915 Tranny, Is it usable on a 914 with a 3.0L? Options

[Kevan]

What do you need to do to make a 915 tranny work on a 914-6 with 3.0L and up motors?

Kevan

[Brad Roberts]

My shop number...LOL

We can flip the 915 diff for mid-engine and set it up with a WEVO mid engine shift linkage . Plan on 5k+. Every single 915 we have pulled apart for R+P flip has needed a new pinion bearing carrier. They are all loose in the cases after 100k miles.

It can be done on the cheap.. but if you want it to shift like a late model car...

Oh.. the 5k included a new Limited slip.

Bottom line.. price is dependant on your core tranny.


B

[Britain Smith]

Lots of stuff...you should give me the 915 tranny for my car.

Actually, you have the flip the diff to make it set-up for mid-engine config. You should also look into WEVO's 915 products for 914's. They make a badass end plate casting to convert a 915 for 914 use. Here is a pic on a race car with a 915.

(IMG:http://www.britainsmith.com/Porsche/Yeaman/images/128_2837_JPG.jpg)

-Britain

[Brad Roberts]

7500$+ in that box with short ratio gears/new LSD and all labor involved for a rebuild and new bearing carrier. This doesnt include the shift linkage.


B

[Britain Smith]

more...

Side View:
(IMG:http://www.britainsmith.com/Porsche/Yeaman/images/128_2852_JPG.jpg)


Hydraulic Throw-out bearing...
(IMG:http://www.britainsmith.com/Porsche/Yeaman/images/128_2840_JPG.jpg)

[Britain Smith]

Last one..in the car...

(IMG:http://www.britainsmith.com/Porsche/Yeaman/images/128_2868_JPG.jpg)

[Kevan]

All I need it to do is work. With no grinding between 2 and 3 and an LSD or short gears isn’t need. So what would be the estimated cost for the ring and pinion swap with a new syncro for second and the WEVO mid engine shift linkage?

And will the 914-4 half shafts bolt up to the 915?

Thanks
Kevan

[Kevan]

Thanks for the nice pixs of the tranny.

Kevan

[Dave_Darling]

I think that some year 915s have flanges that let the 914-4 CVs bolt up--but not all years.

If you do not get the über-trick Wevo parts, you will need to fabricate a shift linkage or find an old old Vellios "916" setup.... And I'm not certain of the quality of those any more. You will also need to deal with the clutch linkage, though that is a lot easier than the shift linkage.

Someone makes a cable-shift setup for the 915 in a 914. It works--mostly. I know one guy who has that setup, a 3.0 + 915 with cable-shifter. His comment is, "Big mistake. I should have just bought two 901 side-shifters and enough parts to build them 3 or 4 times. It would have been cheaper and easier, and worked better."

The stock 901/914 gearbox, when fresh, will hold up to a stock 3.0 for a good while. Just ask MikeZ.

--DD

[Kevan]

I just don’t think the 901’s first gear with a 3.0L can handle SCCA Pro Solo’s. And if I started off in second it might be too slow off the line.

Guess I’ll half to wait and see what happens with the 901.

Kevan

[TimT]

You can get shorter 2nds for a 901 a bit spendy though... you need a 904 mainshaft...not a expensive as the 915 WEVO upgrade though

most 901 boxes Ive opened had F, G or GA, second gears...

Id have to rummage around and find out the shortest second you can install D or E?

I have a 250+hp 3.2 with a short geared 901....and a built spare tranny (IMG:style_emoticons/default/laugh.gif) I only use the car on the track so first is only used to get rolling

[Kevan]

Where could I get a shorter 2th gear?

What is the differences between F, G, GA, D, E gears?

Thanks
Kevan

[TimT]

Porsche made alphabet soup with the gears in the 901 boxes. Each letter represents a gear ratio....

To use a shorter second gear... you need to use the 904 mainshaft, so you have the cost of the mainshaft plus the cost of the gear set you choose

I have the info somewhere...maybe someone else will pipe up with the letter/ratio cross ref for 901 gears..

[Brad Roberts]

Oh.. Kevan,

Your 6 conversion mount came in.

R+P flip: 200$ plus parts (the case needs minor clearancing as well as a shift rod mod)

The WEVO parts are 1800$

You can use a stock clutch cable (I can show you how to do this)

The 914/901 R+P will only last about 6 months of "Christmas Tree" launches before the teeth decide to the leave the premises.


B

[Dave_Darling]

Charlie Davis has a table of the various 901 and 915 gear ratios that were (at some point) available. Many are NLA or rare as hen's teeth now, but Paul Guard (gears at gte dot-net) can generally rustle up or make any of them you really really really need.

On a 901, 2nd gear is part of the mainshaft. To change it, you either get another transmission, or you swap to the 904 mainshaft. Which is big $$.

There's a decent chance that a 901 1st-gear will stand up to a 3.0 launch, as long as you never "dump" the clutch. Z used to do burnouts in his, and it didn't explode for the several years he owned the car after he put the fresh tranny in.

I wouldn't think that the R&P would be a problem with a stock 3.0 motor. I know that it is in a 2.8 L full-on SCCA race motor, though. The pinion gear teeth start galling, then they shear off the shaft. Making for a very interesting paperweight and conversation piece. "Hey Dave--know what this means??" "Uuhhh... No...." "It means I have enough torque!!" (IMG:style_emoticons/default/lol3.gif)

I am told that the R&P mesh is a problem with built 3.0s and 3.2s. There was a discussion about that a year or so ago on the Racing list over on Rennlist.

--DD