LSD Question

[03MSP]

Ok, to my understanding an LSD locks both front tires and gives them equal power. Maybe I am not understanding the concept of our "torque sensing" LSD, but I just don't understand how we have an ungodly amount of torque steer.

[jred321]

under normal operation, both wheels spin with the same power. if one slips on an open differential car, all power would be sent to that slipping wheel. the lsd prevents this from happening. if one wheel starts to spin, it keeps sending power to the other wheel so you can still move straight. that's my take on it anyways.

i have minimal to no torque steer compared to other torquey fwd open differential cars. maybe you're just not used to torque on a fwd car

[girth]

That's not what the LSD does -- what you discribed is a LOCKING differential. The limited-slip diff just senses when 1 wheel is "spinning" and either cuts power to that wheel or transfers some of its power to the opposing wheel (I'm not sure if it's a power cut or a transfer in power). Doesn't really matter though - point is it's not a locking differential.

Edit - Jred beat me to the punch :p

[RyanJayG]

well, think of having an LSD as having one axle all the way through your transmission driving both wheels.

this would work if you only drove straight, and never turned. This obviously wont work because you would eat tires like nobody's business. so what an LSD does is turn both wheels when applying power, but allows the wheels to turn at the slightly different speeds to account for the different radius of the inside and outside wheels durring a turn.

confusing enough yet? :)

[unwrittenLaw]

whats confusing is the STI's setup...geez

[girth]

Originally posted by unwrittenLaw
whats confusing is the STI's setup...geez

LOL, you got that right!

RyanJG, what you described is just 'any' differential. All differentials allow for 1 wheel to turn faster than the other. A locking differential is the exception - that ensures that both wheels ALWAYS are turning at the same speed - thereby making it very hard to turn.

I guess the least confusing way to put it is to say that in normal traction situations the LSD is just like any differential. Like Ryan said, in a normal differential the power will be transferred to the wheel that's doing the least amount of work - meaning if 1 wheel is on ice and the other is on concrete, the one on ice is going to get all the power. If that happens and you have an LSD, the LSD "sees" that 1 wheel is getting all the power and so it transfers some of that power to the wheel that has the traction. Basically all it does is keep the 2 wheels in check to ensure that 1 doesn't sit there and spin crazily while the other one does nothing.

If that hasn't confused you thoroughly, then we could talk about the STI's differential. That's not only 4-way limited slip but also adjustable for power from front to back!:cool:

[KyRaceFan]

www.howstuffworks.com has a GREAT write up on differentials on fwd, rwd, and awd cars, and also how LSD's work.

[RyanJayG]

I was just trying to give it in laymans terms to describe that it forces both wheels to turn when slippage occurs

[^tyrant^]

damn i think im more confuzed after reading this thread then i was before i read, thanks guys! heh

[Glowmunkey]

As to why we still have torque steer:

It's caused almost solely by unequal length driveshafts. The longer shaft has a greater tendency to twist than the shorter one... essentially the shorter one transfers more power to the ground.

The operation of a limited slip, or locking differential, does very little to combat this... even with the complete lockup of a mini-spool, you're still driving two drastically different length shafts.

[rocketspeed]

Many powerful FWD cars have very little torque steer. My GTI VR6 didn't torque steer 1/2 as much as the MSP, even without the LSD. It can be engineered out to a large degree.

[AutoBox]

one way of engineering it out is by placein the tranny more in the middle....makin the driveshafts more equal

[jred321]

go drive a fwd dsm with some stuff done to it, that's torque steer. the msp is nothin

[AutoBox]

oh yeh any fwd is gonna trque steer....there is no way to haev a tranny exactly in the middle...cus its run off the side of the engine...ull always have some sort of torque steer....a lsd makes it more pronouced

[rocketspeed]

Drive an SE-R Spec V. That car torque steers like mad.

[MSP Pro]

Didn't you guys with the MSPs that torque steer like crazy ever read the post that told you it was due to improper alignment settings? My MSP has only the mildest bit of torque steer, and then only when I floor the accelerator when going around a corner.

Dare I say it???:D USE THE SEARCH BUTTON!!!!!:D :D :D

(insert yashooa vaginal response here)

[KyRaceFan]

i remember that thread.. i need to get my bushings replaced anyways.. i'll call the dealer and have them align it too.. and try to get a new front seat!

[03MSP]

Thanks for all the replies guys.

And, as to the statement that I may not be used to torque steer on a powerful FWD car, my old car was an MX-6 turbo with more than 200 ft-lbs of torque:D

[Maniac0301]

The SRT-4's have equal length drive shafts so it is possible just takes a complete re-working of the K-frame. If you want torque steer try driving one of the old Omni GLH turbos with work done. Its not unusual for those old Dodge turbo engines to see 260 hp 340 lb/ft.

[Notorious]

I just got my car aligned last thursday because I changed the springs. It doesn't help any and my car still had crazy torque steer. If you run more boost its of course gonna be worse.

[GA_MZDASPEED]

just so you guys know (if i'm right....and not crazy).......the term "torque steer" aplies ONLY to the the tendancy a car has to pull ,left or right upon straight line acceleration....it does not apply to effect one tire with traction will have on the direction you are trying to go.........i.e. if you have a 1 spinning tire (no traction)and 1 with traction (do to LSD) the vehicle will want to rotate on it's longitudinal axis due to the uneven application of force..............does this sound right....?

.......and I'm spent!

[Notorious]

sounds right to me, if anything the lsd will pull the car is a straight line. If the road has a crown, then i could see it pulling to the right.

[Tex]

After three dealerships and three alignments, the third dealer finally did an alignment that drastically reduced my torque steer. The service manager at that dealership said my car was aligned according to regular Protege specs, not MSP specs, and after they aligned it according to a bulletin from Mazda, the torque steer almost went away.

He also mentioned something about a bearing, I think, or some part, that is in our cars, which is there to reduce the torque steer. Forget what he called it exactly.

[GA_MZDASPEED]

the part that he was talking about might be rubber-like counter-weight that is added to the axle that would cause the torque steer (the weight equallizes the torque).....my honda had one one axle......one axle was almost 1 foot longer (no carrier) then the other and with the weight no noticable torque steer

[Tex]

GA....I like yur sig, lol.

[GA_MZDASPEED]

just an example of how true the signature is

current bal $-518.28
paycheck (tonight) $ 608.18
money til next payday (2 weeks) $ 89.90

that sux.....soooooo i guess i'll hold off on the mods for now ....and go tell my girlfriend (who just got paid) that I loooooooves her! (grin)

[98turboteg]

Actually, the msp hooks pretty well, my buddies is running 10lbs. with an intake and Joe P FPR and it still hooks better than my car.
Imagin what it would be like without it.