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Posted by: BillJ Mar 31 2023, 12:46 PM

Not looking now

Posted by: rgalla9146 Apr 1 2023, 09:02 AM

I think you're looking for a 911 trans from '70-'71, not a 901 (911 300 000 00) It's the first version with the pull type clutch.
As you probably know a 914 trans can be converted, I have the correct throw out arm.
My brother has a 911 type for sale but it's here in NJ
I sold one to Joe Cogbill of CogsCogs a couple years ago, he's from Georgia
Call me if you like, I pm'd you

Posted by: BillJ Apr 1 2023, 12:58 PM

Hey Rory. Actually the boxes used in 914s and 911s and 912s up to 71 are all 901 type gearboxes. They just have quite a few variants. From 1970 to 1971 the ones used in the 911s changed to the pull style. Here is the secrion from.Cogs Cogs website:

""The first transmission designed for the 911 was called the 901 transmission. This unit was used in different variations in the 911, 912, 914 and 914/6. The early versions used sand-cast aluminum cases and the later ones used pressure-cast magnesium. These were 4 and 5 speed transmissions with a torque input rating of 138 lb/ft, later uprated to 148 lb/ft in 1969. The fact these transmissions have been used with engines producing more than 230 lb/ft of torque, albeit with shorter lifespans (measured in broken gear teeth), speaks volumes about the basic design. In 1970, Porsche changed the 901’s clutch actuation and called it a 911 type gearbox. These were still 901-type transmissions now coupled with a larger, pull-type clutch actuating mechanism. Clutches used in these cars were the 215mm unit used from 65-69 and the 225mm unit used from 70 to 71"

Gonna call you in a bit

Posted by: ClayPerrine Apr 1 2023, 06:23 PM

The 70-71` 911 transmission that used the pull type clutch was different in the bellhousing area. The pivot point for the throwout arm is in a different location than the 914 trans, and it is reenforced with a steel "top hat" insert to prevent pulling out the threads.

Converting a 914 trans is NOT recommended. It will pull the threads out of the case in short order.

Also, the throwout bearing and pressure plate are unique to the 70-71 911. You can put in the later pressure plates, but they have too much pressure for the 70-71 911 clutch setup. And the throwout bearing is completely different from the later ones.

I know all this because I have a 71 911 trans that is converted to a side shift 914 trans, re-geared for the 2.4 S motor it is hooked to, sitting on the floor of the garage. I have a plan for the whole drive train, but it has not come to fruition yet.

Posted by: BillJ Apr 2 2023, 07:46 AM

Hey Clay. Yes my current box is the 70-71 as well. I either need to get a second box in the same config or change gears (haha) and switch to the more common 901 push style. Honestly it would be alot more convenient to have the more ubiquitous configuration as on race day i would assume if something breaks there are a lot more spares around for other 901 boxes than the 2 year only 911 version. Not to mention the pull style isnt a great design.

Posted by: Bernie B Apr 2 2023, 10:41 AM

Hi Bill- We have a 914 Side shift with 7:31 R&P, GT Torque sensing LSD with A, GA, KA, S, Z gears. under 1,000 miles since built. Street not race miles.

Posted by: davep Apr 2 2023, 10:56 AM

What you want is another 914/6 box; it has the vent in the correct location and the end cap to mount to the 914.
The internals of the case are generally 901/902/911/914 so spares are in good supply. Some of the very early 901/902 may have a smaller threaded section on the input shaft. You really want to stick to the 911/914 differentials since there were a few incompatible versions with the 914; particularly the aluminum case. There were two 914/6 cases, an early and a late with the late version in greater numbers. The two can be distinguished by the location of the serial: on the rib or off to the side; the latter is more desirable.
The 914/6 is set up for the 215 clutch/flywheel. The 225 clutch/flywheel has more capacity, and the pull type actuation is a direct draw on the 914 dispensing with the pulley.

Posted by: rgalla9146 Apr 3 2023, 09:15 PM

Bill the box I sold to Cogbill was a flipped diff. '70-'71 911 with pull type TOB, side
shifter and 914 rear cover.
Maybe he still has it.
I do have the clutch fork and a NOS TOB.
The bad part about this trans especially for a race car is the method needed to
seperate the trans from the engine.
My brother has at least one of these transaxles.
Going to Carlisle ?
Maybe we can meet

Posted by: BillJ Apr 4 2023, 01:10 AM

Not going to make it to Carlisle but would have sure been nice to meet up!

I need to make a decision on this and will do so soon. Will be reaching out to inquire on some of these options soon. Leaning toward selling my current box and using those funds to move to a simpler model. And i just bought a new clutch. Figures lol

Posted by: stownsen914 Apr 6 2023, 04:02 PM

I realize this seems to be turning into a tech thread, but the pivot point for a 70-71 911 clutch fork is in a slightly different spot than the earlier 901s and 914 transmissions. (It also has an insert to have stronger threads and also spread the load.) and I found this out the hard way lol when I had a 914 trans case "converted" to 70-71 style case, and the machine shop missed that the pivot point was different.

I've had the 70-71 style in my 914 racecar for many years and generally has been trouble free using a late 915 aluminum pressure plate. I did break a pivot bolt once, a known weak area.

Posted by: ClayPerrine Apr 7 2023, 05:45 AM

I think I said this already...

The reason the pivot bolt breaks is due to putting a later 915 pressure plate on it. It has a lot more clamping force and the stock pivot bolt can't handle the load. If you are going to use that pressure plate, then you need an aftermarket bolt. They are generally stronger and can handle more load.

Posted by: BillJ Apr 14 2023, 10:17 AM

Ok so headed a different direction. Will be offering my current box for sale and am working with Dr. Evil to get one built up. Thanks everyone for their knowledge and advice.

Posted by: stownsen914 Apr 14 2023, 12:46 PM

There are a couple things. The bolt itself, and the insert in the case. Sometimes people try to just screw the later pivot bolt into a 901/915 case. Not strong enough, and not in the right place either.