Clutch and Gearbox changing

Changing clutches (or transmissions, once you've got it out it's no more work to put in another one, especially if it's of the same type). Some helpul hints are on this page, but it's not meant as a substitute to the workshop manual. Please read your workshop manual carefully. The usual safety warnings apply, gearboxes are heavy (about 40 kilo for an M47, about 55 kilo for an M46, both including bellhousing) and have some sharp edges and protrusions. They also tend to be greasy and thus prone to slip from your hand. Having a curved bottom they also tend to slip off ordinary jacks.

Changing gearboxes is no more difficult than changing a clutch. If you get a replacement box of the same type it's a straight swap. Bellhousings tend to come with the box. Try to avoid seperating the box and bellhousing, the bellhousing is the front cover of the box and oil will run out if you seperate the two. You'll also need a new gasket (Volvo, approx $15). If you get a different type of gearbox (say M46 to M47) you also need the driveshaft, crossmember and if applicable speedo drive from the donor car. Beware that M46 and M47 come both with and without speedo drive, some cars didn't need them due to taking the speedo off the electronics. A box with speedo can be used in a car that doesn't need it, the other way around you'll lose speedo and odo.

The 6 upper bellhousing bolts are likely to be 18 mm on B21/B23/B230/B200 engine cars (at least they are on my 940), a size not found in most wrench sets. Bottom 2 are ?? mm. On a B18/B20 engine car the upper 6 are 5/8" with the bottom 2 being 9/16". The top one (two on the upright B18/B20) you get out by using a relatively long spanner and skinning your knuckles between the engine, firewall, and hoses/other stuff in the vicinity. I got a long 18 mm ring/open spanner (the ones with the ring straight on are the best) and welded the open ended part of a short 5/8" to a piece of bar stock. The rest you get out with a socket, wobbler attachment and extension pieces. An air impact wrench really helps, I didn't need to bother with penetrating oil or anything of the kind. Really speeds up work, too.

The box (M47) weighs about 40 kilo (I was easily able to lift it by myself, a fair bit heavier than a 12 bottle crate of soda) including the bellhousing. A regular large floor jack (not the small $25 kind) will work fine, although you'll have a problem keeping the tranny (curved bottom) on the jack (nearly flat dish). I solved this problem by ducttaping the tranny to the jack.

You keep the engine up either by placing a 2*4 between the engine and firewall or by putting a second jack under it.

While you're in there, at least change the pilot bearing and throwout bearings, and possibly the rear crankshaft seal. Check the clutch, if it looks dodgy replace that as well. Clutch parts are cheap, pulling a tranny is annoying.

(M47, possibly M45/M46) If you unbolt the stick carrier from the tranny you can leave the stick and carrier in place after taking out the small allen bolt at the bottom of the stick and pushing out the wrist pin. Saves you from having to mess around with the center console.