mcssboy13

Wanted to get some insight since I'm not sure I trust the dealer at this point.

I had a minor leak from the rear differential. While in for service, the dealer replaced a seal and performed a 'differential service'. A couple days later after leaving work, something seemed to pop and bang and all of a sudden it sounded like I was dragging something. I limped to the dealer and had to leave the car. I seemed to drive, but it sounded noisy and like something was grinding a little bit, even with the clutch in. Almost like what I would imagine it would be like if the gear was no longer aligned correctly.

This morning they said something must have gone wrong and it needed a new pinion and bearings, and implied that it was the result of their service, which I believe to be the case as nothing else has recently changed. I then mentioned it has a 373 gear instead of the stock gear. (this had been installled at least 20,000 miles ago with no issues).

This afternoon, the tune changed - after I had revealed that the gear wasn't stock from the factory, they couldn't cover it (even though it's extremely likely that their service caused the issue). They claimed that they retorqued the bolts to specs (maybe the 373 has a different spec?), which leads me to believe they loosened it up first or did something - so they were doing more than replacing a seal. They are Ford Racing gears.

Thoughts? Anyone know what exactly they would have done with a 'differential service'? If I had known they were going to even touch the gears I would have declined the service and just had the seal replaced. Basically now they are saying that it will be a $1400 repair job (which is obviously more than simply replacing the gear and pinion). I am supposed to meet with the service manager on Friday to discuss as I feel that it was their service that caused the issue, not the fact that the gear is not the factory part.

yourmom6990

Sounds like bs to me. Changing a diff seal is a piece of cake. Unbolt the cover, clean the residue, put on new seal and bolt cover back on. Then replace fluid. I don't see why they would be screwing with the gears at all. Unless a piece of crud got into the gearbox while they had the cover off. Or if you have a limited slip diff and they didn't put the correct additives. I wouldn't have told them that you had 3.73s in her. You might've just screwed yourself. I would ask them for a detailed description of the work that was done.

tbear853

You do mean while it's rolling forwards but the clutch held in don't you???
You are talking about a pinion seal I'm thinking, not a gasket for the rear end cover?

Sorry to read that. This is another of those tales that is the reason I am almost relieved when warranty is run out on a vehicle. No warranty, no "decisions" .... I just get her fixed.

I wasn't there, I don't know what he did, but I'd bet dollars to doughnuts that when the mechanic replaced the pinion seal he likely stripped the pinion shaft, changed seals, then slid the flang in place with some sealer and re-torqued a new pinion flange nut back to some torque number about where it was when a new pinion is set in .... but then you are crushing a crush sleeve that sets the bearing preload.

If you loosen and remove the nut like to replace a seal (and use a new nut as he likely did) you can very easily go too far and add more crush to the sleeve which shorten the distance between pinion bearing inner races drawing them closer which then preloads the pinion bearings tighter and they won't last long that way.

Unless you are going to purposefully reset pinion bearing preload using a new sleeve, there is one proper way to replace a seal "in my book".

First, I drop the driveshaft after marking it (don't "drop" it, just get it out the way). Use a small dial torque wrench and putting a socket and adapter on the pinion nut, I turn it and see how much torque it takes to turn. Write it down.

Carefully and accurately mark the pinion nut, the flange, and the end of the pinion shaft itself with a center punch on one side together and I even record the exposed thread count.
Then I remove the nut and flange and swap seals and reinstall the same flange with the same teeth merged so my marks line up, some sealant on the flange at the pinion shaft, then apply some lock tite on the threads and in the nut and install the pinion nut (and any washers) to the exact same position from which it was removed so my dots line up and my thread count is the same. I know the torque is gonna be lower because the crush sleeve is already crushed.

I want the nut, flange, and pinion shaft in the exact same relationship as they were before I removed them.

I can't guarantee that with a new nut.

I'll then use a small dial torque wrench and see how much torque it takes to turn the pinion shaft and compare to my first reading.

If the nut with lock tited threads seems not "tight" enough to the threads to stay locked, I will even lightly stake the threads in two places.

I've replaced pinion seals on a couple of my assigned state police cars over the years and I've done it on some personal vehicles and to date, I have never had a hiccup yet, no nuts flying off, no blued shafts with melted bearings, not even in many miles of serious road use .... and never any more leaks. That makes "my book" right enough .... for me.

Back when I was in my very early '20s a friend and I did replace a pinion seal on my '69 Dart's 8.75" rear and he just tightened the nut to some torque number a book he had called for .... and the pinion bearings were toast in a few miles. We both talked about it some then and from then on, I have done it this way.

They are probably gonna show you a preferred method laid out in a book.

And this ain't gonna help now, but last year into this year our 2008 GT had a regular pinion seal leak. Everytime I got it up to check something or make a mod or service her, there was differential lube drops hanging from the center of the rear axle and it was coming from the pinion seal. I bought a seal with the aim of swapping it ..... but as I was underneath getting ready to do it one day just after a good hour's drive I checked the lube level and when I removed the plug ..... "swoooosh" came the pressure and some grease spit.

I immediately suspected the axle vent which is a short vent with a small spring loaded disc under that cap for a vent valve. I removed the vent and got a hose barb that fit in place and ran a hose up and through a 180 degree bend and back down and into a frame rail.
Suddenly ..... no more drops of differential lube hanging under the axle center section when I look. She's remained dry since.

mcssboy13

Yes, correct.


Yes, unfortunately I didn't know that at the time. I had thought it was leaking from the gasket, although in all honesty, even if they had told me it was a pinion seal, I'm not sure I would have known exactly what they would have had to have done.

I wasn't expecting it to be covered under warranty, I just figured it was related to something that they had done wrong and wanted it fixed. I learned a little more today though.

Basically they didn't know it was a 373 (apparently it wasn't tagged), so they worked it as if was the stock gear. So it seems you are exactly correct in that it was not put together they way it should have been, but according 'to the book'. They showed me the parts and expalaine what had been done - the bearing carrier (crush sleeve?) was bent up and a few of the bearings had popped out (I expect it wasn't like this when it had been reinstalled of course). He said if he had known it wasn't a stock gear, it would have been done differently (pinion offset or something). Of course if I had known that they were going to need to touch it or needed to know, I would have said something up front.

It still makes me think I would have been better off just letting it leak a little bit, but in the long run, that may have caused different damage on it's own. I think I would have felt better about it if there had been a problem down the road rather than within 100 miles of the service work being performed. Of course it may have cost me more if that had been the case.

They did at least provide some assistance by cutting the labor rate in half and eating part of the cost - but it's still costing me more than the original gears and install (plus what I had already paid to get the leak 'fixed').

I keep learning more and more that I know less and less...

Thanks for the input!

PNYXPRESS

Ignorance on their part shouldn't remove blame.

It's just like saying you didn't know the speed limit because you didn't see the sign. You will still get a ticket for speeding.

tbear853

At least they are attempting to look like they are meeting you part way I guess.
I think they the dealership should do the fix on their dime as it was their screw up ....
.... but I also understand wanting to get the whole mess behind you and get back into your "pride and joy" and not let it absorb your thoughts. Life is short enough.

Take care ..... and here's hoping they fix it right this time.

PNYXPRESS

Dealer did the same thing to me. Drove my splitter into a curb and cracked and popped the paint on it. When I pointed it out to them they said they didn't do it but would split the cost to repair it.

I believe this is their way of saying yep we screwed up but we don't want to admit to it so we will look like a good guy and "help" you out.