One by one all the variables are becoming constants and progress is speeding up as our project heads towards completion. Engine development has been slowed to let us finish the chassis, but the fuel injection system has already been sorted out and run on Vintage VeeDubs' turbo Beetle: On April 19 Boris' 1998cc Beetle recorded 11.667 seconds at 117 mph on Eastern Creek's quarter mile.
The choice was Microtec, which is screwdriver adjustable and is also available locally..
But back to this issue, which is all about the details of the suspension design and general tryout of the chassis.
The suspension has been the biggest jiggle and jostle you'd have ever seen, but it's the heart of the car -everything on the car has been arranged around the suspension geometry, as it's this that decides how the car goes, stops and corners. And driver comfort also comes into it, as comfort and confidence is necessary for truly quick lap times.
The rear axle uprights were fabricated to suit the arms and frame, with some joggling about the engine. Although the flat four gives a nice low centre of gravity, the heads get in the way. Persistence won through though.
Alloy uprights would have been nice but there are benefits to be had from steel ones—mainly that they are repairable and deform rather than crack, which are two big pluses.
The rear suspension upright is assembled around an IRS bearing housing which has been surgically removed from a trailing arm.
Yes, there is life after IRS!
An IRS stub axle, bearing drive flange and CV joint flange all fit as normal. Depending on the position of the gearbox, either VW or Porsche CV joints can be used. Changing the weight distribution by moving the motor and gearbox forward 7.5 inches reduces the polar movement of inertia, but the angle of the axles trails radically rearward to the outer CV joints, necessitating the use of Porsche CVs there— justifiable in the pursuit of improved handling.
Moving the engine forward means the bellhousing face is now in line with the rear outer hubs and the whole gearbox, flywheel and clutch unit is forward of the axle line. This layout or standard VW gearbox and axle positions is allowed in the Sport Sedan Racing rules but mid-engine is not. It wouldn't be desirable due to air-ducting space considerations and exhaust system complications—not to mention safety and simplicity. After all, it's a Beetle, and that means a rear engine to me...
Thanks to the driving position the fuel tank can be mounted in the safest place—right in the middle of the car, out of harm's way. The battery and dry sump tank are mounted on the flanks of the central seating position, which was dictated by the frame design but was also desirable for weight distribution and safer. It also means the driver will enjoy the protection of two cages.
In front of the driver is the 10 inch steering wheel connected to a 1:1 ratio custom made steering rack. The rods are also custom made and are the same length and use the same pivot points as the front wishbones.
The gearlever lives just to the right of the steering wheel and will be a cut-down VW item operating a VW shift rod to the rear of the fume then forward diagonally to the gearbox via two universal joints.
It feels right to have the important bits genuine VW!
The front stub axles are Type 3 units, chosen for their adaptability to helm joints, their geometry and their disc bakes. There's an interesting range of calipers that fit the two different model stubs: Alfa Romeo, Commodore and three different VW callipers all fit and are reasonably priced, with trick pad material available.
Terry at Arrow Brakes has been a big help in this area: We've had a lot of success racing on Arrow's non-asbestos pads before and they're our choice again.
The other features of the Type 3 stub axles are the removable steering arms and their high strength and moderate weight. And when you think of their low price and great availability, there's no point looking any further.
While on the brakes, I'll let you in on a little secret: VW ventilated discs will soon be available from Vintage VeeDub Supplies with optional Porsche bolt pattern. Rear drums or discs also with Porsche bolt pattern will also be available. The big deal is that with the Porsche bolt pattern you can get ex Porsche street and race wheels and tyres at reasonable price because the Porsche people keep trading up to the next dearest or latest trend, leaving a trail of unwanted wheels and tyres. You can get them from 15 to 18 inch" in diameter, plus when you go to sell your wheels and tyres you have a dual market of VWs and Porsches.
The pedals and brake master cylinder have ended up pure race car style due to limited space available and the fact that tandem (side by side) master binders are needed to provide the best front to rear brake bias adjustment.
PBR units are cheap and readily available and will permit Type 3 callipers at the front and Beetle callipers at the rear, or Alfa Romeo front Type 3 rear, or even Commodore all round.
Koni coil-over shocks are adjustable for shock and spring rates, providing absolutely tuneable suspension. The stabiliser bars are the hollow tube type with adjustable ends for finer tuning of the handling.
With roll, dive, squat, oversteer, understeer and turn-in adjustable, the potential is unlimited.
If you want to learn about how handling and geometry work call up Vintage VeeDub for a selection of recommended books.
Much modern technology exists in your standard VW. That's why they were known over the years for their better handling compared with ordinary production cars of the era.
Engine and gearbox mounting is by an adapter plate and front Berg type brace. This was the lightest and stiffest way to do it and it also permits easy mounting of the gearbox forward or backward to suit various layouts.
A flywheel was simply made with extra offset to compensate for the 250 thou alloy plate sandwiched between the engine and gearbox. This is to allow the use of other gearboxes, such as Hollinger, Hewland and Porsche.
Which one to use depends on your requirements, price and availability. The Beetle box can be built tough and you can use a Berg five-speed conversion kit, but for racing, Hollinger and Hewland boxes are the ultimate for ease of changing ratios. Porsche boxes are big and tough, but one I tried to lift was very heavy, so there are horses for courses.
Despite being neglected for a while, the engine and fuel injection system have been coming along. The throttle bodies (55 mm) have been machined and assembled and the Microtec injection computer chosen for its simplicity and it can be custom made for any application.
As mentioned, its first test was on Vintage VeeDub Supplies' turbo Beetle, with great success. We're working on a simple constant boost intercooled set-up to blow through the throttle bodies without boost control being necessary.
Specially lightened Type 4 two-litre rods have been prepared, along with a 180 mm flywheel to accept a Tilton Formula 2 and sports sedan dual-disc ultra-lightweight clutch and flywheel combo.
Both rotational weight and dead weight have been removed to allow the best acceleration possible, to take advantage of the car's handling.
Once the chassis is completed the fun bit will start with the final assembly of the body and mudguards to achieve the lowest, tightest fit possible—just like the new 3.8 RSR Porsche, but in the form of our favourite car, the Beetle!
See you next time!