Gearbox identification again - please.

[MTemp]

I am restoring a 66 SWB LHD 911 in the UK (see my DDK thread - ID MT on DDK - if you're interested) - the engine is per the CoA but the gearbox is not.
In the car was a 902/02 Serial No 1284779 with date stamp 2/68 (could be 2/66)
Body casting No 901.301.101.0R

I have also got another box in similar (good) condition 902/01 Serial No 224034 with date stamp 33/65. Body casting No. 901.301.101.02

Can those of you with either good memories and/or the necessary paperwork give me the details of each - 4 or 5 speed, ratios , casting metal etc etc - and any opinion as to which would be the best match to the car for both originality (assume the earlier box) and performance/reliability/suitability (the later one?)

I have searched both this website and DDK and get part of the story.
Any advice much appreciated.

Mick

[ajwans]

902/02 A-F-M-S-X
902/01 A-H-Q-X

They are both sand cast aluminium based on those
dates. Mag cased transaxles were introduced during the
1969MY.

andy

[davep]

In the car was a 902/02 Serial No 1284779 with date stamp 2/68 Body casting No 901.301.101.0R
I have also got another box in similar (good) condition 902/01 Serial No 224034 with date stamp 33/65. Body casting No. 901.301.101.02
Mick

1284779 is a 1968 MY trans.
224034 is a 1966 MY trans but should be type 902/1 which is a 5 speed A F M S X , please confirm.

[MTemp]

You are right Dave - 902/1 - didn't take enough care with the typing. Also can you tell me what the A-F-M-S-X etc indicate (gear ratios?). Do I gather that I therefore have two identical boxes (re 5 speed, ratios, casing metal etc) in everything but build date and casting part no?

[ajwans]

A 11:34
F 18:34
M 22:29
S 25:26
X 28:24

The 902/ boxes were original fitment to a 912, others will know more than me but
I have read that Porsche used gears of cheaper manufacture when building 914
boxes, I wonder if this also applied to 912 transaxles.

Grady would know for sure, I'll email him to see if he would mind chiming in.

andy

[preS]

A 11:34

The 902/ boxes were original fitment to a 912,

I don't think that is all correct. I do know that the 902/02 was a 912 box, but the 902/1 is a standard 911 box from summer 65 on.

As for the gears. 914 gears are VW gears (and not marked). 911 and 912 gears are bot Porsche gears.

Just my $.02
Richard

[ajwans]

Unfortunately I don't have the source of this scan, here's
what I have on 902 transaxles:



I do see 902/0 & 902/1 against 911 also. I will defer to Richard
regarding the 902/1 being standard for 911.

andy

[Grady Clay]

Mick,

OK, you have:
Type 902/02 transmission Nr. 1284779 with date stamp 2/68.
Type 902/1 transmission Nr. 224034 with date stamp 33/65.

Andy & Dave are correct (as usual).
The 902/02 #1284779 is a 1968 MY, cast in the 2nd week of January 1968.
This 4-speed was geared A-H-Q-X with the ratios as Alex notes. EDIT 902/02 is indeed a 5-speed; AFMSX.
This transmission has the ‘simplified’ differential, needing update.
You can confirm the ‘simplified’ differential by the lack of aluminum plug in the center of the transmission axle flange (you can see the hex head of the stretch bolt).

The 902/1 #224034 is a 1966 MY, cast 33/65.
The online week number calculator:
http://www.comptoncity.org/index.php...ate=1965-08-15
Reports week 33 of 1966 as: Sun. 15 Aug, 1965 - Sat. 21 Aug, 1965.
This seems unusual as most of West German industry was closed for holiday.
Anyone have input?

The 902/1 # 224034 is a 5-speed geared A-F-M-S-X and is appropriate for your 1966 MY 911.
Type 902/xx transmissions were not unique to 912s and were commonly used in 911s (including my ’68).
The 902/1 has the ‘regular’ differential, not needing update.
You can confirm with it having an aluminum plug in the center of the axle flange.

The 902/1 does not have the ‘reinforced’ input shaft (started ~mid-’67).
If (when) you ‘go through’ this transmission, this is a worthwhile update.


The 901, 902, 904, 905, 906 and 925 all used the same high-quality Porsche gears manufactured by Hirth, Getrag and more.
The type 822 gears (used in the 904/6 and others) are similar high quality with additional lightening and many ratios between the others.
These are easily differentiated from the interchangeable but lower quality and unmarked 914 gears.
The Porsche gears have matching ‘pair numbers’ on each gear.
The date-of-manufacture is stamped in each.
The number (I for input or II for pinion) of each in the pair is stamped in each.
The gear ratio (and differentiation of 3rd gear) is stamped in each.
With many early sets, the part number of the individual gear is stamped in that gear.

As with everything about early Porsche, the above should be taken with a ‘grain of salt’.
There are many variations with time and manufacturers.


These transmissions are very easy to DIY repair and re-gear.
Only a few operations require professional (and special tool) setup.
Once set, re-gearing and many repairs can be done without re-adjustment.
Be sure to measure the (usually several) shim gaskets between the intermediate plate and the main casting.
These are the ‘final setting’ for the pinion depth position.

Since you already have two transmissions, consider buying other ‘cores’ for spare parts (and the desirable ‘F’ 2nd gear ‘reinforced’ input shaft).
You can accumulate a selection of ratios to use for various applications.

Please post your VIN and engine number. Dave’s list may help you narrow the range of numbers for a closer-to-original number transmission.

I hope this helps.

Best,
Grady

[MTemp]

Thanks for this Grady - one clarifying question. You say box 902/02 is 4 speed, but the Andy's grid shows it as 5 speed, geared the same as my 902/1 box.
Both boxes have been reconditioned 1284779 just completed, 224034 by a reputable recognised specialist, but some years ago.
The Kardex shows the original box as 902/1 231609, so my plan was (is as long as it's a 5 speed) to use the 902/1 box and keep the other as a spare.

The engine No is 908021 as per CoA/Kardex stamped 901/05 4889 to right of the fan shroud, Chassis No 304780
Kardex shows car as a 1967 MY RS Deluxe. DavP has the details from my UK DDK restoration thread.

Mick

[Grady Clay]

Added above:
EDIT 902/02 is indeed a 5-speed; AFMSX.

Dumb and blind ol' me jumped a line.

Thanks for the correction.

Best,
Grady