Vintage Thing No.42 - the Tonkin-VW Special

Another vehicle that I liked at the Launceston trial was this neat VW buggy entered by Ryan Tonkin. Its workmanlike appearance caught my eye and it had obviously been recently painted. I noticed a couple of tell-tale scrapes along the sills and, in talking with the crew, I discovered that it had already seen quite a lot of action, despite having only been completed the previous summer.

Ryan Tonkin bought it already converted into a buggy but substantially reworked it to make it more competitive. His passenger (sorry I didn't catch your name) showed me a picture on his mobile phone of what this machine looked like before the rebuild. It was certainly distinctive. Some would say it was cosmetically challenged. To me, it looked like the result of an unnatural act between an agricultural tractor and a submarine. I hope they get to see this blog and maybe they'll send me a picture of it in its original form. As it currently stands, it looks a whole lot better and is also substantially lighter.

Again, this is one of those vehicles that the more you look at the more you see and, through chatting to Ryan before the start of the event, I was able to learn about some of his other mods.

The first thing that caught my eye was the front disc brake conversion. Ryan designs programs for CNC machinery that has to have a well-equipped workshop just to make sure his software controls the hardware properly. Consequently, he made converting Volkswagen front axle to taking a disc brake sound easy but that is often the gift of the gifted. Although it's not a particularly good photograph, if you look closely you can see how close the bolt heads are the disc itself. Ryan had to skim them down to fit. I can't remember what discs and hubs he used but the drop of machining down the stub axle to accept the new bearings for the hub was a relatively easy job in comparison to get on the discs to physically fit into the space available.

The bodywork is all new and made a much lighter frame than the original structure, which, from their description, sounded more like ballast than anything with any strength. Compared to some buggies, the driving position is quite high up but visibility and comfort are major plus points.

I regret that I didn't question him much about the chassis but, to my eyes, it doesn't look as if it has the conventional VW floorpan underneath.

What I did notice, were the fancy looking dampers mounted on the rear bulkhead. These are adjustable air shocks from a high spec Range Rover. They are linked from side to side, not unlike the Hydragas system on an Austin Metro but the whole raison d'être is to keep both rear wheels on the ground much as possible. As the wheel on one side gets pushed up, the one on the opposite side gets pushed down. Combined with the rear engined layout, this makes a traction control system pretty well superfluous.

Then Ryan casually mentioned that he had done a similar disc brake conversion on the back and -- low, and behold -- there were the rear disc brakes. Again, he made that sound easy but then I suppose if you know you're doing then it is easy. I can't remember what these discs originally fitted but he did mention VW Transporter parts in passing.

Despite doing such a neat job on this VW buggy, which for want of a better name I have christened the Tonkin-VW Special, Ryan is no fan of VW engines. The present unit is a 2 litre with a vertical fan but Ryan has a Peugeot 205 GTi engine and gearbox sitting around doing nothing so it's only a matter of time before that gets installed. He reckons that at present there is too much rear overhang and a transverse powertrain will improve his performance even more.

In the meantime, he's made his own fuel injection system -- like you do -- using Rover 400 injectors. I think this might be a proprietary kit, possibly along the lines of a Megasquirt, but I find the idea of making your own tailor-made injection system hugely appealing, although a little daunting at the same time. I suppose the principles are simple enough and if you can do an Excel spreadsheet I don't see why you can't program the system. I can remember fantasising about fitting the fuel injection system of the then brand-new Kawasaki Z1000 to my Morris Minor. Starting from scratch actually sounds easier than trying to get the factory supplied injection and ignition systems to work in your special.

A 1970cc (94mm x 71mm) "suitcase" engine from a VW Transporter (with the fan on the end of the crank) puts out about 70 bhp and nearly 100 lb ft as standard with a 7.4:1 compression ratio and twin Solexes. In the VW-Porsche 914, the same engine put out 100bhp with fuel injection. Many people have disproved the age-old maxim that you can't tune Vee Dub motors but if you're not obliged to use them in your chosen formula of motorsport there are easier (and cheaper) ways of finding power.

Although Ryan didn't win the Launceston trial, I believe he had a good event. Certainly our little section didn't tax the Tonkin special very much. I'll watch out for him in other local trials and see if that Peugeot engine gets fitted soon.

Vintage Thing No.41 - the Cattley 7

One of my fellow marshals on the Launceston Trial turned up in this delightful little car. Warin Kelly has owned it for years and say the best thing about owning a special is that you can add to its specialness. This car is one of those that invite closer inspection. And the more I looked the more I saw that I liked about it.

In recognition of its original builder, Warin calls it the Cattley 7 and, although he's owned it for some time now, it was originally built in the mid-fifties. Mr Cattley made the body himself out of aluminium on an ash frame and when Warin first got it the powerplant was the usual 747cc sidevalve Austin motor.

Curious, isn't it, that sometimes the numbers 747 make you think of jumbo jets and at other times of tiny willing 4 pot motors, revving far higher than their designer ever intended, thanks to ingenious backyard tuning by an enthusiastic but knowledgeable amateur?

However, just like anyone else, Warin wanted more power and found a 598cc overhead valve Reliant engine that had been used in 750 Motor Club racing.

There is a link between Austin 7 engines and Reliant's own design of powerplant. In 1938, Reliant renounced the JAP V-twins they were using in their girder forked 3-wheeler vans and adopted the Austin 7 engine. I don't know if the end of production was foreseen by Reliant or not but when Austin 7 production finished in 1939, Reliant began production of something very much like it in their own factory. Some say there was total parts interchangeability between the two brands of engine.

Reliant later moved the valves upstairs for greater efficiency and changed to aluminium instead of cast iron in the interests of weight saving - always a matter of concern when you have to meet an 8cwt weight limit to qualify for the cheaper road tax that a 3-wheeler enjoys in Britain.

The 598cc engine that Warin originally got hold off sounds to me like quite a motor. With a bore and stroke of 56mm x 61mm, it would rev to 8,500 rpm. 750 Motor Club racers could wring over 50bhp from these all alloy engines in full race form. (Well, obviously they weren't all aluminium but the head and block were and that's what makes them so appealing - "they don't weigh hardly anything" as we say round these parts.)

The only trouble was, all that power was delivered in the wrong place. Fortunately the Reliant motor grew by degrees to 848cc – 60.5mm x 61mm (sometimes quoted as 60.96mm but that’s the more exact metric equivalent of 2.4 inches) gave 701cc, an extra 2mm on the bore gave 748cc (compare this to 56mm x 76mm for the Austin 7) and then a longer stroke finally evolved into the 62.5mm x 69.1mm 848cc big daddy engine. Compression ratios also increased from 8.5:1 to 9.5:1 and power as standard ended up at 40 bhp (29kW) with 46 lf ft (62Nm) of torque.

These days Warin uses an 848cc version on a single SU carb and a tubular exhaust manifold complete with a reliant gearbox. It’s an interesting alternative to souping up the original Austin 7 engine, which often involves supercharging for a really good output. I mentioned some blown examples I’d seen before and he grinned and said one gearbox he had in the Cattley 7 was so worn everyone thought the whining noise was a blower. Naturally aspirated Austin 7s often use Phoenix cranks these days but they’re quite expensive. They can’t arf rev, though.

I like the colour of this engine, too. It reminds me of the egg shell blue I used to paint my Airfix kits and looks sort of aeronautically technical.

Warin said there are four bolts that mount the engine in the frame but the chassis flexes so much the fourth one is never done up tight – it’s there more as a helpful guide, really, politely suggesting where the engine should be but not getting too wound up if it wanders around a bit in the engine bay. Do them all up tight and you run the risk of breaking the ally mounting points on the block.

To make the Cattley 7 even more suitable for its intended purpose of trialling, he fitted the lowest back axle A7 ratio he could find, namely that from one those little vans they used to do with an 8/45 crown wheel and pinion (5.625 final drive ratio). An 850 Reliant Kitten used a 3.23 back axle and boasted a top speed of 80 mph. Warin reckons anything over 50 mph is a bit cruel on the Cattley 7.

It’s had an illustrious trialling history, though, beating works Morgans and many other more powerful machinery. It doesn’t get out so much these days because of the roughness of modern classic trials sections. Warin had to re-shape his rear mudguards the last time he entered.

He gave me a lift in it after we’d finished marshalling and it was great fun blasting through the mud in Lew Wood. Because of the narrow track, the Cattley 7 is always sliding into and out of one set of wheel ruts, which can slow you down but makes for more of a challenge. Leg room for me as a 6’ 1” passenger was okay but my knees were wedged up against the dashboard so a long journey would probably have been out of the question.

Warin has been in touch with Mr Cattley’s son who remembers his father bending sheets of ally round drainpipes and banisters when he built the car. He also said that his dad had no time at all for Lockheed brakes but thought the world of Girling, the other big name in brakes in the British motor industry. He asked for their advice in designing the hydraulic braking system – essentially using parts from an Austin Big 7.

Girling sent an engineer rep who stayed with the Cattley family while he worked on the car. He’d brought a pair of master cylinders with him, expecting Mr Cattley to opt for a hydraulic clutch, but he was quite happy with a cable arrangement. So, instead of taking the surplus master cylinder back with him, he fitted a dual circuit system. If you look closely in this picture you can see their fluid reservoirs snuggling up to each othe rin teh engine bay. I’ve no idea when this was all fitted but it seems that the Cattley 7 was highly advanced in the braking department for its day.