[s-cars] V8 Differential Swap Instructions - Long

[Sean Douglas]

Well, if spent the afternoon *removing* the V8 diff that I installed in the
summer.

 

Why you ask?

 

This summer, when I did the suspension upgrade, at the same time, I
installed a V8 diff, complete with new seals and I even cleaned it up and
painted it. The problem is that after test driving it, I noticed a lot of
slop in the drivetrain. After inspection, it turned out there is a lot of
play between the input flange and the axle flanges, I can turn the input
flange about 10 mm before it engages. I presume this is caused by play in
the ring and pinion. I should have checked this before installing it.

 

I wonder if it can be shimmed to remove the play. Anyone have any
suggestions?

 

Fast forward to today. I finally decided that I had enough of the play and
decided to put the old one back in. So, I installed 2 new seals and added
1.5 litres of OEM fluid.

 

Seven hours later, it's done and my back hurts! I did it without any help
(save my wife who did help a little).

 

The basic instructions are:

 

-          remove rear wheels

-          remove exhaust at double clamps, support exhaust, remove hangers
and pull out exhaust 

-          remove plastic tray under gas tank

-          remove bolts attaching trapezoidal arm to subframe, this allows
clearance between the inner CV joints and the axle flanges

-          remove cover plate on left side of axle

-          remove left handbrake cable bracket to diff

-          unbolt right handbrake cable bracket from diff (one of the bolts
is obstructed, I used vice-grips)

-          remove handbrake cable brackets holding to body (near driveshaft)

-          remove triple square bolts from inner CV joints to the axle
flanges

-          remove  driveshaft CV joint to input flange bolts

-          remove single nut holding the rear diff mount to the subframe

-          remove muffler support cross member

-          remove diff front cross member and support diff

-          lower front of diff down slightly

-          remove diff cross member from diff bracket

-          remove diff bracket from front of diff and slide bracket over
input flange

-          lower the front down farther and when at about a 30 degree angle,
lift the rear up allowing the rear mount bolt to clear the subframe

-          lower diff to floor and remove

-          remove rear mount bracket and install on new diff

 

As they say, installation is the reverse of removal, a few tips.

 

It's easier to lift the diff into position manually without a jack, although
its pretty heavy (~100 lbs). It took me a while to figure this out after
several fruitless attempts to use a floor jack that I have outfitted with a
12x12 square piece of 1 inch plywood bolted to the saddle. I did this by
lying on the garage floor and angled the rear up at the same 30 degrees and
guided the rear mount bolt into the upper hole on the subframe. Once it's in
there, you can jack up the front and install all the brackets and cross
member. Be careful to makes sure the handbrake cables don't get caught. If
you have the car on a lift, I'd suggest two people lift the diff and have a
transmission jack handy to support the front once the rear mount bolt is
engaged in the subframe.

 

Since I had all new hardware from the suspension work I did in the summer,
all the bolts and nuts came off nicely; others may have issues with rusted
fasteners.

 

After a nice long test drive, I'm happy to report that the driveline slop is
gone!

 

Hope this will help others doing the V8 swap and make sure you inspect the
play before installing.

 

Cheers,

 

Sean Douglas

1997 S6