Advantage of the 4 speed
03-01-2005, 11:59 PM
#1
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Advantage of the 4 speed
I know this question is O/T, but I was wondering if anyone knew what was the advantage of porsche using the 4 speed transmission in the early 930's instead of a 5 speed ?
03-02-2005, 02:21 AM
#3
Race Car
Strong like bull.
Also, a weak-weak-weak-then-strong-strong-strong-strong motor doesn't benefit from close-ratio gears. With boost, you want to let the thing wind out.
But mostly, it's: strong like bull.
Also, a weak-weak-weak-then-strong-strong-strong-strong motor doesn't benefit from close-ratio gears. With boost, you want to let the thing wind out.
But mostly, it's: strong like bull.
03-02-2005, 03:34 AM
#5
RL Technical Advisor
Originally Posted by JackOlsen
Also, a weak-weak-weak-then-strong-strong-strong-strong motor doesn't benefit from close-ratio gears. With boost, you want to let the thing wind out.
But mostly, it's: strong like bull.
But mostly, it's: strong like bull.
I raced 935's in the late seventies and early eighties and they did FAR better with close ratio gears, given the narrow power range these have and the state of tune that a 935 is in,....
One used an 80+ MPH 1st gear with 1000 RPM splits for most short tracks. Daytona, Brainerd, and Road America used different gears, of course.
03-02-2005, 04:28 AM
#6
Race Car
You're correct, of course. But I'm looking at it from the perspective of the street-driven 911, where feeling the boost kick in is such a big part of the fun (and keeping it 'on boost' is simply not a prudent option.) You get more of a sense of a 'launch' with long, tall gears. I'm sure the Porsche salesmen loved it.
I have no idea if that played any role in Porsche's decision to only have four gears, though. Probably not. In fact, it's probably a decision they almost immediately regretted, since it made for less-flattering ad copy.
I have no idea if that played any role in Porsche's decision to only have four gears, though. Probably not. In fact, it's probably a decision they almost immediately regretted, since it made for less-flattering ad copy.
03-02-2005, 05:03 AM
#7
RL Technical Advisor
As you probably know, Porsche discovered that the 915 was woefully inadeqate in the Carrera Turbo RSR 2.1 and if they were to race these cars sucessfully in FIA Group 4/Group 5, a MUCH stronger tranny was required.
Since they went through the same thing with the 917 (5-speed failures) they elected to do a 4-speed to ensure sufficient strength and a margin for those 24 hr races with 700+ HP. FIA required homologation for every part so the 930 HAD to be sold with the same 4-speed that they needed for the race cars (934/935).
I still have all my 934 and 935 factory manuals with all of the FIA homologation documentation,.....
Porsche chose the (lousy) 930 gear ratios with EPA CAFE regulations in mind,.........a tall 4th was required to avoid gas guzzler penalties and a low 1st to avoid toasting that smallish 240mm clutch.
Voila',.............Now one had an ultra-wide ratio box ill suited to the peaky power delivery. They didn't address this problem until after the 934/935's were retired with the G-50/50 Turbo 5-speed. Thats one strong hombre,......
Since they went through the same thing with the 917 (5-speed failures) they elected to do a 4-speed to ensure sufficient strength and a margin for those 24 hr races with 700+ HP. FIA required homologation for every part so the 930 HAD to be sold with the same 4-speed that they needed for the race cars (934/935).
I still have all my 934 and 935 factory manuals with all of the FIA homologation documentation,.....
Porsche chose the (lousy) 930 gear ratios with EPA CAFE regulations in mind,.........a tall 4th was required to avoid gas guzzler penalties and a low 1st to avoid toasting that smallish 240mm clutch.
Voila',.............Now one had an ultra-wide ratio box ill suited to the peaky power delivery. They didn't address this problem until after the 934/935's were retired with the G-50/50 Turbo 5-speed. Thats one strong hombre,......
