Need a bit of advice on 8.25 pinion checking distance

[Georgia Mike]

How does one go about checking the height of the factory Chrysler 8.25" pinion? I'm doing a gear swap and am at a loss here. Technically I'm going to swap all of the guts from my bent housing into a better, straighter one, but my issue surrounds the pinion head of the stock 3.55 gear set. Every other gear set I've dealt with have had a machined surface that could easily be measured, or at least have the height offset engraved to give an idea where to start with the new pinion.

I'm unsure where to start. The head of the stock pinion is still in its rough forged condition, so measuring in thousandths there seems pointless. There is, however, what appears to be a "-4" in paint pen. Is this the offset, as in -.004"?


The only machined surface on the head of the pinion is directly over the teeth, but are machined at an angle. Again, seems pointless to try to get a measurement here.


On the shank of the gear there are some more paint pen markings that are hard to decipher. Looks like maybe a "3" there?


Anyway, if anyone can help me out I'd sure appreciate it.

:thumbup:

 

[clean4drxj]

I would set up the pinion as it were it the other housing with marking compound and see what it gives you, go from there..

 

[Serious Offroad]

Pull the bearing off the pinion and use the shim under it as your baseline. Add or subtract based on the pattern you get.

 

[themauler]

Bent 8.25 housing? I figured they were pretty beefy axles.

 

[mtbxj87]

I've either reused the shim(s) or used new shins the same size for initial set up. Majority of the time it's right.

 

[Georgia Mike]

Bent 8.25 housing? I figured they were pretty beefy axles.

They are. Best I can figure it was my own stupidity that bent it. I used to loop a chain over the center section when tying it down to my trailer. I suppose thats what bent it since the tubes are pointed at an upward angle and toward the front of the XJ. It's either that or it's just from abuse off road. I'm not easy on this thing, but I still believe it's from chaining it down.

 

[Georgia Mike]

Made a little headway on it this weekend. I started with the shim stack that was on the pinion already since it was the easiest thing to try first. Turns out the stack was .0375", and looked like this @ .008" B/L:




Looks a bit too deep, so I swapped to the .0305" shim that was on the factory pinion in the housing I'm swapping it all into, and it looked like this @ .008" B/L:




Didn't look a whole lot better, so I took a wild swing at it with a .0267" shim stack and came up with this with .0105" B/L:




So, should I loosen the B/L a bit more, or is there more adjustment to try?

Warning: long winded read ahead, but it'll provide valuable info on these gears' history

Now, let me back up a bit and give a little insight on this gear set, and the housing they were previously installed in. I rarely drive this on the street. I think I'd be lucky to say I've driven it 3,000 miles since I bought it 2-3 years ago. Originally it had a roaring noise and thought it was carrier bearings, so I went ahead and bought a rebuild kit. When I pulled it all apart, I discovered it was actually the axle bearing on the passenger side that was bad. So bad that it had chewed up the shaft and introduced metal particles all throughout the housing. I cleaned it all out as well as I could and rocked on with new axle bearings and a junk yard replacement shaft. This quietened it down considerably, but I still had more noise than I was comfortable with.

A few months later I took it back apart to do the carrier & pinion bearings, and this is when I discovered the carrier caps were misaligned. It could be seen with the naked eye. From two feet away. I initially thought whoever reassembled it had gotten them mixed side to side, but that wasn't the case as they were even more misaligned when switched.The races were chewed up pretty well, as were the bearing rollers, so I knew there was no help for it and I reinstalled everything with the old bearings. No sense in wasting the new bearings on a housing that will just chew them up. I did, however, tighten the B/L back into spec.

Races that were removed from the old housing. Notice the perfect line where the wear starts at the misaligned caps:




Keep in mind I still didn't know why the housing was bent, I just knew it was. I wasn't until I was chaining it down again that it dawned on me...that could've been the cause :doh:

This time when I opened it back up, the B/L had opened back up to .025", but when I put it back together last time I know I set it at .009", torqued the adjusters to 125 lb/ft and the caps were also torqued to spec, and they still were when I checked them before taking it all back apart. Only things I can think of is extreme carrier bearing wear, or the housing is grossly distorted.

So at this point I know the gears will never be perfect, I'd just like them as good as I can get them so I can drive it on the street occasionally for some weekend adventuring to local spots. No DD'ing, no super long hauls (100-200 miles in a day max). I'll worry about new gears some time down the road if these die, but I just don't have the $$ for new ones right now.

 

[Transpoquick]

Last three pictures look good. Bearing races do not.
best luck.

 

[Georgia Mike]

Lol yeah those races are shot for sure. Old bearings don't look much better. New bearings and races going in with the rebuild.

Thanks

 

[Transpoquick]

That's what I would do.
Install new bearings, and hopefully get that pattern.
Using the marking compound is the best way. If you keep using the same process, everything should be good.
I would roll the last three pics, w/ new bearings.

 

[md21722]

If the side adjusters are not torqued down well, liquid metal and that wear patterns on the carrier bearings can occur. I would aim for 125-150 ft-lb as you have done, not the 75 that the book suggests. Seems strange that the axle would bend with tie down chains. I don't know how you'd manually tighten the chains enough to do that.

 

[Georgia Mike]

Chain binder + DOT ratchet strap tie down on the front bumper. It was enough to bow the side of the trailer when tight. I'm just paranoid like that lol

 

[Georgia Mike]

But as I said before, I'm not 100% certain that's what caused it, it just seemed too coincidental since the bend is in the exact direction the chain would pull.

 

[Georgia Mike]

Just for future search references by others:

I was reading on Randy's Ring & Pinion website about gear patterns and I came across a diagram that suggested used gears should be read on the coast side due to there being less wear on that side. Going by the pattern chart shown, I should have left it with the .0305 (or therabouts) shim that came in the housing I'm building, so that's what I will be returning to and going with that if the pattern looks the same as before.

Thanks for the help, guys
:thumbup:

(something is up with Randy's site this evening so I couldn't post a direct link, but I found another pic to show what I'm talking about)