How many types of 901 trans 5 speed?

[dan67]

hallo! 2 questions:
How many types of 901 trans 5 speed? mag or alu? All 901 trans are suitable?
I have 911 2.2 E 1971 (big fork trans)

[Grady Clay]

Dan,

No, not all 901/911 transmissions are suitable for your ’71 911E. You have a type 911 transmission (probably a type 911/01 5-speed). This transmission is unique to ’70-’71 911s. There are only a few (and rare) parts that allow a 901 to fit your ’69-’71 axles.

The most significant differences between type 901s and type 911s are the clutch size (225 mm vs. 215 mm) and the method of actuation (‘pull-type’ vs. ‘push-type’). There are other differences. Most type 901s have aluminum castings. A few ’69 901s have magnesium castings. All ’70-’71 type 911 are magnesium castings. The type 911s have slightly wider 1st (+ 0.6 mm) and 2nd (+ 0.8 mm) gears necessitating some different hardware and parts.

Early (pre-’68) 901s have a smaller input shaft threaded portion. The ‘reinforced input shaft’ started in late ’67.

All transmissions’68 to ’71 (possibly including yours) have a “simplified differential”. This proved disastrous as it can cause unexpected complete failure of the transmission. Please search Pelican archives on ‘simplified differential’. You should find out if your transmission has been updated. Instructions on how to determine this and how to update are in the archives.

Depending on your use, many like the earlier gear ratios. This makes 2nd through 5th slightly ‘shorter’ (901 5th closer to 911 4th). You probably have gears labled A-GA-O-V-ZA and many 901s have A-F-M-S-X.

Best,
Grady

[dan67]

perfect!