5-speed shift pattern: 915 vs RUF 930

[blue72s]

Gentlemen,

I wish to inquire about the forward gear inside the front cover of the 5-speed 915 and the RUF 930.

What gear (1st or 5th) was inside the front cover with the reverse gear of the 915 and RUF 930 respectively? If both were 1st gear, why was shift pattern of the RUF 930 different to the 915?

Is it true that both the 5-speed 915 and RUF 930 only had four gears inside the main gear housing?

Secondly, if Porsche were able to put a forward gear inside the front cover of the 915, why weren’t they able to do that in the 4-speed 930 as well?

[javadog]

A 915 has a reverse and fifth gear inside the front cover. A Ruf 5-speed has a reverse and first gear there. That would explain the shift pattern difference.

Yes, both had only 4 gears inside the main housing.

It's impossible for me to second guess why Porsche did anything, but I'll toss out a couple of possibilties. Porsche decided that the 930 needed stronger, larger gears, to cope with the gretly increased torque capacity of the transmission. They also likely figured (rightly so, in my opinion) that four gears were enough, given the flat torque curve of the turbo motors. They also decided to use a larger version of the rubber centered clutch than was designed for the 915, thus they needed a longer bell housing to accomodate the dimensions of the clutch assembly. When Ruf built their five speed, they used a different type of clutch and cast new housings for the gearbox, including one that shortened the bell housing, as the rear of the gear box got longer with the added gear.

JR

[blue72s]

Thanks