1G AWD w/quaife LSD in front is being unruly

[aaronmatusz]

My car was pretty well sorted and handling was very neutral before I put in the front LSD, but now it won't turn even in at parking lot speeds. I've autocrossed it twice with the new diff and it understeered bad unless I somehow flung the car over hard enough to nearly lift the inside front so the power could overcome grip there. When I managed this, the outside front would catapult me into the turn with such force I injured my neck.

Are these LSDs supposed to be this vicious or am I doing something wrong?

 

[kchaazz]

No, it shouldnt behave that way. My friend put a Quaife in his 1G awd, and it behaved as though it were stock with just a bit better turn in, though sometimes the car would pull right to left a bit as the dif shifted power. If its understeering badly even at slow speeds, Id suspect a bad center dif, as this will eliminate the abilities of the front and rear wheels to turn at different speeds, independantly as they should. Notice any chirping of the tires at these slower speeds? Did you inspect the center dif when you put in the front LSD? If everything is functioning properly, stiffer spring rates, rear swaybar upgrade and rear active toe eliminator kit will counter much of your understeer problem.

 

[90gsxjuice]

That's the nature of the beast when you get an lsd that works. They are more for traction out the hole than anything else. Lsd tent to not want to corner since they try to keep speed of the wheels the same and cause the tires to screech when you turn.

 

[aaronmatusz]

Oops, I made it sound like I worked on the tranny.
I took it out of the car for a new clutch and saw that the output shaft going to the x-fer case was badly worn, so I took it to Beyond Redline (a shop in Green Bay, WI) to have the whole trans looked at and upgraded for general toughness. It got some of the basic upgrades like the torrington bearing & others, a fistful of syncros, bearings and a four spider diff. I then went completely bonkers and ordered the quaife.

Also take a look at my DSM profile, the chassis really did handle very well before this trans work.
Thanks for the input, I forgot about the center diff 'till you mentioned it.

 

[kchaazz]

The Quaife should not make the car understeer as badly as he is experiencing because the Automatic Torque Bias of a Quaife does not positively lock the wheels together, but instead is able to actively sense slip and transfer power to the opposite side, unlike a traditional mechanical LSD that locks both wheels together, and this is just one of the reasons many people prefer the Quaife in the front slot. I run a Kaaz mechanical in my front slot, which locks the wheels together under input torque and I dont even experience understeer like OP is describing, but I run stiff springs and RM swaybars so my inside front is unloaded enough so as to avoid understeer when cornering.

EDIT: You have the suspension and other handling mods taken care of, perhaps some new alignment settings are in order for some reason, though I cannot understand why youre experiencing such severe understeer. What happens when you drive the car more aggressively??

 

[aaronmatusz]

Driven normally, it just plows really bad. If I thrash it hard enough, there is a chance I might unload the inside front enough to overcome traction there, but here's the catch: In order to initiate the right set of events to make the car turn, I need to turn the steering wheel much further than I normally would. And then very suddenly it turns in better than it ever has.

This behavior is very scary when there are hard & heavy metal poles in the infield of the track!

 

[ACM]

A Quaife LSD will cause understeer if you go through the turn off-throttle. The degree of understeer will vary depending on your suspension setup, but it can be quite severe - my auto/x car will often just go dead straight if I have to lift mid-turn.

The flip side is that if you go through the turn under a healthy amount of throttle, the car will turn in and hold line far better than it can/does with an open front diff. This is because it is a 2-way LSD.

What are yo running for front camber/caster/toe ? Having asked that question I actually can't be much help, since your avatar show a 1G and my experience is purely 2G

 

[LandSpeed-DSM]

This is the opposite of what I have experienced with the Quaife in my 1G FWD. I don't road race either.. however, but this would seem to be a situation where both chassis/drivetrains would behave somewhat similarly.

The only time it feels like it wants to push the front is if I entered the turn hard and completely off throttle.. it feels like what I suspect is the diff juggling the speed difference between the inside and outside tires as the engine applies braking torque in vacuum.

Wouldn't call it unruly though.

 

[aaronmatusz]

Thanks for the replies. I'll post more after I make some changes.