Instructions for installing an extended chain case in a XP/XM
We tried to make it easy for you to install this chaincase. It uses all the stock parts and as many stock mounting holes as we could use. You will need a 2.5” and a 2.16” hole saw, some pop rivets, and normal tools.
You will have to find someone who can weld aluminum to fabricate the flange under the chain case.
The following is a customer's first hand account of installing this chain case:
I just completed this project with a C3 Syncrodrive on mine. Here's my Reader's Digest version:
Follow the steps in the service manual(if you don't have one, get one) to remove the jackshaft/secondary and track shaft/track. Grind the heads off the rivets from the inside. The pyramidal chassis structure bolts to a tab on the top of the chaincase. Heaven help ya to get at the backside. Remove enough bodywork to access the other ends of those rods and disconnect them from the other ends, one near the steering post and the other at the clutch tower. There are miscellaneous other things(wiring and other BS) tied to everything in there so be patient and clear out the space you need. The chaincase and those two crossmembers will come free as one assembly.
Now take your pick: either this part will make you cry or final assembly will after you've done this wrong. Just kidding-there are some critical bolt holes in the chaincase and clutch side bearing relocator which pave the way for you here; in fact, 3 of the 5 holes in the side of the tunnel lined up and another was almost perfect. The fifth is a bit tricky, moreon that later. The horizontal plate will fit exactly where the old one did, you'll drill the holes ONLY after the chaincase sits flush against the tunnel. You'll have to cut the foot boards enough to wrestle the new case into a position where the new bearing cup can sit flush against the tunnel. Cutting the rolled lip off the bottom of the tunnel will be required.
Using longer bolts than what you'll use for final assembly, approximate the location of the chain case such that you can trace around the outside of the bearing cup with a felt or scribe it with an awl. The you can drill a couple reference holes where the marks terminate at the existing opening. Find something that is the same diameter as the bearing cup and trace around it using your reference holes from the inside. It's easier to work from the inside of the tunnel. We used a drill, connecting small holes and working our way around for lack of special tools. It's good to have a buddy watch and guide you from the outside. We rounded things smooth with a cone stone.
Once you have the opening enlarged it will bear the rough sillouette of an 8 and you can try lining the case up. There is a lip at the front near the E-module which may hang you up. Grind this down until it's out of the way. You may find that one of the bolt holes toward the rear doesn't quite work anymore now that the case is flush; just chase it with a 1/4" bit. The fifth hole- I got a canadian tire drill 90 attachment to drill the final hole deep in the footwell. You can now secure the chaincase to the tunnel for final mockup and, using a 1/4" bit drill upwards through the bulkhead drill the 2 holes through the anchor plate.
Disassemble the two chassis crossmembers from the old chaincase and place them back in the chassis, securing them at their opposite ends. You will use these to determine your hole location on the top tab. Mount them in a forward location relative to where they would sit after final assembly. Remember, if this hole is wrong it will distort the clutch tower. Thread the drill bit through both eyelets positioned on the front of the tab(they will be assembled as stock on the rear afterward) and use them as a guide to drill the hole.
The clutch side bearing relocator has two holes on tabs which protrude from one side. Their placement is no accident; simply use the stock brake caliper bolt holes to orient, trace and remove the required material(I'm not pounding all that out again). By now you'll have a handle on this. (Note that the top fingers will have to be cut off after the relocator is installed. They will hit the track.)