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Tue Feb 28, 2012 9:39 am

Okay, please don't flame me for the following:

I have a Fiat 850 and we commonly use old VW trannies when we put in a larger engine that rotates CW so I know that works.

This thread caught my eye because it would give me 5 speeds instead of 4. My engine rotates CCW, not CW like a Subaru engine. Since the tranny is flipped around to go in our cars we don't need the reverse ring and pinion.

Here's my question:

Will the Subaru tranny work ok in reverse? I'm not a drivetrain expert so I don't know if the syncros will function okay rotating backwards.

As far as I know this has never been attempted in an 850.

Thanks,
Stan in MA

Tue Feb 28, 2012 1:15 pm

Hey Stan, I replied to your email but it is also a worthwhile discussion to have on here.

Trannies are not really designed to be spun backwards - this reverses the thrust loads on the gears and shafts and they try to spin apart and out of the casing in the other direction.

Having said that, given that you are not putting much power through it and don't expect it to last forever, I would give it a shot. It should work, no real reason why it shouldn't last for a while.

Tue Feb 28, 2012 2:23 pm

It may be noisey too.

Tue Feb 28, 2012 5:09 pm

Thanks Todd, that's the kind of response I figured I'd get. I was wondering why it hadn't been done and now I know. Nobody want to be cruising on the highway with a tranny that's trying to blow itself apart.

Still it might be a good option for folks installing a CW engine as long as they use your ring and pinion set. Having that fifth gear would be great.

We have to use an adapter plate to run a VW tranny with a 124 engine placed into an 850. Not sure if the patterns still exist but I know guys are still doing it.

Our engines typically put out around 50HP but I know one guy that put injection and a turbo on his and he says he's making around 92HP.

Subarugears wrote: Trannies are not really designed to be spun backwards - this reverses the thrust loads on the gears and shafts and they try to spin apart and out of the casing in the other direction.

Having said that, given that you are not putting much power through it and don't expect it to last forever, I would give it a shot. It should work, no real reason why it shouldn't last for a while.

Tue Feb 28, 2012 5:42 pm

szdonick wrote: Thanks Todd, that's the kind of response I figured I'd get. I was wondering why it hadn't been done and now I know. Nobody want to be cruising on the highway with a tranny that's trying to blow itself apart.

Still it might be a good option for folks installing a CW engine as long as they use your ring and pinion set. Having that fifth gear would be great.

We have to use an adapter plate to run a VW tranny with a 124 engine placed into an 850. Not sure if the patterns still exist but I know guys are still doing it.

Our engines typically put out around 50HP but I know one guy that put injection and a turbo on his and he says he's making around 92HP.

Subarugears wrote: Trannies are not really designed to be spun backwards - this reverses the thrust loads on the gears and shafts and they try to spin apart and out of the casing in the other direction.

Having said that, given that you are not putting much power through it and don't expect it to last forever, I would give it a shot. It should work, no real reason why it shouldn't last for a while.

On a related note, one of Todd's customers is using the reversed Subaru 5MT in a rear engined Fiat 500. They are actually installing the complete Subaru drivetrain with an EJ25 engine too. A conversion like that in an 850 Spider would be pretty cool.

David

Tue Feb 28, 2012 5:55 pm

Holy crap, 155HP in a car designed to handle 21! That's gonna be wild.

D Clymer wrote:
On a related note, one of Todd's customers is using the reversed Subaru 5MT in a rear engined Fiat 500. They are actually installing the complete Subaru drivetrain with an EJ25 engine too. A conversion like that in an 850 Spider would be pretty cool.

David

Tue Feb 28, 2012 6:28 pm

One of my dream projects is a FIAT 850 coupe with my 1.8 Lancia Beta block connected to a Porsche or VW transmission.

Google 'Abarth OT2000 America' to see what the old Abarth version looked like, badass - 200hp in a car originally designed for 47hp.

Back to the topic, in terms of shifting pattern, how are people handling that?

For instance, for a subaru installation the shift pattern would be like this (I am assuming):

1 3 5
2 4 R

But if you just put the gearbox in back and don't do anything with the cable linkage you would get something like this:

2 4 R
1 3 5

or even worse:

R 4 2
5 3 1

I haven't read the whole thread yet, but was wondering if there is a shop that offers solutions like this?

Tue Feb 28, 2012 10:51 pm

keithwwalker wrote:
But if you just put the gearbox in back and don't do anything with the cable linkage you would get something like this:

2 4 R
1 3 5

or even worse:

R 4 2
5 3 1

I haven't read the whole thread yet, but was wondering if there is a shop that offers solutions like this?

I did cover this early on in the build thread, but I don't mind giving you an abridged version.

The front to rear shift pattern actually ends up correct when the transmission is installed backwards in a rear engine VW. By some miracle, Subaru uses a shift lever with the pivot point below the linkage, while VW uses a shift lever with the pivot point above the linkage. Because of this the front to rear movement of the VW shift lever moves the linkage rod in the opposite direction - the right direction to shift the turned around transmission.

The side to side on a Vanagon would have ended up being reversed with first/second on the passenger side and the 5th reverse slot closest to the driver. I incorporated a ball and socket mechanism into my shift linkage design. It replaces a clevis and pin arrangement and reverses the rotation of the shift linkage rod. This corrects the side to side shift pattern. Older VWs already use a ball and socket, so with all other rear engine VWs besides the Vanagon, the stock linkage will work. The geometry isn't ideal since the Subaru shift rod has less movement/travel than the original VW transmission did, but it works. It ends up being an ultra-short shift arrangement.

David

Wed Mar 14, 2012 10:51 am

Moderator Edit

This thread comes from:

http://www.thesamba.com/vw/forum/viewtopic.php?t=407222

Sun Apr 01, 2012 1:19 pm

There are 5-speed conversion kits for the original Fiat 4-speed trans in the 600/850-series cars... try PBS Engineering in California (www.pbseng.com), or Scuderio Topolino (http://www.scuderiatopolino.com/generalcatalog_ind.php?id_area=11) for info & pricing.

bryan