Getting Your Rear in Gear (or what you need to know for the back end)

by Jim Deatsch

When restoring a Spitfire from the frame up it's assumed you will remove and overhaul (at least partially) the rear suspension and differential. It's a good idea to at least do seals and bushings in this area since it's so much easier to do these pieces when the body tub is out of the way.

We need to remove all of the rear suspension and drive pieces. This is pretty obvious and there is no need to go into disassembly details. The only warning is to watch out for the rear spring when you are unbolting things. You wouldn't want to get thwapped by that puppy.

There is one thing you won't want to do yourself unless you are a masochist. You're better off taking the rear axles to someone who has the correct tools for removing the hubs. You will most likely damage them by attempting to use a puller on them. There are horror stories about those who have tried to do this themselves.

When replacing the pinion seal you should make note of where the nut is at this point BEFORE disassembly. Scribe the nut and the shaft and the body of the mount. Make it easy on yourself and make sure it goes back together just like it was. The nut torques to 85 ft lbs.

When you remove the 6 nuts on top of the differential that are holding the spring down you will undoubtedly have some or all of the studs come out as well. This is not a problem. Get yourself some 3/8 x 24 bolts to put back in the holes. These holes go all the way into the differential and you WILL get dirt in there unless you're very careful. After removal of the differential from it's mounts, turn it upside down with the studs out and let it drain through those 6 holes. This will help clean them out and remove any dirt that was allowed in.

If your differential needs internal attention (besides the pinion seal) it needs to go to a specialty shop. Setting up a differential's carrier bearings is not something that just anyone can do. This is a very touchy and critical adjustment and should only be performed by an expert.

Reassembly is pretty straightforward. Honest.

First we need to remount the differential. Some documentation describes this process as something like the following:

Using a floor jack, lift the back of the differential into position and then install the long bolt that holds it in place. Using the floor jack, raise the front of the differential into place and (after having put the large rubber donuts in place) put the rubber washers, metal washers, and nuts in place.

Yeah Right!! On some cars this will not work as the front mount will contact the frame before it's in place. I had to lift the differential into place so that the front mount was set and then run the rear mounting bolt through it's holes. Your car may be different. In fact it WILL be different. Trust me.

Once the differential is mounted then we can move on. We need to mount the rear axles to the differential and get things ready for the road.

Mount the axles to the drive flanges on the differential. Make sure you use the correct bolts as length is critical here. If the bolts are too long they will hit the allen bolts that hold the flanges on the differential. Use new nylon locking nuts for these bolts. Get thee to the hardware store. After mounting and tightening the flanges to the differential (46 ft lbs.) we need to get the suspension done up.

Mount the spring to the top of the differential using the 6 studs, flat washers, and nuts. Don't forget the top plate. After the spring is mounted then we need to get it attached to the vertical links on each side of the car. This is a tight fit and will take some work and a little prying with a bar. Don't hurt yourself or the car. Be careful. It might be a good idea to get someone to help you out here. This can either go very well or be a pain.

Don't forget to refill the differential with 85/90 wt gear lube.

I can give you one piece of advice here. Heed it well. Use anti-seize on any bolt that goes through a metal bushing inside rubber. Just do it!

After the spring is mounted and secure it's time for the shocks. Same deal here. Be careful and work safely. This is a no-brainer but it can be touchy. Just take your time and things will work out well. You DID put gear oil back in the differential. Right?

Now it's time to sit back and admire your work. Pop a cold one and take a look. Invite your spouse out to survey your handwork. A little praise can be a good thing.