I’ve collected my loan differential and swinging sump from Nova engineering so I thought I’d post a couple of pictures. The differential has been a bit of a TV star before when it was used on in the Discovery series “Kit Car Crisis” where a guy was building a car to come and race ion RGB.
Unfortunately the series didn’t show Kit car building in a very good light and mainly served to highlight some of the pitfalls that can befall an inexperienced car builder who is badlya advised . Me, I doubt I could go racing without the vast store of knowledge and experience that my mates in Cam7 and the RGB racing fraternity happily share with me.
However none of that is relevant to the Diff.
The main reasons for changing over from the existing diff are 
The new diff offers an engine driven reverse. This removes an area of constant irritation because every time you adjust the gear ratios on my existing diff (by changing the drive sprockets) you have to move the diff to retension the chain and then you have to spend a good 30 minutes readjusting the electric reverse system. This discourages me from making changes in the paddock as I know it just takes ages and I’m usually stuck for time. Plus I’ve been known to forget and an inoperable reverse is a common reason for RGB cars to get excluded (disqualified). Plus after a couple of seasons racing one of the key lessions I’ve learned is to keep it simple stupid! Any thing that requires unnecessary precise adjustment, or simply adds to your workload in the paddock is bad. You’re there to race!.. Everything else is a distraction and the more of those mechanical distractions you can remove the better.
- The engine driven reverse actually has a chance of moving me backwards… unlike the current electric system.
- The current electric system which also has an alarming habit of blowing batteries by over discharging them (I’ve already damaged 3 like this). This means that I can probably lose some weight by going for a smaller battery too.
- The drive ratios are very easily changed by simply removing the blue aluminium mounting ring and bolting on a new driven sprocket (which also hides a cush drive to help reduce driveline shunt). In fact by changing both the front and rear sprockets you can get a very fine range of diff ratio adjustments although I think this would more faffing around than it’s worth. Currently I can’t change the driven sprocket as it is encased in enough steel to make the Forth road bridge extension so I can only change the front sprocket which is a bit of a pain and also only give quite coarse adjustment, plus my current diff’s chainwheel needs replacing and some of the mounting bolts have a habit of coming lose.
- It runs entirely enclosed so hopefully won’t spray grease all over the engine bay like my current setup.
- It weighs a bit less than my current setup (about 3 Kg), so I get these advanteges for no weight penalty. Although as it’s a prototype unit no doubt at some stage I will pay a penalty of some sort as we hit teeting troubles. However Graham at Nova will hapily machine up some bespoke mounting brackets for me so quid pro quo. Grahams long term plan is to be able to use it as a stressed member, and hopefully over time we can reduce the weight even further.
While at Nova I also collected the billet sump pan, at this stage it is without the oil pickup so I can only dry assemble the engine, but that’s ok as my current primary requirement for the sump is that it has a flat bottom. This is because tomorrow after a hefty bit of garage tidying I intend to start fitting the engine and the new diff. And having an engine that will simply sit flat on its bottom while I line it up and make the engine mounting frame around it will be a great advantage. The standard sump is pyramidal and the engine wants to do nothing but fall over at the moment.
The sump is very nicely machined from a large chunk of billet, but again it is a prototype unit.
After handling it, and looking at it for a few minutes two or three potential enhancements come to mind.
- It needs a small drilling so that you can lockwire the sump plug in place
- It need a fitting for an oil temp sender
- it needs an extra mounting eye in the appropriate place so that the oil filter can be lock tied to it. Oil filters tend to unscrew themselves on bike engines if not held in place with a suitable jubilee clip or tie wrap and I know at least one engine that has been blown like this.
- It could do with some cooling fins machining into the surfaces.