Differential Master Overhaul Kits

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

How necessary is it to install master overhaul kits when doing the ring and pinion swaps? It cuts the cost of doing this project in half and allows me to maybe get new 32s before winter...

tommudd · **Posted:** Fri Nov 14, 2014 11:45 pm

NAMoulton1 wrote:

How necessary is it to install master overhaul kits when doing the ring and pinion swaps? It cuts the cost of doing this project in half and allows me to maybe get new 32s before winter...

May cut the cost in half when adding up parts BUT you need the kit

JeepMorrison · **Joined:** Thu Jul 16, 2009 11:34 am **Posts:** 1236

You NEED the kit. Anyone who tells you other wise drug test them.

nFodzy · **Joined:** Sun Oct 06, 2013 1:30 pm **Posts:** 389

4x4kayak2112 wrote:

You NEED the kit. Anyone who tells you other wise drug test them.

John3:17 · **Posted:** Sat Nov 15, 2014 1:28 pm

My kit for the front wasn't awful expensive - around $125

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

John3:17 wrote:

My kit for the front wasn't awful expensive - around $125

The ones I have been seeing cost as much as the ring and pinion themselves.

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

So...how long can I run 32s until I need to regear? I'm sure I'll notice a huge power loss and mpg loss but with winter coming I'd like to put some fresh tires under her. I'm currently at 6/32s with the General Grabbers which would get me through winter, but not as nicely as I'd like.

tommudd · **Posted:** Tue Nov 18, 2014 1:42 pm

NAMoulton1 wrote:

So...how long can I run 32s until I need to regear? I'm sure I'll notice a huge power loss and mpg loss but with winter coming I'd like to put some fresh tires under her. I'm currently at 6/32s with the General Grabbers which would get me through winter, but not as nicely as I'd like.

How long ?? Hard to say, with mine I couldn't use overdrive at all at normal highway speeds even on flat roads with no hills. If I tried it just shifted back and forth, engine would run hotter, transmission slipped if I continued to do it, engine would just lug down to where it wasn't running right. Mileage dropped 6 or more MPGs . So sure you can run it, but with increased wear to both engine and transmission. Plus the extra cost of the gas you'll be using.
I'm glad I only had to run a couple of weeks before my rear gears could be done ( already had a front 4.10 diff) With the way KKs seem to suck gas anyways I think I'd find someway to do the gears ASAP

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

tommudd wrote:

NAMoulton1 wrote:

So...how long can I run 32s until I need to regear? I'm sure I'll notice a huge power loss and mpg loss but with winter coming I'd like to put some fresh tires under her. I'm currently at 6/32s with the General Grabbers which would get me through winter, but not as nicely as I'd like.

How long ?? Hard to say, with mine I couldn't use overdrive at all at normal highway speeds even on flat roads with no hills. If I tried it just shifted back and forth, engine would run hotter, transmission slipped if I continued to do it, engine would just lug down to where it wasn't running right. Mileage dropped 6 or more MPGs . So sure you can run it, but with increased wear to both engine and transmission. Plus the extra cost of the gas you'll be using.
I'm glad I only had to run a couple of weeks before my rear gears could be done ( already had a front 4.10 diff) With the way KKs seem to suck gas anyways I think I'd find someway to do the gears ASAP

*sigh* well, could I do my rear axle and just not use 4WD or does the transfer case still spin the front differential?

tommudd · **Posted:** Tue Nov 18, 2014 7:16 pm

Do the rear and remove the front driveshaft until you do the front diff

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

tommudd wrote:

Do the rear and remove the front driveshaft until you do the front diff

...You're a genius...just need to find a 4.56 gear in my price range and for the '05 or newer C8.25 axle. Is there a way to tell the difference between the two?

Bmxer524 · **Posted:** Tue Nov 18, 2014 9:05 pm

Why 05+? I thought it all just had to be for the 29 spline 8.25. I'm a newbie with regearing so I could be entirely wrong.

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

Bmxer524 wrote:

Why 05+? I thought it all just had to be for the 29 spline 8.25. I'm a newbie with regearing so I could be entirely wrong.

From what I'm seeing they changed the axle in some way for '05 and newer. Not sure why...but I think the splines are different. If I remember right, the older ones were a 27 spline. So if that's the case then Chrysler went to a 29 spline...for some reason.

tommudd · **Posted:** Tue Nov 18, 2014 9:48 pm

All KJs were 29 spline, even last model year of the XJs

Bmxer524 · **Posted:** Tue Nov 18, 2014 9:59 pm

Yep 01/02+ should be 29 spline. Are there any specific brands to look at? I've heard a lot of brands sell the same product and you just pay for the name.

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

The way I see it is it's a hunk of metal spinning via a different hunk of metal...so long as the teeth rotate it should be good. I have heard of rings breaking or tooth fractures in hard wheeling though.

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

tommudd wrote:

All KJs were 29 spline, even last model year of the XJs

Well that gives me really good info haha...a lot of the gears on the internets are a 27 spline for C8.25.

Edit: I can't seem to find an 4.56s that are a 29 spline...

Bmxer524 · **Posted:** Tue Nov 18, 2014 11:17 pm

http://eastcoastgearsupply.com/i-139755 ... -4-56.html
http://eastcoastgearsupply.com/i-117855 ... -4-56.html

Pretty sure they're 29 spline. They claim they fit 01+ Libertys. I'm assuming they group the 01 XJs in that.

NAMoulton1 · **Joined:** Tue Aug 12, 2014 7:01 pm **Posts:** 1054

Nitro 4.56: http://www.justdifferentials.com/C8-25-456-NG-p/c8.25-456-ng.htm

Motive 4.56: http://www.summitracing.com/parts/mgr-c8-25-456/overview/

Both of which state that these are a 27 spline. Unless each company makes a 27 and a 29 spline...

Arctic_4x4 · **Posted:** Wed Nov 19, 2014 4:06 pm

You can try http://www.my4by.com/chrysler-8.25-inch-842.html

Differential Master Overhaul Kits

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