Rear-end question...

[hittinboost]

Ok I recently had new seals, bearings, frpp carbon diff, moser 31's, frpp diff cover installed by a reputable mechanic near me and it's leaking. I spoke to my mechanic about this and he said chances are it's the pinion flange, which after spending about $700 on parts he neglected to tell me about, a $40 part that could leak. He told me that the 8.8's are known to leak from the flange and even putting a new one in wouldn't guarantee the leak to stop. Is this accurate? It's not leaving a puddle, it's more of a few drops that accumulate to a few more drops over and over. Thanks.

 

[caveeagle]

Did he replace the pinion bearings? If so, then he must have replaced the pinion seal (or should have).

If not, then you just had him replace the carrier and half-shaft bearings? I suppose if you knowingly took a shortcut and did not pay to have the pinion bearings replaced then I could understand why a mechanic would not want to be held responsible for the leak.

I had my 8.8 IRS start leaking at about 20k miles. It was replaced under warranty, has been fine since then. I am not aware of any 'chronic' 8.8 pinion leakage.

 

[ReefBlueCoupe]

Ok I recently had new seals, bearings, frpp carbon diff, moser 31's, frpp diff cover installed by a reputable mechanic near me and it's leaking. I spoke to my mechanic about this and he said chances are it's the pinion flange, which after spending about $700 on parts he neglected to tell me about, a $40 part that could leak. He told me that the 8.8's are known to leak from the flange and even putting a new one in wouldn't guarantee the leak to stop. Is this accurate? It's not leaving a puddle, it's more of a few drops that accumulate to a few more drops over and over. Thanks.

- Pinion seal* - not flange
- The part is around $10 from Ford
- 8.8's aren't singled out as "known to leak from the flange" - any rear end with a pinion seal can leak.
- A new one isn't guaranteed to stop the leak, as nothing in the world can be assured 100%, but in 999 out of 1000 cases, replacing a leaking pinion seal on an otherwise healthy rear end will stop the leak.

If he did not replace the pinion bearing and it has some play, that could cause early failure of a new pinion seal. Did he replace the pinion bearings and seal? Did you ask him to? From the sound of it, this was not discussed.

If the seal wasn't lubed with a light amount of gear oil before the yoke is reinstalled, the dry seal could be overheated by the dry yoke and could cause early failure of the pinion seal.

Solution: He just built the rear end. If the pinion seal is already leaking (you didn't say specifically how long ago it had been), he should replace the seal at his cost. Unless of course you supplied the parts, then you should be responsible for the new seal and replacement labor. This is standard among shops as far as them vs you supplying parts.

A pinion seal should last tens of thousands of miles before any leak occurs.

 

[hittinboost]

Did he replace the pinion bearings? If so, then he must have replaced the pinion seal (or should have).

If not, then you just had him replace the carrier and half-shaft bearings? I suppose if you knowingly took a shortcut and did not pay to have the pinion bearings replaced then I could understand why a mechanic would not want to be held responsible for the leak.

I had my 8.8 IRS start leaking at about 20k miles. It was replaced under warranty, has been fine since then. I am not aware of any 'chronic' 8.8 pinion leakage.

He told me he installed all new bearings and seals in the whole rear. However he said that the pinion flanges are known to leak, and even with installing a new flange and seal that could leak also.

- Pinion seal* - not flange
- The part is around $10 from Ford
- 8.8's aren't singled out as "known to leak from the flange" - any rear end with a pinion seal can leak.
- A new one isn't guaranteed to stop the leak, as nothing in the world can be assured 100%, but in 999 out of 1000 cases, replacing a leaking pinion seal on an otherwise healthy rear end will stop the leak.

If he did not replace the pinion bearing and it has some play, that could cause early failure of a new pinion seal. Did he replace the pinion bearings and seal? Did you ask him to? From the sound of it, this was not discussed.

If the seal wasn't lubed with a light amount of gear oil before the yoke is reinstalled, the dry seal could be overheated by the dry yoke and could cause early failure of the pinion seal.

Solution: He just built the rear end. If the pinion seal is already leaking (you didn't say specifically how long ago it had been), he should replace the seal at his cost. Unless of course you supplied the parts, then you should be responsible for the new seal and replacement labor. This is standard among shops as far as them vs you supplying parts.

A pinion seal should last tens of thousands of miles before any leak occurs.

1986-04 Mustang 8.8" Rear Pinion Flange at LRS - Free Shipping!

I was told flange, not seal. I suspect ^ that is what he was talking about. When I spoke with him he asked if I wanted all new seals and bearings throughout the entire rear, I said yes. He provided the parts (bearings and seals), it was done around Jan. this year and I've only put maybe 1000 miles on it. When I mentioned the leak to him he just simply said that's what 8.8's do, some leak, some don't. I asked a few buddies on facebook if it's normal and they said their rear's have drips to them too. :shrug:

 

[WhiteFoxGT]

They will leak from the flange. The fluid comes up through the threads on the pinion and out from the nut. There really isnt much in fixing it, just back the nut off, clean, and coat threads with RTV

 

[hittinboost]

They will leak from the flange. The fluid comes up through the threads on the pinion and out from the nut. There really isnt much in fixing it, just back the nut off, clean, and coat threads with RTV

Yea I've heard this also. Seems like I'm getting mixed feedback, some say that it's 99% chance it's not going to leak with new seals (which I have), then others say that even with new seals it'll still leak. It's not a huge problem, I just don't like a leaky car and I'm tired of looking at the drops on my garage floor :cuss: