924Board.org

[ptheskil]

I don't mean in a racing situation but in normal driving when you are trying to preserve transmission/synchro life. No special techniques like double declutching but ordinary single declutching with rev matching. I have always changed reasonably slowly allowing time for each of the operations to complete during the change.

I heard an argument recently that you should always shift as quickly as possible so that you provide the maximum force on the synchro cones and allow slip for as little as possible. Whereas I always believed that a steady approach was better since the medium for shear force transfer is the oil film which will transfer the force with little wear if you are using the correct oil.

Would be interested in your opinions.
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1981 931 series2 Euro spec

[ideola]

Bottom line, if you shift too quickly / firmly / forcefully on the G31, you will grind the dog teeth to nubs. So nice easy "pushes" and "pulls" are ideal. All of my street cars now have G31s, and all have been rebuilt (aside from the CGT, which shifts perfectly); in all cases, if you "power shift" from 1st to 2nd, you WILL catch the dog teeth even on a freshly rebuilt gearbox, which over time will ruin them. There's sort of a rhythm to it. In some theoretical universe, there may be some ideal way to shift to preserve the synchros (which I am not qualified to comment on), but in my opinion, it's not the synchros you should care about as much as the dog teeth. Synchros are relatively cheap and still obtainable. Dog teeth, not so much.
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erstwhile owner of just about every 924 variant ever made

[MikesCoupeGT]

In regards to how fast you should change gears. I find that if you are deliberate in how you change, there is no point in rushing the gear change. Keep it fluid and smooth and in the end if you are enjoying your car that is what matters.

When I shift I blip the throttle on up and match rev's on down shifts. That is my way of doing it.

regular street driving you don't need to be fast. For track driving you want to speed it up, but it always gets faster with practice.

just my two cents.
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Cheers;
MikesCoupeGT
'76 924
'83 944
''19 Elantra GT N-Line

[Rasta Monsta]

Interesting theory on the quick shift, but I don't buy it. On my 931 with snailshell, I treat shifting (especially the 1-2 shift as mentioned by Dan) as a two step process. . .1 to N, then N to 2. I think this keeps my snail happy (along with Redline gear oil).

FWIW, I also am in the habit of rev-matching and double clutching on downshifts, so my snail will probably outlast the car!
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[fiat22turbo]

Here's a quick drive in my 924 with the snailshell:

http://youtu.be/4XgLYJVX3gQ

Just testing the camera (wrong location and wrong recording setting), but it should give you an idea on how slowly a snailshell shifts, especially 1st/2nd.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[Ponz]

If I am not in a hurry I skip gears on all my cars without any problems.
Sometimes 1-3-5, 1,2,4. I have been doing it forever and never had a tranny fail. Around town in slow traffic normal shifting.
Porsches owned about 9 in 45 years. Not bad, I think.
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77 1/2 track car
79 931 Euro
87 911 Targa

[staticsan]

I find my non-snailshell 5-speed box can usually take faster shifts than I am willing to do, especially once it's warm. But I don't like doing that because it feels I'm forcing the selector. I much prefer that the gearbox "wants" the gear when I change. Which means not too fast - it is technically a selector, after all, and shouldn't need lots of force! (My Lancer was the same, which I had to remind my Dad a few times.)

On downshifts, I sometimes, but always, blip the throttle coming down. I often come down from 4th straight to 2nd. But I've done that in all the cars I've owned.

Wade.
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'82 British NA - Which I think I've been very lucky with!

[Fasteddie313]

edit, decided to make it a new thread...
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80 Turbo - Slightly Modified

[924RACR]

Certainly they'll pop out of gear pretty quickly, as you're just unloading things. I'd say, as a rough measure, that around 1 second to go from Neutral to in-gear is a good rough guideline, at least on a non-snail box. Though yes, we do it a bit faster in the racecar, and it can deal.

But on the street, I prefer not to force things. Unless I'm driving a test car; then I've had it down to as little as 200ms. (with data to prove it)

Oh, yeah - it's also possible to go TOO slowly, and then the synchros don't work due to lack of enough pressure to operate, and you end up grinding the gear anyway! LOL But it's pretty obvious to tell when you've done that...

HTH...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[pmcaya2]

As Mike said " Keep it fluid and smooth". It's hard to hurt a manual transmission in normal driving.

It's more important when you shift than how fast. I regard my 924 as peaky - wind it up in the lower gear and shift smoothly to the higher gear with enough revs to stay on the power curve for the up gear. In other words, don't bog it down.

Fluid and smooth - the engine shouldn't know you shifted. Likewise if you have to slow down in traffic, down shift to stay on the power curve - again don't bog down the engine. If I could make a rule - shift to please your engine.

[SlayerSST]

G31/Dogleg = Junk. Remove and take to scrapyard for money.

[Rasta Monsta]

Lolz
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Cedric]

[fiat22turbo]

[pmcaya2]