Gearbox Stripdown

06 October 2008

Over the last week, I've been working on getting gearbox off of the engine, and taking the bellhousing off of it. This turned out to be a bit more involved than I'd hoped (I should have learned by now).

First job was to remove the gearbox. Nothing too complex to start with, had to remove a few bits and bobs to get at all of the bolts, but that was easy enough. Then I made a bit of a mistake. I had lifted the engine slightly using the hoist, and figured I'd just pull the gearbox off. Well it was a bit harder than that, and required a fair bit of persuasion with my trusty rubber mallet, a bit of levering with lengths of softwood, and much wiggling. However I finally managed to pull it free...and promptly nearly dropped it on my toes. The thing must weigh close on a hundred pounds, much heavier than the honda box (which is the sort of weight I was expecting). I'd forgotten, of course, that it also had the differential attached to it, which is quite hefty.

So lesson learned. I should have left the engine on the floor and supported the gearbox using the hoist. Hopefully I didn't knacker anything by having it hanging off the engine, as I wasn't supporting as much of the weight as I thought I was. Still, it was off, so I left it to drain overnight.

 

It looked as if I'd then have to remove the differential, but that the bellhousing would then just unbolt from the front of the box. So I set about removing the diff, which was simply a case of unbolting the cover and lifting it out in one piece...nice and easy.

So then I unbolted the bellhousing, and started "persuading" it off. Didn't get very far though, it would only move about half an inch. After a lot of time spent peering and wiggling, I gave up and retreated to see what the manual had to say. Well, it didn't really, but it did show how to strip the box down. Not something I really wanted to do, but after spending so much time without getting anywhere, I figured I had no choice.

So that's what I did. I didn't get very far on the first attempt because I needed a 32mm socket which I didn't have, but after that it was reasonably easy.

   Fifth gear, apparently. These gears have to be removed to allow access to the plate which holds the rest in the casing.
  Off comes the casing (left). The left-hand shaft is the input, the right-hand the output, and the one in the foreground is reverse.
"...and there were all these little cogs, and just the light of Les' torch...s'rubbish"
(with apologies to those who weren't fans of "Men Behaving Badly")

Most mechanical things become obvious once you take them to bits, but I confess that it still looks as if a bit of magic is involved somewhere in there. I am quite glad I don't have to put it together again!

So I spent some time cleaning everything up, and I now have the bellhousing. Still not sure if it'll turn out to be useful or not at this point. The next thing is to offer up the honda box to the engine and get an idea of exactly how bad things are! To that end I've started stripping some more bits off of the engine itself to make room. At some point I will have to take the bellhousing off of the honda box, I need to find out exactly what's involved there - I really hope it doesn't need a full strip down like this one...