911/01 Transmission issues

[Brett Voigt]

About a year ago I bought a 69' 912 that had a VW 1600 DP engine in it. It drove around ok, but I had the intent of putting in either a 912 engine or a 911 engine. In retrospect, it didn't shift very well and would grind a fair amount when trying to shift into 1st and reverse, but I figured it just needed a new clutch. Well last fall, my grandfather found a 68' 912 engine that was a perfect fit for it. After bolting everything up, we noticed a grinding everytime we tried to shift into gear. We figured it was the clutch and installed the Sachs clutch kit, but still had the same issue. After looking closer at the trans, it wasn't the 901/06 as should have come in the car, and turned out to be a 911/01 from a 70-71' 911. We bought a new transmission fork that we thought would work, part #90111671200, but there's a gap in between where the fork connects to the throwout bearing. It's off by about 7/16". I've searched a number of places but can't find a fork that looks like it will fit. Here are some pics to help.

Notice the gap between the fork and the throwout bearing (measures 7/16")



The old fork is on the Right and it looks like a PO modified it to fit for the VW engine. We found the new fork on the left for about $50



All that in mind, does anyone know of the part number to a fork that should work?

If not, what is the best way to modify it? Would it be better to drill into the case 7/16" closer to the bearing and move the ball (and seal up the old hole) or drill into the fork and move the nylon cup?

Also, it looks like the ball in sunken in. Does anyone know how elevated it should be from the case?


Last, we haven't seen any pictures of a transmission fork that has a bend in it like ours... is that normal or did we buy a bad fork?

I'm posting this in the 911 section purely solely on the fact that this is a 911 transmission but I can move it to the 912 section if need be. Thanks.

[Jon B]

You have a 911 transmission designed for a "pull clutch" arrangement.
There is no bolt-on fork that will work with a 912 clutch unless you drill the case for a different pivot pin location.

[Brett Voigt]

Originally Posted by Jon B

You have a 911 transmission designed for a "pull clutch" arrangement.
There is no bolt-on fork that will work with a 912 clutch unless you drill the case for a different pivot pin location.

If we move the pin 7/16" closer to the throwout bearing, the new pin hole will overlap with that of the old pin hole. The exact center of the pin would be right at the raised edge and the outer rim where we'd drill reaches would contact the outer rim of the old hole. I'm no engineer, but I imagine that can't be very strong. That in mind, is there a way to fill in the old pin hole to increase stability?

[Jon B]

Originally Posted by Brett Voigt

If we move the pin 7/16" closer to the throwout bearing, new pin hole will overlap with the old pin hold. I'm no engineer, but logically that can't be very strong.

I would agree, I was not recommending it, although someone else might say that they've done it and it worked fine for them.
I was only saying that there is no stock, bolt-on fork that will work on that transmission with a 912 clutch.

[Brett Voigt]

What about getting a clutch fork from a 911/01? I'd assume that should have the correct spacing... but would it be more structurally sound to adjust the clutch fork as opposed to the transmission case?

[Jon B]

Originally Posted by Brett Voigt

What about getting a clutch fork from a 911/01? I'd assume that should have the correct spacing... but would it be more structurally sound to adjust the clutch fork as opposed to the transmission case?

That is a different type of clutch fork. It pulls the bearing towards the transmission, and the cable end faces the other direction...

[Brett Voigt]

Should the clutch for have a bend like that? Also, does anyone know how high the pin ball should be?

[Hawk2109]

Brett, I think that this issue that you are having with your gearbox grinding is not clutch related, but rather synchronizer wear instead.

I would recommend that if you are going to continue to use this gearbox, that you rebuild it with some new parts, and probably new bearings and seals. This should take care of the grinding issue that you are having. As to the fork not reaching the TO bearing correctly, I would think that you have two options. One would be to use the 911/01 fork, and the other would be to have a machinist make you a new fork out of billet aluminum or steel. I would not think that this would be overly hard for most shops.

Good luck, and let me know if you are in need of any rebuilding parts. We work on these all the time.

Erik Johnson
(720) 899-6005 phone

[Jon B]

Originally Posted by Brett Voigt

Should the clutch for have a bend like that? Also, does anyone know how high the pin ball should be?

The surface on which the pivot ball sits measures 100mm from the end of the bellhousing on a 901 transmission.
From the photo, your replacement fork appears to be bent.

[Brett Voigt]

We are still deciding which route to go... that in mind we were wondering how much the throwout bearing needs to travel to engage/disengage the clutch? If we move the pivot point closer to the bearing, then we will not get as much travel. If that's the case, I think our best fix would be to find a 911/01 clutch fork and modify then ends to fit my needs.

[Trackrash]

Originally Posted by Brett Voigt

We are still deciding which route to go... that in mind we were wondering how much the throwout bearing needs to travel to engage/disengage the clutch? If we move the pivot point closer to the bearing, then we will not get as much travel. If that's the case, I think our best fix would be to find a 911/01 clutch fork and modify then ends to fit my needs.

You might want to do some more research on the pull clutch design. It's a can of worms to switch over to that design, and parts are not cheap, considering they were only used for two years. The throwout bearing is $260 and will it work on your clutch? '70 and '71 clutches used 225 mm pressure plates. A new clutch cable will be needed and it will use the loop on the transmissions side plate. Look here for the parts you will need. 1971 Porsche 911 S Coupe/Targa - Clutch & Flywheel - Page 4

Do a search, this topic has been discussed previously. Moving the pivot has been done, I'm not sure if it is a good option.

Obtaining the correct transmission may be a better choice.

[john walker's workshop]

Better off finding a '69 transmission. There's one on Seattle craigslist right now. One year only. The 70/71 fork will not work as a push type. It's pull only. The hook on the end points the wrong way. A 914 fork is the same as the 901 fork.

[Brett Voigt]

Originally Posted by john walker's workshop

Better off finding a '69 transmission. There's one on Seattle craigslist right now. One year only. The 70/71 fork will not work as a push type. It's pull only. The hook on the end points the wrong way. A 914 fork is the same as the 901 fork.

When we bought the 68' engine, the guy was selling the matching trans with it. Really kicking myself for not springing for it.

[Matt Monson]

If it were me I would find an earlier case, pay for a rebuilding and have them move everything over. You need someone who knows how to set up a ring and pinion. But your build deserves it. I've read some of your other threads in the 912 forum. It's worth doing this right.

[Jon B]

Originally Posted by Brett Voigt

When we bought the 68' engine, the guy was selling the matching trans with it. Really kicking myself for not springing for it.

If your car has 69 axles and CV joints, a 68 transmission will not work without early 69 axle flanges that fit early differentials.
Those are pretty rare & expensive items.
Nor will an early aluminum-cased 69 transmission work without those same axle flanges.

I think you should open your current transmission, and if in generally good condition, have it re-cased with a magnesium 69 main housing, or any 914 main housing after re-positioning the breather.
If your transmission has major issues inside and is not worth re-casing, then find a complete 69 transmission to replace it.