The history: regarding the latest work....
I bought the bus with the original gearbox and a 1776cc engine. The engine revved far too high at any reasonable speed, even at 80km/hr. The 1776cc twin 36mm Dellorto carbed engine was also far more powerful than the original 1200cc 25hp engine that was in there, which is great for performance but not for the gearbox, I thought.
So I went to Villiersdorp to have a gearbox made up and my learning curve starts here, two years ago.
Andreno Motors made up a “Beetle” main gearbox, with reduction boxes (RGB), but it doesn’t fit, the Beetle box is 40mm longer than the split case box in the pre-58(?) bus. The RGBs on the longer gearboxes have 46mm castle nuts, not 36mm like the earlier RGBs. Arno came up with a very elegant solution, change the existing RGBs from a 1:0.75 ratio to 1:1 ratio. This was done and we got good driving results but not good reliability and we developed a rumble after only 3000km.
Drained the oil and saw that it was full of metal. In order to keep the bus on the road, I installed the insides of a spare set of 36mm RGBs which I had acquired and sent the 1:1 ratio RGB interiors away for “re-engineering”. (This re-engineering process has been taken away from the guys that did the original 1:1 conversion and has been given to Bugger, he will hence answer any questions on that.)
I had a persistent oil leak on the rebuilt reduction boxes to the point where I asked Bugger to fly down to come and help. We strip and rebuild, and discover that the one 36mm RGB driven shaft is in fact not the same as the other, the OD of the driven gear on the shorter drive shaft is 96mm and only 92mm on the long driven shaft. Phone The Fig… He informs us that halfway through VW’s transition from the 36mm RGB to the 46mm RGB, that is the transition from the 1200cc to the 1500cc, or the transition from the split case gearbox to the 40mm longer “beetle” box, they did make a lower ratio 36mm RGB with a longer stub axle. (My luck to end up with one of each…) Fig, feel free to add details to these transitions… they apparently occurred between 58 and 62?
The goal:
I want a drivable bus (original is no longer an option, it wasn’t original when I bought it, not is it desirable), with which I can tow. For that I need a strong tranny, a good engine and good brakes… er… and a towbar…
The solution:
I have to make that long gearbox fit into the short space, the one Arno built for me, with the long final drive (diff) ratio, flipped over, and beefy 46mm RGBs. The 2270cc (ex Razor Edge) 106kW motor has become available, so all the more reason for the stronger tranny. But before I even go there, I have to think brakes.
So I researched and finally imported a new remote vacuum assisted brake servo (or booster). The drums on the 46mm RGB are also wider, heavier, better, and the front bay window discs that are already on the bus and giving me problems are going to be replaced with ventilated discs by Dave Rowley. So I re-plumbed in the brake lines, all new and shiny, using the existing (not original) bay window dual circuit master cylinder. The dual circuit brake booster is mounted in the rear under the fuel tank next to the gearbox and clutch Bowden tube.
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The vacuum comes off the rear (only) of the twin carb inlet manifolds (ie numbers 1 and 3 cylinder). No one-way valves (aka check valves or non-return valves) were deemed necessary, as per consultation between Dave Rowley and Dave Ingle.
The backing plate on the 46mm RGB is of course different from the backing plate on the 36mm RGB and this requires the use of the later hand brake cables (it doesn’t have that infuriating little fitting which holds the hand brake cable Bowden tube, here the Bowden tube just slides in) Of course, the later hand brake cables are around 6 inches longer than the old ones, and I assume this is because the hand brake cables are adjustable from inside the later bus as opposed to underneath on the earlier bus. (Fig?) I just had them made shorter.
I replaced the slave cylinders with new, had the drums skimmed and shoes re-lined and built up the old 46mm RGBs with new stub axle seals and O-rings and new booties and a new starter motor and bush as the old one’s shaft is thicker than the new one so it didn’t fit into the Beetle gearbox (more about that later).