I am going to have my trusted mechanic Tom replace this, and at the same time put in the limited slip diff I bought several years ago. Two questions:
1. Should I buy a rebuild kit and have him replace all the bearings while he has it apart?
2. Is there more than one 8 1/4" rear from a '75 Duster? Should I order parts or is it better to let Tommy order after he looks inside? In other words, is there a chance I could order all the wrong parts if I got them from Mancini for instance?

Thanks. Sam

_________________

I would let the guy doing the work get the parts, then there is no "those parts you made me install were junk BS". He will own the job, and have to service it if there is a problem.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

x2, let him get the parts he prefers to work with and trusts (and can stand by the warranty).
there is only one A-body 8 1/4" rear, but... there are some differences in bearings/seals in the axles made before 1973 (i.e. those installed in the early run 1973 model year cars) vs. the 1974-1976, so best to have him pull it apart and confirm what is really needed in case that 1975 car got an older axle from a September 1973 Valiant...

Thanks. I will let him buy the parts. Nothing is happening untill the snow is over. Grrr.

Sam

_________________

Car is on the lift at Auto Masters with the rear torn down. All bearings in the center section were bad. They are awaiting a kit, which may be here tomorrow. I am sure eager to get it back. Cruise season is right around the corner.

Sam

_________________

Steve, who is the major old car guy a Tommy's has the rear back together and he needs a spacer for the ring gear. This rear is a 2.73 and the ring is too narrow to get the correct clearance. He has to order a spacer and is worried about finding one. Is this a reasonable concern? I pointed him towards Randy's and Mancini. Any other suggestions? This is an 8 1/4".

Sam

_________________

Sam,

Isn't this the original differential case and gear set to the axle? 8 1/4 axles don't use shims. Does Steve know about the threaded carrier bearing adjusters?

_________________
Joshua

It is, and he knows about it. He has adjusted it all the way to the center as far as it will go, and it is too loose. Do you think he his missing something here? He used the term "adjustment" in our conversation. He says the posi unit we are trying to put in is designed for 3.23 and bigger gears. He is hoping somebody makes a spacer for it, otherwise the spider gears are going back in.

Sam

_________________

Sam, I believe there are 2 different sure grips for the 8 1/4. one for the 2.XX gears and one for the lower rear ratios. Ryan bought one on E-bay a few years back and it was too narrow also. The guy that did the install had a local machine shop make him a spacer. No idea what it cost.

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

The spacer is a common thing to have to do in GM pass car rear axles. Check into proper length ring gear bolts too. If the same pitch as the GM stuff you may be able to find them in a good brand (ARP?) with the needed extra length.

_________________
Thom

Cross-threaded is tighter than Lock-tite

The 2.45 ratio used a different carrier for sure, but 2.76 and up I thought were all the same. I've never seen a Chrysler 2.73 axle.

_________________
Joshua

Steve counted the teeth and did the math. There was also a tag on the axle cover that had 2.73 stamped into it. So there you go. This has turned into a partial bust as a project. It is going back together with the open diff. I wish I knew how to set up a rear myself. I have never seen it done, but have heard lots of horror stories about guys who did it wrong. Had I been doing this myself I would have felt like I had time to research things. As it was I tied up my friend's lift for more than a week. I know they are eager to see this thing done in any way possible.

They could not find a spacer for the sure grip, so the plan is to put the old open diff back in with new bearings. I have no idea what this is going to cost. He will have assembled the rear twice at this point. I told him to leave the new bearings in the sure grip and I would look for a spacer of some kind when I have time. Since I am not racing this car, and do not drive it in snow, the sure grip was a little gratuitous anyway.

The entire history of mankind can be summed up in the following words: "It seemed like a good idea at the time." That is all I can say about this rear project.

Sam

_________________

2.73 could be February 1973. You don't have to count the teeth on a Chrysler ring and pinion as the ratio is stamped on the ring gear. Did Sam lay eyes on the ring gear?

_________________
Joshua

Not to look closely at it.

Sam

_________________

Joshua, my apologies are due you. It is a 2.71. I remembered it wrong. Things are back together. Bearing noise is all gone, but there is some gear whine noise at 35 mph. I have Red line synthetic in it now. Would it be quieter with standard 90w gear oil. This ring and pinion are now 41 years old with 200,000 on them. It goes away at speeds above or below that. Is this something I should complain about? More important, would this go away with tweaking of some kind? I actually feel grateful Tommy is willing to fool with my old car.

Sam

_________________