Failing rear end bearing? ring and pinion work?

[Duane Black]

So when I first switched to Michelin slicks at VIR in December, I noticed rolling off fight corners that it was tricky to get power down for a few laps - the roms would jump but you didnt really hear or feel wheel spin (not in my sound muffled helmet anyway) but the issue seemed to go away after a few laps and I attributed this to cold race slick problems as the ambient temps were 40-50 degrees.

I had the same issue at Roebling this past weekend, in the same type of corners.

However, on the drive home, I noticed what I thought was a pinion bearing noise. The car makes a whirring sound under acceleration from about 20 to 60 mph, and it goes away immediately after taking your foot off the gas

In either event, I need. left side axle seal... but it hasn't leaked so much that it would be from low fluid...

So are Torsens known to fail? I thought they just snapped if they broke... or could this all be a bad wheel bearing?

the sound doesnt change if you lean the car on one side or the other. the gas pedal is the determining factor.

 

[blacksheep-1]

Let me try my way back machine..
I think pinion bearing noise goes away on deceleration. In any case, the fact that there is any noise is cause for pulling the cover. These cars use axles that double as the bearing race ( think GM 12 bolt, not Ford 9inch) and with that axle seal leak, you may have your answer.
Before you pull it down, throw some sand under the rear tires and do a mild burnout and see if both black stripes are the same length.

 

[Duane Black]

The axle is a race. If thats the problem, does that mean I need to replace the axle?

 

[blacksheep-1]

The axle is a race. If thats the problem, does that mean I need to replace the axle?

I've had them fail with 20K miles. When you pull the axle to change the bearing, put a straightedge on the axle bearing area and see if it is level. If it is level and not pitted, then send it, pits or dips, then change it out.

 

[Duane Black]

mKay... so I dropped my trailer and drove to my parents house and couldnt do a good burnout... I used some dirt at my parents and it made two nice paths...

I was getting ready to tear it down and realized the problem wasnt a wheel sealz but its blown out of the axle vent... i ised a wire tie and its still mostly full (the diff)... and get this, its not NEARLY as noisy.... the rear end always had some whine and its basically what it normally had been.

could it have been my street pads rubbing the race pad varnish back off the rotors? I've never quite heard it like this...

maybe my trailer has a bad bearing? thats my dads idea.... it got hot going to georgia and "went bad" when it cools.

 

[Duane Black]

Now with sound! My dad thinks its just the ring and pinion wearing....

rear end sound

youtube.com

 

[blacksheep-1]

FWIW, the 8.8 is a " noisy " diff, more so thant the pumpkin style. That sound seems a bit abnormal though. Are you using the correct weight diff lube?
Whatever it is, it doesn't sound like it will catastrophically fail. More like an " I'll whine until it drives you insane" kind of noise.

 

[Duane Black]

I think its the 85w140? i think its mobil 1

 

[blacksheep-1]

Also... saw this

Diff Expansion Tank with Hardware https://trackmustangsonline.com/classifieds/diff-expansion-tank.572/

 

[Duane Black]

Also... saw this

Diff Expansion Tank with Hardware https://trackmustangsonline.com/classifieds/diff-expansion-tank.572/

hmmm...

what kind and weight diff oil do you recommend? and what are your thoughts on the finned diff cover?

 

[blacksheep-1]

I have a fondness for Lucas oil products, not sure what they recomend. Virtually every person I know that runs one of these has issues with the venting... yes, I would recommend a finned cover, preferably one with the girdle,but they may not clear your PHB.

 

[JDee]

I run Lucas diff lube, haven't had a single axle overheat since I switched to it, used to get them regularly on hot days. No cooler, Torsen rear end.

 

[Duane Black]

I run Lucas diff lube, haven't had a single axle overheat since I switched to it, used to get them regularly on hot days. No cooler, Torsen rear end.

Which viscosity?

 

[JDee]

75W140, and I went and looked and it's not Lucas it is RedLine.