Re: Snapey's 1935 Racing Biposto

Posted by Matt snape On 2011/6/20 6:28:49

So it was a productive weekend, made even more so by my father (who has a wealth of experience in such things) who was staying for the weekend and I managed to convince should offer some advice.

First was consideration of the overall length and width of the chassis. At just over 39" wide at the seating position the chassis, as it stands, is not a bad width for a 'comfortable' 2 seater, remembering that the body won't sit outside the line of the chassis at all. For handling it has been decided to reduce the wheelbase to 120" - which gives us a 2:1 wheelbase to track width ratio - just nice and on par with the race and sports cars of the day. This will be done by cutting 15" off the front of the chassis and moving the front axle and spring hangers backwards. I hope to reuse the forged hanger ends from the rear of the car at the front and will fabricate new rear hangers for the front springs inside the existing chassis and much higher. This will drop the overall height of the chassis 6-8" closer to the ground. Starting at the back of the crucifix, the rear of the chassis will be cut and pulled towards the centre so that what are currently the rear hangers of the rear springs will sit only about 24" apart. A tubular cross bar will then be used to anchor new 'outrigged' rear hangers at the existing width but higher so as to match the chassis height from the front end alterations.

The rear leaf packs have been removed so that I can organise for new top leaves to be made. Both packs have fractured main leaves with one being 'replaced' by pulling out the original second leaf and putting in another main leaf with one good eye/end so there are eyes on both the top and second leaves. The other pack had one eye brazed back together (!). The two spring packs look completely different but I am hoping to be able to just have 2 new top leaves made and then mix and match the rest to create 2 packs the same. Front and rear spring packs will be reduced from the current 9 leaves to probably 5 or 6. The car will be much lighter than the original so this will improve ride and handling as well as reduce the overall weight of the car. The original shock absorbers will be used but will have to be relocated due to the change in the chassis rails at the rear. I still have to find a pair of shocks to suit the front - although I am keen to keep the rate adjustment feature that the '34 car had originally at both ends.

The engine is now also sitting in position and waiting for the fabrication of engine mounts from some 4mm plate. Given that this car is to be the 'racing/sports' version it must be remembered at all times that 'weight is the enemy'. Locating the engine & gearbox is something of a compromise. I want to move the weight down and back as far as possible, but this is restricted by the chassis 'crucifix', the brake cross shaft and common sense. I could get it much closer to the ground, but it would look ridiculous and not be in keeping with the era and future use of the car. Also this would create problems with the drive shaft and the centre of the crucifix would have to be heavily modified. As it sits now, the lower, rear most point of the gearbox sits just above the brake cross shaft and lines up nicely with the gap through the crucifix. Given that I am lowering the chassis so much this should work fine. The seating position itself will end up a little further forward than my original intention, but it will still work and will also provide for some decent storage area in the tail (perfect for a fuel drum and crash helmet or the picnic basket).

We also looked at locating the supercharger. Dad brought down one of the 'blowers' he had in stock - although it is just a shell it is the same as the one I will fit to the car but is still in 'storage' at my brothers place - a Wade RO34 originally off an English 'Commer Knocker' truck with the TS3 2 stoke diesel engine. This unit supplies approx. 3.4 litres or air for every revolution and I still have to do all the calculations but think it will need to run at around 1.2 to 1.4 times engine speed to give around 8 pounds boost and mean that I will still be able to run premium unleaded pump petrol. The blower will sit out the front of the engine between the chassis rails - like the 'Blower Bentleys' - and be shaft driven off the front of the motor with a chain drive to control speed somewhere in the mix. It will probably suck through twin Stromberg 97 downdraft carbs mounted directly to the top of the blower and then a custom manifold will stay low down the right hand side of the motor and up into the 4 inlet ports. The exhaust will come straight out of the exhaust ports then out the side of the bonnet and run along the side of the car ending behind the rear axle.

So yes, it was a productive weekend with some work done but a great deal more planned. And thanks to Dad for his help. He reckons he has never seen anyone turn a 'truck' into a sports car before and spent a lot of time questioning my sanity and upbringing - he kept asking himself where he went wrong... I now know where I got my sarcastic streak from!

Photos to come when I get a chance.