Help diagnose a 8.8 rearend issue

05stroker · Feb 12, 2012

I have a 8.8 with Detroit True Track, 3:73 gears,welded tubes, and Strange c-clip eliminators. Today while driving I noticed a slight howl from the rear end only when I would go on and off the gas. Also when I was filling up with fuel I looked under the car to check for any leaks and such since this whole setup is new. While looking under the car I noticed some gear oil coming from the vent tube on the rear axle tube. When I returned home I drained some of the fluid thinking I must have overfilled it. Well, I had. What I noticed while draining is the issue. Lots of metal! So, what I am looking for is some help to diagnose what the issue may be. Looks like I may have set something up wrong. Here are a couple of pics.

05stroker · Feb 12, 2012

Has to be from the center bearings, the pinoion or the gears themselves.I pulled the rear tonight and pulled the axles along with the eliminators and everything looks good there. The bearings feel nice and smooth. I cleaned them up and there no pitting or anything. I guess its good I caught this early what ever it is. Tomorrow night I will check the backlash and pull the center section out and inspect the center bearings. After that I need to check the preload on the pinion and then remove it to inspect the pinion bearing. Right now with the axles removed the pinion takes a little more force to turn by hand then I would like to see.

TexasBlownV8 · Feb 13, 2012

The howling itself sounds like pinion bearings. Metal may have confirmed it for you.
Yikes.

05stroker · Feb 13, 2012

TexasBlownV8 said:
The howling itself sounds like pinion bearings. Metal may have confirmed it for you.
Yikes.

All the bearings looked good except the large pinion bearing, it had some scaring. The bearing races on both pinion bearings were very warn. I think that is where the metal in the oil came from. Looks like I had the pinion preload set to high and the backlash was tight as well. When I set this thing up I remember every thing checking out. I didnt check the pinion preload though since I was reusing all the bearings and crush sleeve.

New setup is as follows.

: Pinion preload is at .015 with new bearings and the same crush sleeve
: Backlash is at .011
: All other bolts are torqued to spec. (Just need to recheck the Strange sec for the axle retanors)

tmcolegr · Feb 14, 2012

the crush sleeve isn't recommended to be reused. You also might want to read through this thread

FRPP's gear set instruction sheet recommends 8-14 in. lbs pinion bearing preload w/used pinion bearings or 16-28 in. lbs. pinion bearing preload w/new pinion bearings. Backlash is suggested to be .008-.012" with a max. variation of .004" between teeth. Differential case runout should not exceed .003"

TexasBlownV8 · Feb 14, 2012

+1 on the crush sleeve; cheap enough to pick one one and replace it if it's torn down. Kind of late now

The preload seems a little low for new pinion bearings, too.

05stroker · Feb 14, 2012

I was afraid to go any more on the pre load becouse of what happend before. Even at 15 in. lb. it seems stiff to turn by hand. If the crush sleeve is a very big issue, I can pull it back apart tonight and install a new one. The rear is out of the car and on stands. It would only take an hour or so.

05stroker · Feb 14, 2012

Went to get the upgraded crush sleeve and nut at my Ford dealer today, they didnt have it in stock. So, I went talk to a tech that works there I have known for a while about a tool they use to hold the pinion gear to to install the new crush sleeve. And what do you know, he just happens to have a few new sets! And I was able to borrow the tool!

05stroker · Feb 14, 2012

Here is a pic.

I have it redone now with the new crush sleeve and pinion nut. New specs are as follows.

Pinion pre load is at 20 in. lb.
Back lash is at .011

Thanks for the info guys!

TexasBlownV8 · Feb 15, 2012

now you're on the right track!!!
Any pics of the pinion bearings/races where the metal probably came from?

05stroker · Feb 15, 2012

TexasBlownV8 said:
now you're on the right track!!!
Any pics of the pinion bearings/races where the metal probably came from?

I can post some this evening.

Also one thing to note is it took 240 foot pounds of torque to crush the new sleeve. If I remember correctly the old sleeve only took about 140 to 160 pounds to crush.

GrnBullitt08 · Feb 15, 2012

tmcolegr said:
the crush sleeve isn't recommended to be reused. You also might want to read through this thread

FRPP's gear set instruction sheet recommends 8-14 in. lbs pinion bearing preload w/used pinion bearings or 16-28 in. lbs. pinion bearing preload w/new pinion bearings. Backlash is suggested to be .008-.012" with a max. variation of .004" between teeth. Differential case runout should not exceed .003"

This^^^

You definitely had something out of wack if you had howling during deceleration, check all specs as stated above and dont reuse the crush sleeve.

kevinatfms · Feb 15, 2012

also make sure if you are using the HD pinion bearings that you have the spacer behind the inner bearing race. and you only use it with the HD bearings(gt500/bullit pinion bearing set)

tmcolegr · Feb 15, 2012

05stroker said:
I can post some this evening.

Also one thing to note is it took 240 foot pounds of torque to crush the new sleeve. If I remember correctly the old sleeve only took about 140 to 160 pounds to crush.

That sounds correct. The new HD crush sleeve takes considerably more effort to collapse than the old spacer. I thought I was going to blow a kidney tightening mine to spec

05stroker · Feb 15, 2012

Also I put 4.25 pints of fluid this time instead of 4.25 qts as I did last time.

Its no wonder it was coming out the vent! LOL

GrnBullitt08 · Feb 16, 2012

05stroker said:
Also I put 4.25 pints of fluid this time instead of 4.25 qts as I did last time.

Its no wonder it was coming out the vent! LOL

4.25 qts? WTF! Haha I'm surprised your differential cover didn't blow off.

05stroker · Feb 16, 2012

GrnBullitt08 said:
4.25 qts? WTF! Haha I'm surprised your differential cover didn't blow off.

IDK, I could have sworn I filled till it cam out the overflow plug but man there was a lot of fluid in there! LOL

05stroker · Feb 19, 2012

TexasBlownV8 said:
now you're on the right track!!!
Any pics of the pinion bearings/races where the metal probably came from?

TexasBlownV8 · Feb 20, 2012

Wow. That race didnt hold up very well. How do the bearing balls look?
What do the carrier races look like?
What fluid were you using?

05stroker · Feb 20, 2012

TexasBlownV8 said:
Wow. That race didnt hold up very well. How do the bearing balls look?
What do the carrier races look like?
What fluid were you using?

Bearings were scared. The third pic is carrier bearing race. I was running dino oil.

I think the issue cam about when I swapped the pinion flange for the new DS setup after the rear had been setup and installed. I removed the fac. flange and installed the new one with an impact. I think at that time the pinion preload was compromised and was too tight.

Help diagnose a 8.8 rearend issue

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