, but the FWD has the diff inside the transmission. So automatics are totally different then manual gear boxes and everything is different. \

Also automatics, not matter how fast they are in the straight line do not couple the engine directly to the transmission, they use a torque converter and also when you let off the gas in d4 or what ever it freewheels like a mountain bike rather then compress and reduce the vehicle speed. I believe that will have an effect on how a LSD would behave.

FWIW with the OEM LSD option there is still torque steer under heavy acceleration. Can't comment about a comparison without the LSD.

The OEM LSD is not really a true LSD (clutch type), its a torque biasing diff (TBD). But I'm guessing, that even if using a clutch type LSD it still allows torque differential between the wheels by design so some torque steer will be evident at high enough torque. I would imagine the only way to completely eliminate torque steer would be to fully lock the differential e.g. spool, but then trying to go around corners would be quite difficult.

EDIT: I got it wrong, the OEM LSD is a conical clutch type LSD. It's not a TBD.

OEM R56 MINI S LSD is a clutch type LSD, although not the same ability as Porsche clutch pack. Helical LSD are torque sensing LSD's and are very effective and used in many sports and race cars. OEM differentials in most Nissan's are viscous LSD's (350z), as well as some AWD applications and are not very good but better then a open diff.

I am not sure what you mean by a traction sensing diff, but i belive those are alot like and electronics lock up diff found in some VW based cars, like the Gti, which just reduce the overall power like a traction control rather then re biasing torque.

I would agree with that. I got the LSD and sport suspension with my 07 MCS. If I really get on it in a turn the torque steer is pronounced but not extreme.

I haven't tried it in an MCS without LSD.

I could not imagine trying to drive a mcs without the LSD

it breaks the tires loose too easy in sharp turns, and torque steer is pretty high


my wife was scared of my mcs at first, the torque steer makes the car jittery she's been driving rear wheel drive bmw's for the past 10 years, she's used to it now, but still complains about it

I had a brain fart, I meant to write "torque biasing diff (TBD)" instead of "traction sensing diff". I think I got messed up because the OEM LSD is described as a "torque sensing LSD". I'm pretty sure the OEM LSD is actually this TBD http://www.gkndriveline.com/drivelin...super-lsd.html Can't remember where I read it though. Is there information that the OEM LSD may be a clutch type? It looks like it uses planetary gears and not clutch plates. I'm thinking that MINI engineers would not want to use a clutch type LSD on the MINI for these reasons:
- more expensive
-overkill for street use
-clutch plates need to be replaced every 2-5 years (very costly)
-clutch type LSD locks on deceleration too, which could create understeer and not really be desirable for a FWD car on the street or even autoX.

EDIT: I got it wrong, the OEM LSD is a conical clutch type LSD. It's not a TBD.

Your right about the reasoning about the clutch type,but the OEM is a clutch type just not as good as the ones you mentioned. If you look at the data sheet you can see that the operation is that slider gear is pushed onto the taper ring from the springs that are loaded by the pinon. That sliding onto the taper ring causes a linear locking of the differential.

A a non clutch type like a torsen 2 would lock up to do friction generated in the helix gears, the angle of the helix causes the rate of lock up.

Edit: It even says it is a clutch action on the taper ring, i just realized that..

Good grief you're right :eek2: It is a cone type LSD. I was wrong :sad: Serves me right for not reading the datasheet. I was just looking at the absence of plates and assuming that MINI would just go for the cheapest easiest solution for the broadest application. I actually kind of like the clutch type LSD for low friction surfaces. Hmmmm, now I'm wondering:
- I wonder how durable the taper ring is. I don't see LSD maintenance listed in the service schedule. In a few years there are going to be some very PO'ed MINI owners paying to drop the tranny to replace the taper rings. Either that or owners will be driving around with essentially open differentials, blissfully unaware their LSD has worn out.
- How much lockup is set into the preload spring under decel, if any? I wonder if the LSD equipped MINIs understeer more than the open diff version.
- Can the tranny handle the increased heat from the LSD during track/autoX?

Is it the shape of the pinion gears that define the OEM LSD as a "Conical Clutch"? So even though there aren't any clutch plates in this LSD like I've seen in other diagrams, you'd still call it a clutch type?

Sorry, I'm new to all this and I'm trying to understand it all. :)

since this is a standard clutch type, with clutch plates
http://www.billzilla.org/trdlsd2.jpg

and this is a standard Helix (Torsen 2)
http://www.billzilla.org/trdlsd.jpg

I believe it is much closer to a clutch type then a Helix, just not as good as the clutch pack shown above.

mf.illuminatas If you are bothered buy torque steer, a LSD will only make it worse. But then again I'm an old man whagt do I know. Just look really closely begore you plop down two large.

Motor on

I did not push the test driver too hard in a curve, but my LSD equipped car does pull the front end into the curve more if you lift quick than if you lift gradually. It rotates much more than my LSD equipped 91 Escort Gt, especially at high speed. My guess is, the MINI has what wikipedia refers to as a 1.5 way diff or a 1 way.

I don't notice the torque steer in my car as much as I did on the test drives, but that may be that I am just used to it now.

edit:

BTW, at the strip last weekend, it pulled pretty straight, even under wheelspin. I only notice the torque steer when accelerating hard with the wheel turned, which is in itself an improvement over previous FWD cars I have owned.

Yeah, I've noticed a very different feeling with steer when accelerating into a someone sharp degree turn in 1st or 2nd gear.

Usually happens when I'm coming from a stop at a red light and gunning the car to get used to it's handling better.

I'll have to keep this new info mind about the LSD next time I do that and try to pick up on how the car is behaving.

I know there are probably many other variables I should be taking into account... but at least I'm learning little by little :)

torque steer blows! Ive never driven a car that did that. I almost took the car back becasue of it. Since I have an auto, there is nothing I can do to get ride of it....

Wrong-o buckaroo! I just threw on a set of H&R springs a few days ago, and my torque steer is basically gone! :nod:

Stiffer springs = less front end "wandering" and more traction = almost zero torque steer! :grin: Couldn't be happier!

That's awesome!

I have no issues what so ever with torque steer in turns...I have LSD and JCW suspension with Mach V springs....The suspension upgrade made a HUGE difference.

What made you go for the Mach V springs over the JCW's? Did you previously get the JCW's or do you have the option to not buy them with the rest of the kit?

I find that the torque steer is very manageable, it just requires more driving finesse than I was used to with the STi. Of course if I downshift and get on it halfway through the turn or really romp on it on uneven ground it's there but I'm quickly learning how to maximize traction in any condition. Driving skill is a huge factor. If you're not getting much that says a lot about your skill level as well as the benefit of the mods you have. I'm probably going to have the JCW suspension kit put on my car eventually :).

You don't have to get the JCW springs when you get the kit, cause the springs aren't included so you have to order them separately. I went with the Mach V springs cause I wanted a little more of a drop, and stiffer progressive springs for better handling. My setup with the LSD and suspension is an awesome setup, but as I said, I noticed a huge difference in all around performance once I got the upgraded suspension installed over the stock setup. And I do have some years of racing experience, which never hurts.