Porsche 901 Transmission Help

I have a 4-speed 901 tranny in my speedster. It was "new" when I got the partially assembled car, and it only has 1000 miles on it since I've completed the build, but like many of the supposedly "new" items on the car, it's broken.

When the car is stopped, it grinds when I shift into 1st or reverse. From what I understand, 1st and reverse share the same synchro, so it's busted. I changed the tranny fluid, which helped a little bit.

I've read about some high-tech synthetic gear lube that porsche guys use to temporarily fix this problem. Any ideas what it is?

Notes:
~ I start the car in the gear I want to be in, so it doesn't grind when I first take off - avoiding embarassment - so you can forego that suggestion ;)
~ I'm too broke to get the tranny fixed right now, so I'm just looking for a band-aid

Thanks in advance,
Adam

Do you have enough clutch pedel travel to fully disengage the clutch?
ed

The stuff you're looking for is Swepco- very popular lube for
these boxes, I use it in mine. I'm surprised your car was fitted
with a 901 box, yet a 4, not 5 speed. If your tranny is wearing
out you could pop in a 901 5-speed and get the extra
ratio.

When the 901 box conversion was done, was the little intermediary support bracket and bushing installed in the tunnel? Did they use the Porsche shifter and housing? Without the second support bracket, you'd have difficulty in getting a clean shift into each gear.

Might be nothing more than the install rather than the trans. Over-all the 901 is a pretty stout unit, capable of handling WAY more than the VW engine will ever deliver.

Luck,

TC

The four speed 901 transaxle was a production unit primarily for the US market in the early long hood cars. The last four speed 901 was the 911T model in 1971. The 901 continued in the 914 until that car was discontinued. So there are quite a few people who are well acquainted with 901 transmissions especially if you look over at the Pelican Parts BBS board.

So best case, your transmission is only 35 years old, possibly rebuilt but definately not new... These actually shift decently however and should shift quite well with a rebuild. As you mentioned no other oddities, only the shifting for reverse and first, its likely that everything actually was overhauled and set as required.

So investigate the clutch first. 901 transmissions use a cable clutch and they REALLY strench in the first 1000 miles. The cable always has a bit of tension on it, more than you would suspect is proper. Suggest you adjust up slowly, a bit at a time and if it improves, you are on the right track and that's the problem.

That's the easy, cheap, free fix. Swepco is always a good choice. Check bushings etc. Really check shift linkage adjustment. Just a milimeter can make surprising difference. Do not discount a failing clutch. If you pull the transmission carefully examine and replace that if necessary.

If you wind up replacing the transaxle, as suggested above, look at a 5 speed 901. The later 915 transmission is quite a bit larger and I would be doubtful of its fit without "additional" work.

Hope this helps. Having a "crunch box" stinks!

angela

The 5 speed swap is in the works, as is the 911 motor (which is in pieces in my garage). However, with two years of law school left, and an upcoming wedding, it's going to be a while.

If the clutch isn't fully disengaging, why would it only grind in those two gears?

I'll go find that Sepco stuff and try it out. And take a look at adjusting the clutch.

As far as it being "new," the previous owner said it was rebuilt, just like he said about the Porsche 912 motor that came with the car. However, within the first 4 miles it broke a valve spring, and the flywheel fell off - the guy didn't exactly do the highest quality work with everything...

Where is that bracket and bushing you're talking about, TC? I'lll get under there and check today if I know what I'm looking for.

It is the porsche shifter and housing (and fancy shift knob).

It will grind in reverse and 2nd first to embarass you. Just kidding...

Reverse is always the hard gear to get. 1st is a standard gear but takes the most use so the synchro wears out first. This selector also takes the most wear. A shift problem that is clutch shows up here (1st reverse)first and then becomes evident elsewhere. Once the car is rolling, an out of adjustment clutch (too loose) is not that bad to live with.

Again, the adjustment is easy/free. Bushings and adjustment to the linkage are very strong possibilities.

angela

"Where is that bracket and bushing you're talking about, TC? I'lll get under there and check today if I know what I'm looking for."


IF you're car has the Porsche shifter and shift rod, the builder would have had to fabricate a support bracket for the shift rod.

The bracket would be welded inside the tunnel exactly where the stock Type I support would be. You can't use the beetle part 'cause the 912 shift rod is 1" outside diameter while the Beetle is something like 3/4". Check to see if there is a cut on the side of the tunnel by the shifter to indicate the install.

If you have a stock Type I shift rod and support, hooked to the 901, then none of this applies, obviously. Since your 901 is just a four speed, you may have the Type I set-up in place.

You problems don't really sound like they have to do with brackets and bushings, though. More like syncros and layshaft.

Luck,

TC

I just came across the recommendation for SWEPCO lubricants. Which would be the best weight? 80-120 which would you use with the heat in phoenix, AZ? What weight motor oil 20-50 or which?