Everything was all going so well too. I assembled the left rear suspension, using all those bearings I made a while ago, and assembled the upright using the nice shiny new driveshaft.

Rats!

Bugger!

If you remember, a while ago I was concerned that the driveshaft was going to bash into the chassis. I had just about convinced myself that with the diff in the real location and the proper driveshafts, rather than the cut and shut ones, then it would be OK. However, that wasn’t the case, at least for half of the movement of the diff. The problem with the Riot/J15 chassis is that the space for the rear chain is quite limited (hence the longer chassis that I’ve got) and the shorter a chain run is then the hotter it runs. As such, I didn’t want to lose the rearward half of the diff adjustment. Clearly, the chassis was going to have to change but it wasn’t clear how.

I spent most of the night musing about it, and ended up doing what’s in this photo here. The photo’s of the right hand side of the chassis, as the photo was a bit better. Essentially, I’ve cut that diagonal tube in two and added in two additional support tubes, one along the side of the chassis and one to the rear bulkhead. Hopefully, that makes a sufficient number of triangles. As you can see there’s yet more POR-15 here, not applied particularly well because I was getting pretty cheesed off.

With all that done, of course it took a considerable amount of time, I could get back to re-assembling the rear suspension and transmission. This time it all went pretty well and in a while the whole rear end was assembled, bar a few nylocs and a missing bolt. If you look hard, you can see a long bit of thread sticking out of the upper right wishbone. This is a lump of studding I had lying around and is there in place of the bolt that ought to be there, but which seems to have gone walkabout in my hopelessly disorganised garage. I’ve probably put them somewhere safe. (The left hand side does have a bolt, as I managed to find and old M12 bolt of the right length but I couldn’t find another one.

Still, the tranmission and rear suspension is together now, barring a few bits and the still unmanufactured dampers.

Now I have to work out what to do next. I wonder what’s going to go wrong this time?

As you can see in the photo I’ve done what I said I’d do in the last post and added some tabs to which to bolt the diff support plates. Of course, that’s messed up the powder coating and I’ve had to resort to POR-15 to cover up the bare metal.

I’ve also added a couple of additional diagonals to the rear engine mount which you can also see in the photo. I’ve been thinking about doing this for a while now, after noticing when the mount came back from the powder coaters that the lower tube of the engine mounts was bent. At first I thought that this was due to the heat from the powder coating but as the mount still fitted the engine perfectly I’ve come to the conclusion that it was like this before, and is just much more noticeable due to the colour.

I’ve been drawing force vector diagrams in my head for some time working out whether I needed to add these tubes but as I had to mess up the coating anyway for the diff supports I thought I’d just as well do it anyway. At least that means I can stop fretting about it.

Just imagine what it’s like inside my head, if you can. All this worry is mixed up with tons of useless knowledge including the bit of set theory mentioned at the start of this post. The post, by the way, is the 100th of the new WordPress era.

With all this done, I can hopefully get the diff mounted for a final time this coming weekend. That’ll be a relief. The problem is that the race season is approaching train-like at the moment. I just got my licence for the new year through and the first race is really only 6 weeks away, and I’m going away skiing for a week in there too. It’s increasingly clear that I have no chance getting the J15 ready for the start of the season and at some point I’m going to have to check the Fury over, which is been languishing at the side of the garage for ages now.

I added another two of the little b*******s to the car today, the first being the “shoulder” panel in the photo. By the way, in the background you can see the Fury sitting there all unloved and neglected. However, I’m going to have to start re-invigorating it soon. I’m hoping to get the J15 to a rolling chassis versi0n fairly soon so as to facilitate that.

I also added the panel at the front of the passenger side of the car, as in the photo.

The next thing I want to do is to add the side panel along the passenger side of the central tunnel. As on the Fury, I want to attach this with rivnuts so as to facilitate access to this area of the car. It’s rather less important than on the Fury, as there isn’t a propshaft in there, but nonetheless it would seem daft to make the top panel the only access.

While thinking about this, it dawned on me that as the handbrake lever was attached to the outside of that chunky upright, just near where the handbrake lever is loitering, then it’d make sense to make this panel in two pieces, one for the front of the space and one for the rear. As I’m using the same rear calipers as on the Fury I’m going to have to do the same sort of thing to increase the mechanical advantage of the lever as I did there. (Essentially a pulley giving a 2:1 advantage.)

I’m also going to have to arrange for the cable from the lever to turn around a corner, due to the geometry of the lever. Looking at Jeremy’s photos, a detail of which is shown here, he seems to have done this with a block of some plastic, and I could probably use a lump of Delrin for the same job, as used for the suspension bearings.

Now I’ve got the footwell panel in place, I can see the space that Jeremy uses for the fuel tank, as shown here. I did some preliminary calculations a while ago and the volume here was suitable. I did wonder about mounting the tank further rearwards, at  the back of the passenger compartment, but this is probably the easiest place just at the moment.

Now I can see the space properly, I’ll measure up and draw out a tank. I can then get it made, as I’ve done before.

The only difference between this and the previous ones, is that I’ve made one of the spacers that hold the plates in the right position. Of the other two apices of the triangle, one will bolt to the rear engine mounting and the other will have another spacer, but one with a connection to one (or two, I haven’t decided yet) turnbuckles for getting tension in the chain.

Many thanks to everybody for their suggestions about the sprocket conundrum. The more I look at it, the more I think the sprocket was just not machined properly. Or, perhaps the diff wasn’t. Really, I should have tried the sprocket on the diff before splitting it, and I’ll try the other sprocket I have soon like that.

One thing though, is that I was talking to Andy about it yesterday at the 750 Motor Club awards do. He reckons that it wouldn’t actually have an effect and, oddly, I tried running a chain around the sprocket today and it seemed to run just fine. In fact I now understand all this even less!

By the way, with respect to the comments, you may notice that some people, like me, have a pretty little picture by their comments and other people have a rather bizarre symmetrical bitmap. If you’re commenting on this blog, and others, you might like to whizz off to the Gravatar site, where you can set up a “Globally Recognised Avatar”. That isn’t something to do with the ruler of the 3D blue cat people (I haven’t seen it, I’d rather poke my eyes out with a blunt stick) but a little picture that applies on lots of sites.

Anyway, I put the sprocket issue to one side and moved on. One aspect of this is that I picked up the driveshafts at the 750MC party. They’re the shiny ones here, next to my fabricated dummies. They’re made out of some special Swedish unobtanium steel and should work well.  Yes, I know the new ones look as if they’re shorter, but that’s just parallax.

Unfortunately, it was time to get back to the panelling. Oh joy. First thing was to turn the chassis upside down and put the floor panel on. The plan is to completely cover the front part of the chassis, back to the front of the engine compartment, with a single piece of aluminium. I don’t actually know yet how big I want to make this at the front, so currently it’s the full width of the aluminium sheet. I’m planning on a lot of attention to the aerodynamics on this car and just throwing away plan area without using it seems daft. So, I just rivetted on like this. As you can see, there’s a lot of rivets here, this just wouldn’t work without an air riveter.

With the chassis back the other way up, I got stuck into refitting all the panels I made a couple of weeks ago. Only this time they were rivetted and bonded in, not just held in with clekos. As you can see, I’ve also bolted in the pedal box, this time using nylocs.

Next thing to do is to make the panels for the other side of the car. Although all of the panels shown here are rivetted in, I’m planning on using rivnuts for some of the other panels, so as to facilitate better access. In particular, I want to do that for the seat backs as I’ll need to get access to the exhaust side of the engine.

Here’s another photo. The hole in the panel at the side of the pedal box is there so as to get access to the pedal box’s bearing shaft.

First, though, the forward bits. Most importantly, the chassis is now back home again. As you can see, I took the trailer off back up to Soham and collected it. To be honest it isn’t a fantastic job, but it’s good enough. It’s not quite the shade of grey that I was after either, but that’s no big deal. Mind you, I wonder if I want to make the roll cage a different colour from this? In which case, I wonder if it’s possible to paint on top of powder coating? Seems possible that it’s not.

In addition to the chassis itself, I got this big pile of suspension and engine mounting bits. The coaters were not as good as they said about keeping the coating out of the threads, and in one case they’ve got it in the threads and not on the housing around the threads. But, it’ll do. I’ll soon get along to fitting all these parts to the car.

In the meantime, I wanted to finish off the diff carrier. Last time, I said I was a bit concerned about getting the bearings on to the diff journals. After much discussion and thought, I decided to actually have a go at pulling a bearing onto one of the journals. So, using a long M10 stud righ through the middle of the diff and a little dolly I made on the lathe, I had a go. To my delight it pulled in without any great drama. I stopped after a few millimetres because I didn’t want to make getting it off too difficult, which is the state it’s in the photo. However, it was clear that this wasn’t going to be too big a problem.

So, I finished off the various bits for the diff carrier plates. Here’s the first of them here. This is the outer side of the plate and you can see the bearing in situ and the holes that allow access to the bolts that retain the sprocket on the diff.

That looked as though it was going to work so I took the plates apart and pulled the bearings onto the diff with the inner bearing carriers in place. I could then bolt the plates and the outer bearing carriers in over the top of the bearings and I ended up with the whole lot as one piece. As I started drawing this months and months ago, before I got the chassis from Jeremy, this is rather a relief.

At that point I went into a bit of a decline.

I thought I’d try fitting one of the sprockets I bought ages ago to this lot. The plan, if you’ve been paying attention, was to split these sprockets so that I could bolt them to  the diff without taking the whole lot apart. In fact, putting the complete diff carrier together was a deliberate experiment on my part to see if this whole process was going to work.

First, though, I needed to cut one of the sprockets in two. So, with a new blade in the hacksaw frame I did this carefully and then proceeded to bolt it to the diff.

And then I noticed this.

On one side of the diff the gap between the two halves of the sprocket is considerably larger than on the other side, as you can see in the two photos above. Clearly, this can’t happen, as the sprocket should be registered on the mounting points on the diff flange. There’s something screwy about this that I don’t understand at the moment. One possible problem is that the mounting  holes in the diff are specified at 27/64″ with a 14mm registration dowel in two of them. (I’m not making this up…) I’ve got an M10 screw (not even a bolt at the moment) in the 27/64″ holes. That means that there’s 0.7mm of a gap at the side of the bolt. All the same, I thought that the whole thing was put into registration by running up against the body of the diff itself. In fact, there seemed precious little slop when I put it together. The hole size is very strange though. The largest imperial size that’s going to go through it is 3/8″ which leaves even more clearance than the M10 one.

Hmm, I’ll need to think about this. What I’ve got at the moment is clearly unacceptable.

While the rear bodywork was on, I took a few photos of the space under the rear engine cover, just to remind me what it was going to be like at some point. Here’s one of them. It’s interesting to see how much space there is behind the chassis.

Also, there’s that odd central “tunnel” in the rear bodywork, almost like the exit from a diffuser. Jeremy uses this for the place to put the silencer on his car-engined cars, as in the photo of his red car. However, I’m not sure how it’s going to be for me. I am going to have to be a little careful about the RGB regulations for underfloor shape.

After the experience stretching the central tub, which went fairly well, I’ve put my mind to it and stretched the two sidepods. The end results are seen here disporting themselves against the garage door. Long term readers will remember that I have a habit of using the inside of the garage door as a place to test, and clear out, spray guns. Hence the rather fetching collection of redness there.

Like the tub the two sidepods are 60mm longer than they were originally. This means that I’ve now got a collection of bodywork that will actually fit the chassis, although I’m still intending to lay up some GRP on the inside of those bits of aluminium, even though that would probably be slightly heavier than the aluminium. I’ve long thought how nice it would be to have a complete aluminium body. However, that would involve learning to use things like a wheeling machine, something that I suspect would require about 25 years to perfect.

Eagle-thoughted readers might well wonder how I managed to take that last photo, as surely the chassis was in the way? Well, it isn’t because I took it, and all the various parts I’ve made over the last months, off to GKL Coatings to have them powder coat the whole lot. Well, hopefully excluding things like screw threads and circlip grooves. Hopefully, I’ll get it all back, in a fetching shade of grey, in a week or so. In the meantime I’ve got loads of things that I can carry on with.

And, it’s boring; did  I say it was?

The photo on the right is of the footwell area. The reason for the odd arrangement of two panels is that I need to provide enough space for the pedals to go into at maximum angle of dangle. As you can see, I’m using lots of Klekos too. If you’re planning on doing anything with aluminium panels, then go and buy a bunch, they’re fantastically useful. What’s more, they’re cheap enough these days, they used to wallet-bursting. As you can perhaps tell, I bought a load of new ones, in readiness for this build, a while ago.

I make these panels, by the way, by first making cardboard templates, as in the second photo. It’s much easier to make a template as you can extend it when you cut it a bit small, and shove it past obstacles. Once made it’s relatively easy to cut a bit of aluminium to size.

Up to now I’ve made most of the panels around the driver, although I need to do the seat back and the bit on top of the footwell. The former is a bit tricky because I really need to make that panel removable so that I can get access to the exhaust side of the engine. The top of the footwell is also a bit tricky because I’ll need to make some sort of frame that sticks up above the chassis for my toes to protrude into. (And, as I write that, I’m wondering if some of this should be in steel…) What’s more, the steering column needs to thread its way through some how.

As I got so bored, I decided on a bit of light relief and to press on with the rear brakes. As I discussed a while ago I bought some of the same discs as I use on the rear of the Fury from Rally Design. I also bought some aluminium blocks to make some mountings for the radial mounting calipers. The photo here shows one of the calipers and one of the blocks. This is just a lump of aluminium of a size that’s in the right region for making a mounting.

In an ideal world, one would use a milling machine to do the right thing to this block, but I don’t have one of those.

However, I do have a lathe and I thought I’d worked out how I could use that to do a suitable job. And, after a goodly portion of time hunched over the lathe collecting aluminium chips in my hair I ended up with this.

This bolts onto the upright using the mechanism I discussed a while ago in that I tapped the upright to M12x1.5 (that’s normal wheel stud size) in the manner shown in the next photo.

The one obvious thing missing here, apart from the caliper, is a couple of h0les drilled and tapped from the top of the block, as shown here, for mounting the calipers. I’ll probably sort that after I get back on the panelling grind…

However, as I said, I reckon it’s going to be fairly easy to patch up the GRP on the inside as the aluminium makes a pretty good mould, as you can see in the next photo, especially with the addition of suitable release agents whether film or wax.

That all meant that I could fit the bodywork to the tub again and actually see if the steering column was going to fit or not.

With much faffing about I decided that I was going to have to shorten the lower column which actually turned out to be quite easy as I had some tubing of pretty much the right size to sleeve the Escort-sized lower column.

This photo is of the bottom end of the column once I’d done everything. You can see the sleeved lower column and  you could also see that I welded some little plates to the chassis to which to mount the bearings; note that I need some spacers to put the bearings in the right place. I’m still going to have to grind a little bit off the brake pedal pad, but only a small amount.

One issue about all this is that if I just assemble it as it it then I’ll end up being unable to remove the aluminium sleeves and bearings from the column. This is because they won’t fit over the welds that attach the spline at the bottom end of the column or the steering wheel attachment at the top of the column. I think I’ll just put up with that. I could grind the welds so that they’re not proud of the column tubing at all but that seems like a daft thing to do to what’s essentially a safety critical part of the car.

The thing is, I wanted to check the steering rather more carefully, and perhaps change the routing of the column a soupçon. In order to do that, I needed to check how it fitted under the bodywork. The problem is, I had to do lots of faffing around to get the central portion to fit over the cage; for example to allow the front hoops of the cage to stick through the bodywork, and also to allow the steering column to poke through the front of the central bodywork section. You can see both of these in the photo on the right.

The problem was, even to get the bodywork down here I needed to fit the rear portion around the cage’s rear hoop. I always knew this was going to be tricky as I’ve got the long wheelbase version of the chassis, which is 60mm longer at the rear. The problem is, the bodywork isn’t. Longer, that is. That meant that the rear section of the bodywork was pretty much in the same position as the rear hoop and that wasn’t going to work.

I discussed this with Jeremy right at the start and the original plan had been to split the bodywork around the rear of the central tub area where the shape is essentially a 2D curve. That means that it can be put back together with a 60mm spacer of some form without messing about with the shape. I had originally intended to leave this until a lot later in the process. However, as I was doing the steering it seemed more and more as if I was going to have to cut the poor girl in half right now.

So, I did. Not without a considerable bout of loin-girding though.

The end result is shown in the photo, although the rear bit is just resting there at a jaunty angle hence the variable gap. The plan now is to seal this up with a strip of aluminium, riveted in place with the gap maintained at 60mm. Once I come to finishing off the bodywork, I will put some release film under the aluminium and layup some gel and CSM on the inside to extend the bodywork. Using the film should get a pretty good finish on the outside (it’s shiny stuff that doesn’t stick to resin at all) without resorting to excessive application of elbow grease, a commodity in short supply around here.

I’m hoping that with the aluminium attached the bodywork will be a bit more robust; at the moment it’s rather floppy because the two sides are no longer attached at the rear. What’s more, I’m hoping that I’ll be able to remove it from the cage without any further surgery. That was, after all, the reason for making the cage backstays removable.

In between worrying about that, I did manage to get something done. Starting with the driveshafts I bought some skinnier tubing for sleeving the shafts and, coupled with moving the diff slightly, it does seem as though I might be alright at avoiding the chassis. Of course, the proper driveshafts should be skinnier again than these ones. So, I’ll press on at the moment.

The photo above shows the completion of this exercise, with two driveshafts in position. As I mentioned, the next step with these is to get some proper ones made. One concern here is that the shafts are of very different lengths. They’re on the rear so hopefully I won’t end up with armfuls of torque steer as a result but we’ll see. If that does happen, there are some approaches to it, such as using an additional bearing in the longer shaft, but I don’t really want to go there, at least not now.

One thing I’ve been wanting to sort for a while is the rear brakes. The rear uprights are the same configuration as those for a Fiesta, if you remember I bought some proper Fiesta ones originally so as to get the hubs. However, as I want to use 4-pot brakes on the rear I’ve got to do something to arrange that. I spent quite a long time poring over catalogues of brake discs and decided that the best thing to try was some discs from a little baby Fiesta which are 10mm thick solid discs. The problem is the depth of  the disc as I’ll need to machine some mounts to fit.

The photo here, and indeed the one above, shows one of these discs in position. The caliper mounts are nearest the camera and there’s a decent clearance between the mounts and the disc.

However, there’s a problem in that the 4 pot calipers are quite wide, so the caliper projects a few millimetres beyond the wheel mounting face of the disc. This is not a problem in most road cars because they tend to use single piston calipers where the piston is on the inside of the disc. However, the 4-pots have a couple of pistons on the outside of the disc. The problem here is that don’t know whether this would actually be a problem, as it depends on the shape of the inside of the wheel. What I do know is that tried one of the Fury wheels (they’re Compomotive CXRs) on the Fiesta disc, as shown above and it fitted fine over the brake caliper. The problem with this is that the Fury wheels are offset ET19 whereas the ones I need for the J15 are ET38. If you’re not familiar with those numbers it relates to the lateral displacement of the wheel mounting face from the centre line of the wheel. “ET” is short for a German phrase: “Einpress Tiefe” which means something like “pressed in amount”. In this case ET19 means the wheel is inset 19mm in the car from the centre position. ET38 wheels have the wheels 19mm further in. Of course, that means that the disc/caliper gubbins is, relatively, further out. Of course, if the inside of the wheel face is shaped the same way on the two wheels then it wouldn’t make any difference. However, I do know that one of the ways that wheels are made is that a single casting is used for several different offsets, with the mounting face being machined to accommodate a range of offsets.

All of that means I haven’t got a clue whether these discs will fit. In fact, the only sensible approach really is to get some ET38 wheels and actually try it. So, I shall phone around  tomorrow and see if I can find a Compomotive CXR with the right offset. What’s to bet there won’t be any available until next August?

An alternative approach would be to use some discs with a deeper bell. The rear of the Fury does use such discs at the rear and I temporarily robbed one of them. The photo here shows that disc and one of the Fiesta ones side by side. The right hand one has a bell that’s about 12mm deeper. It fits fine on the J15 uprights but there’s another problem in that the clearance between the disc and the caliper mount is too small to get a bolt head, for clamping the caliper mount to the upright, in the space. It’s only 2.5mm too tight so it would be easy to space the disc out with a small spacer. However, that doesn’t seem very pleasant really.

So, with the brakes returned to the back-burner, I got back to the chassis. It was, amazingly, time to take the engine out. This has gone from being perched on some thermalite blocks to being held in with a rather complex mount. I did want to know if it was possible to get the engine out with the mounts attached so I connected up the crane, took the bolts out and tried. It was possible, which was good. It wouldn’t be a huge problem if I couldn’t have done this, as it’s always possible to bolt the mounts to the engine when it’s in the right place.

With the engine out I removed the mounts and took the backstays off the cage. I then took this photo of all the bits I’ve been making. All of these have got to go away. The driveshafts need to go up to Yorkshire to be turned into proper shafts and the rest of the stuff needs to get powder coated.

I do have a few bits that need doing to the chassis though, things that I’ve been leaving until I could invert the chassis so as to get at things more easily.

So, I turned the chassis upside-down as in the photo here. By the way, note the little trolley that the welder is sitting on. I made this a while ago and it’s made getting the welder around the garage much easier, I have no idea why I didn’t do it ages ago. That gas bottle is just about empty, I shall have to get it refilled before the Christmas break as doubtless the local BOC outlet will be closed at just the vital moment.

I’ve just about finished all the upside-down welding, I’ll do the rest tomorrow probably. The final thing I do have to do to the chassis, though, is look into the seat belt positioning. As I did on the Fury I think I’m going to have to put another tube into the roll cage so as to make sure that the belt angle fits with wearing a HANS device. This was the other reason for taking the engine out, actualy, as I need to sit at about the right place in the chassis to check where my shoulders are.

While all this is going on, I’ve been slowly sourcing all the bits I need. For example, I bought this fuel pump off eBay this week. In fact, I bought two so that I’ve got a spare. In fact, I think I’m now perilously close to having all the bits I need, apart from a few vital things like the dampers.