[roger1]

I'm just finishing the restomod on my '69 GTO convertible that I've been working on for 3 years. I haven't even put 50 miles on the car yet.

Yesterday while driving it I started hearing a hell of a noise coming from the rear of the car whenever I let off the gas pedal. I nursed the car home and immediately put it up on jack stands to inspect. It didn't take long to find the problem. The yoke on the differential was all sloppy! So, that would mean to me the pinion bearings are toast.

I bought all the new parts including gears for it and then paid to have it assembled. Like it said not even have 50 miles on since then. The machine shop I used to assemble the engine recommended the guy to me for the rear end assembly. He said just bring me the rear axle and I'll have him come pick it up and assemble it for you and bring it back. So I never met the guy that did the work and don't who he is. I will start out by calling the machine shop guy on Monday and see what he advises me to do.

Here's a photo of the parts I bought. New Dana 3.55 gears, a Yukon bearing kit which as I remember are Timken bearings and a Auburn Gear limited slip differential.



Any info you guys can give me as far as what might have gone wrong and what other damage this might have caused? Any suggested guidance going forward for me would be appreciated too.
I also hope to get some guidance from the machine shop owner when I talk to him on Monday. It wasn't his fault but I hope he will he feels some responsibility to help assist me in getting this issue resolved.

[steve25]

Hard to say.
My first thoughts are .

1) did not torque the new crush collar to the right spec.
2) Used the old crush collar, and if so hopefully by mistake.
3) a piñon bearing was defective..
4) the yoke failed.

[mgarblik]

Most likely Steve25's #1 is the issue. It's extremely difficult to crush that collar, especially with the axle out of the car. In that situation, I use a torque multiplier to get enough force on that nut to crush the collar. With new bearings and the center section removed, 30 inch lbs. rotational torque is correct, no more than 35 in lbs. It takes 250-275 ft. lbs to crush the sleeve and begin to apply preload. They don't give a spec. for rotational torque with the unit assembled, so to really do it right, the center section and axle shafts should be pulled out. Damage is unknown. May be fine once assembled correctly. A visual inspection and a pattern check should show any issues.

[roger1]

Thanks guys.
After reading 1 thru 4, I thought the most likely thing would be #1. I hope the new gear set and Auburn unit are OK The axles were new too btw.

I don't know if I'm going to get the problem solved with no cost to me because of the way I chose to get it assembled. As it seems most likely to be #1 and the
assembler's fault, I can't prove that it wasn't #3. Not sure I'd have any options if they guy who did the work wont stand behind it.
The only thing I was told was that the guy that assembled it has an unrelated job and does rear-end work on the side. I did think the charge for assembling it was high. I didn't ask what the price was before I just told the machine shop owner to go ahead and send it out to his guy and was a little shocked when I got the bill.
If the guy did mess up, I'm not even sure I shouldn't just take the cost hit and take it to someone else if I can find somebody.
I do want to see what the machine shop owner says when I call him on Monday before I decide anything though.

[sdbob]

I'm hesitant to comment. However Tom Watt showed me how to install bearing 'without' the crush sleeve. It takes multiple times assembling,checking shimming. Then 'throughly' clean pinion and use loctite stud and bearing lock. My SD has been to Norwalk multiple,10 times. My race car forever. So it can be done. I've also reused crush sleeve but made sure of clearances,pattern. Follow factory service manual. I learned because of case like yours.

[roger1]

One follow up question here.

It would seem that the issue is either assembler error or a defectively made bearing or a failed yoke. And a higher chance that it was an error. And most likely the error was not torquing the yoke nut correctly to crush the collar and get the bearings to the right pre-load.

If I find out tomorrow that the person who assembled it wants to tear it down and find out what happened, will he be able to detect if it was his error or a defective bearing?

With the way this deal happened which was through the machine shop owner sending it out to have assembled, I'm not in a good position to be able to argue for a no cost solution if the assembler is not totally honest.

[Formulas]

Good parts, 50 miles, sloppy pinion yoke, I bet you (or someone) did not put oil in it and ran it dry no mention of oil leaking past a sloppy pinion either

Anything that moves will need to be inspected for wear and galling either way with a competent eye after its apart and thoroughly flushed before re'assy and i would change the oil after a few short drives after rebuild to take care of any other debris a strong magnet somewhere would be good as well

Pull the cover before barking up any trees


.

[roger1]

I put the oil in it right after installing it and before it was driven. So I know that wasn't the problem. Only a few drips from the pinion seal. I don't think it was run long enough to get to a big leak. After I saw the yoke was floppy, I looked at the seal and could see the rubber was still there. I then I removed the fill plug and the oil level is right there close to the top of the hole.

[roger1]

https://www.youtube.com/watch?v=UW8VSRmxYAk

[Formulas]

Thats good to hear theres oil in it, some parts likely will be reuseable.

hearing stories like this reinforce's my belief in doing things myself others get close enuff with a little education and some tools you can get it right, good luck in your quest.

[mgarblik]

A bearing failure is always a possibility, but I really doubt that's the cause. My guess is the pinion just lost it's pre-load because the crush sleeve was not collapsed enough during assembly. It happens. I think your looking at a good resolution requiring only a new pinion seal and re-checking and setting up the pinion depth, case pre-load and doing a pattern check. Basically, they just need to inspect and put it back together again.......correctly. It's possible their is damage inside, but I doubt it. Watching your little video, due to the pitch on the pinion nut, it probably would take less than one turn of the nut to remove that end play. But they should start from scratch, and you should center punch the pinion and nut so you can re-check it regularly for back-off. I also load the threads of the pinion nut with Locktite 271. Especially if the nut is going to be re-used. I feel pretty good about your chances of the parts being OK except for the pinion seal.

[roger1]

Thank you very much for your help. You obviously have a lot of experience with this. This will help me be more knowledgeable when I talk to the machine shop owner a little later this morning.

Also good to hear that the chances of parts damage is low. Another thing that leads me to think you are right is the fact that when I feathered the gas pedal and brake to keep a little pressure on the drive line, it didn't make any noise. It only made the awful noise when it was coasting.

[roger1]

The machine shop owner picked up my car on a trailer yesterday evening. They guy he sent the rear end out to now works full time for him at the shop. He is going to get this resolved for me. Agrees it probably that the pinion not torqued correctly and most likely no damage beyond the pinion seal but will get right on it and check it all out.

[steve25]

That's the way to run a business!
Thumbs up.

[roger1]

Originally Posted by steve25

That's the way to run a business!
Thumbs up.

Yeah, and we must have shot the bull for about an hour too.