Chained up backwards

Still flushed with success from the weekend, it was back to the J15. What’s more, I’ve managed to actually do a couple of small things which is a relief. In particular I decided to finish off a couple of things at the back of the car.

First up was to finish off the clutch. So, I put the chain guard, which contains the housing for the clutch slave, on the engine and then the slave cylinder itself. I then connected up the hose that I left coiled up here a while ago. Mind you, looking at the photo, I might have left too much slack in the hose.

I then moved onto fitting the reverse motor. Here there was a problem. I checked ages ago that the motor was going to fit with the clutch slave in situ. However, I hadn’t allowed for the fact that the banjo bolt in the hydraulic connection was going to be there. And, inevitably, the banjo wanted to be where the motor was. So, guess what? I got out the grinder and set about the motor’s castings until it all fitted.

And then I tested it, and it didn’t work. Well, to be accurate the solenoid pulled in but the motor didn’t spin. Took a heck a lot of current too; I’d connected it up with some jump leads and they got really rather hot. So, I took it all off and tried to find out what was going on. When I was young I was always leaving things in bits when I couldn’t get them back together again. (And I spent years looking a sewing machine trying to work out how it could tie knots by just moving the needle up and down.) In this case I ended up with the motor in bits in a slightly surprising moment. I just thought they were the bolts holding the motor in; it turned out that they held the motor together.

Luckily, it didn’t go sproing and shoot commutator brushes around the garage. (Been there, done that.) It was still a bit tricky getting it back together though.

In the end, I just worked out that the wiring was a bit odd; in particular the ground for the solenoid and the motor are stoically not connected to each other. I managed to get it all back together and onto the car. This time using another set of jump leads I was able to make it spin the engine’s output sprocket. I must admit, though, that I’m really unsure whether it’s going to work successfully.

I’d also decided that it was time to fit the chain. I’ve never fiddled with bike chains before so this was a bit of a leap into the unknown. I bought the chain ages ago, following the now established RGB principle of finding the most expensive chain I could and buying that. Here it is, along with an alarmingly expensive fitting tool (the black bits at the bottom).

Then it was several hours of fiddling about working out how to do things, how not to drop the little “X-ring” seals and how to use the black bits for which the instructions are written in a curious English-like language.

I’ve chosen to start off with the largest sprocket on both ends that I’ve got (15/52 teeth). The Fury is geared for 131mph maximum on its 185 section tyres. At the race at the weekend the fastest I got to was 130.03 mph which was a gnat’s whisker off the limiter. These sprockets are actually a slightly shorter ratio than the Fury’s crown wheel and pinion (3.47 instead of 3.21). However, I was planning on using 205 section rear tyres which more than compensates and should gear the J15 for 135mph. I think.

Eventually I got it all together and here’s the chain in place on the sprocket. If you look hard you can see the link that I’ve inserted. It’s the one that’s extra-gungy with the chain lube. You can see it because the rivets are different from those in the normal links.

When doing all this I adopted the policy of positioning the sprocket at the shortest position. That way as the chain stretches (apparently they do) I’ve got some adjustment. Also, if I decide to use a shorter ratio (14/52 would make it 125mph which might well be good for Brands Indy and Mallory) I’ll be able to move the diff backwards.

What I haven’t done yet is added the device that I want to add for tensioning the chain, although I reckon the current arrangement will stay in place succesfully. Essentially, I want to add a couple of turnbuckles at the side of the diff. Hopefully, I can get these made at the weekend. Problem is, I’m giving a paper at a conference next week and I’ve got to write the presentation.