Transmission

It's going to be a hard sell, to persuade me to go down any route other than a steering wheel mounted paddle shift mechanism, with a mechanical linkage to the sequential gearbox in my next sports car. The paddle shift enables a super quick gear change, without having to take your hands off the steering wheel. The mechanical link provides direct driver involvement that electronic systems simply can't replicate. It is simply the best way to change gear.

I am not denying that electronic assistance and actuators will result in faster gear changes but, this car isn't about lap times and headline performance figures. These systems deny me the highest level of driver involvement, which is my top priority. With a mechanical (cable) link to the R1 gearbox in my Fisher Fury R1, there is no feeling your way into the next gear. These gearboxes are designed to be foot operated, so you have to fire it into gear, using a very positive action.

Gear Shift

This is covered in the instruments and controls section.

Clutch

This car will use the standard bike engine but, with an uprated clutch. On a bike engine, you have to be careful not to pull the clutch in too far and a hard pedal stop is required to ensure this doesn't occur.

Clutch Cable

The clutch will be foot operated via a cable linkage. The move from front engined to mid-engined means a longer clutch cable is going to be need but, things are not as bad as might first be thought. The cable required to operate a bike clutch is really quite thin and light in weight. I expect this move to add less than 500g.

There will be the same settling in issues experienced on my Fury though, where the new cable stretched a little in the first few months.

Gear Ratios

Bike engines require a lot of gear changes when installed in a car and they are not really smooth gear changes either, especially relaxed gear changes.

Propshaft

A prop-shaft is required to run down the length of the car. In my Fury I used a heavy steel item. I plan to use something much lighter in this car and this should save over 4Kgs.

Chaindrive

I did look at rear mid-engine design and if going down this route, it is better to use a chain drive arrangement.

Sylva R1ot chain drive This is the transverse engine and chain drive as installed in a Sylva R1ot. This is very close to what I have in mind. Photo by Scott Makin.

The alignment of the cogs needs to be perfect or there will be excessive wear on them and the chain. Even then, the chain will have a limited lifetime. In chain-driven race cars it is not unusual for the chain to be replaced after every race. A mechanism is also required to tension the chain.

Both the Sylva R1ot and the J15 are slightly compromised in having to support installation of a bike or car engine. A narrower chassis and longer wishbones at the rear of the these cars would be beneficial to handling. My design will address this as it will be optimised for bike-engine power.

Belt drive This is an interesting electric car build that has got me considering using a kevlar belt drive. This technology has moved on massively in recent years. It should be quieter and more reliable but, the experience of Andy Bates with his RGB race cars suggests that these belts are not really strong enough for the forces involved. They are used on 275bhp snow-mobiles but, they have a lot less grip to contend with. Other downsides are the wider (heavier) pulleys required for the belt and the higher transmission losses.

Differential

Sylva R1ot quaife differential This Sylva R1ot build is also a good example of Quaife torque sensing differential I'd like to use. Photo by Scott Makin. This essentially acts like a limited-slip differential.

To honest, you don't really need an LSD in a car like this. I've only ever missed it in my Fisher Fury R1 whilst on track. The lack of a LSD can be beneficial in keeping the car on the road in damp and slippery conditions, with excessive power slipping away via one wheel. It's a subtle reminder to be less heavy with the right foot!

Overall Design

The combination of engine, gearbox, final drive and wheels & tyres is optimised for acceleration and a fairly low top-speed. My Fisher Fury R1 will reach its 130mph top speed on track and with improved aerodynamics and more power, the planned top speed of approximately 140mph is very realistic.

Reverse

The new IVA test dictates that cars now have to have a reverse gear. This will add approximately 3Kgs, maybe even more :-(

This can be an electric reverse and it only has to move the car a few feet on level ground. This now also means that the car needs a reversing light. Words can not describe how much this new rule upsets me ;-) It is going to be removeable!

Electric Reverse

My preferrence is for an electric reverse as this is the lightest option. It typically engages a small cog onto a larger cog, mounted directly to a drive shaft. I like this solution as it is easy to remove the electric reverse element.

Integrated Solutions

It is possible to buy a differential with integrated reverse capability.

Reverse Box

It is possible to buy a reverse box, which sits between a prop-shaft and a differential. This might work well with a front engined car but, isn't going to work so well with a chauin drive.

Top • Last page update: 22 Oct 2015