Sunday, 2 September 2012

Gearbox

So, I decided to leave sorting out the top diff mount until the engine and gearbox were in. That way I can be sure everything is aligned properly.

The next logical step was the gear box, but first a very quick diversion by way of the prop shaft, which I did months ago, whilst waiting to get around to something else. It was pretty rusty, but I cleaned it in petrol and then dismantled the U/Js and threw them all away. I am not going to keep anything like that, whether or not it looks OK. The de-rusting was quite satisfying as it eventually came up very well. I used DeOx-C gel, as I don't have anything big enough to soak the whole shaft in. Once the whole thing was painted with gel, I covered it in Cling Film and left it overnight. In the morning I washed it off and scrubbed it clean, rinse and repeat a few time and hey presto! no rust. A couple of coats of POR15, and install new UJs and that's it .

So, gearbox....

What's to say. The box was in a filthy state, but cleaned up well with a wire brush on the grinder. With all the surface rust gone I set about dismantling the box for inspection. I was a bit nervous it, but I read through the Haynes manual and jumped in. I had decided to renew the oil seals and bearings whether they looked OK or not, since the box has been hanging around for at least the last 13 years, and I've really no idea of its history. However, the more I took it apart, the more I realised that this box had hardly been used. I think it must have been rebuilt shortly before the car was taken off the road.

I did find some oddities: One of the gear selectors appears to have been replaced the wrong way around



According to the Haynes manual and pictures of the box I found on the web, only the reverse selector boss faces forwards. 1st/2nd and 3rd/4th selectors face backwards. What the effect of this is I don't know. Also,  the 1st/2nd gear selector was badly worn. I couldn't find any reason why this might be, so I can only imagine that it was not replaced at the rebuild.

The casing was full of sludge though!



In the end the only other wear I found was some chipped teeth on the reverse gear.  After scratching around I eventually found someone who stocked them. The price was a bit of a shock. £80 argh!, still,  in for a penny as they say, so I ordered one. After getting the box back together one came up on E-bay for £15.

On examining the lay shaft I found that it was poorly machined:



There appears to have been a fault in the steel before machining. This fault would sit immediately under the roller bearings at the rear of the lay shaft so it had to be replaced. New one on top.

There was a silver lining  to this minor cloud. Re-assembly of the lay shaft requires that you re-assemble the shaft and needle bearings on a short, dummy, shaft to stop the rollers falling out, then drop the shaft into the box and push the real shaft through from the outside, thus pushing the dummy shaft out the other end and keeping all the rollers in place. I now had a dummy shaft for the lay shaft re assembly. I just needed to grind off one end to size!

Anyhow, I replaced the bearings and the front and rear oil seals and reassembled following the manual, and it all seems fine.