I am not sure who first built a roller starting machine for an air-cooled car like ours, but Garry Simkin had one long before he built one for me, and when I took it and the Walton JAP to the UK in 2002 it was, I think, the first that had been seen there in air-cooled circles.
Be that as it may, it proved its value and was then enhanced somewhat with adjustable feet so that it could be levelled and/or raised or lowered to level the car. The only limitation with this approach is that you have to cart the machine around with you, and if you have to do a restart it’s all a bit of an effort. Because there is normally no differential on an air-cooled car you also need a helper to jack the opposite wheel off the ground then put it back down and push the car off the starter rollers when it is running and ready to go.
One day at Shelsley Walsh, I saw a Vincent powered car that seemed to self-start well, and having embarked on building a brand new engine from scratch for the Walton JAP I got stuck into the on-board starter motor problem.
First you have to attach a ‘flexplate’ with a ring-gear to the engine. You get one of these from your local ring-gear shop (mine was ex Daihatsu with 100 teeth) and attach it to the engine sprocket with a suitable spacer and screws all lock-wired in place, of course. Obviously, the ring-gear has to clear the chassis and the primary chain. In my case that was straightforward but it is best to dummy the whole thing up before cutting metal.
Next you need a starter motor and I just went on-line and found a brand new unit available in Melbourne for custom big V8s to which the supplier fitted a starter pinion to match my ring gear. Probably a much smaller motor than my 2.5hp job might have been fine but I was not taking any chances.
Obviously you will already have thought about how and where to mount the starter and you can really only do it in front of the engine. In my case there were three mounting holes in the chassis forward of the engine for a supercharger that Bruce once had on the car and it proved easy to use these (see below, guessing Templestowe, Victoria. Ten mm thick aluminium plate was cut, machined and screwed to form a T piece mount with slotted holes so the starter could be moved when the engine was moved. If the starter motor was mounted on the engine rather than the chassis then of course there is no need to adjust it when the engine is moved to adjust the primary chain.
Bruce Walton and the supercharged Walton-JAP, here with a Mk1 JAP engine and Marshall cabin blower supercharger
The wiring is simple. You need an Anderson connector to connect your portable starter battery to the motor. You need a starter button in the car which is wired to the starter motor and that is it. From day one it has worked flawlessly and clearly has a heap of grunt to spin the JAP over and fire it up without hesitation. I do have an electronic ignition set-up with automatic retard so that doubtless helps too. Not having to hump around the roller unit is an advantage and there are no issues with the car sliding off the rollers or needing help to restart other than somebody to connect and disconnect the battery. Obviously you are carrying a bit more weight up the hill.
Starter motor as installed in the Walton JAP using the supercharger mounting holes
There was a stage when I was having problems with my first set of flywheels shifting and thought the starter motor might have been responsible but some expert opinion (naa … no worries!) and some high-tech computer modelling (thanks Roald) dismissed this worry. A more recent and more compact solution has been built by Brian Simpson which he describes as follows:
The flexplate is from a BA to BF Ford Falcon with a strengthening ring welded to the centre . A JAP spline from an old sprocket is welded to the ring so it is easy to change the gearing by simply sliding the flexplate off then the sprocket (I am using a speedway type splined sprocket carrier) I then had the finished article dynamically balanced. The starter motor is of course from the same model Falcon with no modifications needed. Brand-new off e-bay the motor was under $A100.00 & the flexplate was $A40.00 from a wreckers.
Click above to play video
The car needed rewiring with heavy cabling to the starter motor & the fitting of a battery isolating switch to keep CAMS happy. I have also fitted an Anderson socket and plug for a slave battery to do all the work in the dummy grid area. The car is wired so it will start on the slave battery only with the on board battery totally isolated. Interestingly the car starts easily with its own battery & there’s at least 3 or 4 starts before it starts to weaken.
Addendum: The picture below of the Walton JAP shows the starter motor and fuel pump shielded by a cowling identical in shape to a pannier fuel tank which sits on the other side (bottom)
Oops, no pee in Simkin