5 speed in a bay

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Tofufi

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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:

0lQjdHj.jpg


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.

DSC_9462.jpg~original


Rear gear coupling

DSC_9463.jpg~original


Front gear coupling

DSC_9472.jpg~original


Engine hasn't moved...

DSC_9475.jpg~original


Looks totally stock from inside the cab.

DSC_9453.jpg~original


Back together and good to go :)

DSC_9477.jpg~original


And the proof of the pudding - much lower RPM (The old 4 speed gearbox would have been doing 4000RPM at ~70mph):

IMG-20140606-00102.jpg~original


You can see the difference in gear ratios in this handy graph I made...

ratios.jpg~original


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
    $%28KGrHqV,!jkE9Vk%29NjQbBPWY8Kuyd!~~60_35.JPG
    :D

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. :)
 
Very nice work Jim. Really impressed.

Suprised how simple and effective the conversion has been. I'd have expected more issues. Must help mpg too. Thanks for sharing. :D
 
Cheers folks :)

aspro said:
Very nice work Jim. Really impressed.

Suprised how simple and effective the conversion has been. I'd have expected more issues. Must help mpg too. Thanks for sharing. :D

Indeed, it's surprisingly straightforward. I'm currently tracking the MPG - my van managed 25MPG fully laden during my ~2000mile trip climbing across the Pyrenees last year, so I'm hoping to better that on longer runs. Problem is the temptation to go faster as a result of the lower RPMs at speed :lol:

dubdubz said:
amazing - couple of Q's

can any other porsche box be used - a later one with better syncro?
I can't download the article from fotki

cheers

Darren

Hi Darren, I think the G50 was the first Porsche gearbox to use the better synchros. It might be worth you doing a search for 'Porsche 901 Baulk ring synchro' and seeing what you can find. The gear ratios of the later gearboxes really would be far too tall for the aircooled engines, as the speed of the fan is important for cooling ;)

To be honest, I only notice the slow synchro on the first few shifts, before the gearbox oil has warmed up at all. By the time I'm a mile away from home, it doesn't seem any slower than the standard 'box, but with the stock shifter you don't want to be changing gear too swiftly anyway.

More info on the Porsche boxes can be found here:

http://www.cogscogs.com/transmissions.asp" onclick="window.open(this.href);return false;

and a lot of info on the 901 gear ratios and so on here:

http://www.blueskymotorsports.com/index.php?option=com_content&view=article&id=17&Itemid=6" onclick="window.open(this.href);return false;

On fotiki there is a button top right just above the main picture which allows you to download the picture. Or does this not work?

http://images34.fotki.com/v1523/file81mi/42c5c/3/34243/408283/Porscheinbus.jpg" onclick="window.open(this.href);return false;

:)
 
dubdubz said:
amazing - couple of Q's

can any other porsche box be used - a later one with better syncro?
I can't download the article from fotki

cheers

Darren

The G50 comes in 2 guises, short nose, and long nose... A short will fit with no chassis mods, the long would require the centre of the torsion tube being removed...

But unless you drop onto a real cheap G50, then it's going to be out of the price range of most people... £6500 for an unknown box IIRC

I'm currently fitting a 915 to my van, mainly as the stock 091 6 rib just wasn't giving me what I wanted performance wise...
I dropped onto mine for a bargain price, but I bought it as a stripped box that some pieces had been robbed from it, but it was ideal, as it gives me the opportunity to go through all the bearings, and upgrade the main shaft bearing plate as that is the weak part in the 915s.

419417_10151290619635099_1497452166_n.jpg
 
Paul Weeding said:
dubdubz said:
amazing - couple of Q's

can any other porsche box be used - a later one with better syncro?
I can't download the article from fotki

cheers

Darren

The G50 comes in 2 guises, short nose, and long nose... A short will fit with no chassis mods, the long would require the centre of the torsion tube being removed...

But unless you drop onto a real cheap G50, then it's going to be out of the price range of most people... £6500 for an unknown box IIRC

I'm currently fitting a 915 to my van, mainly as the stock 091 6 rib just wasn't giving me what I wanted performance wise...
I dropped onto mine for a bargain price, but I bought it as a stripped box that some pieces had been robbed from it, but it was ideal, as it gives me the opportunity to go through all the bearings, and upgrade the main shaft bearing plate as that is the weak part in the 915s.

419417_10151290619635099_1497452166_n.jpg


£6500 for a box :shock: yikes
 
Just a quick update - the last few weeks have been spent rebuilding my 1600TP engine, so the van hasn't been in use. I bolted the engine in on Saturday, and on Sunday ran it in with a approx 150 miles, mostly on motorways.

With a freshly rebuilt engine, it was able to sit very comfortably at an indicated 60mph on the motorway in 5th gear (sat-nav 56mph), and seems to have returned approx 30mpg in the process. I'm hoping this will improve slightly once I have a chance to sort a small misfire and adjust the carbs properly. :)
 
Canny little write up!! :D
I've always wanted a 5 speed in my bus to improve MPG & lower the noise of the revs down a bit, but if you're talking mega bucks to do, then the fuel savings make it not worth it! :(
 
I replied to your PM earlier, but I think I'm right in saying that the 901:

ch10-01.jpg


is the same gearbox as the 914 gearbox, but has a different nosecone, which has the gear linkage coming out of the side of the box rather than the end.

0561359510657.jpg


I think it'd therefore be much trickier to fit... be interesting to know if someone has done it :)
 
Oh, and as an update.. I've now done over 1000 miles in my bus since fitting the gearbox (it was off the road for much of last summer for a planned engine rebuild), and all seems well. On the steepest of hills, the new taller 1st and 2nd gear ratios feel a little bit too tall with the 1600, but it's transformed how it is to drive on A roads - it's refreshing being able to hustle it along A roads without holding up traffic, at least until you get to steeper hills :)
 
There is another option ...
Subaru gearbox, there's a business in OZ that manufactures internals to
make it work in bugs and buses
"Subarugears" is the name, lots of good info on his site
as well as prices
Can be bought as a kit or complete box.
(No affiliation with above business )
Chris
 
Those Subaru conversion kits look really well engineered :)

Bit more expensive than a cheap secondhand Porsche box, although if you're getting a reconditioned Porsche box it's probably a more similar comparison price-wise :)
 
The 914 box is indeed a 901... But you'll need to do a little bit of work to it to make it work!!

So you'll need to flip the diff, and relocate the breather, as the now flipped diff will spray oil out of the 914 breather location!!

As for the nosecone you'll need to order a new one from bug@5speed :cool:
 
From the info i got from talking to the business owner,
All 5spd awd subaru gearboxes(not 6 speed or fwd) can be used,turbo boxes as well and he reckons using a hydraulic clutch set up from the subaru is easy to set up and worth the effort
Makes running a Subaru engine even more attractive
 

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