Rear end of car swaying

[Newman]

Traded a local guy my rear end with eaton tru trac and 4.10's.

He said he bolted everything up correctly and tight,

And now the rear of the car is swaying side to side.

I never once had a issue with that .

Any ideas what the could possible be?

Nothing internal in the rear end could cause that , correct ?

 

[TexasBlownV8]

Hm, seems like it would do that if the panhard bar was left off.
Get some pics of the install, and that may help.

 

[Newman]

Nah, he's up in Conroe, that was my first thought too. But he says everything is tight

 

[dysan]

The $1,000,000 question is did he torque everything with the suspension loaded and the car level or did he do it with the frame on jack stands and the suspension loose?

 

[BruceH]

Have you looked for anything obvious? Things like bolts without nuts, missing bolts, loose nuts on bolts, things like that?

 

[UltraKla$$ic]

Tell him to let the 'ol lady ride in the front seat!!!!

 

[fdjizm]

Upper bushing OK?

 

[Newman]

The $1,000,000 question is did he torque everything with the suspension loaded and the car level or did he do it with the frame on jack stands and the suspension loose?

This is what he just wrote me . He said he torqued them all right .

So the car drives fine under a load it happens under the following conditions when under deceleration or coasting that's when you'll get the the movement . Jacked the rear up and no movement side to side with the rear .... It feels like the rear of the car moving around.. Like the locker is locking up one side then the other

Have you looked for anything obvious? Things like bolts without nuts, missing bolts, loose nuts on bolts, things like that?

He's about 100 miles away , we each took out our rearends he drove down here dropped his off and picked mine up .


So I have no clue what happened past that . He's just telling me this today .


I'm about to go trade the car off on Monday . I really don't need to have to swap this dude rear ends again, and have to give him money back.

Upper bushing OK?

Not there to check everything

 

[BruceH]

I'm not following something here. Do you have possession of the car and if so is it swaying when you drive it? Or, is he telling you that the part you sold him is swaying on his car?

 

[Newman]

Part I sold him is "not right " . He gave me his stock rear .

 

[Newman]

There is no way for the eaton tru trac to cause what he's experiencing ?
I had not one single issue with it.

 

[quiksilver15]

Yah that's a suspension issue, not diff IMO.

 

[Whiskey11]

There is no way for the eaton tru trac to cause what he's experiencing ?
I had not one single issue with it.

It is entirely possible the TruTrac is the cause of this, especially if he is coming from a decent clutch based setup (or at least a newer T-Lok).

A clutch based differential will have some lock up on decel, a TruTrac and other Torsen style torque biasing differentials DO NOT. In fact the transition between acceleration (where you have biasing going on, not lock up) to deceleration where the differential has absolutely no control over the axles can exacerbate the feeling. Suspension setup, damping, all that plays into how the car will drive under braking. It's entirely possible that your setup was softer than his and masked the movement better or you just didn't notice it while you were driving.

My car with a Torsen T2R does this on braking and it was EXTREMELY disconcerting the first time I drove the car and it felt exactly like he was describing. Worked amazing under power and as soon as you let off after a good acceleration it would "wobble" a little. I've come to get used to the instability on deceleration/braking/coasting after a hard acceleration.

Certainly have him check everything though, I would definitely have him check axle end play with the rear axle in the air and make sure the C-Clips are still seated correctly. If they are and all the bolts are tight then I'd chock it up to the diff behaving differently than the T-Lok he is coming from.

 

[quiksilver15]

Huh! Learn something new everyday.

 

[dysan]

A friend of mine's car is doing something similar but not the same. His car will shift/move when part throttle and you give it just a little gas. If you hammer the gas it's straight as an arrow....It did it when he got the car and it still has the stock control arms top and bottom, stock diff, etc. Since then he purchased quite a few of my "old" parts to try and remedy it but to no avail. Put my locker diff in, J&M LCA's and I believe a UCA but zero change. It will do it no matter what tires are on the car.