Detroit noise and backlash

I got a Detroit and 4.56 r&p installed in my 8.8 at the shop.

It seems like there is alot of backlash or slop going from a stop or from FWD to REV (but I've heard Detroits can do this). It is also quite noisy at highway speed when coasting.
The owner had warned me of these symptoms, and said that he had been in contact with Detroit and had double checked the backlash, etc. I trust the owner take care of any issue, but.....


Any advise or idea what could cause this?

Back lash is normal but it's shouldn't make any noise at all at highway speed. When I had mine done, I noticed a metal on metal shaffing sound and it turned out that the 8.8 crush sleeve wasn't installed correctly.

Sounds like your issue to me.

The crush sleeve is on the pinion? Is this critical and needs to be fixed immediately?

The sound is only at high speed coasting and isnt a grinding, and I almost wouldn't call it a howl, but it is loud and definitely sounds like its from the rear-end.

SnagglePuss said:

The crush sleeve is on the pinion? Is this critical and needs to be fixed immediately?

The sound is only at high speed coasting and isnt a grinding, and I almost wouldn't call it a howl, but it is loud and definitely sounds like its from the rear-end.

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Yes, the crush sleeve is critical! It can, and will do damage to the pinion bearings, and even the gears if not installed properly.

The noise sounds like it could be your pinion bearing, that is preloaded by the crush sleeve.

It's also possible the shop messed up the rest of the setup, sounds like they haven't done many if he said it would be noisy! My 8.8 with 4.56s makes no noise at all.
EDIT:
Also, remember with the lower gears your DS will be spinning faster, so if you have anything wrong there, it will be more noticeable (u-joints and t-case output bearings for example)

Thanks guys - I appreciate the info.

How is the crush sleeve set properly? Is this done by torquing the pinion nut?
Would the crush sleeve/pinion bearings make noise on the coast side only?

SnagglePuss said:

Thanks guys - I appreciate the info.

How is the crush sleeve set properly? Is this done by torquing the pinion nut?
Would the crush sleeve/pinion bearings make noise on the coast side only?

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It is set by using a in. lb. torque wrench to measure the pinion preload. The crush sleeve must be crushed or you will get a false reading, probably the case here. It takes a lot to get the sleeve to start to crush, like 200+ ft lbs, but once it starts, it's easy to get it too tight. Once the sleeve starts to crush, measure the preload and turn the pinion nut in about 1/4 turn increments until the preload is in spec. It's a pretty tedious process, and a good idea to have an extra sleeve just in case.

And yes, it can cause the noise to occur only while coasting. When there is a load, the bearings are loaded, although inproperly, and the noise will stop.

Don't let it go though! Driving it will make it worse and can cause permanent damage to the gears, especially if they don't break in properly.

I also want to note, the extra backlash you feel from R to D is probably normal. All auto lockers introduce extra backlash, as long as it's not in the R&P you should be fine here.

Thanks again. I love this site for this kind of help.

I wish I could check this at home, but I dont have the tool to measure the preload.

TRAILREADYXJ said:

Once the sleeve starts to crush, measure the preload and turn the pinion nut in about 1/4 turn increments until the preload is in spec.

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Ummm...no. If your close to spec, 1/4 turn is going to put you way over spec!

Once you start to crush the sleeve you tighten it a little at a time until the play in the bearings is gone, then very small increments you can tigten the nut until your specified preload is reached.

Here's a good watch:

http://www.youtube.com/watch?v=8APYO2sZyJU

I doubt the OP has any slop in the pinion bearings as it would be very loud and chance's are the pinion seal would be leaking.

Awesome! Thanks for the video, Sero.

Sero said:

Ummm...no. If your close to spec, 1/4 turn is going to put you way over spec!

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Well, that's what's in the yukon manual... But you're right, once you get close it tightens up very fast.

Sero said:

I doubt the OP has any slop in the pinion bearings as it would be very loud and chance's are the pinion seal would be leaking.

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He said it makes noise, and I have seen this same thing happen first hand. The seal didn't leak, but would over time for sure. Also, the noise was minimal. The problem was found and fixed (by me) shortly after the initial install, and he didn't have anymore problems with it.

Like has been said, the sloppy backlash is part of how an automatic locker works. As far as the noise at highway speeds only on coast, that has nothing to do with the locker, the locker is just the carrier and won't make noise in that situation. Also like has been said, if the noise is only on coast, it should point to something with the pinion or pinion bearing. However, it's possible it could also be driveline noise, as on coast the pinion is pushed down increasing the driveline angle, and if the angles are real close it could push it to the point of being far enough out of alignment to cause noise. The lower gear ratio could be just enough extra resistance to cause this. Just another possibility to check out and eliminate.

I'd check the pinion end u-joint for starters - all of my 'noise on decel' issues have been that...

also - there is a crush sleeve eliminator or 'solid spacer' available for the 8.8 - and that takes the guesswork outta crushing the crush sleeve... then you just throw it all together, and torque the pinion nut.

XJ_ranger said:

also - there is a crush sleeve eliminator or 'solid spacer' available for the 8.8 - and that takes the guesswork outta crushing the crush sleeve... then you just throw it all together, and torque the pinion nut.

Click to expand...

I saw, and considered going that route on mine, but I already had the install kit.... and am a cheap a$$ .

This route does require shimming to get the right preload (like most Dana axles), but it sure would be nice to not have to deal with the crush sleeve!