Apart that is, from the really annoying problem that the taps I ordered turn out to be duff in that they cut, and then wrecked, the threads. So, that mounting block in the photo above has nadgered caliper mounting bolt threads in it. This means I’ve chucked away one set of taps, ordered some more from somewhere else and I’m going to have to generate a lot more aluminium swarf in order to make another mounting block. However, the whole process seems to work which is good. It’s just very annoying that I’m going to have to waste half a day hunched over the lathe.

I need to get the the chassis off to the powder coaters. I phoned them yesterday and they said they’d go a small problem in that their shot-blaster had had “relationship problems” over Christmas (! ) meaning that there was going to be a bit of a delay. That’s probably no problem as I’ve got lots to be doing. I’ll probably  try and take the chassis over at the back end of this week as I’m going to be dead busy next week anyway.

Next thing was to do the panelling over the top of the pedal box. However, I’m a bit unsure where the bonnet is going to be, so I put the pedals and steering column back on the car, and put the tub and, for the first time!, the bonnet on the car. It now looks like the photo here. (Except that the camera seems to get a bit confused about the colours.)

This means that I can now look underneath and have a look at how much clearance there is between the column and the underside of the bonnet, something that I’ve really  been guessing about up to now.

One of the reasons I bought the J15 is that I reckon it’s got a fairly small frontal area. That means the bonnet is low (and there’s no annoying induction lump in it).

As you can see, although the perspective is confusing, the suspension, positioned here at full droop, is pretty close to the bonnet, although there is about 30mm clearance so that’s OK. The steering column is well clear so there’s ample room to build an aluminium “tent” over the top of it.

After getting the chassis and other components ready to go to the powder coaters, that’s probably the next job. As you can tell, I’m putting off doing the rest of the really boring panelling.

At the right hand side of the previous photo, you can see the lower edge of the bonnet. Interestingly, there’s a substantial flat portion on the bottom of this bonnet. At first sight, this looks to be pretty much at the level of the bottom of the chassis. If so, that means I’ll be able to extend the undertray forwards so that the bonnet rests on it. I’m intending making it so that the bonnet just lifts off, rather than hinging things. As such, the undertray looks as though it’ll perform a couple of functions.

However, I’ve been waiting so long I decided to just work around the problem which I think I can. I certainly shan’t be putting any business their way in the future though.

Still, at least I could get going on this now. First thing was to fit the diagonal to the rear hoop and weld that to the chassis. So, I tacked things together and tacked the hoop to the chassis after cutting the bottom of the legs so that it would all end up vertical when it was fixed to the non-horizontal plates on the chassis. However, with it in position I realised that it could easily be too far forward in that there might not be room for a crash pad behind my helmet. So, I fixed a bit of hardboard to the hoop and checked how much clearance there was; in fact I videoed myself as it’s really quite difficult to work out how much clearance there is around your helmet when you’re wearing it!

That testing showed that the hoop was indeed too far forward and I had to move it back to the position that you can see in this photo. The problem with this, if you look at the bottom of the hoop, is that the legs are no longer above the chassis.

So, I had to extend the hard mounting points on the chassis which I did by welding in a chunk of box section in as shown in the photo, and then extending the plate I’d already welded to the top of the chassis.

With that done the hoop seemed to be fine, although the upcoming problem is working out how to attach the harnesses to the car. I’ve always known this was going to be an issue but I’ve never worked out what to do about it. There’s really two possibilities. One is to weld an additional horizontal harness bar into the cage over which the harnesses will loop before going to the chassis mounts. (This is what I did on the Fury when fitting the HANS device.) The second is also to weld an  additional tube into the cage, but to use that directly for attaching the harness to. Any suggestions gratefully received.

Anyway, with all that sorted I welded the diagonal properly into the hoop and welded the hoop to the chassis.

Then I had a nice cup of tea.

Next up was the backstays. As I’ve mentioned I wanted to make these removable. So, I turned some lumps of steel so that I could weld a pre-made insert into the end of the tubing into which I could mount a rod end. The joints I’m using are actually rather more expensive that the ones I normally use. They’re rated at about twice the maximum radial load that a normal cheapie joint is rated at. I decided I wanted to do this properly, you see.

I then welded some mounting to the cage and the end result is shown in the photo.

So, that meant that the back end of the roll cage was all done, and a view of the whole rear end is also shown.

I now had to fit the front hoop. First thing, though was to again check that there was sufficient clearance when I was wearing my helmet. So, I cut the base of the hoop at the correct angle for mounting it to the chassis (although I don’t yet have the hard points in the chassis) and held it in position with, errm, two G-cramps and a length of ½” tubing held in place with gaffer tape. Luckly, the tubing is CFS so it should be strong enough.

With that done I again videoed myself climbing in and checking this. You should think yourselves luckily that I’m not showing you any of this riveting video. The conclusion was that it seemed to be fine.

So, the next job is to put the hard points in the chassis and weld the front hoop in place. Then I need to do the roof bars.

The problem with all this is that the cage is horribly heavy. The regulations have changed and the whole thing is much heavier than the equivalent cage I have on the Fury. Oh well, I suppose there’s not much I can do about that…

Finally, the dampers have moved on a bit. I’m now being promised these at the end of January which will be OK for me; I’m getting more and more convinced that I’ll need to start the new season using the Fury, to be honest so it’s a good job that I haven’t sold it. To tease you a bit, though, here’s the latest rendering of the damper and reservoir!

As you can see, it fits in pretty well. In fact, the CAD model seems to have predicted how it will fit exactly which is nice to know. Also, with the diff at this position, and with the largest sprockets that I’ve got fitted, the chain seems to be clear of the diff mountings and the chain guard around the drive sprocket. Admittedly, it’s not far from the latter, but hopefully OK.

The main issue now is how to retain the bottom of the frame around the diff. There seem to be two ways of doing this. The first is shown in the CAD model and uses a couple of plates with  slots cut into them into which the bottom bolts on the triangular support plates fit. That will require two more laser/water cut plates though, and positioning the plates might be a bit tricky. Mind you, from what I can see of the current position of everything, a little bit of inaccuracy on this is probably no great problem.

The alternative is just to use a couple of turnbuckle like things, perhaps just lengths of studding really, to restrain the bottom corners of the triangles to the engine frame. In fact, I could even use turnbuckles that were arranged in a slight (plan form) triangle so as to locate the bottom of the diff laterally. That’s essentially what’s done on the Radical that I showed you the photograph of in the same post. It has the advantage of ease of manufacture and, perhaps, slightly easier adjustability.

While musing about this, I’ve pressed on with a few other things. You may remember that in an earlier post, I mentioned that the front lower damper mounts were really too low and wouldn’t allow enough droop in the front suspension. I did spend a while talking to Jeremy about this and he suggested that he could make some different front rockers. However, I thought I’d just do what I said and space the damper mounts up slightly which, as you can see from the photo, I’ve now done. This second set of holes is 30mm above the normal ones, which are themselves raised 25mm above the “standard” ones because of the lowered chassis on this car.

I’m now just about at the point where I’ve finished all the various bits of welding to be done to the chassis. The main thing left is the roll cage. The parts for this are currently  languishing in Fedex’s depot up the road in Huntingdon and I’m going to go and pick them up tomorrow. Or, perhaps I’ll just get them to deliver them while I’m actually in.

I’m planning on just welding the roll cage to the car directly, not bothing with making it removeable as I’ve done before. In order to do so it seems sensible to beef up the mounting points with some chunkier lumps of steel. So, I’ve started this off by welding some 3mm thick plates where the main roll hoop will mount. Also, you may remember that I’m planning on making the rear diagonal stays removeable so as to ease fitting of the bodywork. So, I’ve welded some attachments for the lower end of these stays to the rear of the chassis. The intension is to use a ½” rod end at each of the removeable stay so as to make fitting the stay straightforward. This at least means that the positioning of this attachment isn’t fantastically critical. This is something else, though, that will need a bit more welding when I can turn the chassis upside-down, hopefully in a week or so.

You can see these two hard-points, the ones on the left of the chassis, in this photo.