Drivetrain Torque steer and limited slip...
#1
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.
#3
What about limited slip vs. a locker? Would a locker get rid of torque steer completely?
Thanks!
#4
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.
Last edited by Bhatch; 10-23-2007 at 06:09 AM.
#5
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.
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.
Last edited by smackboy1; 10-24-2007 at 07:07 AM.
#6
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 traction sensing diff (TSD). 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.
The OEM LSD is not really a true LSD (clutch type), its a traction sensing diff (TSD). 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.
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.
#7
I haven't tried it in an MCS without LSD.
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#8
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
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
#9
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 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.
- 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.
Last edited by smackboy1; 10-24-2007 at 07:08 AM.
#10
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.
- 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.
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..
Last edited by Bhatch; 10-24-2007 at 06:04 AM.
#11
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..
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..
- 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?
#12
#13
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.
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.
#14
#15
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.
Last edited by scabpicker; 10-24-2007 at 01:37 PM.
#16
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
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
#18
Stiffer springs = less front end "wandering" and more traction = almost zero torque steer! Couldn't be happier!
#21
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 .
#22
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 .
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 .
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