TJ High Pinion Front Axle Upgrade
[an error occurred while processing this directive] Short Cuts

By: John Nutter - 9/1/2002

Get Your Front Drive Shaft Away From The Rocks!

The high pinion Dana 30 front axle from an XJ Cherokee is an obvious but seldom seen upgrade for a TJ. The Cherokee front axle is a direct bolt in with all the suspension brackets in the same place as a TJ, but it has the advantages of a pinion that is around four inches higher and a 30% stronger gear set. A more subtle advantage is the shimmed pinion pre-load versus the crush sleeve found on TJ front ends. Using shims for pinion pre-load is more stable and tends to help reduce leaky pinion seals when compared to similar crush sleeve equipped axles.



Photo by: John Nutter
The pinion is noticeably higher on the XJ front axle (right).
Photo by: John Nutter
The XJ front end ready to be rebuilt.
Photo by: John Nutter
You can save a little time by removing the axle shafts and unit bearings while they are still together.
Photo by: John Nutter
Keith cuts the air line for the old ARB. The reliable Detroit Locker needs no air to operate and is very likely the strongest part in the entire axle assembly.
Photo by: John Nutter
Waiting for the new front end.
Photo by: John Nutter
There is a slight difference between the upper control arm bushings. Note the different heights raised shoulder part way down the steel sleeve.
Photo by: John Nutter
The unit bearing from the '88 XJ is slightly different from the TJ part. We were going with the TJ knuckles and brakes anyways, so it was not a concern for us.
Photo by: John Nutter
The TJ and XJ steering parts appeared to be identical. These will make good trail spares.
Photo by: John Nutter
You can see the differences between the TJ knuckles (right) and the XJ knuckles (left). The TJ brake calipers don't fit the XJ knuckles. the TJ brakes were in good shape so we swapped the TJ knuckles onto the XJ housing.
Photo by: John Nutter
The pinion is now much higher than when we started. The drive shaft ended up higher than the lower control arms.

I've wanted to swap a non-disconnect Cherokee front end into a TJ for a long time. The opportunity came when my friend Keith Thomas' ARB started leaking air out the differential vent. Keith had been happy with the Detroit Locker in his rear axle and now seemed like a good time to upgrade the front to a Detroit as well. I mentioned the possibility of raising the pinion up several inches using an XJ front housing and Keith's decision was made.

The decision to use an XJ housing should be easy for any TJ owner who is going to change gears, because other than the gears everything swaps over. The housings can be found for under $100 in many areas because XJ production was very high after '87 and now many of these vehicles have 200,000+ miles on them and are finding their way into the wrecking yards. If you are going to change to lower gears anyways, the only extra cost would be the housing itself.

A couple weeks later Keith, Jerry Hunnicutt and I went to a local U-Pull type wrecking yard and got a complete non-disconnect front end from an '88 Cherokee. The non-disconnect front ends are easy to spot. Either look inside and see if the Jeep in question has a transfer case with a full time 4WD position or just look under the vehicle and make sure the passenger side upper control bracket is welded to the tube as seen in the accompanying photos. The disconnect type axles have the passenger side upper control arm bracket cast as part of the disconnect assembly. The non-disconnect front end is desired because the TJ axle shafts are a direct swap into that housing and because the vacuum disconnects can be troublesome. You could also go with the original XJ axle shafts, but these would have smaller U-joints on the earlier Cherokees.

The build up was very straight forward. The XJ housing was cleaned and stripped of all the original parts. Once the housing was cleaned a new set of 4.56 gears for a high pinion Dana 30 and a Detroit Locker were installed. It is important to note that the gears from a TJ front end will not work in an XJ front end. Add the cost of new gears into your project plans. Once the gears and locker were in place the axle was re-assembled with the TJ shafts and outers.

We noted an interesting thing when we installed the XJ front end into the TJ. There was no provision for the caster adjustment cams on the lower control arm mounts on the XJ front axle. This was not a problem because Keith had adjustable control arms. You could slot the holes and weld some metal on to make the caster cams work, but I think adjustable control arms provide a better solution for aligning the Jeep. Beyond this minor point the XJ axle was a direct bolt in. All four control arm brackets, the track bar bracket and even the steering stabilizer bolt in the exact same way on both axles. Keith's existing front drive shaft worked for this application as well, but that is probably due to the fact that Keith had never lengthened it after lifting his Jeep. Lift height could be a consideration on this swap. Keith has 5 inches of lift on his TJ, and raising the drive shaft posed no problems. If your Jeep has less lift you should check carefully to be sure the drive shaft will clear everything at it's new height.


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