That brings the project up to date as of June 2010.
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That brings the project up to date as of June 2010.
Looking good Tom thanks for the update
You need one of these. :D
Tom
Hey Tom; OK, I'll bite. Which one?:D Had a good laugh when I logged on, enjoying the morning here in the Piedmont. Tom
In the photo showing the routing of the oil lines through the longitudinals, it appears that there are only 3 holes for the spring plate cap bolts. Is this just an optical illusion?:confused:
The top one of course! It's for real and still in the Akin/Stuck/Bell car to my knowledge. Good old "Southern" hospitality.Quote:
Originally Posted by Flunder
Let me know if you're going to be around. I'd love to show you the new garage.
Best,
Tom
AEJQX
In 1970 a new version of the 901 transmission was introduced in the 911, designated appropriately as the 911/01 transmission. While the design retained the traditional race oriented five speed shift pattern with a dog leg first, the transmission case was magnesium and a pull type clutch linkage was introduced.
The 911/01 was designed to use the same extensive selection of gears that the factory cataloged for the 901 transmission. While the series production 911/01 gear box had second gear machined integrally with the mainshaft, as did the 901, use of the 904 main shaft out of the Race Department's parts bin allowed racers to build track specific gear boxes.
Old guys like me still associate a dog leg first gear with real race cars at the Targa and LeMans, and we decided to use the original gear box that came in the project car 911 S for the sake of nostalgia and D Series correctness. Outwardly the box looked bog standard and bore no hint of what was stuffed inside.
Last week Scott McPherson tore down the box for inspection. The box still had its factory intermediate plate and side plate intact and of course its original mag case.
An inspection of the internals revealed the standard 7:31 (4.44) ring and pinion but incredibly a very nice surprise: an early factory 904 mainshaft and a custom gear set:
First A 11:34 i = 3,091 pn 901,302,906,10
Second E 17:34 i = 2,0 pn 904,302,909,10 Note: same second gear spec'd for Hill Climb
Third J 21:31 i = 1,48 pn 904,302,927,10 Note: same third gear spec'd for Airfield Circuit
Fourth Q 24:27 i = 1,14 pn 904,302,917,11
Fifth X 28:24 i = 0,88 pn 904,302,923,10
Main shaft allowing interchange of all pinions: pn 904,302,101,00
Limited slip differential pn 904,332,053,00
Finding the 904 main shaft and the AEJQX gears surprised - and delighted - all of us. The last three owners of the car were unaware of the gear box internals but an old POC decal on the quarter window goes some way to explain how they got there: this 1971 911 S nbr 694 had been built up to race in club events at some point in its distant past. But when a car like this well used 911 S coupe became just another old beater, details like a special gear box were forgotten. Today, finding a custom gear set on a 904 main shaft reminds us that these cars were loved dearly and used hard and also that owners spent evenings poring over the gear charts and the factory parts manuals and studied hard to find what worked best at their home track.
Scott will freshen up the box and install an NOS multiple disc self locking differential from Zahnradfabrik Friedrichshafen AG (ZF or "zed eff"), the limited slip differential that fellow board member 911Quest supplied for the project a while ago.
The 901 and its direct descendant the 911/01 set the standard for sports car transmissions and drew rave reviews from the motoring journalists of the day. It continues to delight drivers of the early long hood Porsche 911. Unquestionably, the 901 transmission is a masterpiece of design and its use is one of motordom's great pleasures.
Yup, good enough for a hot rod.
Gear Sets
Code Ratio Gear
A 11:34 (3.091) 1
AA 12:34 (2.833) 1
B 14:37 (2.643) 1
C- 12:29 (2.417) 1
C 15:36 (2.4) 1
CA ?:? (2.31) 1
D 16:35 (2.188) 1
E 17:34 (2) 2
F 18:34 (1.889) 2
G 18:33 (1.833) 2
GA 18:32 (1.778) 2
GB 16:30 (1.765) 2
H 19:32 (1.684) 2,3
HB 19:31 (1.632) 2,3
HA 20:32 (1.6) 2
I 20:31 (1.55) 2,3
J 21:31 (1.476) 3
K 21:30 (1.429) 3
L 22:30 (1.364) 3
M 22:29 (1.318) 3,4,5
N 23:29 (1.261) 3,4,5
O 23:28 (1.217) 3,4,5
P 23:27 (1.174) 3,4,5
Q 24:27 (1.125) 3,4,5
R 25:27 (1.08) 4,5
S 25:26 (1.04) 4,5
T 26:26 (1) 4,5
U 26:25 (0.9615) 4,5
V 27:25 (0.9259) 4,5
W 27:24 (0.8889) 4,5
X 28:24 (0.8571) 4,5
Y 28:23 (0.8214) 4,5
Z 29:23 (0.7931) 4,5
ZA 29:22 (0.7586) 4,5
ZD 31:22 (0.7097) 4,5
Note that the factory gear chart excerpted from the Sports Purposes manual and attached below provides calculations of speeds in each available 901 gear, The calclulations on this chart are made with a 7:31 ring and pinion and a 4.75/10.00-15 Dunlop Racing CR 65 tire. Alternative charts are provided for the 6:32 r&p and similar charts appear for various tire/final drive combinations, indicative of the high level of importance that the Race Department ascribed to proper gearing.
Great news Tom, most appropriate for another hot rod!
Hoping to get my box and engine out later this year to see what is in there!
Another nice surprise Tom !
Coincidentally I bought a gearbox with those same ratios for my latest project - some interesting information/opinions on the suitability here:
http://www.early911sregistry.org/for...ghlight=ratios
Nice find Tom!