8.8 rear differential making humming noise

[90FoX]

I have an 8.8 rear end that has 3.73 gears in it already. My pinion seal is leaking and its not terribly leaking fluid but there is fluid splashed on my exhaust and under body.

I am planning to replace the seal but before committing to it I want to know if I need to rebuild the entire rear diff.

When I drive straight under any load I do not hear any humming. The humming only occurs during turning. For example when I am on a freeway on ramp I let off the throttle and through the turn I can hear humming, it reverberates like whoom whoom whoom whoom whoom quickly. If I give it some throttle(ie load) it will stop making the sound. I don't normally hear it when turning slowly right or left.(like at a stop light etc). I suppose because I am not going as fast as I am when on an on ramp.

I know my clutch packs are toast too.

Anybody ever have this? Can anybody let me know what to look for when I crack the diff case cover.

I think it might be a bad bearing or excessive run out from a worn out S spring or clutch packs thickness out of spec. I just hope I didn't notice the leak to late. But I doubt the rear has run low on fluid.

Thanks :beer:

 

[no2moro]

It sounds like rear axle bearings or grooved axle.

 

[Toasty]

I have an 8.8 rear end that has 3.73 gears in it already. My pinion seal is leaking and its not terribly leaking fluid but there is fluid splashed on my exhaust and under body.

I am planning to replace the seal but before committing to it I want to know if I need to rebuild the entire rear diff.

When I drive straight under any load I do not hear any humming. The humming only occurs during turning. For example when I am on a freeway on ramp I let off the throttle and through the turn I can hear humming, it reverberates like whoom whoom whoom whoom whoom quickly. If I give it some throttle(ie load) it will stop making the sound. I don't normally hear it when turning slowly right or left.(like at a stop light etc). I suppose because I am not going as fast as I am when on an on ramp.

I know my clutch packs are toast too.

Anybody ever have this? Can anybody let me know what to look for when I crack the diff case cover.

I think it might be a bad bearing or excessive run out from a worn out S spring or clutch packs thickness out of spec. I just hope I didn't notice the leak to late. But I doubt the rear has run low on fluid.

Thanks :beer:

If you're pinion seal is leaking and your clutch packs are shot, I'd suggest just going through the whole diff and refreshing everything. When you replace your pinion seal, make sure you replace the crush sleeve too.

 

[Toasty]

I have an 8.8 rear end that has 3.73 gears in it already. My pinion seal is leaking and its not terribly leaking fluid but there is fluid splashed on my exhaust and under body.

I am planning to replace the seal but before committing to it I want to know if I need to rebuild the entire rear diff.

When I drive straight under any load I do not hear any humming. The humming only occurs during turning. For example when I am on a freeway on ramp I let off the throttle and through the turn I can hear humming, it reverberates like whoom whoom whoom whoom whoom quickly. If I give it some throttle(ie load) it will stop making the sound. I don't normally hear it when turning slowly right or left.(like at a stop light etc). I suppose because I am not going as fast as I am when on an on ramp.

I know my clutch packs are toast too.

Anybody ever have this? Can anybody let me know what to look for when I crack the diff case cover.

I think it might be a bad bearing or excessive run out from a worn out S spring or clutch packs thickness out of spec. I just hope I didn't notice the leak to late. But I doubt the rear has run low on fluid.

Thanks :beer:

If you're pinion seal is leaking and your clutch packs are shot, I'd suggest just going through the whole diff and refreshing everything. At the very least your pinion seal, pinion crush sleeve, axle bearings, axles seals, clutch packs, etc. When you replace your pinion seal, make sure you replace the crush sleeve too.

 

[006]

If you're pinion seal is leaking and your clutch packs are shot, I'd suggest just going through the whole diff and refreshing everything. At the very least your pinion seal, pinion crush sleeve, axle bearings, axles seals, clutch packs, etc. When you replace your pinion seal, make sure you replace the crush sleeve too.

Gimme more info on this....because I have the same humming noise, but it only happens while giving it slight throttle. I've replaced all my bearings, axle shafts and U-joints, it still makes noise...plus my pinion seal is leaking. (I already replaced the first one and on my 2nd).

So, I need to know more about the diff clutches and why this would cause the pinion seal to leak.

 

[90FoX]

NOMORO - I took the car out today and the humming sound only occurs when I turn right. It doesn't happen when I turn left. Also it will not happen at slow speeds. I was swerving between three lanes and it takes some speed to make the sound. I notice it a lot when entering the freeway, on the on ramp.

Because it only makes the sound turning right, does that help determine which side the sound is coming from?

When I pull the axles out what do I look for on the bearing and the axle? Will the axle likely have an obvious groove in it? How do I test the bearing or what do I look for with the bearing?

Toasty - I really don't want to have to replace all the bearings on the pinion and carrier etc if it's not necessary. But if I do end up rebuilding the rear end, will I have to measure pinion depth backlash and ring gear run-out all over again?

 

[Toasty]

NOMORO - I took the car out today and the humming sound only occurs when I turn right. It doesn't happen when I turn left. Also it will not happen at slow speeds. I was swerving between three lanes and it takes some speed to make the sound. I notice it a lot when entering the freeway, on the on ramp.

Because it only makes the sound turning right, does that help determine which side the sound is coming from?

When I pull the axles out what do I look for on the bearing and the axle? Will the axle likely have an obvious groove in it? How do I test the bearing or what do I look for with the bearing?

Toasty - I really don't want to have to replace all the bearings on the pinion and carrier etc if it's not necessary. But if I do end up rebuilding the rear end, will I have to measure pinion depth backlash and ring gear run-out all over again?

From my experience watching other people do my gears over the years and being a PITA with questions while they do them, I can say that every installer I have ever watched reuses the same pinion gear shims and the same thickness of shims on either side of the carrier.

When I first bought my car (factory 3.27's) it had a loud humming/howling noise coming from the rear end. It would also clunk letting off the gas while gently coasting.

It turned out that someone had replaced the pinion seal at some point and had not replaced the pinion crush sleeve nor had they correctly torqued/tightened the pinion nut and allowed a great deal of slack for the pinion gear to move back and forth which had essentially ruined the factory gear set and resulted in the howling/humming and clunking. The wear pattern on the factory 3.27's was really bad compared to what it should have been. My new 3.73's fixed that problem. I had my installer replace all the bearings, pinion seal and crush sleeve and repack the posi with new clutches and more clutch discs to get better breakaway torque capacity. I replaced my own axle bearings and seals about 6 months before having my gears done.

 

[90FoX]

I see. My humming only occurs during right hand turns when up to speed like 35+mph without being on the throttle. It goes away when I give it any amount of throttle.

Also I do not have any clunking noises. Just a humming when I turn right. Many people have said axle bearing etc.

How hard was it for you to replace your axle bearing? Just a slam hammer to pull it out then a race/bearing installer to hammer it in right? Then the seal last.

 

[Toasty]

I see. My humming only occurs during right hand turns when up to speed like 35+mph without being on the throttle. It goes away when I give it any amount of throttle.

Also I do not have any clunking noises. Just a humming when I turn right. Many people have said axle bearing etc.

How hard was it for you to replace your axle bearing? Just a slam hammer to pull it out then a race/bearing installer to hammer it in right? Then the seal last.

Again, due to variances in tolerances and the exact problem you noise may or may not be related to what I had occur, but it wouldnt surprise me if it was something similar.

A disassemble and checking of the pinion backlash with a dial indicator AND a reading of the wear pattern with marking paste would be in order i would think. I would also check the breakaway torque on your pinion nut to see how much force it requires to turn it (should give an indication as to whether or not your pinion bearing or carrier bearings are in bad shape.

OR, you could do what I did and just replace your axle bearings and seals in the hope that the noise goes away. Mine didnt, which is why I took it in for a inspection which revealed the pinion crush sleeve problem, excessive backlash and incorrect wear pattern on my factory 3.27's - which is when I went with the 3.73's and a full replacement of pinion and carrier bearings and repacked the diff with new and extra clutches..

 

[90FoX]

Again, due to variances in tolerances and the exact problem you noise may or may not be related to what I had occur, but it wouldnt surprise me if it was something similar.

A disassemble and checking of the pinion backlash with a dial indicator AND a reading of the wear pattern with marking paste would be in order i would think. I would also check the breakaway torque on your pinion nut to see how much force it requires to turn it (should give an indication as to whether or not your pinion bearing or carrier bearings are in bad shape.

OR, you could do what I did and just replace your axle bearings and seals in the hope that the noise goes away. Mine didnt, which is why I took it in for a inspection which revealed the pinion crush sleeve problem, excessive backlash and incorrect wear pattern on my factory 3.27's - which is when I went with the 3.73's and a full replacement of pinion and carrier bearings and repacked the diff with new and extra clutches..

I see what you mean.

I just took the cover off today when I got home. Clean the inside of the case up real good. That fluid is very slick and not fun when turning wrenches haha.

I'm going to further disassemble it tomorrow when I wake up.

I can already see the gears which sit above and underneath the side gears inside the carrier, I think they are called spider gears, are chewed up and missing some material off many teeth. Both spider gears have this problem.

I tried pulling the pinion shaft out but its very difficult to remove the last half. I'll see about that pinion shaft tomo.

Where can I get shims for the carrier and pinion bearing to make adjustments. Do they come with a rebuild kit?

:beer: