Changing gearign with a locker...

Alright, I'm not sure how or where to look this up, so I'll just ask.

I have an auto tranny '98 with the Crys. 8.25 rear, and stock gearing. A few years ago I put a Detroit in the rear. I have since put a lsrger lift and 33's on the Jeep.
What do I have to look at to determine if I can just get new gears (both front and rear of course) and pop them in there, or do I need to get any other components?
I've heard I might need a new carrier break, but how can I tell?

For a stock D30, if you have 3.55s and want to go 4.10s, 4.56s, or 4.88s, you will need a new carrier.

The Detroit in the rear is its own carrier ... I THINK you can just get new R&P and set them up.

The 8.25 has a carrier break... but it's numerically below anything people run in an XJ, so you can ignore it. Pretty sure you can just do the R&P on that one like MrSimon said.

As for the d30, the break is at 3.73 to 4.10 iirc (or 3.55 to 3.73, I'm not sure) so either way if you are going to gears that will be at all reasonable for 33s you will need a new carrier.

The way to find the carrier break for yourself is to look at axle datasheets/catalogs, look on gear maker/seller's sites, or search .

I think I'd go with 4.56's, then I would see a big change in low end power compared with what I've got in there now.

So, it sounds like rear is going to be fine but front I'll likely have to get a new break. Thanks for the help guys, and I will look up those tables to verify.

The Adam Blaster said:

I think I'd go with 4.56's, then I would see a big change in low end power compared with what I've got in there now.

So, it sounds like rear is going to be fine but front I'll likely have to get a new break. Thanks for the help guys, and I will look up those tables to verify.

Click to expand...

you need a new carrier(the thing that holds the ring and pinion gears) because the carrier break is/or above 3.55

"carrier break" is the ratio at which a different size carrier is needed because when changing gear ratios, the size of the gears change. if you use the wrong size carrier, the gears will not mesh proporly.


for the detroit locker, it has its own carrier and is considered a full case(carrier) locker. i would look at a site that has detroit lockers to see what the carrier break is for the rear axle you have.

I just looked on Tellico4x4 to see, and they have different listings, like this:
Locker for Chrys. 8.25 model# 123 for 2.56 and up
Locker for Dana 30 model #789 for 3.73 and up

So, it looks like the front will definitely need a new carrier for the new gears, rear should be fine though.

Side note, that site is expensive!!!! lol
They are charging almost $1000.00 for those lockers, I got mine for around $500.00 shipped to me here in Canada.

If you're gonna bother to do gears in the front I suggest you go ahead and install a full case locker for greater capability and added strength. The parts of the stock D30 carrier are known to be weak.

The Adam Blaster said:

I just looked on Tellico4x4 to see, and they have different listings, like this:
Locker for Chrys. 8.25 model# 123 for 2.56 and up
Locker for Dana 30 model #789 for 3.73 and up

So, it looks like the front will definitely need a new carrier for the new gears, rear should be fine though.

Side note, that site is expensive!!!! lol
They are charging almost $1000.00 for those lockers, I got mine for around $500.00 shipped to me here in Canada.

Click to expand...

which detroit did you get? there are a few from detroit/eaton?

http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Differentials/index.htm

It was the actual "Detroit Locker" that I got for the rear.

I haven't decided 100% on getting new gears for it just yet...
I'm figuring out how much it's going to cost, and I still have yet to drive the Jeep with the lift and 33's on it. I would like to see how it feels in the power department first. If I get in the mud and can still spin the tires easily, I might not bother.

What I really need is a front bumper with some tow points, that is the biggest hindrance on the trail right now...

I'm also thinking about dumping money into somewhat weak axles, and whether that is even worth it? And considering I may eventually want to go to 35" tires, I might just build up a totally different vehicle from a different starting point.

Ahhh... it's all up in the air right now. lol