Ford 8.8 Axle Swap
Article by Ed Holnagel
First of all I have to say that our Dana 35c has performed admirably for us over the 10 years that we have been wheeling it. A lot is said on forum groups and magazines about the Dana 35 not being up to the task of hard use off road. I have been running mine with an ARB air locker and 34" Super Swampers for the last 4 years with no issues. However out of 5 rigs here at NWJeepn that started life with the Dana 35 only two have yet to break an axle shaft. One in our group has been ritualistically beating the proverbial crap out of his D35 on a YJ with lockers and 35" tires for over 13 years with multiple trips to the Rubicon trail and has yet to break a shaft. He has blown up a locker (Detroit) but not the shafts. And, myself, with 10 years of wheeling my TJ without a broken shaft. The only parallel I can draw is that both my Jeep and the YJ are both running automatic transmissions. Of those that I know who have broken shafts it has always been a manual transmission and more than likely just a bit too much stupid pedal. 2 out of the 3 rigs have only broken one shaft over 10 years of wheelin' on some of the hardest trails here in Washington, a fact that I chock up to cautious and skillful driving. For both of these owners they say that is an "acceptable" failure rate and doesn't constitute a need to swap up to a bigger axle. In most cases if you are smart about the lines you take, easy on the stupid pedal and drive an automatic I don't think you have to worry about the D35 exploding.
However, it is generally felt that the D35 isn't long for this world when combined with a locker and 35" tires. For that reason (and because I don't have room to be carrying spare shafts with me on the trail) I made the decision that upgrading the rear axle was in my future as well as 35 or 36" tires.
For the budget conscious there are a few choices in axle swaps that make good candidates for the TJ. One is the Dana 44 from another TJ. Also just as common is the Ford 8.8 axle from a Ford Explorer. Less known choices are the Dana 44 from an Isuzu Rodeo or Honda Passport. There are of course many other good candidates but the prices start to climb and the support for some other axles is not as good as for the aforementioned.
We decided on the Ford 8.8 for several reasons. First, it is a stronger axle than the D44, sources claim as much as 30% more and more than 120% more than a D35. Second, disk brakes! We wouldn't even consider an 8.8 out of anything older than a '95 Explorer because of the disk brakes. Yes the 8.8 is still a C-clip design like the D35, however, from the testimonials of many in the Jeepin' community the durability of the 8.8 is legendary. Breaking one is unlikely and if you do, the disk brakes will keep the wheel from walking away from your rig unlike the D35. Some may ask "why not a D44 from a later model TJ that came with disk brakes?" The answer here is not only a much bigger price tag, but also the fact that the axle tubes on the TJ D44s were the same thickness as the D35! Yes the axle shafts are bigger but many of the failings of the D35 have to do with axle tube flex putting too much stress on the shafts, the D44 is still just as susceptible to tube flex but the shafts are thicker and harder to break.
Our Ford 8.8
We found our 31 spline, 8.8 axle on Craigslist complete with the calipers, disks and E-brake lines for $300. It had come from a 2000 Ford Explorer and although we gave the axle a good once over when we went to get it, it wasn't until we had gotten it home that we noticed the driver side tube was bent. A little research put our minds at ease that the bend was in fact an easy fix and required nothing too much more high tech. than a good pair of jack stands, some chain and a bottle jack. Had we seen the bend we would have negotiated a lower price. Using the techniques we found here, we were able to straighten the tube with ease. A runout test using a dial indicator and with the axle set on jack stands showed a runout of not more than 1/16" which is close enough in our book. One other good way to test is if you can easily insert the axle shafts into the carrier. When we took our axle apart we could easily slide out the short shaft with one finger. The long shaft however had to be beat out with a hammer because of the bind created by the bent tube. After straightening our tube the long shaft slid in and out just as easy as the other side! The moral here is if you find a good 8.8 with disk brakes but it has a bend in it don't let that stop you. Offer to get it off the owners hands for free and he won't have to pay the dump fees to get rid of it.
The Build Process
We started our build by completely tearing down our 8.8. We will assume that if your handy enough to be attempting this swap that you know how to pull the carrier and axle shafts. If you don't intend to change gearing then there is no reason to remove the pinion.
All of the mount brackets will need to be cut off to make way for the TJ style of mounts. Some prefer to use a 3" air driven cut off saw to cut through the welds and then beat the brackets off with a hammer. We opted to use our plasma cutter which makes quick work of the thin metal on the stock Ford spring perches and swaybar mounts. Finish up with a hand grinder to remove all the welds. Now we have completely clean housing to start with.
While we were in the cutting mode we decided to trim the case a bit as we knew from others experience that the TJ rear swaybar would hit the case in a couple of places if not trimmed. We removed the ABS sensor from the top of the diff. housing and proceeded to cut the protection fins off using a 3" air cut off saw. After removing the fins we cleaned up the area with a hand grinder. Removal of the fins may not be necessary however we would rather do it now rather than get the axle under the Jeep and find out we should have.
A rectangular metal plate will be fashioned to cover the ABS hole and mounted in place using the old ABS bolt and sealed with RTV sealant.
Next we remove some of the casting from the passenger side of the housing. Again the 3" cut off saw works good here. We started with the cuts you see in the picture at right but decided to take more off to be sure that we won't have any fit problems with the factory swaybar.