77 NYB Rear Axle repair help

75LandYacht

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Evening Gents, And Ladies, if we have any. lol.. So the challenges continue with Ginger, My 77 NYB. In an attempt to get to "GO" right before I get "Show" right, Ive recently had the transmission completely rebuilt, the engines is running great and most other mechanicals are in orders. NOW the reared is making a horrible noise. Crunching and grinding is best way I know to explain what I hear, but only when backing up or when maneuvering to park. no noise at HWY speeds. Since I don't want to bandade the problem and trow good money after bad to try and find the individual problem, I wanna do a FULL rebuild on the Axel and driveshaft U joints. What I need from you guys is suggestions on where to get the best parts to do it. I have a local shop that can do the work. Should I let them use the parts they have or buy what I want / what you guys suggest and supply it to them?.

Thanks in advance for your appreciated knowledge.

John
 
www.doctordiff.com is a quality supplier of parts. Bad U-Joints can make a lot of noise at low speed, you might want to check them first before springing for a rebuilt rear end. If the noise is coming from the gear set, you are probably headed for a rebuild. Remove the oil filler plug and take and Q-tip and dip it in the oil. If the gears or bearings are failing, there will usually be visible metal in the oil.

Dave
 
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Pull the rear drums and make sure some brake hardware hasn't come unhinged. That could cause a problem in reverse that might not affect forward travel. If everything is marvelous there, onto the diff.

One nice thing about a 9.25 diff is it has a rear cover you can remove in minutes and fully inspect all the components.

Start at the rear yoke and give it a good shake. If it moves a noticeable amount in any direction other than around, it's failing a pinion bearing or someone has had the yoke off without replacing the crush sleeve and it's lost its preload.

If it seems to be solid, pull the rear cover and see what is laying in the bottom of the case ie gear teeth.

Kevin
 
www.doctordiff.com is a quality supplier of parts. Bad U-Joints can make a lot of noise at low speed, you might want to check them first before springing for a rebuilt rear end. If the noise is coming from the gear set, you are probably headed for a rebuild. Remove the oil filler plug and take and Q-tip and dip it in the oil. If the gears or bearings are failing, there will usually be visible metal in the oil. Which rear end do you have?

Dave
Appreciate the info Dave, I should’ve mentioned in my initial post, I did have the fluid changed a couple of weeks ago, but the noise was there before the fluid change, my buddy that did the work said he didn’t notice anything out of the norm such as metal flakes or pieces parts in the fluid when he changed it. When I acquire a new toy, I always do a complete fluid change, everything from the power steering fluid to the rear axle and everything in between just as good housekeeping. So I think it’s a combination of a few things in there going bad. So I’m probably going to do a soup to nuts rebuild on it anyway just so I’ll never have to touch it again.
 
Pull the rear drums and make sure some brake hardware hasn't come unhinged. That could cause a problem in reverse that might not affect forward travel. If everything is marvelous there, onto the diff.

One nice thing about a 9.25 diff is it has a rear cover you can remove in minutes and fully inspect all the components.

Start at the rear yoke and give it a good shake. If it moves a noticeable amount in any direction other than around, it's failing a pinion bearing or someone has had the yoke off without replacing the crush sleeve and it's lost its preload.

If it seems to be solid, pull the rear cover and see what is laying in the bottom of the case ie gear teeth.

Kevin
Thanks Kevin, I just responded to Dave with information they will probably answer some of your questions. I did have the car on the lift this morning and there is quite a bit of play between the ring and pinion. No other movement was noticed other than the way it should rotate. I did hear some crunching and binding from the wheel bearings. So because I never wanna have to go into this axle again, I’m just going to do soup to nuts on it.
 
Good luck with this project, please post your progress and any updates as I am not super familiar with Chrysler differentials so I would love to see how it all works out.
Thanks,
77newyorker440
 
I doubt you'll find a repair shop that allows you to supply the parts.

Reasons:
They get a jobber discount, and sell you the parts at hte price you'd pay at the store (or maybe higher!), so they'd miss out on revenue.
They cannot determine what quality of parts you'll supply, which feeds into whatever warranty they provide.
If you miss some parts, and they don't discover until into the job, they are delayed on the lift, which delays another paying job being started.
And they might get a 'reputation' for using supplied parts, and they don't want that to creep into their business model.

Parts that are only available used might be a different story, though.
 
Is this a 9.25 or an 8.25 Diff (Formals had both depending on powerplant during the production run)? Peg leg or Sure grip? A suregrip going bad can sound crunchy, but you'd almost assuredly have fragments in the fluid.

A lack metal filings/ gear fragments during the fluid change leads me to thinking it's bearings, which should be relatively cheap (as opposed to replacing pinion/ ring gear).

Concur on Dr Diff if you need Pinion/ Ring gear. Good time to Sure Grip it if that's your want.

Keep us posted.
 
Is this a 9.25 or an 8.25 Diff (Formals had both depending on powerplant during the production run)? Peg leg or Sure grip? A suregrip going bad can sound crunchy, but you'd almost assuredly have fragments in the fluid.

A lack metal filings/ gear fragments during the fluid change leads me to thinking it's bearings, which should be relatively cheap (as opposed to replacing pinion/ ring gear).

Concur on Dr Diff if you need Pinion/ Ring gear. Good time to Sure Grip it if that's your want.

Keep us posted.
Thx Mr C. It’s a 9.25 rear.. I’ll be pulling the axle and delivering to the shop, since I’ll be installing New Leaf and hardware I got from Springs and Things few month back. Also thought it be easier for the shop to bench work the axle vis having an 20’ car sitting around taking up space. Lol
 
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