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> Boxster Transmission into 914?
roamer
post Oct 6 2007, 06:02 PM
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Ok Guys-

I have searched around the board for some time as I begin formulating my plan for an STI swap into a 914. One of my primary concerns is the transmission. The 901 will not withstand my power goals (~450hp), nor will a 915. A 4-speed 930 transmission is inappropriate for the subie powerband. I know that a G50/xx will work, but what about the transmission from the boxster? It is my understanding that the torque capacity of these transmissions are equivalent to the G50 and it seems to me that it would be a better solution since it was designed for a mid-engined car.

Any guidance would be greatly appreciated!

Thank you.
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GeorgeRud
post Oct 6 2007, 06:06 PM
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It's been done, but it takes a buttload of fabrication. The entire rear trunk is basicaly removed from what I've read. Check with Search.
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Dave_Darling
post Oct 6 2007, 06:45 PM
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There's a thread on the Pelican 914 BBS with a link to an older thread that has pictures...

--DD
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Beachbum
post Oct 6 2007, 08:01 PM
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QUOTE(roamer @ Oct 6 2007, 05:02 PM) *

Ok Guys-

I have searched around the board for some time as I begin formulating my plan for an STI swap into a 914. One of my primary concerns is the transmission. The 901 will not withstand my power goals (~450hp), nor will a 915. A 4-speed 930 transmission is inappropriate for the subie powerband. I know that a G50/xx will work, but what about the transmission from the boxster? It is my understanding that the torque capacity of these transmissions are equivalent to the G50 and it seems to me that it would be a better solution since it was designed for a mid-engined car.

Any guidance would be greatly appreciated!

Thank you.



This is a great question. There has to be more options then the 915 930 G50 route. There are so many other porsche and other transaxles out there. What about the newer 996 and 997 Boxes?
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davep
post Oct 6 2007, 08:09 PM
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Some of these can be used I guess. You have to be able to reverse the output or you will only have one forward gear, and a variety of reverse gear selections. You also will have to fabricate your own drive shafts. The may also be interesting problems adapting the engine & tranny, installing a clutch and the starter. Gear shifting could be a problem as will speedo connections. Mounting could also be a big problem. Nothing is impossible as long as you have the cash.
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neo914-6
post Oct 6 2007, 08:35 PM
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search here or Pelican for abc914 or 914abc, it is running with a 3.2 six. There are 5 and 6 speeds, the later is stronger but highly doubt either are as strong as a G50 for your hp. Me and ajracer have the 5 speed. His is mated to a V8 and he has ran it, mine is directly mated to an Audi V6tt and mounted in the car. I am working on the wiring and other details. The trunk is intact but the trunk to engine bay wall was fabbed.
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Chris Hamilton
post Oct 6 2007, 09:11 PM
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Would it be more or less expensive than the awesome ZF gearbox from a pantera?
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wbergtho
post Oct 6 2007, 10:49 PM
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QUOTE

This is a great question. There has to be more options then the 915 930 G50 route. There are so many other porsche and other transaxles out there. What about the newer 996 and 997 Boxes?

Those are G50 series boxes and need to be mounted inverted (cannot flip R & P).
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roamer
post Oct 7 2007, 12:45 PM
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So if I understand everyone correctly, the Boxster tranny is actually a less appropriate solution than a G50 from a fitment standpoint?

In that case it seems like a G50 is a better solution. Other than mounting adapters, CV Joints and linkage, is there anything else needed to make the G50 work?
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Brando
post Oct 7 2007, 12:56 PM
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Could try a 951 transmission or 968 transmission. 968 has 6-speed. You'll already have to fab up shifting, but you can do a cable setup for either of those. Shifter input is on the top/rear of the trans.

You would have to devise starter mounting, and release lever mounting.
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BMartin914
post Oct 7 2007, 03:50 PM
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QUOTE(Brando @ Oct 7 2007, 10:56 AM) *

Could try a 951 transmission or 968 transmission. 968 has 6-speed. You'll already have to fab up shifting, but you can do a cable setup for either of those. Shifter input is on the top/rear of the trans.

You would have to devise starter mounting, and release lever mounting.


and a way to mate the clutch sine those T/As have the clutch in the bellhousing at the other end of the torque tube. Would be interesting to see it done that's for sure.
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Brando
post Oct 7 2007, 03:56 PM
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On opposite sides yes. Supposedly the spline count on the input shafts for those is the same as the spline count for the driveshaft where the clutch rides. There's a clamp between the driveshaft and trans that goes over both splined ends.
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SirAndy
post Oct 7 2007, 03:57 PM
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QUOTE(roamer @ Oct 6 2007, 04:02 PM) *

my power goals (~450hp)


i know of at least two 914s (seen and touched both) that have double that HP and both of which run a 930 gear box ...
(IMG:style_emoticons/default/shades.gif) Andy
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roamer
post Oct 7 2007, 04:27 PM
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QUOTE(SirAndy @ Oct 7 2007, 05:57 PM) *

QUOTE(roamer @ Oct 6 2007, 04:02 PM) *

my power goals (~450hp)


i know of at least two 914s (seen and touched both) that have double that HP and both of which run a 930 gear box ...
(IMG:style_emoticons/default/shades.gif) Andy


Andy- Unfortunately the 930 tranny won't match well to powerband of the 2.5 turbo.

The 951 tranny also seems like more fabrication work than is reasonable. I am not trying to invent a new way, just find a way that works best.
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Brando
post Oct 7 2007, 04:28 PM
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Well... Hello Boxster trans, goodbye rear trunk!
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SirAndy
post Oct 7 2007, 05:16 PM
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QUOTE(roamer @ Oct 7 2007, 02:27 PM) *

Andy- Unfortunately the 930 tranny won't match well to powerband of the 2.5 turbo.


could you re-gear it to be a better match?
(IMG:style_emoticons/default/idea.gif) Andy
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Twystd1
post Oct 7 2007, 06:39 PM
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You can buy darn near any gear set imaginable for the 930 trans.

They ain't cheap. And they are available.

The 935 used the 930 trans. Hence the plethora of gear ratios.

Clayton
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Brett W
post Oct 7 2007, 08:53 PM
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The Boxster tranny has no provision for a starter. Have one in my shop for use in my race car. You will have to come up with another way to start the car.

Might want to look at the Subie tranny. But I doubt you will make that much torque. I would guess you probably won't make more than about 300ftlbs and it will come on late in the game so you won't be snapping first gear off the shaft. Turbo cars are pretty easy on gearboxes compared to NA engines.
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roamer
post Oct 8 2007, 11:45 AM
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Thanks Guys!

4 speeds will be tough to match to the somewhat limited powerband of the 2.5t, so the 930 tranny is out (the stock is a close-ratio 6-speed). It also sounds like it is more work than it is worth to make it work in the 914.

It also sounds like the boxster and 951 trannies are out as well.

Besides renegade, does anyone else modify the housings of G50's to fit into the 914? (I like their products and will probably use many of their components, but some seem overpriced) KEP makes the mounting adapters, but does not appear to modify the transmissions from what I can tell.

Also, who would you recommend as a source of used/rebuilt transmissions and other used parts?

Thanks again.
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Brett W
post Oct 8 2007, 04:41 PM
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How much torque do you anticipate making? The Audi 016 box could be an option.
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