Ford 8.8 Axle Swap

Page 4

 While getting ready to install our air locker we discovered a little known fact about the 8.8s mentioned in the ARB installation manual that we have never seen discussed elsewhere.  Mainly that many of the 8.8s left the factory missing an oil return gallery for one of the axle tubes.

In normal operation the outer axle bearings are lubricated by differential oil that flows the length of the tube, the oil returns to the differential through an oil return port that should be cut in the casting at the LOWER side of the tube to improve drainage.  It would seem that some axles were missing the return port on one of the tubes.  Ours was missing on the passenger side.  We therefore used a small hand grinder to grind away some of the casting to provide an oil return port.

Oil Ports     Oil Ports     Oil Port

Notice in picture 2 and 3 the new oil return port we have added to help in draining the tube.  Picture 3 shows a carrier shim in place.


Driver side brake hose

Passenger side brake hose

Brake Line Routing

We used two right side caliper hoses available through NAPA (pt# 380528) for each side.  The T-fitting/hose was included with our Rock Krawler suspension and has an extended hose line for the added lift and articulation.  The T-hose is held to the axle with the axle vent fitting.

 We cut small blocks of 1/2" thick by 1" bar stock then drilled and tapped them for 5/16" bolts to secure the caliper hoses to the axle tube.  The blocks were welded just above our Shock Shifter brackets and just below the spring pads.

As we didn't intend to save our D35 housing (who want's a D35 anyway?) we salvaged the driver side hard brake line for our 8.8.   The stock Jeep hard line was already bent just right leaving the T-hose so all we really needed to do was cut it to length and put a few bends in it to meet up with the hose fitting.  Since the stock Jeep hard lines are wrapped in a coil of steel wire it is fairly easy to put new bends in it without tubing benders.   Using a double flaring tool we re-flared our line and attached it to the rubber hose union.

As our 8.8 had a long section of hard line attached to the passenger side we decided just to re-use it and bend it to follow the contour of the differential.  After cutting it to length we re-flared the cut end and connected it to the T-hose.  One thing that is of utmost importance is bleeding the brake lines very well.  We have learned from many on the forum groups that you should do a complete brake bleed TWICE!  Watch for any leaks from fittings and flares that you may have done.  Tighten if necessary and then completely re-bleed the system.

A word about proportioning valves:  We had intended to use a 2004 Rubicon valve and bypass the ABS pump all together.  However we found out that the line fittings from the ABS pump to the brakes are different than the holes in the valve.  Either we would have to cut the lines, install new fittings and re-flare them, or find adapter fittings.  As time was an issue and we had an appointment with the exhaust shop we opted to go with the stock valve.  We have noticed no issue with the brakes using the stock valve and disabling the ABS pump system.  We will only need to pull the bulb in the dash for the ABS light as pulling the ABS fuse will not extinguish it.

There are several options for the parking brakes.  Many sources on the net claim to use stock Grand Cherokee parking brake cables.  We have also seen that the stock Ford cables can be used but require some kind of modification where they attach at the equalization bracket under the TJ.  There are commercially made cables available just for the 8.8 in a TJ that are 3" longer than stock to allow for better axle articulation without pulling the cables tight, but we were a little put off by the price.   We would prefer to have longer lines due to the amount of lift and articulation we have so the Cherokee cables will be in our future.

In the meantime we decided to use the stock TJ cables and adapt them to work with the Ford brakes by making up some simple adapters using 1" flatbar.  We had seen adapters like this on another web site for sale but frankly we felt they were off their rockers wanting $40 for the pair, honestly there isn't $5.00 worth of metal here and they aren't that hard to make.  Click here for a measured drawing of the adapters.

Ebrake adapter     Ebrake adapter    Ebrake adapter


Ford 8.8 Axle Swap Conclusions and Technical Data