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Special Parts

Engine Mounts

Bike engines are mounted "hard" in bike-frames, with no rubber mountings.   In car chassis's it is customary to use mounts.  Fisher Sportscars use rubber suspension bushes, while other manufacturers use none.

Each engine is subtly different but the basics of mounting them is the same. Engine mounts require triangulation to make the engine rigid.

You will need to fabricate the mounts from steel or aluminium depending upon the tools you have available.

Here are some photos of the Fisher Fury Fireblade steel engine mounts taken at the Donnington Show 1999.

Eng Mount Front
Front Engine mount:
Eng Mount Right
Gearbox side
Eng Mount Left
Overall engine installation
Eng Mount Box
Righthand engine mount

Here are some more pictures from Ruari Coles R1 Engined Striker. These are made from Dural and are rather sexy!!!

R1 mount1 R1 mount2 R1 mount3R1 mount4
Ruari Coles R1 Engine mounts

A Sketch of Ruari's engine mount system has been kindly provided.

R1 mount sketch
Ruari Coles R1 Engine mounts Sketch (Copyright R.Coles 2000)



Propshaft & Drive

The output from the bike gearbox is a splined output shaft. Ordinarily the main chain-drive sprocket fits onto this and a locknut keeps it in place.

R1 spr1
R1 Sprocket - Small eh?!!

R1 spr2
Caterham first Sprocket on Doug Newmans GoldArts Car

R1 spr3
Westfield Welded Sprocket

R1 spr4
Caterham Prop-plate Nice!



Dashboard Instruments

A bike instrument binacle typically consists of the following displays:

Bikes do not usually have fuel gauges – but sometimes have a low-fuel light.

Standard car gauges can generally be used with one or two exceptions.




All bike engines feature a 6speed sequential box as standard. Gearchanges on a bike are accomplished by pressing down on a lever with the left foot, or lifting the lever with the foot.

Manual gearchange

Implementing a gearchange lever for a  Sequential gearbox in a car is relatively straightforward.
The basic principle is to use a vertical rocking lever sticking-up out of the tunnel and use a forward pushrod to transfer the motion towards the engine. A bellcrank can then be used to lift or drop the gearshift lever on the engine.

A sketch of this is shown below (courtesy Ruari Coles):

Ruaris Gearchange Mechanism
Ruaris Gearchange Mechanism (Copyright R.Coles 2000)

Electronic gearchange

Due to the simple nature of the change lever (just up or down) it becomes easy to see an electronic solenoid actuated system.

Commercial system

There is a commerical offering called KlikTronic. This was originally designed for racing bikes but works fine for cars. The system is based around an electronic control box and a two-way push-pull solenoid.

The system is robust and was designed to cope with big American bikes with very heavy shifts.

The system is available from "??" and costs 320+vat/p&p.

Home-Made system

A home made system is easy to design based around some cheap solenoids. It costs a tiny fraction of the price (around 20 to 40).

What you need:


The Solenoids

The solenoids must be powerful but fairly small. After some experiments the ideal solenoids were found to be the type that sit piggy-back on pre-engaged starter-motors. I managed to buy two starter-motors from a 15year old SAAB 900 for just 7.50 each. Once removed from the motor assembly and cleaned up they looked as good as new. These solenoids are very powerful and draw around 12A and 12V when engaged! They also have a nice long 1" throw on them too. This is great value compared to buying new solenoids from Maplin/CPC/RS etc as these typically cost twice the price for a quarter performance!


Once the solenoids have been sourced they must be mounted to actuate the gearshift arm.

The solenoids are pull-types and must be arranged one above, one below the lever (or one at each side if the lever is rotated through 90degrees).

Some solenoids (SAAB included) have retention springs inside which push the actuator shaft out normally. Thus to arrange the solenoids we must have them opposed and pushing each-other in about half way. This is so that when one solenoid pulls the actuator on the other springs and moves. If the solenoids were mounted to give their full throw when one pulled the other would have its actuator yanked hard and not move!

Finding the correct position for the solenoids in relation to the shift-lever and engine mount holes is a trial-and-error thing. You only need to concentrate on one at a time as the other is a mirror image.

Note that solenoids seem to have all sorts of different actuator shaft outputs. Some have just a plastic rod-end (avoid) while others have a nice sturdy steel actuator loop (SAAB – good).

Our actuators will have to be attached to the gearshift shaft via a bolt of some type. The steel actuator output is too big for a normal bolt and so to make the action smooth it is best to weld on a penny-washer to the actuator end. The link through the gearshift shaft is then a simple bolt.

To hold the solenoids in place a bracket will be required. There are some convenient bolts/holes on the bike-engine casing near the gearshift shaft and it is assumed that these are to be used.

Solenoid Positions
Solenoid Positions


Wiring it up

So now we have the solenoids mechanically fixed we need to look at the control of them. For the uninitiated a solenoid is simply a coil of wire in a ferrite former. This is to provide a concentrated magnetic field when a current is applied to the coil. A law of physics states that if current is passed through a coil of wire a magnetic field is generated within the coil. If a ferrite core is then positioned in the coil the magnetic field will "drag" the former along and linear motion is seen.

The coil will draw quite a large current when the voltage is applied. From 8Amps to around 15Amps with some solenoids. It is inadvisible to route cables directly to dashboard/steering-wheel switches due to this requirement. A better system for direct control would be to have the dashboard/steering-wheel switches trigger relays which can be mounted near to the solenoids. This is shown below:

??Diagram of basic relay controlled ??

This method still relies upon the driver understanding how to operate a bike box. I.e. the gear-order is one shove down to first, then subsequent pulls-back for 2nd, 3rd etc. Going down in gears is the opposite.

There is also a problem getting neutral. On a bike to get into neutral you do a "gentle" lift/press of the lever when in 1st/2nd gear respectively. To translate this to button presses requires a "tap" of one button then the next to only part-move the lever.

To obtain a "pure" up and down gear functionality on the steering-wheel it is necessary to employ a controller box. The one that I have designed is based around a PIC microcontroller with some solid-state FET relays. This has the advantage of allowing the tricky neutral "taps" to be pre-programmed and also gives an easy indication of which gear you are in via an LED display on the dashboard. The development of this box is way out of reach for anyone who does not design electornics for a living and so will be discussed no further here. The author may be in a position to sell these control boxes once their function has been proven.









Hydraulic/Pneumatic gearchange






Reverse Gear

Bike engines do not have reverse gear (apart from the enormous Honda Goldwings). So how do we get the car to go in reverse?

Commercial Boxes

There are two commercially available systems on offer.

  1. The first is the "Reverson" and is the system offered in F27, Fisher and Westfield cars. It is a small box which sits in the transmisison tunnel and interfaces to a split prop. The unit contains a system of gears that normally allows direct coupling of the input and output shafts. There is a small lever on the side – when pulled this brings a gear into play which has the effect of reversing the output shaft direction.
  2. The Reverson is available from "??" and costs ??+vat

    Reverson Reverson2

  3. The second version is almost identical to the Reverson but also features a piggy-back solenoid for reverse selection via a dash-mounted button.

    This is the unit used in the Caterham Blackbird cars and is thought to be rather more robust that the Reverson box.

    The box is available from "??" and costs ??+Vat

    DCs Reverson DCs Reverson
    BlackBird Reverser


  4. The great Ron Champion has an offering originally intended for use with his fireblade locost chassis.


Home-Made Solutions

Other solutions for reverse are electrical – relying upon an electric motor to propel the vehicle backwards while the engine turns over in neutral.

This can be done by using some form of gear on a propshaft and a mating gear on the motor. To erradicate losses it is important that the gears are not permanently in mesh.

An ideal mechanical setup would appear to be a small pre-engaged starter motor. A dash button can be used to seperately control the solendoid action to mesh the gears, and then the starter motor drive can be controlled by a box of electronics by using PWM techniques.

There are some major problems with this idea though: