912 trans

[effvee]

Hello everyone. I have a question concerning the late model 912 (1978). My question is, in the late model 912 there was a 915 installed; instead of the 901 with a tail shift. However, if the 915 was also used in the 912 withe different gears, can anyone verify this? Also would there be an out side marking on the case? I have a Super Beetle that I would like to install the trans into, without forsaking to tail gear ratios. Anyone know of this?

[WFBowen]

The 912E (1976 model year only) used a type 923 gearbox. Unique ratios, etc. These gearboxes are getting a little hard to find in useable condition (some of the 911 autocross guys also like them for their ratios.)
I'm no VW expert, but considering the availability of parts, price, and the fact that your existing case (dimensions, mounts, etc.) could be used wouldn't it be better to merely "re-ratio" your existing transaxle?
Bill.

[effvee]

Hello, I really want a 5 speed trans, with a .82 fifth gear. Gene Berg sells a conversion kit, but by the time you buy the kit, have the pinion welded to except the fifth gear; this transmission will cost about 2,500. The trans you have mentioned, is there a code for it, or some type of outside the case designation for it? At one point I bought a Rhino case, and Quiafe ATB, but the extra 2,500 just made me believe to much money going into the trans area. I will still need to re-think this matter, thank you

[C. Clark]

I don't have any idea but try here http://www.912bbs.org/index.php they have E site.
Chas.
356
912
911
no 78E to my knowledge

[WFBowen]

The trans is designated 923/02 (not sure if there was an "01".) Again, these are pretty rare items - how about a good old 901 5sp? Lots of these around and an almost infinite number of factory/aftermarket gearsets available.

[effvee]

Hi, thanks for you help. The 901 I'm told have a weak first gear. Even though a 915 will over come the first gear weak spot, it leaves allot of modding for my Super Beetle; and then there is the issue of to tall gearig. So the 923 looks like a very good option, and I'm not in a hurry. I'll keep at it, but thanks allot

[MarKoBrow]

Why not just regear a 915? Lots of them around and you can sell or hold on to that rare trans for future use. The same amount of work would go into either conversion

[effvee]

Hi, my problem with the 915 trans is, not with the 915 trans itself; but all of the different ratios there are out there in the 915 trans. I don't know of any outer marking on the 915 that would let me know the gearing. No doubt the 915 will handle more that I can throw at it.

[MarKoBrow]

I think there is Literature that outlines the ratios available based on year and model installed

[JP Noonan]

With domestic rear ends it's pretty rare to find one with the build tag still on it. What is normally done is to turn the drive shaft input (with a camshaft install card/protractor) until the axle goes around one time.

On a trans-axle I see your problem. Nice thing about Porsche tranny's is the code is cast into the bottom of the case, bad thing is the bottom of the case tends to scrape on the ground.

On top of all the different gears there are at least two ring and pinions. The 923 and some pre '75 915's 7:31, later they get a 8:31 to improve MPG.

I wonder how many REVERSE gears there are? If there is only one then maybe you could figure out the Ring and Pinion by turning an unknown "crunch-box" in reverse. Once you know the R+P ration you can figure out the five forward gears.

Other things about the 923/02 vs. the 915:
The clutch guide tube and the release mechanism are different (more like a 901 than a 915 or a 930 4 speed)
The input shaft has smaller clutch hub splines, and I'm not sure the 915 has the guide bearing the Type-IV has.
and of coarse different ratios.

FWIW my 912e owners manual list the 923/02 as
Ring/Pinion Ratio 7:31
1st gear-11:35
2nd gear-18:33
3rd-23:29
4th-26:25
5th-29:21

The 1976 911s Type 915/44 trans
R/P Ratio-8:31
1st-11:35 AZ
2nd-18:33 HX
3rd-23:29 NT
26:26 QQ
28:22 SN

[effvee]

Hi, from what I found out, all the gear ratios are different because of the 4 cylinder engine. I would like to find a 912 trans, maybe in need of syncro replacement, and buy it. What is the price range of one that jumps out of gears in your pinion?

[JP Noonan]

Tom will tell you that the parts alone to freshen up a 915 are about $700.00

Last time I did one was a 915 out of a 73 targa I think.Cost about $750 for gaskets, nuts,bolts, and 1st gear syncro. Got some used parts and borrowed the tools to rebuild it, so figure $1000+ to have a shop do it. I think $1500 is common for a warrentied rebuild.

Some short cuts are to swap the gears around to "shorten" 2-4 and still have a decent over-drive. I drove a 930 with the short bell housing 4 speed that had tis done. 1st gear was literaly 0-10 mph. I could not down-shift into it at all, and if I tried to cruise 15 mph in a school zone in 1st flames would shoot out my hollowed out wastegate muffler. I can't remember the exact letters, but ask a tranny guru and they'll know what your talking about.

Basically if you get a pre 1976 or 1975 with the higher ring and pinion you'll be O.K. with a torque heavy Type-IV.

Another consideration is after physically throwing these trannies around...a 5 speed 901 is about 75 lbs a 915 is 115-125 and a 930 4 speed is a "team lift" 175lbs give or take. The 5 speed 901 is a lot smaller in the mid section too. Done right a 901 can easily hanle 200 hp.

Sickly rear shift 901's are dirt cheap. 915's that are not a "box-o-rocks" still cost $500 if your lucky, and $750+ if you go to a Porsche graveyard. Look at the boneyard adds in the back of Panorama or Excellence. You'll pay maybe $100 more but they will know for sure what they are selling you .vs a swap meet hustler.

[effvee]

I see I will have my hands full. My engine is going to be a 2.9 type IV twin turbo. I really hope for at least 300 horses. At this point its either the 915 trans or a type II automatic fully rebuilt. I pretty much have all the engine parts except for the cylinders, and I'll get them just as soon as I deal with a legal matter in Germany. Attorney fee, I bought a set of high performance heads for my project and the guy sent me very badly damaged goods un-insured through bulk mail. That was 4000.00 US and no telling what's the legal fees are going to cost.

Thanks for all of your help.
fvercher@charter.net

[Matt Monson]

Might I suggest based on your location you get in touch with Shan at Rancho Performance. he's kind of unique in that he deals with a lot of type II and type IV VW stuff in addition to 356 and early 911. He might have some ideas as to what sort of transmission set up would be best for your project. He builds top notch trannies and is a great resource that isn't all that far from you.

As for your earlier questions, while there are many many ratios available for 915's the vast majority of cores out there would still be filled with stock gears. If you find a tranny that you consider a viable candidate to build upon, just post up the type number off the bottom of the box and someone here will be able to provide what ratios should be inside of it.

[effvee]

OK, I'll contact him, and I also will keep my eye open for a 915 to post for spec's on ratios.

Thank you very much