Need help with installing my 8.25 gears

srmitchell

NAXJA Member
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Doing my first gear install at my work. (mopar dealer, with supervision from my coworker.)
Chrysler 8.25, 4.56 gears.
The last gear set was installed poorly, so it was noisy and the backlash was whack. Bearings failed too.
So I do not want to just re-use the shims as a depth reference.

My question- I have all new Motive gears, and Timken bearings. Factory 8.25 gears should have the "+ or -" markings indicating the addition or subtraction of shims. (As per our FSM at work.)

My old gears, and the new ones do not have this. Can someone explain what these numbers mean? Thank you!

Old-
Untitled by Sean Mitchell 707, on Flickr

New- I know the "170" is the matching number for the ring.


Untitled by Sean Mitchell 707, on Flickr

-Columbus
 

whitexj98

New member
Only factory gears do the math for you. The +/- is deviation from the standard depth. So you just subtract 4.125 from standard C8.25 pinion depth.

But I just looked in my 98 FSM and standard depth for the 8.25 is not listed...but they did list it for the 30 and 35.... They must have forgot it.....

I’m sure someone will know it...or google might
 

whitexj98

New member
^ right, the +/- is just a starting point that should get you close. Still need to run the pattern and adjust as needed.
 

jeeperjohn

New member
Those numbers are for using a pinion depth gauge to set the pinion. I find it easier and quicker to just use setup bearings and cups to dial it in.i usually don't make more than 2 changes to pinion depth to get a good pattern.
 

blondejoncherokee

NAXJA Member
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make setup bearings for the carrier and setup pinion races. you can start with your old shim stacks on the pinion and on the carrier to see where its at, and then check the pattern and measure BL. start there, and go at it until you get BL around 8 to 10 thousandths. You'll want lots of gear marking compound if its your first time since you'll probably be running lots of times , remember your final BL might change when going from setup bearings to final bearings , so keep that in mind and be ready to pull it all apart again, or , when you are setting up BL air on the high side, since it will probably come in 1-2 thousandths, like if you're around 11, it'll possibly suck into 9 thousandths, or maybe 7 or 8 .



Read the dana 60 gear setup by billavista on Pirate, and read through lots of gear setup walk throughs.


also, don't forget to determine the proper pinion preload shim stack early on( i didn't on my 44 and it added more work later on) , and remember that adding a pinion seal actually seemed to increase my pinion preload , as well as the final proper torque , so keep that in mind, you could set it on the lower side of whatever the requirement for the 8.25 is (the 44 is roughly 19 in lbs, so in that case set it to say 15) and then when you finally give the thing hell and install the seal and the last nut and torque it down it will more than likely gain a few inch pounds.


as far as final pattern, you'll want to post up some pics if its your first time, with BL measurements.



Also, keep track of every shim change on a piece of paper somewhere. Pinion shims, carrier shims, everything as you go so you can see where your changes where made and what helped and what didn't. Once you are almost there and its real close you wont need to track it as much , mostly for the first 4 or 5 patterns you run.
 

cr2000xj

New member
No offense to you on this blondejoncherokee, but theres a few things to point out for the 8.25 that is different from what you posted.

The 8.25 does not use shims on the carrier and also doesn't use shims to set pinion bearing preload. The backlash is set using side adjusters so it can be set up using the new carrier bearings initially. It also has a crush sleeve for the pinion bearing preload which is only installed on final assembly and set.
 

Digger87xj

New member
Aftermarket gearset makers don't use the same grinding machines that OEM uses, hence no + or - offsets. Disregard that section if you are using a factory manual.

4.125 is the master housing dimension (truth be told it is actually 4.124) of the 8.25. It really means nothing to you unless you have the pinion depth setting gauges.

Winging it, as you will be, you will need to at least start with (even though you don't want to) the current pinion shim and go from there. You need a starting point and it's better than nothing.
 
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blondejoncherokee

NAXJA Member
NAXJA Member
No offense to you on this blondejoncherokee, but theres a few things to point out for the 8.25 that is different from what you posted.

The 8.25 does not use shims on the carrier and also doesn't use shims to set pinion bearing preload. The backlash is set using side adjusters so it can be set up using the new carrier bearings initially. It also has a crush sleeve for the pinion bearing preload which is only installed on final assembly and set.
Oh damn. Sorry for the bad info. I've never done a 8.25. Side adjusters and a Crush sleeve make it sound pretty darn easy. Sounds like the only thing that will take some messing around will be pinion depth.
 

srmitchell

NAXJA Member
NAXJA Member
hanks for the advice guys. We got it together and the pattern looks great.
But I got screwed putting it back together. Slid the shafts in, and the C-clips I have are too big for the recess on the outer gears of the locker. It is for sure the correct Detroit for this axle.
I was thinking that I could grind the clips down just enough so they would fit it. Anyone see an issue with this?
 

foxwar71

New member
hanks for the advice guys. We got it together and the pattern looks great.
But I got screwed putting it back together. Slid the shafts in, and the C-clips I have are too big for the recess on the outer gears of the locker. It is for sure the correct Detroit for this axle.
I was thinking that I could grind the clips down just enough so they would fit it. Anyone see an issue with this?
I had to barely shave down the c-clips when I put a No-slip in my old 8.25. No big deal, never an issue and never a concern.
 

jeeperjohn

New member
You should not have to alter the c-clips to get them in but if you do then shaving a little off the outer edges of them should be no problem.
 

srmitchell

NAXJA Member
NAXJA Member
Yeah they are close, but just won't drop in. Pretty lame consider the locker cost 700 bucks.
My jeep is stuck at my dealership so I only get to work on it during or slightly after buisness hours so I need to get it done and home ASAP.
Once I figure this out, I just need to torque the locker cap bolts, install the brakes, diff cover, wheels and fill it with oil!
 

Bryan C.

Member #674
NAXJA Member
The arb locker Tim and I installled into the giveaway rig had 3 different thickness c clips for the 8.25. Had to try a few different sizes before settling on the right set. I am not sure if they came with the aftermarket axles or the locker itself. I think we got 10 factory shafts so maybe start with a call to them and see?

if it were me, I would use a die grinder and a roloc disc to start shaving them down. Keep em cooled off regularly while grinding and run them. But, that is me....
 

srmitchell

NAXJA Member
NAXJA Member
Thanks Brian!

I might just grind them. I'll be sure to go very slow, we have a bench grinder 10 feet from where my jeep is stuck on the rack. I know these aren't load bearing, it's just retainer for the shaft! Either way, lame that it didn't just pop together like I had hoped.

This is where it has been since Thursday! haha

Untitled by Sean Mitchell 707, on Flickr
 

jeeperjohn

New member
Yeah they are close, but just won't drop in. Pretty lame consider the locker cost 700 bucks.
My jeep is stuck at my dealership so I only get to work on it during or slightly after buisness hours so I need to get it done and home ASAP.
Once I figure this out, I just need to torque the locker cap bolts, install the brakes, diff cover, wheels and fill it with oil!
I recommend some loctite on those case half bolts unless they are drilled for safety wire.
 

srmitchell

NAXJA Member
NAXJA Member
I had to grind my C clips to get them to fit with my Detroit as well. Seems like a common issue.
Thanks dude. I'll tackle it tomorrow after work. Can't wait to drive it.

I recommend some loctite on those case half bolts unless they are drilled for safety wire.
The one bolt that is loose is the retaining bolt for the center shaft. It has a little patch of blue thread locker already. I may go ahead and add some more to be safe. As far as the other bolts, I'd expect that they are already tight and locktighted. They specifically recommend against taking the thing apart so I hope that step is done. I'll double check the torque of all bolts before I reassemble.
 
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