Locker causing pushing in turns...

[mrn2obelvedere]

I got the locker rear end installed in my plymouth and I can already tell that it might cause my car to understeer...what can I do setup-wise to avert this behavior?

[Lowend]

Can you give a little more info...
What chassis is this and how is it setup right now?
What makes you think the car is going to understeer vs open diff?

[JRouche]

I got the locker rear end installed in my plymouth and I can already tell that it might cause my car to understeer...what can I do setup-wise to avert this behavior?

That kinda makes sense. If you are getting more traction in the turns now at the rear you would get more understeer. Do you have a rear sway bay? If not then its time to look for one. If you do then make sure it is in good condition, the rubber pads. If they are broken down or hard they will produce some "snapping" understeer to oversteer.

I have a feeling you dont have a rear bar. But if you do, and all the rubber parts and linkages are secure then I would look at a higher rate front bar. Keep the rear bar as is if you have one and its in good condition. If no rear bar thats the next step.

No fears buddy. You are on the correct path. Its acting just as it should. You increased rear traction and got a lil more understeer. Be happy. You installed a part and it did what is predictable for the part.

Yer on the right road. Good for you. JR

[Norm Peterson]

It'll probably corner OK as long as you're off the throttle while doing so - that will let the outside wheel overrun assuming that nothing is wrong inside the locker to make it behave like a spool.

On large radius turns, which includes nearly every turn at any race track bigger than the really small circle tracks, it shouldn't get too much in the way even if you are on the throttle, if you're going fast enough for the rear tires to be at much of a slip angle. Not everybody commonly drives this hard, though.

It's throttle on in small radius turns where the locker being locked by throttle-on that'll cause understeer. When the two rear wheels insist on turning at the same rpm exactly, the rear axle as a unit is going to try to keep the whole car going straight ahead, IOW understeer. Side note - this is why circle track racers use tire stagger, as a locker (when it's locked up under power) or a spool (all any time) will then naturally try to make the car turn left.

Lockers are a little like light switches. They're either locked or they aren't, and this can make for some sudden changes in cornering behavior if you're at at all indecisive with the throttle or use too much of it when you aren't going straight.


Norm

[mrn2obelvedere]

The car is a b-body mopar

1.125 front sway bar, 0.875 rear sway bar. All of the bushings are in good shape.

Tubular adjustable front control arms, set up with -0.75 deg camber and 4 degrees caster.

In the rear I am still running the leaf springs, with the addition of afco front spring pivots and solid shackle bushings.

The leaf springs and front torsion bars are stock and probably need to be replaced with some stiffer parts...will do that when I can save the funds. I would like to run the fiberglass monoleaf springs in the rear when I do get to that point.

I have QA1 stocker star shocks at all four corners.

[a67]

I got the locker rear end installed in my plymouth and I can already tell that it might cause my car to understeer...what can I do setup-wise to avert this behavior?

Pull it out and replace it with a Torsen or a limited-slip unit.

As the others have mentioned, a locker does just that. With forward thrust it locks the axles together. So in turns and such need to reduce engine output so that it unlocks and the vehicle is between steady-state and coasting.

Even then it can click and tend to jerk the rear side-to-side.

Hit the throttle and it will lock, even in a turn.

Had a locker in the '92 for a while. At the time needed the traction and it was an easy way to go. Replaced it with a Torsen.

Friend of mine didn't care for lockers, said something about having them "sound like stuff in the rear was breaking." Which was exactly what they do sound like. Crunch, bang, slam.

And the clicking, pull into a parking spot and there is a rapid clicking sound that emanates from the wheel (acting like a speaker cone). Had many-many people come up to me telling me that there was something wrong with the car.

Bending over and shaking the rear tires and all. Got to the point I just kept walking while telling them it's OK, supposed to do that...

Bob.

[mrn2obelvedere]

Haha...I actually like the noise it makes...clunk clunk clunk clunk

People always are coming up to me asking what it is...they show nothing but appreciation for the car, so I'm really not worried about it.

There's no way I'm about to pull that rear out again anytime soon.

[JRouche]

Great!!! Sounds like your car is far along. So you have the bars in place, and they sound like a good match. You could increase the rear bar some but I wouldnt at this point.

I would drive it and see if it becomes more predictable. Meaning more comfortable to recognize its character.

As for the locker. I would have one over a limited slip (which I have). Just my opinion.

To be honest I think you are in good shape. I like to have a loose car VS a pushing car. But thats just my stupid driver feel. I like the excitement. Cause I am actually faster with a car that tends to push a lil, I drive it deeper and faster, wear more tire off, burn more brakes up unfortunately.

But a "heavy" feeling car (understeer) will make me feel like I can take it further and hotter into and during a turn than a "light" oversteering car.

Kinda like the car is on ice skates when oversteering, quick and very responsive, but Im working hard to not fall (spin out).

Where the understeering car feels like Im driving though tar, a lil sluggish, but then Im not afraid to give it more power and power my way through the turn. Just as long as I dont get haired out and throttle lift and get some snap back.

Anyway. Its a fine line. Over or under steer. But I will always tune my car on the side of understeer if I can. Tires and brake pads are cheap compared to fender panels and control arms (curb whack). JR



The car is a b-body mopar

1.125 front sway bar, 0.875 rear sway bar. All of the bushings are in good shape.

Tubular adjustable front control arms, set up with -0.75 deg camber and 4 degrees caster.

In the rear I am still running the leaf springs, with the addition of afco front spring pivots and solid shackle bushings.

The leaf springs and front torsion bars are stock and probably need to be replaced with some stiffer parts...will do that when I can save the funds. I would like to run the fiberglass monoleaf springs in the rear when I do get to that point.

I have QA1 stocker star shocks at all four corners.

[mrn2obelvedere]

I guess I was asking more along the lines of how would I tune my setup to alleviate this problem?

[a67]

I guess I was asking more along the lines of how would I tune my setup to alleviate this problem?

Uh, Pull the locker out and replace it with a Torsen or a limited-slip unit.

You can't tune around locked axles... Locked is locked.

Bob.

P.S. I'm beginning to wonder why I post here.

[mpozzi]

Agree with Bob with the exception of the P.S. as a locked diff with anything that has significant power will drive right through the front wheels and tires in turns and you'll get that dreaded understeer.

To correct this, work on you instead of the car. Your driving mantra will be "Brake, Turn, and then transition back to Gas ..." to negotiate a corner without appreciable push. You'll have to learn how to drive the traction circle and feel when push starts. Once there, you'll have to flirt with this limit and brush against it without going over. It takes a lot of talent to track a car well with a locked diff over one that has a true LSD but it can be done.

The other option is to work with the car and get rotation. It can be done using a rear bar and sometimes tire pressures but you'll often be slower through the corner and can get into some serious trouble (read: oversteer) if your timing is off. For a street car, this isn't good ...

Mary Pozzi

[exwestracer]

Mary is spot on, IMO. That is something you're going to have to drive around. Tune the chassis to get the corner entry speed up (bigger front tires?) and roll through to a late apex so the car is more or less pointed the right direction when you pick up the throttle. Because the locker engages immediately, you probably won't want to be anywhere near the outside of the road when the power comes back on.

A lot of supermodified drivers adopt this style because the torque arm and live axle severely tighten the car under power, stagger or no stagger...