I thought today would be the day I finished swapping the gears in the 8 1/4 rear axle in my brother's Duster. I was wrong.

Vehicle:

1974 Duster. Originally an all drum SBP car with a 7 1/4 rear axle.

We switched to front discs so we needed to get a LBP rear axle. I found a good deal on an A body 8 1/4 rear axle. The only catch was that the axle has 2.2 gears in it. I didn't care because it was a really good deal and I thought I could swap the gears out.

I knoew that the 2.2, 2.4, and 2.7 gear ratios used a different carrier than the 2.9 and numercally higher gearsets. I went to a junkyard and bought all the guts from an 8 1/4 with 3.5 gears, including the 3.5 gear carrier.

I install the 8 1/4 axle. Years go by, the car stays on jack stands in my garage as my brother and I work on it in fits and starts as time and money allow.

A few weeks back (months, actually) we finally decided to bite the bullet and force outselves to get the gears swapped in the axle. We completely tore it down and replaced all the seals and bearings on the axle and the 3/5 gear set. We got it all buttoned back up and were in the process of setting the gear mesh and checking the tooth contact pattern when we discovered that the pinion and ring gear teeth were barely making contact. There was less than 1/8 of an inch contact between the two.

The carrier bearings were already adjusted so that the carrier was all the way to the passenger side of the car (towards the pinion) so there was no way to adjust the ring and pinion closer together.

At this point I recalled noting that the 2.2 gears were much larger in diameter, especially the pinion, than were the 3.5 gearset.

Here is my question:

Was I mistaken about the carrier being the only thing that needed to be swapped? Were the actual castings for the 2.2 an 2.7 gear ratio housings different from the housings for the 2.9 and numerically highrer geared 8 1/4 axles? Specifically, were the 2.2 gear ratio axle center housing cast with the pinion centerline ofset more towards the passenger side of the axle?

I am afraid that I have waste hundreds of dollars and hours of my time on this rear axle and now need to scrap it and start over again. Ugh.

Any input is greatly appreciated. Thanks.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

The only think that needs to change is the carrier. When I updated from 2.45 to 3.55 that was changed. I also went to a limited slip carrier and Randy's did it in an afternoon.

Would a spacer behind the ring gear help????

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

A spacer behind the ring gear would do the trick. Right now the carrier bearings are adjusted so the carrier is as far to the passenger side as possible and the teeth BARELY mesh.

Where might I find a ring gear spacer? I might give Randy's a call next week and chat with their tech guys.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

I don't know if anyone makes them, but Ryan had a local machine shop make one up for his carrier.

Not sure what it cost him, it has been a while.

Rick

_________________
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

Thanks. It is surprisingly difficult and expensive to get custom parts made up in my town. My internet searching has not revealed a source for a spacer, but I am going to call Randy's Ring and Pinion tomorrow.

Is all else fails I can break out my crude machining implements and get some flat stock from Home Depot.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

Summit has them for GM 8.5

Wonder how close those are.........

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I was looking all over the internet last night. It sems like the GM 10.5 spacer is the only one readily available. I am going to call Randy's Ring and Pinion today and see what they say. f that doesn't pan out then I will try either a diferent carrier or a whole different rear axle.

A body rear axles are getting very expensive and hard to find these days! I remember being able to go to a junkyard and pick from racks of complete 8 1/4 rear axles for only $125 each. Now I am lucky to even find an A body in a yard, much less with the part I want already pulled and on a shelf.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

OK- Randy's Ring and Pinion doesn't stock or sell ring gear spacers, open differntial carriers, or even thicker gear sets for the Chrysler 8 1/4. Pretty disappointing.

For the life of me I can't figure out why these gears won't work in this case. Some part is clearly different between the 8 1/4 axle in the Duster and the 8 1/4 axle from the early 70s Dodge van in the junkyard. With the 3.5 carrier centered in the differential adjuster range the ring gear teeth don't even contact the pinion teeth. There must be some other difference in either the carrier or the actual axle housing.

I guess I will be fabricating a spacer, or paying someone to fabricate it for me. I really need to invest in a home hobby sized metal lathe and mill.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

Reed, You are running into a similar problem I had about 9 months ago with my 8 1/4" rear. Some things about your situation are a little surprising. The ring gear for a higher ratio has more teeth, and is bigger and fatter. I tried to put a 2.73 ring and gear on a carrier that was made for a higher ratio, and I had the same condition you are encountering. I was told I would need a 3.23 or higher gear set to fit the carrier I have. If you got the carrier and gears from the same casing, it seems it should work.

I also called Randys Ring and Bearing, as well as a few others, and met with the same results you got. A custom spacer is going to be needed. In my case they said it was about .250" short of mating correctly. My solution was to go back to the open diff that came with the gears and sell the posi that I had bought. I lost only $25 so did not feel like too big a dummy there, but I did pay a rear end buy to try and make all this work, which was expensive.

Sam

If you machine a spacer it will need a recessed ring on the carrier side and raised ring on the ring side to center the gear. The gear is centered by a raised ring on the carrier. It was all disappointing, and made me wish i had just bought a good 8 3/4" rear right off and paid to have the LBP axles but to fit. In your case, you might not need to do that. If I recall you are putting this in a can, so existing B body 8 3/4" rears might fit. That I do not know about.

My answer was to put a Ford rear in. I have not regretted that decision. It seems no one is interested much in supplying parts for or working on the 8 1/4" Mopar rears. I might encourage you to see if an Explorer rear will fit here. Good luck, and let us know how it goes.

_________________

Sam-

It is good to hear I am not alone! I went out and did some measuring with a micrometer and found that I needed a spacer that was about .250 inches thick!

However, while I was thinking, I decided to check the old carrier to see how much closer it put the ring gear to the pinion. It looks like it puts the ring gear about .250 inches closer to the pinion!

3.5 gear carrier on the left, 2.2 gear carrier on the right. Note how the gears themselves are the same thickness.



I am going to try swapping the 3.5 ring gear onto the 2.2 carrier along with the 3.5 spider gears and new carrier bearings. If that works then I don't have to pay for a spacer to be machined, I don't have to try and source the left-hand-thread specialty ring gear bolt n a length 1/4 inches longer than stock, and all I have to do is get some new bearings ($30 delivered by Friday!). I will keep you posted on how this goes. I hope it works.

Switching to a Ford axle was one of the options I was strongly considering. Parts are getting hard to find for the old 8 1/4, which is surprising. If I can't get this axle to work I will be doing an Explorer 8.8 swap. However, I already ave invested hours of time and hundreds of dollars in this axle, so if I can get it to work then I really want to. However, in the future I think I will just go straight to a Ford axle if I am working on an axle swap in an A body.

I am ordering the new bearings today and will get the ring gears swapped. This week. This weekend will be the test of if the 2.2 carrier will solve the spacing problem.

P.S.- yes, this is going into a 1974 Duster.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

Also, yes, each geaset and carrier are matched sets. The 2.2 gears and carrier were in the acle when I bought it and worked together, and the 3.5 gearset and carrier were pulled from one axle in a junkyard and all worked together in that axle. This makes me suspect that Chrysler made different axle housings as well as carriers.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

I think you must be right. It seems as if the nose must be longer on the 3.55 housing.

SAm

_________________

I was thinking that the casting for the center section had the tube for the pinion offset more to the passenger side. I didn't notice any length difference in the pinions when I had them side by side, but the 2.2 pinion was noticeably larger in diameter. All the carrier dimensions seem the same save for the ring gear offset difference.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

Those kinds of differences were typical in older 50's and earlier Mopar, but I thought they had abandoned that kind of one-off designing by the late 60's. Obviously there is something different.

Sam

_________________