A few people on here have enquired about the 5 speed conversion I've done on my bus, so here goes...
It started with my frustration with the standard set of gear ratios. I was normally in 2nd gear by 5mph on the flat, 55mph was all I was comfortable doing on long journeys due to the high RPMs in 4th, and the gaps between the gears meant that up hills you were either lugging the engine at low RPMs, or changing down with the engine screaming away. I should say that I've only got a stock 1600 engine with a pair of twin Dellorto 36s and a standard Beetle backbox with two bus tailpipes, so probably around 60bhp on a good day.
Having done some searching, I came across the following magazine article which had been posted online:
http://public.fotki.com/vdubjim/tech_articles/porsche_5/porsche_in_bus.html#media
I essentially followed the guide throughout (click the link for pages 2-4). It took less than 20 hours of my time to go from a running van to a running 5-speed van, spread across a week as the final gearshift coupling parts were a little late in arriving.
My gearbox is a 1965 Porsche 901 gearbox with the earlier (push) style clutch - I think this was used up until 1969. This is a 5 speed box, although the same casing was used with 4 speeds too, so check the gearbox codes carefully before buying. A pair of Beetle CV joints bolted straight to my box, but some boxes use different style axles, so be careful when buying. I believe both the axles and the clutch can be converted, but that's extra work.
Anyway, enough chat, so here are some pictures...
5 speed box in its new home.
Rear gear coupling
Front gear coupling
Engine hasn't moved...
Looks totally stock from inside the cab.
Back together and good to go
And the proof of the pudding - much lower RPM (The old 4 speed gearbox would have been doing 4000RPM at ~70mph):
You can see the difference in gear ratios in this handy graph I made...
Red(to purple) lines are the standard gearbox RPM at a given speed in each gear, blue ones are the Porsche 901/01 gearbox I have. You can see that the Porsche and standard gearbox 4th gears are essentially the same ratio.
The one thing the article doesn't go into is what to do with the shifter mechanism. The standard lockout plate prevents you from reaching first gear without pressing the stick down, and doesn't allow selection of reverse. This I modified by replicating the 'ramp' towards the back of the lockout plate, before removing the one at the back. My bus now slips into first normally, but you cannot go into reverse without pressing the lever down first. This is particularly important given the shift pattern of the box, which puts reverse where you'd expect first to be.
So, the good points:
The bad points:
The only other minor job is that my shift rod makes a slight clunking noise on the downshift from 3rd to 2nd. That's on my to-do list. :msn4:
I've only done about 100 miles with the new gearbox, but it's made a real difference to how it drives. Hopefully someone else may be interested in getting it done.
Thanks go to Paul Weeding at LVH restos (see http://thelatebay.com/index.php?threads/lvh-engines-restos.10833/ for the help he gave me in finding a suitable box and so on. He's done a couple already, so if you're not confident in doing it yourself, I'd recommend giving Paul a call.
It started with my frustration with the standard set of gear ratios. I was normally in 2nd gear by 5mph on the flat, 55mph was all I was comfortable doing on long journeys due to the high RPMs in 4th, and the gaps between the gears meant that up hills you were either lugging the engine at low RPMs, or changing down with the engine screaming away. I should say that I've only got a stock 1600 engine with a pair of twin Dellorto 36s and a standard Beetle backbox with two bus tailpipes, so probably around 60bhp on a good day.
Having done some searching, I came across the following magazine article which had been posted online:
http://public.fotki.com/vdubjim/tech_articles/porsche_5/porsche_in_bus.html#media
I essentially followed the guide throughout (click the link for pages 2-4). It took less than 20 hours of my time to go from a running van to a running 5-speed van, spread across a week as the final gearshift coupling parts were a little late in arriving.
My gearbox is a 1965 Porsche 901 gearbox with the earlier (push) style clutch - I think this was used up until 1969. This is a 5 speed box, although the same casing was used with 4 speeds too, so check the gearbox codes carefully before buying. A pair of Beetle CV joints bolted straight to my box, but some boxes use different style axles, so be careful when buying. I believe both the axles and the clutch can be converted, but that's extra work.
Anyway, enough chat, so here are some pictures...
5 speed box in its new home.
Rear gear coupling
Front gear coupling
Engine hasn't moved...
Looks totally stock from inside the cab.
Back together and good to go
And the proof of the pudding - much lower RPM (The old 4 speed gearbox would have been doing 4000RPM at ~70mph):
You can see the difference in gear ratios in this handy graph I made...
Red(to purple) lines are the standard gearbox RPM at a given speed in each gear, blue ones are the Porsche 901/01 gearbox I have. You can see that the Porsche and standard gearbox 4th gears are essentially the same ratio.
The one thing the article doesn't go into is what to do with the shifter mechanism. The standard lockout plate prevents you from reaching first gear without pressing the stick down, and doesn't allow selection of reverse. This I modified by replicating the 'ramp' towards the back of the lockout plate, before removing the one at the back. My bus now slips into first normally, but you cannot go into reverse without pressing the lever down first. This is particularly important given the shift pattern of the box, which puts reverse where you'd expect first to be.
So, the good points:
- Lower RPMs at speed
- The 5 speeds are closer to each other, meaning that while it is underpowered, it's far more comfortable climbing hills and accelerating through the gears
The bad points:
- Cost. I spent £700 on the (unknown/untested) gearbox - a gamble which seems to have paid off, and another £200-250 or so on the starter motor, CV joints and shifter parts
- The Porsche gearbox uses an older style of synchromesh design, so the shifts aren't quite as quick as the VW box, especially when cold
- Being able to do 70 with much less engine noise highlights the leaky cab door seals
- The unusual shift pattern takes some getting used to
The only other minor job is that my shift rod makes a slight clunking noise on the downshift from 3rd to 2nd. That's on my to-do list. :msn4:
I've only done about 100 miles with the new gearbox, but it's made a real difference to how it drives. Hopefully someone else may be interested in getting it done.
Thanks go to Paul Weeding at LVH restos (see http://thelatebay.com/index.php?threads/lvh-engines-restos.10833/ for the help he gave me in finding a suitable box and so on. He's done a couple already, so if you're not confident in doing it yourself, I'd recommend giving Paul a call.