hey folks, I need your help identifying a noise from the rear diff. First I have a 99' F350 DRW 7.3l with a Dana 80 4.10 LS rear. I had the both axles and pinion seals changed due to a clogged vent line. I picked it up and drove it to work about 45 miles with the radio on (probably louder than I should have) and didn't notice anything, but on the way home without the radio on I noticed when I lift off the accelorater I have a very noticable noice (whiring almost like snow tires on dry pavement) coming from the rear, but only noticable when I lift (unload). The closer I got to the house I could hear it and also start to feel it in my feet. When I got it home I noticed the pinion seal leaking (alot). I got under and can easily move the pinion shaft up and down and side to side with just my hand. The fluid level is now down about 2+ inches from the fill hole. I have an appointment to take it back to have them inspect it. Just wondering what you all might think they should find. I'm no rear end specialist, but I don't think that pinion shaft (is that what it's called?) should be wobbling around. I just want to go in with some idea of what to look for. thank. Mike

 

the pinion shaft should not move at all!! do not drive the truck anymore until it is fixed, it might be safe to drive it slow to the repair place that is it!!!! most likely happened is the pinion nut was nut properly torqued and now the pinion shaft is moving around in the diff, bad news for gears if run long times.

 

Rusty is right but you probably need to be prepared for fight to get them to admit this. Most shops seem to want to reuse the same crushnut instead of spending $10 or so for a new one. This is where the problem lies.

 

Eww....

Definitely sounds like someone didn't torque the pinion flange nut correctly.

Or, it's a one-use nut, and never should have been re-used. But they did.

The Dana 80 is not a crush-sleeve type setup, so the torque on that nut is really a no-brainer. As in, the Sterling 10.5", when you torque down the nut, you have to keep checking the preload on the bearings. With the Dana 80, the preload is done by shims, so once those shims are set right, they just have torque that nut to a certain value and it's done.

The noise when letting off the gas is usually the front pinion bearing - the one right behind that seal.

You're going to have a fight to get this fixed.

I would NOT let them point the finger at the leak or anything else causing the problem, since you never heard the noise before they "fixed" it, RIGHT?!?!?

THEY did not torque it down right. Period.

 

i'd make them pull the cover and make sure the ring and pinion isn't chowed too.i'd not drive it ,it'll do more damage .

 

Just thought I should tell you there0 are a few honest mechanics left in the world. I went up to the shop this morning (driving slowly) and told Kurt (owner/ chief mechanic) that I wanted to be present when they did the tear down and inspection. He put it on the lift and grabed the drive shaft and wabble the pinion around then looked at me and said "I screwed up, I didn't torque the nut properly, I'll make this right." He pulled the case and we looked at the oil (no signs of metal), he then pulled the axles and completly disassembled the differential. He tore it down and I inspected it with him. I looked over all the gears and looked for things like knife edges, spalling and discoleration and didn't see any signs of damage, as a matter of fact it looked very good for a diff with 122K on it. We inspected all the bearings and the only one that showed any signs of damage was the pinion, it had some very small pitting in the outer edge of the race. None of the other bearings or races showed any signs of damage. I asked him what his plan was and he told me that even though only one bearing showed damage he was going to replace all four (pinion, diff, and sides) because even though we couldnt spot anything he wanted me to be confident that there was nothing wrong. He also said since it had Ford OEM bearings and races, he wasn't going to use second source parts. (he called the local dealership while I was there and order them). He also order a new pinion nut and washer. I feel this guy is doing right by me and just thought I should pass that along. Thanks for your input and advise. Mike.

 

Mike, KEEP that mechanic!

He sounds decent.

The ONLY thing I would say is after he gets the bearings in, to check the contact pattern on the gears (which SHOULD be done when doing bearings anyway!).

That'll tell you if the gears are screwed.

By the way, in all the Ford/Dana rear-ends I've ever opened up, the ones with a "non-Timken" front pinion bearing would all show discoloration or pitting on that front pinion bearing.

It seems to be the one bearing they always put an NTN or other Asian-brand bearing in. And everytime I see that type of front pinion bearing, even with low mileage, they all show excessive wear. The rest in the diff are always Timken for some reason

Oh, and another thing to keep in mind.

Dana is one thing. Ford is another. You have a better chance of getting Timken bearings from a truck parts supplier than Ford.