Upgrades to type 911 Transmissions

[randywebb]

I thought I'd start a thread to summarize these topics since we have some recent threads and two curent ones on doing this...

First, the type 911 tranny (aka gearbox for those who used that term in a search to get here) refers to the gear boxes that many call 901 -- but they are really a bit different. They were used in 1970 and 1971 911 cars, are were an imporved version of the 901, before the first (Mg cased) 915 trannies were debuted.

Second, the advantages of these boxes is that they are lighter than the 915s and have the great racing shift pattern with 2nd & 3rd in line. A year or so ago, I posted a pic of all the trans.s used in 911s lined up: 901/911/915/G-50 -- so "the truth is out there." (sensu Mulder)

Now, there are several upgrades that can be made:

1. If your trans has a "simplified differential" you can replace the bolts with the nipples on them (that tend to break) with some pins. There is a thread on this, and a friend of mine is going to post all the p/n's when he gets them ordered.

2. There are some pivot bolt upgrades that can be done...

What else? Are there stronger side covers (as with the 915s)?
Other upgrades that can be done?

Can the differential or R&P be replaced to alter the final drive ratios?

Are there any nicely ratio'd gear sets that one can rob from a 914 box?

[DByers]

Subscribed.
Thanks for starting this thread Randy!

[Grady Clay]

Randy,

Great idea. Please do the Pelican (and other) research and post links. I‘ll review everything and post my lame 2¢.

Here are the links that I keep in my file.

’70-’71 clutch”
clutch cable for 70-71 901
and
'70-71 T.O. arm play?
and
http://forums.pelicanparts.com/porsche-911-technical-forum/166598-clutch-cable-70-71-901-a-post1520882.html#post1520882
“How to ID a Type 911 transmission”
How to ID a 911 ty[e transmission tranny
“Moving the clutch lever pivot ball”
Moving the clutch lever pivot ball

“'70 (pull) clutch woes -- help!” Good photos.
'70 (pull) clutch woes -- help!

'70 clutch still broken, help needed to make race
'70 clutch still broken, help needed to make race

911 Gearbox Rebuild Underway. Beadblast?
911 Gearbox Rebuild Underway. Beadblast?

There are several more recent.

I need to convert them to “URL” format and we need to write an abstract & index for each.


Let’s make the goal of this thread to document the Type 911 transmission from 1970 and 1971. That includes the clutch & linkage, shifter, axles, etc.

Best,
Grady

[davidppp]

Hello all.

Grady I'm sure already knows this, but one of the 911's I've worked on had no needle rollers under 5th loose ( non-splined) gear.
just steel on steel plain bearing..

Seemed to be OK..

Only time I've seen it tho'..

other thing..I beleive the factory 914-6GT racers ( targa Florio) had 911 clutch set-ups..I always wondered why they did not use this to eliminate the clutch cable pulley..then last year found a picture somewhere on the net of the spares taken to the targa..including what I was sure was a pull clutch side shift tranny..

kind regards
David

[randywebb]

Here are the 911 transmissions in chronological order:

[randywebb]

Here is a pivot ball like the one on my transmission:



hope it can be seen ok - for some reason you can only post 100k byte pics... regardless of what the posting box says..

[Grady Clay]

Randy,

You have a 215 mm push-type clutch and a Type 901
transmission not a pull-type common to the Type 911
transmission with the 225 mm clutch.

Here is the arm and parts for the earlier 2.0 215 mm
push-type clutch. This was used ’65-’69.




Interesting when I went to clean the clutch release bearing,
one swipe with BrakeKleen revealed the original Sachs part
number. Note that someone has hand changed the
number. When you see this, “Built by Hand” takes real meaning.




I’ll clean this up with solvent so it doesn’t erase the numbers
and re-post the image.

Note the socket head cap screw still has the original
cadmium plating from ’67.

Best,
Grady

[randywebb]

Grady, FWIW, that isn't the trans in my car. I have a type 911 in the car with a 225mm clutch, and the thing is coverted to push-type operation. That is a pic of a ball head pivot mount stud that is like the one in my trans. {edit made to clear that up}

[randywebb]

1. Throw Out guide tube is longer for the 2.2 than the 2.0.
2. The 2.2 pivot (#5) is not in the same location as the 2.0.





Another trick you can do is to grind a grove in the face of the guide tube (#1 above) where it contacts the transmission case.
The grove should go straight down from the input shaft seal.
This provides an alternate path for any oil that leaks past the seal to
not go directly into the center of the clutch.

[Zeke]

Also, since the pull type cable rides in a plastic piece at the tranny, that is upgradeable to a steel piece, AFAIK. There was something in the Pelican catalog about replacing the plastic sleeve with metal, but it's gone or otherwise not with the model we are talking about cable section. Anyone what to chime in and point that out?
Here's what I'm talking about:


Here's the gizmo in metal:

[Clay Perrine]

Originally posted by davidppp
Hello all.

Grady I'm sure already knows this, but one of the 911's I've worked on had no needle rollers under 5th loose ( non-splined) gear.
just steel on steel plain bearing..

Seemed to be OK..

Only time I've seen it tho'..

other thing..I beleive the factory 914-6GT racers ( targa Florio) had 911 clutch set-ups..I always wondered why they did not use this to eliminate the clutch cable pulley..then last year found a picture somewhere on the net of the spares taken to the targa..including what I was sure was a pull clutch side shift tranny..

kind regards
David

Actually, that is a very easy to do upgrade for a 914. I have a six conversion with a 73 2.4 MFI motor in it. I used a 71 911 trans, with the 914 side shift rods and tail cone. This allows me to use a 225mm clutch, and there is no clutch pulley. The cable runs straight to the firewall, and the clutch tube does not carry a load.

There were no factory 914s done this way, but some of the early conversions, as documented in upfixen, used this clutch setup.

[randywebb]

Zeke - the little metal can? I have it on mine - but it may not work on a 'real' 1970-71, since my car is a '73 with the 911 trans. installed onto a 3.2L motor.

[Zeke]

Originally posted by randywebb
Zeke - the little metal can? I have it on mine - but it may not work on a 'real' 1970-71, since my car is a '73 with the 911 trans. installed onto a 3.2L motor.

Pelican says it's a replacement for the first imaged part that I just now got up there.

'Splain it to me, RW.

[DByers]

Milt & Randy, I have the upgraded metal piece that Pelican shows as an upgrade on my trans which is original to my 71 2.2T. This part is the only part that hasn't caused me any recent problems.

[afterburn 549]

me too (watch)

[randywebb]

Simplified Differential thread:
Simplified Differential!

Pics of the total wipe-out of your tranny when this failure happens:
901 let go with a bang!


How To Do the Simplified Differential Upgrade:

How To: Simplified Differential Upgrade

[randywebb]

Dam Seal and guide tube mods to prevent oiling of the clutch on a 901 (applicable to a 911):

Transmission input shaft oil seal on a 69 what's involved in replacing?

[randywebb]

Info on 901/911 Gear Sets:

How to identify 901 gearsets

and...

Identifying 901/911 Gears versus 915 Gears