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hildi25
21-11-2008, 11:06 PM
I have a chance to get a 915 transaxle but it is a side shifter. Is this transaxle a good idea.

Can I use this as a rear engine tranny or do I have to use it as a midengine?

What about the side shift, can I convert it to a tail shifter?

any help is appreciated

Thanks

letterman7
22-11-2008, 12:33 AM
The 915 trannys are out of Porsche 911's from '73 to early '80's. Depending on the year, the early models had some internal bearing issues. But besides that, the gearing ratios really aren't optimal for a VW motor. The rotation direction would be fine, I think, but you would need some sort of adapter plate for the bellhousing.

R

Spacenut
22-11-2008, 09:28 AM
Apparently it is not possible to turn the crownwheel and pinion upside down in these transmissions for mid-engine applications. The whole transmission has to be turned over to avoid the embarrassment of having one forward gear and 5 reverse!

I'm getting the feeling that even the popular Renault 30 transaxle has to be run the same way. I never realised until recently just how easy it is to do on a Beetle transmission!

Lauren

letterman7
22-11-2008, 02:54 PM
No, not on the 915 and 930 variations. The only tranny that can do that in a Porsche is the 901 out of the 914 (too many 9's....I wonder if Porsche had a fixation...).

hildi25
24-11-2008, 06:07 PM
Ok, so in order to run this tranny as a rear engine, I would need to run it upside down. (I dont know much about trannies) Would this cause a cavitating pump or some type of lubrication issues?
To tell you the truth making some custom transaxle mount has always been on my todo list. This might make it possible to raise the transaxle and motor enough to fix a couple of problems.

1. motor hanging to low/exhaust
2. when you lower the car this custom mount would fix the camber issue on a lowered suspension.
3. may be able to clear torsion bars on midengine application.

If this mount was to be done I would need to change over to a pancake style type 4.

What about the side shift ? can I change this over to a tail shifter?

Alzax3
24-11-2008, 06:29 PM
Unless I'm missing something - I don't think there would be a pump in a manual transmission to cavitate - the gears normally just run in a bath of oil. If you turn the tranny upside down, you'd want to be sure that they were still adequately covered or they'd wear pretty darn quick.

hildi25
24-11-2008, 06:39 PM
Just making sure before I go doing something crazy (again).

But the shifter problem what is the solution

Alzax3
24-11-2008, 06:42 PM
You'll need someone else to help you with that one, I've no experience of side shifters, sorry!

letterman7
24-11-2008, 07:03 PM
I don't know if those early shifters can be swapped to a tail shift configuration. The place to ask would be here: http://forums.pelicanparts.com/forumdisplay.php?s=&forumid=8
Good reseller of parts as well as a helpful forum.

CyCo
25-11-2008, 02:04 AM
I know several Eureka's have a 901 gearbox, and at least one is running both the 901 gearbox & donk from a 914 (one of my favorite Porkers btw). It does necessitate modding the chassis, but not as much as later Porsche gearboxes.

Spacenut
25-11-2008, 12:53 PM
Ok, so in order to run this tranny as a rear engine, I would need to run it upside down. (I dont know much about trannies) Would this cause a cavitating pump or some type of lubrication issues?
To tell you the truth making some custom transaxle mount has always been on my todo list. This might make it possible to raise the transaxle and motor enough to fix a couple of problems.

1. motor hanging to low/exhaust
2. when you lower the car this custom mount would fix the camber issue on a lowered suspension.
3. may be able to clear torsion bars on midengine application.

If this mount was to be done I would need to change over to a pancake style type 4.

What about the side shift ? can I change this over to a tail shifter?

By "rear engine" I assume you mean mid-engine, in which case the answer is yes, you will have to run the transmission upside down. A friend of mine is building up an Ultima with a smallblock V8 and a Porsche transmission, I think the later turbo variant, and apparently the gears are splash lubricated so there is usually no need for additional oil pumps etc., although they are available for this type of application. This particular car has a relocated starter unit, and an Accusump pre-oiler for the engine.

All Ultimas have a shift lever in the side sill, with a straightforward UJ/spherical jointed rod linkage back to the nose (now tail) of the transmission. A simple extension on the end of the shift rod takes the shift sideways to hook up with the shaft. A centre shift would be more difficult to make work, but it can be done (I have a centre shift on Green Machine).

There is a danger your engine will want to sit lower in the chassis due to the inverted transmission (but you will have to use a custom bellhousing that may address this).

If you use the Porsche or VW IRS then you won't have to worry about swing axle camber change. The Porker transmission cannot interface directly with the swing axle driveshaft "paddles" anyway.

You may have to run the engine at an angle in order to clear the torsion bar tubes and chassis "fork". This is how the Manta/UVA Montage achieved a mid-engine configuration. The chassis was modified with a reinforced well around the centre tunnel to accept the sump pan though. Some (all?) Porkies are dry-sumped so you may have more clearance with a flat-6.

Good luck!

Lauren

hildi25
25-11-2008, 04:47 PM
Sounds like a job that would keep me busy for a while :cursing:

I just about finished my headlight inserts and am about to call it quits. I can only think of a couple more things to do, and this car has totally drained me. The last thing that I can do(free) is use the rest of my gelcoat to seal off the floorboards. The previous owner had layed a nice coat of FG over the vw pan so Gelcoating would be helpful.

later!