Pelican Parts Forums - "Proper" way to shift a 3.2 Carrera

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Originally Posted by Quicksilver (Post 5912315)

The problem with the above bit that I've quoted is that it is all wrong except for the part about helical gears being used for road cars because they are quieter. (Listen to the rising scream of the wonderful straight cut gear noise as Hans Stuck tears up the Nordschleife in the M3 GTR.-> YouTube - Hans Stuck (BMW M3 GTR) au Nürburgring. All that rising scream is straight cut gears.)
I'm left wondering how much you know about the inner workings of manual transmissions.
(As to quantity that I know: The first time I was asked by someone on another race team to rebuild and modify a transmission was in 1984. I have done a few... If you want to learn about transmissions I recommend opening a BW T40 or T50. You can completely disassemble one with nothing but a socket set and a heavy duty snapring plier.)

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I have been to a few driving schools and raced in the past but I have never heard anyone suggest this is a big effect in the 87-89 G50s for a street application, albeit spirited. Can you suggest some references? further reading? I understand the turbine analogy...just looking for some more info.

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The reason that race transmissions use straight cut gears is simple and it has nothing to do with shifting. It is simply because helical gears create a side load when force is passed through them.

Straight cut gears have lower frictional losses which is a big deal on race cars.

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The effect of the boundary layer friction is very real even if it counter intuitive. This effect is much stronger if you barely disengage the clutch

I didn't know that, but it might explain why adjusting the clutch stop makes a big diff.

I knew I had my shafts mixed up :)

Thanks for the clarification, Sherwood & Wayne. In the end, I think there is an advantage on the street to double-clutching, but on the track, I've never found time for it. I certainly rev-match, especially on the 3-2 downshift, which I use often, and it definitely allows me to get into 2nd easier.

On the street, I routinely double-clutch from 6-5, 5-4, & 4-3. It's just giving back to the Porsche gods.