Cooling a fevered J15

Back on the J15 front things have moved on a bit and I’m planning on lots of progress over the next few days. 🙂 A lot of the recent progress has been about the cooling system which is now actually completely finished. Well, apart from filling it up and discovering all the bits that leak, that is.

First up, I mounted the radiator at the front of the car. Quite a few people with mid-engined cars try to fit the radiators at the rear. However, it’s difficult to make it work so, at least for now, I’m planning on leaving it at the front although it does mean that there’s a decent amount of coolant, and therefore weight, sitting in the aluminium pipes down the centre of the car.

One problem with the radiator is that it’s a very cheap VW pattern part for which I paid the princely sum of ÂŁ22-88. That’s good really because that one in the photo above is actually bust because I tapped the mounting holes a bit too enthusiastically; as in I tapped them all the way  into the water ways inside. To be honest, it would still probably work by using some thread sealant on the mounting bolts, but I bought another one anyway. I’ll keep the other for a spare.

The problem with this part, though, is that past experience on the Fury is that it struggled to cool that car. However, this time I’ve got a cunning plan. This is to make sure that hot air exhausts from the radiator properly. On the Fury it comes out into the engine bay and then meanders around somehow.

The idea here is to exhaust out of the top of the front bodywork, making some sort of nozzle on the exit. That is, a duct that narrows in cross sectional area. The plan had been to make this out of four carefully bent bits of aluminium (top, bottom and the two sides) but having looked again at the radiator in situ in the bodywork, as in the photo above, I realised that the inside of the bodywork will work pretty well as the top of the duct. So, “all” I need to do is to make the bottom which needs to thread its way around rack, springs and ARB.

By the way, on the subject of springs the wheels have come off my damper plans in that the supplier of the dampers has still not actually managed to make them. As such, I’m now wondering what to do. One plan would be to swipe the Protechs off the Fury until Dave manages to make them. An alternative is to bite the bullet and by some (expensive) other dampers. Oh well…

Back to the cooling. After mounting the radiator I’ve also mounted the expansion tank at the rear of the car (you can just about see it at the top left of the next photo) and assembled a Byzantine collection of bits of aluminium and expensive silicone hoses (note not silicon hoses as Rally Design call them) so as to finish off the cooling system. As I did on the Fury I’ve also tapped into the top hose so as to make a bleed back to the top of the expansion bottle. That’s not standard CBR1000RR06 but it made a huge difference to the ease of getting airlocks out of the Fury’s cooling system. And, it’s noticeable that Honda have fitted such a bleed to the thermostat housing on later engines.

That radiator I used was specifically one with an attachment for a similar bleed; I guess in the VW Polo this goes to the expansion bottle. However, I reckoned that I was going to need some way of bleeding the radiator as it was down the end of a long pipe run and most of the radiator was actually above the pipes. So, I made a little aluminium bleed adapter on the lathe and connected it up to the radiator as in the next photo. I think I may just have mentioned it once or twice, but having a lathe really does make an absolutely huge difference… 🙂

I’ve now fitted the throttle cable as well. At the throttle body end I made another little device on the lathe so that I could use a “noodle tube”, as beloved of ATB, and other bike, riders, so as to go around a corner at the throttle bodies. You can see the noodle tube and the little mounting device (at the bottom of the noodle tube if you look hard enough) in the photo on the right. As usual I’m using cable that’s really intended for ATB brakes sourced from Wiggle. This is nice stuff because it’s very high quality stainless cable and has teflon lined outers which should work well. I must admit, though, that I’m slightly concerned about the heat on this cable as it’s going to get rather hot here near the exhausts. (I’m also concerned as to how hot one Tim gets too, but doubtless I’ll find out about that later.)

At the pedal end of the cable, though, there was an issue. The original plan had been to go down the centre tunnel and make a big loop in the cable at the front of the pedal. However, that really wasn’t working well as there was a chassis in the way. Something Adrian said about the throttle pedal on his Genesis made me think that it would actually be easier coming at the pedal from the front and eventually I modified the pedal to pull on the cable at the top and arranged for the cable to go around the side of the cockpit (where you can see it disappearing off to in the photo above) and into the side of the pedal box. You can see this in the photo above left.

Next system up is the fuel system. You will remember—you are paying attention, aren’t you?—that the fuel tank has a bulge in the bottom of it for a flange to which the pump is mounted. As such I needed to sit the tank on something that would allow the bulge to miss the bottom of the chassis. So, I made the little upstands you can see in the above right photo. I’ll put some bungy foam on these later. They seem to make a decent job of sitting the tank nice and square, as you can see in the next photo. All I need to do now to finish off the tank is to make a couple of straps to hold it in place. I’m trying to avoid my natural tendency to use tie wraps for this; I think I’ve succeeded.

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