Engine 3 - Main Rebuild

I mentioned in the previous post that an expensive box of bits had arrived, full of bearings and sundry missing parts (the first of several "missing parts" orders!)

I used the method in the Jack Gray article to install the bearings and oil seals in the crankase halves. Basically - heat each case up in the oven and then drop the appropriate bearing in place and then watch it be magically gripped in place as the metal cools down and contracts.

The old bearings were in a bad way - this is the gearbox mainshaft bearing but they were all as bad.

 

For this one, I heated up the gearbox end cover with a blowtorch and dropped the bearing into place.

Crankcase gently heating at Gas Mark 6!

And new main and layshaft bearings installed.

The project actually stalled for a couple of months at this stage. First I took off to Australia for a few weeks on a long overdue visit to see family, after the Covid restrictions were lifted. Then, as spring had arrived and it was OK to work outside, I started on the recommissioning of the 1974 Honda 250G5 that I bought in November last year. The aim was to get this running reliably so I could use it through spring/summer and also to go the Manx GP / Classic TT in August if I can't get the Enfield into use by then. If you're interested in the G5 - see here.

So sometime in May I started back on the Crusader restoration. It took me a few hours to get my head back into where I was up to.

I fitted the con-rod to the crankshaft. It's like a car type, with removable bearing cap and big end shells. Then I replaced the inner part of the crank roller bearing. This slides into the separate outer cage, which was fitted into the (heated up) outer case. The picture shows the original, rusty immovable one!

The mating surfaces of each of the crankcase halves were then coated with Wellseal. This junction doesn't have a gasket and there are a couple of nicks in the surfaces so hopefully the Wellseal will keep this joint oil-tight.

A handy tip was to get hold of a mascara brush to apply the Wellseal.

I rested the lower case on some blocks of wood and then set the crankshaft roller bearing into it's housing. Then I lowered the upper case over the crank and studs. At this point, the inner race of the main roller bearing needs to be drifted onto the crank - I used some spare distance pieces as a drift and the two halves came together with a nice clunk.

Note - these references to upper and lower cases are relative to the photograph below - the actual joint will of course be vertical, not horizontal, when the engine is in its correct orientation.

The drift collars in position:

It looks a bit more like an engine now and the crank spins nicely😀.

So that was one of my fears overcome. The next was fitting the gearbox.

This took loads of fiddling around to get a proper understanding of how everything meshes together etc. Not helped by the fact that a superfluous gear had been left as part of the jigsaw puzzle. Once I worked that out, it became a lot more understandable!

Credit to the excellent videos provided by Paul Henshaw of Performance Classics here - a fantastic source of information for Royal Enfields generally and Crusaders in particular. This video explaining how the innards works was really helpful.

Eventually, after much patient tinkering, I had the gear clusters and selection mechanism fitted and working as it should (apparently!)

Then I fitted the gearbox cover, which locates the ends of the mainshaft and layshaft and also holds the kickstart mechanism.