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8.25 axle rebuild problems- am I hosed?
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Author:  Reed [ Sat Nov 22, 2014 6:04 pm ]
Post subject:  8.25 axle rebuild problems- am I hosed?
A few weeks back, some of you may recall I was asking about how to remove a stuck pinion gear from a 8.25 axle housing. By using a two jaw gear puller and my new favorite tool Mjolnir, I was able to remove the driveshaft yoke from the pinion gear and pound the pinion out of the housing.

Upon examing the original 2.2 gearset pinion and the new 3.2 gearset pinion, I discovered some differences and noted some potential problems.

(1) Every source I have read that discusses chanmging gears in a 8.25 axle housing says that when setting up the new gears one should start by using the old shims pack from the old gears. Well, that sounds great, except there were no shims in the pinion when I removed it. I am replacing the gear carrier as well as the rung and pinion gears. Should I start with no shims when setting up the new gears?

(2) This is more troublesome. The ring, pinion, and carrier i am planning on installing all came out of one axle. I believe the axle was an 8.25 out of an early 70s Dodge van. However, upon inspecting the pinions from the two gear sets, I noticed that the 2.2 pinion has a small crush sleeve that sits on a lip machined into the pinion shaft but the 3.2 pinion has a much longer crush sleeve that rests on the rear pinion bearing cage. Here are some pictures:

2.2 pinion:
Image

3.2 pinion:
Image

3.2 pinion crush sleve: (in the upper right of this picture)
Image

The crush sleeves are clearly different and incompatible. The 3.2 pinion lacks the machined lip for the small crush sleeve to sit on.

I am worried that I might have grabbed a gearset out of axle that is not an 8.25 axle. Every company I find that sells crush sleeves for 8.25 axles sells the small ones like were on the 2.2 pinion. I can't find anyone selling the long crush sleves like was present on the 3.2 pinion.

Am I hosed? Did I get an incompatible gearset?
Help!

Thanks.
Author:  Doctor Dodge [ Sat Nov 22, 2014 7:41 pm ]
Post subject: 
There is more then one way to set pinion depth or set the bearing pre-loads...
Example: I have seen the pinion depth shim(s) under the bearing race, instead of being under the pinion bearing itself. Either install position yields the same result.

As for the crush sleeve, long or short, it needs to position the front bearing so it has the correct pre-load. These days, the crush sleeve is replaced with a solid spacer and pre-load set with thin shims.

So it is time to take some measurements...
If spline count, bearing journal sizes and positions are the same, do a trial assembly to see if you can get the proper gear contact pattern & bearing pre-loads.
If you can, set- the unit up and give it a try.
DD
Author:  Reed [ Sat Nov 22, 2014 8:21 pm ]
Post subject: 
Thanks Doc! I'll dig out the micrometer and take some measurements.
Author:  Reed [ Sun Nov 23, 2014 9:12 am ]
Post subject: 
Near as I can figure, because the gears came out of a van, I think that they are 8 3.8 gears, not 8.25 gears. I say this because the 1983 factory parts manual I have (thanks again Dan!) lists part number 3507 575 as a "SPACER,Pinnion Bearing Adjuster" and it looks a heck of a lot like the long crush sleeve pictured above.

So, fingers crossed that the 8 3/8 gearset and carrier will work in an 8.25 housing.
Author:  emsvitil [ Sun Nov 23, 2014 4:11 pm ]
Post subject: 
Sounds like 8 1/4 & 8 3/8 are the same (towards bottom)

http://www.hemmings.com/mus/stories/200 ... ure21.html
Author:  Reed [ Sun Nov 23, 2014 6:26 pm ]
Post subject: 
Thanks! I trial fit the van pinion in the housing today and I think it will work. I am going to pull the old snout bearing out of the housing and use a dremel to turn it into a setup bearing. That way I can get the pinion depth figured out without pressing the bearing on and off a bunch of times.

I think I am OK. I was just freaking out about the diffrence in the crush sleeves. I am going to really cheap out and cross my fingers and re-use the crush sleve from the junkyard. I have lots of shims so I am hoping that I can get the pinion set up where it needs to be by shimming it. Not the ideal method, I know, but I need to get the car back to being mobile and move on to finishing the bodywork. If the rear axle is noisy, I will live with it until I can save up the money to pay someone to rebuild it right.

I will keep you updated with how it goes.
Author:  nm9stheham [ Tue Nov 25, 2014 6:17 am ]
Post subject: 
You ought to be fine for moving around and it may be fine for a long time. I re-used a crush sleeve once when I did not have a new one; raced the car off and on for a long time after that with no issues. My thought is that as long as it gets some fresh 'crushing' action and is not too far 'crushed', it ought to hold tension.
Author:  slantzilla [ Tue Nov 25, 2014 7:33 am ]
Post subject: 
Be aware that the carrier probably has bigger bearings on it than the car 8-1/4 housing accepts. You can put the smaller car bearings on that carrier.
Author:  Reed [ Tue Nov 25, 2014 8:00 am ]
Post subject: 
Thanks guys. The van carrier bearing races/cups are actually the same Timken part number as the car bearing races/cups. I have a full rear axle rebuild kit and I may break down and just replace everything while I have it apart. My only problem is figuring out how to press the old bearings on and off the carreir and pinion. I have a 5 ton press, but not many adapters or tools to hold specialized pieces like the carrier.
Author:  nm9stheham [ Tue Nov 25, 2014 4:30 pm ]
Post subject: 
See if you can borrow a 'bearing separator' from someone or get a loaner from one of the chain stores.
Author:  Reed [ Tue Nov 25, 2014 5:32 pm ]
Post subject: 
I'll scrounge around and see what I can find.
Author:  Reed [ Tue Nov 25, 2014 5:46 pm ]
Post subject: 
Looks like I may go pick up a set of, shudder, Harbor Fraud bearing splitters. If I could find a decent set of used American made pullers at a ;rice I could afford right now, I would do it. Unfortunately, even the $45 for the crap HF tools is money I shouldn't be spending right now. At least this way I can replace all the bearings on the axles and the carrier and pinion and KNOW that it is all new and good. Plus it is an excuse to get more tools.
Author:  Reed [ Wed Nov 26, 2014 1:49 pm ]
Post subject: 
I purchased some bearing splitter shaped toys and long handle punch shaped toys at Harbor Fright today. Hopefully these "tools" will last long enough for me to rebuild this 8 1/4 axle. I will take pictures and document the process as I go and them make a "how to" thread about rebuilding an 8.25 axle. Wish me luck.
Author:  Reed [ Thu Nov 27, 2014 12:04 pm ]
Post subject: 
I discovered that the replacements gears I thought were 3.2:1 are actually 3.5:1. 14 pinion teeth to 49 ring gear teeth. Yay?
Author:  Joshie225 [ Thu Nov 27, 2014 4:18 pm ]
Post subject: 
That will be fun around town.
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