8.8 differential leak

[Shelty]

Hey guys, my 2005 GT seems to be leaking gear oil from the differential. I noticed a small pool of oil on the ground under the rear axle when I last took the car out, It sits 90% of the time. it had sat for a full week between drives I figured maybe it was leaking from the cover so I tossed cardboard under it to see where the leak was. I jacked it up this morning and discovered that the front part of the pumpkin (facing the nose of the car) had gear oil on it, so its making me think that the pinion seal is leaking.

has this happened to anyone else before? Ive never worked on a rear end before so I am not knowledgeable on the subject. its not gushing fluid out, in fact when I cleaned up the leak off my garage floor the small puddle was only maybe 3 inches around, after the car sat for a week. is the leak due to the car just sitting around? can the outer pinion seal be replaced without taking the whole rear apart? or should I just find a good shop to fix everything? I dont want to screw up my car by doing it myself. whats the average cost for such job? I figure while its out I'll have 3:73s put in and maybe have the traction loc rebuilt with the carbon fiber clutches.

I should not that the car only has 75,000 miles on it. It is lowered, would the different pinion angle tear it up like that? its never been apart, stock gears, its not raced or launched hard.

 

[Kalatrax]

Probably the worst seal to go out. You will need to take it all apart and pull the pinion gear to replace it. I would take it to a shop and get the gears, bearings, seals, and maybe the discs replaced all at once. Should be around $400 for the labor.

 

[AnotherS197GT]

I'm actually going through the same thing right now with 110K on my 08. Its totally normal for the seal to go bad after that many years/miles. You will have to have the pinion nut removed to replace the seal. IMO, not something to mess with yourself if you aren't sure. The rear end doesn't need to come all apart. I decided to rebuild my rear end with 4.10s right now though, since I'd rather have everything done right, done once, and not have to worry about my preload on the pinion changing. Before you decide on rebuilding the clutch pack, you may want to consider just buying a new FRPP diff. Its $120 more than the clutches, but you might end up paying more for the labor to replace the discs than you would just buying a new diff. I would also recommend doing axle seals/bearings while you are in there.

Its just an "old" car with lots of miles, I was thinking mine could be pinion angle related too, but I really think this can just be chalked up to mileage.


Parts:

Axle seals/bearing kit M-1225-B1
Bearing rebuild kit M-4210-B2
Friction modifier M-19546-A12
Diff M-4204-F318C
or clutches M-4700-C

Those are all FRPP parts, order them from Tasca. I paid a lot less through Tasca than I would have from another online vendor (shipping included). You'll also need 2 quarts of 75w140 SYNTHETIC gear oil. I chose Amsoil which I bought from Greg Hazlett on this forum. Its cheaper than the RP and Ford fluid.

 

[gray1622]

It's not the correct way but I would just count the turns on pinion nut and replace the seal. I don't think you will have any problems. You can put red silicon around the seal. FYI you are suppose to replace the nut each time you remove it.

 

[eighty6gt]

As above, I've marked the nut and pinion, removed the nut, replaced the seal, and reinstalled the nut. Tightened a very small amount past my mark. No problems, no more leak. I believe Ford did this when they replaced the pinion seal a couple of years ago during one of the 10 or so times they worked on the diff under warranty.

Edit: clean the threads well, use red loctite.

 

[19COBRA93]

I agree, the "proper" way is to remove everything and start with a new crush sleeve. But, I've just replaced the seal, and reused everything many times with great success. It's very important to not over-tighten the nut, but get it tight enough that it doesn't work lose. If you over-tighten the nut, you'll burn up the pinion bearings in no time. I've done that too. It's ugly.

 

[Kalatrax]

Doing it that way will work if you don't over torque the exsisting crush sleeve. If you do your screwed.

 

[Shelty]

thanks guys. think that I will just have the rear rebuilt. I dont want to break anything, plus with 75k on it, I might as well have all the bearings replaced.

 

[BadPiggy]

thanks guys. think that I will just have the rear rebuilt. I dont want to break anything, plus with 75k on it, I might as well have all the bearings replaced.

Or you could buy a takeoff complete rear end from ROUSH for not much more coin than having yours rebuilt. Of course this would depend on what gear you were wanting.

 

[tbuff]

disregard

 

[lee12609]

just did mine a couple days ago. there really is no need to replace anything except the seal and nut (if you're anal).

 

[Synyster06Gates]

I would replace the nut. When my pinion seal was changed, some of the gasket material on the nut was missing so it still leaked.

 

[Deez-67]

Searching this down right now. My 05 has been dripping for a while but last week it was hemorrhage so I put her up tell I can get her fixed up. 140K on that poor girl so I guess it was about time.

So it sounds like if I want I can just drop the drive shaft and mark/count threads then pull it out that way without having to break into the pumpkin?

Do they make Ford Racing parts for that since I just had Ford racing axle baring put in not to long ago?

 

[gray1622]

That's to change the seal only. To change the bearing you have to pull pumpkin. Ford uses timken bearing iirc. If you just change the seal it's probably going to be only bandaid fix in your case. I changed my seal twice before I changed the bearings and I got about 6 months out first one and 4 months out the second one before they started leaking. I think my ds being out of balance caused my problem. If you change the bearing look at upgrading to gt500 bearing. It's more heavy-duty.

 

[Deez-67]

That's to change the seal only. To change the bearing you have to pull pumpkin. Ford uses timken bearing iirc. If you just change the seal it's probably going to be only bandaid fix in your case. I changed my seal twice before I changed the bearings and I got about 6 months out first one and 4 months out the second one before they started leaking. I think my ds being out of balance caused my problem. If you change the bearing look at upgrading to gt500 bearing. It's more heavy-duty.

Thanks for the info man. Sounds like the smart thing to do is to it all and have it done right.

 

[sportinawoody]

the best fix for this is to use a good sealer ( I used honda bond ) and seal the nut and washer. i used 3 new ford seals after a gear install and couldn't get it to quit leaking, asked a friend that does these installs routinely and it is common for the new nuts not to seal properly so he just dabs them all. worked for me, 45k miles and no more drip

 

[thump_rrr]

Do one of these and you'll never have to work on a POS 8.8" ever again.
I rebuilt mine 4 times including a Truetrac and a Wavetrac then I smartened up.

 

[BruceH]

There you have it. The best cure for a rear end leak is a 9". Lol.

 

[thump_rrr]

There you have it. The best cure for a rear end leak is a 9". Lol.

That's how mine started out. Someone tried to replace the pinion seal and he tightened it too much screwing up the backlash. It didn't last long after that.
The next time I put in a Truetrac which lasted a whole year and a bit before it blew up. Then back to stock and blew that up etc.
I must have spent over $4,000 on 8.8 repairs over the last 9 years.
It would have been cheaper to have gone to the 9" from the start.