Slack in Rear Diff

[USE911]

I got 5 29 gears put in professinally about 3 or 4 months ago with a locker in my 89 4runner. From the start, I notice that when I take off, I got a bit of a clunk from my driveline. I replaced the u-joints but its still there. The slack in my rear diff is about a quarter of a crank. My dad (former mechanic) said that it shouldnt be more than 1/8 of a crank, if that. Took it back and the guy at the shop told me that normally there should not be much slack, but beings that there is a locker, it requires more. Any truth to this or is he just not wanting to fix his bad job?

 

[helo-mech]

What kind of locker? Mechanical or E?

 

[USE911]

What kind of locker? Mechanical or E?

Mechanical. It's a Yukon Locker

 

[helo-mech]

Does it do it when you take off from a stop normal? Or only when you "get on it?" With all the lift you have and that amount of torque I would look at whether you have some axle wrap going on.

Did you ever notice if you had any slop before the re-gear?

 

[fourwd1]

It sounds like he may be feeding u a line, but more than 1/8 of a turn in play isn't that unusual either. Was a new bearing kit used for the gear install?

 

[USE911]

It did not do it before the regear. I don't "get on it", It's always when I take off or shifting gears. What do you mean by axle wrap?

They said they did a bearing kit. And it had about half a turn of slack. I figured even at 1/8 would be unusual for having just done the gears.

 

[fourwd1]

Axle wrap is the term used for when the axle housing itself actually rotates a bit when you take off from a dead stop. Normally it's only a problem with high HP race cars, which have traction bars mounted from the axle to frame to prevent it.
It's typically little or none on normal vehicles, but a suspension lift changes the driveline geometry allowing it to happen. The more lift the more it can happen.

 

[helo-mech]

I'm wondering if your locker is catching, locking, and putting a lot of torque on the axle housing. Having your 4Runner lifted the drive shaft is already at a more extreme alignment than it would be stock. Throw in a locker with that gearing and it might be a lot for the housing to compensate for.

Youtube "axle wrap" and you will see that there are different degrees of it. Some are simply visible (no noise in the cab) by the rotation of the axle and some have a good deal of clunking associated with it.

 

[USE911]

After looking up the axle wrap, it appears that might be my issue. You think i could fix that by getting a tighter grip on the axle, like upgrading u-bolts and springs? Or would i have to just set my axle at a better angle?

That still would not effect how loose the pinion was set at, right?

 

[fourwd1]

If axle wrap is the issue a trac bar is probably the best choice. A tighter grip on things isn't going to make a difference.

 

[SV_Dude]

After looking up the axle wrap, it appears that might be my issue. You think i could fix that by getting a tighter grip on the axle, like upgrading u-bolts and springs? Or would i have to just set my axle at a better angle?

That still would not effect how loose the pinion was set at, right?

If axle wrap is the issue a trac bar is probably the best choice. A tighter grip on things isn't going to make a difference.

fourwd1 is right, a trac bar is the best solution. You can get a anti wrap lower leaf spring from another spring pack and put it in your leaf pack. It's not an end all solution but it's a decent and CHEAP alternative that will minimize axle wrap.