I’ve been pressing on with the engine mounts and, after a minor false start, got the rear side of the engine set up as in this photo. The false start can been seen if you look really hard at the bottom right of the photo where you can see the first set of mountings for this transverse assembly. This is at a slightly jaunty angle. This all worked fine but it dawned on me that it was going to be impossible to actually fit the engine like that as it couldn’t move around the top mounts without requiring huge compliance of the rear mounts. It might have worked when I replaced the metal top hat washers with the eventual rubber bushes but I didn’t really want to risk it.
The final story, though, is that the engine is now just siting in the chassis. I know you can still see a jack under it but it isn’t doing anything, honest.
With that it was time to move onto other things, intimately related to all of this. The first thing was about the reverser which I picked up from Andy today. Essentially, it’s a motor, a reduction gearbox with a pre-engaged starter pinion, and a gear to mount on the end of the gearbox output shaft. Having fiddled with it a bit I must admit that I’m slightly concerned that a weeny bike battery won’t have the urge to drive this, because the solenoid for the pinion engagement seems to be taking a huge amount of power. (I tested that it worked with a battery I had lying around.) However, perhaps it’ll be better once in the car.
First thing, though was to check that the drive gear mounted on the engine properly. I cut away the normal drive sprocket surround until I ended up with it looking like 
this. You can see the reverse drive gear mounted on top of the normal drive sprocket. As you can see, I’ve got an old chain in here that I’m using for alignment purposes.
You might wonder what stops the reverser pinion just rotating. It’s actually threaded onto the bolt that you can see. The one problem that occurs to me with all of this is that changing the drive sprocket could be a right royal pain in the bum as lots of bits would have to come off.
The other problem is that the vertical(ish) member of the rear engine mounting that you can see on the left hand side of the engine in the photo at the beginning of this post conflicts with the reverser drive motor. 🙁 So, I’m going to have to cut that part of the mount out and move it. Obviously, I’m also going to have to arrange for something to support the reverser motor itself. I’ll probably do this with a bit of steelwork welded to the rear engine mounting. I might well make it slightly adjustable with a slotted hole so as to allow the motor to move in and out slightly. The biggest concern about this is that the motor is quite chunky and the only mounts are at the business end, on the right of the photo above. It’d be nice for there to be some way of supporting it at the other end slightly.]
The biggest issue I’ve got left is mounting the diff and drive sprocket. I’ve been mocking it up as in the photo here. This is using a 15 tooth drive sprocket and a 52 tooth driven one, both the largest of the sizes that I’ve got.
As you can see, I’m planning on using tie-wraps for locating the sprocket. I just haven’t figured out yet how to make a bearing.
The biggest problem, though, is that I really need to make the drive chain as long as I can so as to avoid over-heating. From all the examples I’ve looked at this is rather short, but probably OK as long as I commit to buying a couple of chains a season. The big problem is that the sprocket here is at the position in the longitudinal direction that it really needs to be in. However, it needs to be about 40mm higher than this so as to line up with the wheels and also so that the chain doesn’t bash into the lower part of the chain guard around the driven sprocket.
I’ve thought about this and the only way I can see how to do it is to modify the rear upper cross member on the chassis, cutting a section out of it. Obviously, I’d also have to join it back up again. I’ll check with Jeremy that he thinks that’s a sensible idea; I’ll also check that there enough room under the bodywork. I’m pretty sure that there is though.
15T is your largest front sprocket? I dont know about the drive ratios in your gearbox, but on the ’12 I went from 18 down to 15 – and I actually never used the 15t as at Lydden the gearing was so low with 16T that it wasnt worth gearing to use 6th. Now I’m using a different motor and probably a larger rear sprocket (cant remember the size), but my point is that smaller sprockets radically increase chain wear (fewer teeth engaged and sharing the load, as well as a tighter bend radius). You’re already expecting problems with a short chain run. It might be worth the trade off to use larger sprockets to reduce chain wear.
Great as ever to follow your progress.
G
Tim, just wondering if you have anything planned for a diff?
I thought I’d mentioned it. However, the plan is to use (and I already have) a Quaife chain diff.
Tim
I took some advice from various people.
The standard size CBR1000RR front sprocket is 16 teeth and they’re available down to 13 (!) without any issue. The advice was that 15 or even 14 should be no problem. There was also an interesting article in RCE earlier this year about losses in chain drives which backed this up.
The other issue is that because of where the engine and rear wheels are, I can’t easily fit larger than a 52 tooth driven sprocket with bashing the chain into the steel chain guard around the drive sprocket. However, time will tell. At least I’ve bought a new chain which, so a little bird tells me, is not the case for everyone… 🙂
Tim
I’ll have you know that the drag race chain I started with lasted considerably more than its expected working life (ie 1/4 mile). Bargain.
That said, the DID X-Ring was a lot less grief all round.
For the first half season or so 1/4 mile was all the car got before it boiled up. Not sure how long the unsealed chain would have lasted once it was up to full chat though…