Yet another odd weekend; one step forward, two steps back, two steps forward. Whatever, I haven’t accomplished what I set out to do. Ho hum.
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?
Hi Tim –
I’d like to sincerely thank you for sharing all of your hard fought knowledge. It’s obviously never easy to be the 1st at anything.
Based on your experience it would seem that another potential (better?) solution would be to add an additional 40 mil or so of wheelbase length to the rear portion of the chassis. I understand that you started with the 60 mil extended chassis but that length doesn’t appear to provide enough chain length for anything other than the very compact Yamaha R1 engine the chassis was originally designed for.
I’d think that the added space for chain length, exhaust, etc. and the slightly better weight distribution from the longer wheelbase would be well worth the additional bodywork modification. Is there some reason that I’m missing why the slightly longer wheelbase would not be a preferred approach?
Thanks again for sharing all of this info.
Chet
Chet,
No problem, it’s actually quite fun writing things up.
Interestingly, someone has recently finished a Hayabusa (a much bigger engine) installation in a Riot with the standard chassis. Mind you, that’s a hillclimb/sprint car and as such it doesn’t have to run for more than a couple of minutes, unlike the 30 min races that I could be doing. Jeremy has talked about adding a bit more to the chassis, and it could well be a good idea at some point in the fiuture. For now, though, I think where I’ve ended up is OK. Pity I didn’t do this before powder coating the chassis though. 🙁
Tim
Hi Tim & Chet
I did hear from John Regan last year that Jeremy had some chassis mods in mind that would allow non-R1 bike engines to fit without having the 60mm longer chassis. Don’t know what though.
David
It’s hard to see what the changes could be. The engine location is essentially fixed, assuming you run it horizontal, by the seat back angle and the rear wheels are where the rear wheels are. Unless, perhaps, he’s moved that diagonal tube that I cut out yesterday.
Tim