View Full Version : What Axles Do I Have?

October 24th, 2006, 11:09
In an effort to cover this topic completely, first I will start off with a few commonly used terms -

Here is an overview of what happens after the driveshaft -
The driveshaft turns the pinion, which contacts and turns the ring gear, which turns the carrier, which turns the spider gears, which turn the axle shafts, which turn the tires.

Ring and Pinion / Gears: The drive shaft turns the pinion, which turns the ring gear. The pinion is held in the housing by its own set of bearings and the pinion yoke. The ring gear is bolted to the carrier or case. These are set up in a very particular manner, not simply slapped in and torque to a spec.

Carrier / Case: The piece that the ring gear is bolted to, that contains the spider gears and the cross shaft.

Spider Gears/Side gears: These are the gears contained in the carrier that physically attach (via splines) to the axle shaft. They are held in place by the cross shaft.

Cross Shaft / Pinion Shaft: The shaft that holds the spider gears (and on c-clip axles the axle shaft in place). This is a "part" of the carrier.

Axle shaft: The part of the axle that translates power from the differential to the tire.

Pinion Yoke: the piece that the driveshaft bolts to that connects it to the pinion.

Reverse Spiral / High Pinion Axle: The pinion enters the axle above the tube center line

Low Pinion Axle: The pinion enters the axle below the tube center line

C-Clip: the little clip that attaches to the end of the axle shaft inside the side gears that retain the axle shaft (on some axles only).

Pig / Differential / Center section: The cast part of the differential housing that contains the gears, carrier, and bearings.

U-Joint: The piece on the front axle that allows the power to be translated to the wheel when the tires are turned. U stands for Universal.

U-joint pieces:
Cap: the cap of the U-joint. For 297/760 series U-joints, this measures 1-3/8" DIA. For the smaller / weaker 260 U-joints, this measures 1-1/8" DIA.
Trunion: The piece that the cap rides on.

Front Axle:

The 4x4 equipped XJ Cherokee's all have a Dana 30 front end. There were many variations on this front end through the model years with many different brake / hub / u-joint / and shaft combinations - I will touch on a few here.

Center section:

1984-1999 XJ Cherokees came equipped with High Pinion Center sections
2000-2001 XJ's came with Low Pinion (often called TJ) center sections.

Axle Joints:
Some 1984 to 1986 XJ's came equipped with CV (Constant Velocity) axle shafts. These are higher maintenance, hard to find, and most people swap them out for U-Joint shafts. These are rare birds, and not found often.

1986 to 1994 XJ's came equipped with the small (260 series) u-joint, EXCEPT All ABS and NP242 equipped XJ's came with the 297 size joint.

1995-2001 had 297 sized (larger and stronger) u-joints.

1984 to 1992 XJ's came equipped with a vacuum disconnect front axle that has an intermediate shaft on the passenger side that physically disconnects from the outer, saving on gas and wear and tear on the drive train. The vacuum shift is shifted by the transfer case.

All ABS and NP242 XJ's have a non-disconnect (often called non-disco) front end

Rear Axles:

The XJ came from the factory with one of 3 rear axles -

Dana 35:
The Dana 35 came on most Cherokees, and was the only rear axle to be offered with ABS. This is identified by its oval shaped differential cover and rubber fill plug cover. The numbers "35c" often appear around the gusset on the center section. The "C" refers to custom - because Chrysler finished the axle in house. There were 2 main variations on this axle - the older style was a non-c-clip rear end and the newer style has c-clips. There were factory limited slip carriers offered for this axle.

Chrysler 8.25:
This axle came in non-ABS equipped Cherokees starting in 1988. It is identified by its flat bottomed casting on the center section. This is a c-clip rear end with 2 major variations:
1988 - 1995
These units were equipped with 27 spline axle shafts and about the same strength as the Dana 35. The only advantage is the housing is stronger.
1995 - 2001
These units are 29 spline equipped and are considerably stronger than a Dana 35 rear end.

Dana 44:
This is the rare bird XJ rear end that everyone wants - It is found in 1987 Cherokees for sure, and rumored to appear in 1988 and 89 models as well.
It is identified by its hexagon cover, non-flat bottom, and metal fill plug bolt.
This axle does not have c-clips. This axle uses the much stronger 30 spline shafts.

What Gears do I currently have?
The only sure bet way to know what gears you actually have in your differential is to take the cover off and count the ring gear teeth and pinion teeth - divide the ring gear teeth by the pinion teeth and boom - that is your gear ratio.
An easier way to identify them is to look for a tag on the differential cover held on by one of the bolts - this should have a 3 part number on it set apart from the other numbers that looks something like "3 07" which would be 3.07. Both the front and rear axles have to be the same - so if you cant read one tag, check the other differential.

As a general rule - the axle ratios are as follows:
4.0L - Manual Transmission - 3.07
4.0L - Auto Transmission - 3.55
2.5L - Manual Transmission - 4.11
2.5L - Auto Transmission - 4.56
BUT! towing packages and other un-explained variations came with different weird gearing options - so be sure to check!

Quick reference:
Dana 35 - 27 spline, carrier break at 3.31 / 3.55, Gears available in 3.07, 3.31, 3.55/3.54, 3.73, 4.11/4.10, 4.56, 4.88

Chry 8.25 - 27 or 29 spline, no carrier break, Gears available in 3.07, 3.21, 3.55, 3.73, 4.11, 4.56

XJ Dana 44 - 30 spline, Carrier Break at 3.73/3.92, gears available in 3.07, 3.31, 3.54, 3.73, 3.92, 4.09, 4.27, 4.56, 4.88, 5.13, 5.38, 5.89

HP Dana 30 – 27 spline inner, Carrier break at 3.55/3.73, Gears available in 3.07, 3.54, 3.73, 4.10, 4.56, 4.88

LP Dana 30 – 27 spline inner, carrier break at 3.55/3.73, Gears available in 3.07, 3.54, 3.73, 4.10, 4.27, 4.56, 4.88, 5.38

Edit for rear axle identification only.
Edit for removal of picture.