Manual Rear Differential Noise with Solid Aluminum Bushings

[kanusky1990]

Hey guys,

I searched and found a few threads but none with video displaying the noise.

I recently swapped my rear differential to a unknown condition USED manual LSD rear diff.

At the same time, I swapped in new solid aluminum rear differential bushings. I read and understand that this will increase noise in the cabin from the rear diff.

The noise is much louder than I anticipated and believe it is a combination of a bad rear diff, and the increase in noise from the solid bushings. let me know what you think.

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I also had a seized rear axle in my rear hub. I tried removing it with a dead blow hammer with no luck. When I got an alignment, one of the employees noticed the rear noise and suggested it to be a bad hub bearing, not a bad rear .

It makes the noise usually above 35 mph, both accelerating and decelerating. The weird thing is if I am in 3rd gear and engine brake, the noise disappears. Which makes me doubt its the hub bearing.

Any help will be much appreciated. Thanks!

 

[black_gst]

sounds to me like the rear diff is out of spec, its loose so on decel you are hearing the backlash because its worn but its far enough out that you can hear in on acceleration too, what fluid are you running in the diff? you could try a heavier weight and see if it lessons and that would confirm it needs to be rebuilt

 

[kanusky1990]

I couldn't remember what oil was in the diff, so I changed it out with some basic 80w90 to be sure (based on TRE's site) and the noise is the same or slightly quieter. I have two spare rear diffs, one auto w/ LSD and a manual w/o LSD. I plan on opening them up and combining them to make a manual w/ LSD.

I'll take pics of the process and post here with any questions I run into.

 

[Nuzzi]

I agree that sounds like the gears are way out, maybe the po replaced the pinion bearing and set it wrong, also check for damage since that can also be caused by running dry or with bad oil in which case even new oil wont fix it.

 

[2slow4now]

When you swapped it in did you pop off the back cover and look over the gears?
It could be the bearings are worn and allowing the gears to mesh weird. Reach up under there and see if you can wiggle the pinion yoke any. Feel for side to side play.

 

[kanusky1990]

hey guys, sorry I haven't responded in a while.

I ended up taking two rear diffs (auto with LSD and manual without LSD) and made a manual with a LSD.

Swapped it out with the one in the car and the noise is very minimal now. Like exactly what I would expect with the solid bushings.

I have the other rear sitting on my workbench, but haven't torn into it yet. Once I do, I'll update. Thanks for the suggestions on the issue!

 

[black_gst]

glad to hear you figured it out, that rear diff must have been bad.