RX7 FC differential bushing removal/installation

Removing steel shell type rubber bushings can be a real pain.

This will go over how to remove the FC rear diff bushings, assuming you have already removed the differential from the car.

This how-to will involve the use of a press. If you do not have a press, I'd highly suggest buying one. They are so cheap now-a-days from Canadian Tire, Princess Auto (or harbour freight if your in the US), Amazon, Ebay, etc...

I've done the burning-out method many times in my younger years; where you torch the rubber, and it smolders and you have to keep it burning forever with help from a torch.... then you are left with a shell that still needs to be cut out, and you end up scoring the bore with your sawzall... Its a mess, and smelly, and no fun... I don't recommend it... But hey, if you don't have the cash to spare for a press, have at er.

Tools needed:

• Hydraulic press w/ press plates
• Air hammer w/ chisel (angle grinder w/ cutoff disk will work if you don't have one)
• Support table for differential (or a helper!)
• 2 1/2" diameter round aluminum, or a seal/bearing driver kit

Approximate time needed: Individual (1 hour), with helper (30 minutes)

Use the air hammer with chisel to drive the outer shell of the OEM bushing up on both edges as shown in photo:

It is best to clamp the differential down to a workbench to do this, as these air hammers can be a hand-full at 100psi. It is easy to damage the diff housing if you don't have a steady hand.

Some more pics of what you are going for:

We have just exposed 2 sides for the diff housing to sit on our press plates. Next, it's time to get this set up in the press.

This is the setup I've used to do a handful of diff's over the years. Of course, if you don't have a sturdy table then you will need a helper!

As shown, I use some wood blocks to support the diff at the right height and position.

And we can have our press plates firmly supporting the diff housing (above).

I have a lot of aluminum round stock on hand, so I grabbed a piece of 2.5" which is a perfect fit for the diff housing bore that gives a little clearance.

You can also use bearing/seal drivers, but it needs to be a pretty close fit. If you use too small of a driver, you risk separating the center pin from the rubber while pressing it out. Then you are stuck tying to remove the outer steel shell...

Lets press that 40 year old bushing out:

It'll go pop at the bottom! Success.

Now to clean up the bore for the new bushing. I like to use a maroon scuff pad (scotch brite) to clean these up.

After scuffing and a wipe with acetone:

That is looking pretty good now, so we can install the new MAD Autoworks bushing (please note this colour is just a prototype colour, and doesn't reflect the product you will receive from MAD Autoworks!).

For 70A bushings, being softer, they like to grip onto the bore while being pushed in. A thin layer of high quality rubber grease, or just dishsoap, works wonders to help drive it in. Just use a soft face mallet to tap your new bushing into place!

Installed:

Thanks for reading! Hope these tips help you out!