A possable cure for missed shifts??

[wayne savage]

Ok I have been scraching my head thinking about this. With all this talk of rev limiters. Why not use a rpm transducer, to fire a silianoid at a given rpm to push in the clutch or cut the cable for that matter.if you hit 3rd gear insted of 5th. Then have your rev limiter shut of the engine.. just thinking?? PS in my 12 years of P car ownership I never killed a engine from a missed shift.However I am knocking on wood right now..



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You can stick a Beetle motor in a 911.But you can not! Put a 911 motor in a Beetle....
Wayne Savage 72S MFI

[pwd72s]

The biggest, and I assume most common goof? Shifting DOWN from 5-2 instead of 5-4. In my years with a 915, never was the 4-5 shift a problem...

[rattlsnak]

>>>if you hit 3rd gear instead of 5th<<<
Well, you didnt say if you were coming from 2nd going up, or from 4th going down! However, PWD is correct, nothing you can do to "solve" a mechanical over rev by going down. The engine technically doesnt even have to be running for this to happen. Something will come apart!

(been there, done that)

[Saffs]

The 5th to 2nd risk is a hard on in my car. For some reason, even though the gearshift is tight (just 60,000 miles on it), it's really easy to hit 2nd from 5th.
I gently ease the clutch in just to check sometimes. Often I just go to 3rd.

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'75 911S Targa
'81 BMW Alpina C1 2.3

[This message has been edited by Saffs (edited 09-30-2001).]

[Saffs]

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'75 911S Targa
'81 BMW Alpina C1 2.3

[This message has been edited by Saffs (edited 09-30-2001).]

[josh912]

Wayne has something going here. Especially with the newer cluch systems being hydrolic. If the engine over reved to a certain, predefined point (due to a miss shift), above where the rev limiter is, the electronics could cut out the ignition, and engage the cluch. This would shut down the engine, 0 rpms. Albeit the engine still would over rev, it would not over rev as long, as the computer is much faster than us, and probably would catch it while the clutch was still initially engaged resulting in the engine not reved up to the full rpms in that particular gear.

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Joshua Harrison
1968 912 Coupe
www.geocities.com/jkh912

[ChrisBennet]

I went with AASCO valve springs and some Titanium retainers. Now I can (seemingly) miss all the shifts I want. In the meantime I've found other ways to blow up my engine.

-Chris

[na2ub]

Side topic. I heard that if you downshift without pre-revving the engine to the appropriate higher rpms, you can burn the valves. Anyone heard this?

[john walker's workshop]

add that to the list of old wive's tales.

[rscupper]

I don't think any OEM would provide the means to shut down your power at speed on the streets. I would guess lots of liability issues - a la 'spontaneous' change of driver input in Volvos, and don't newer models have some sort of power assisted steering & braking?. But, maybe some type of system like this would be OK as supplied by an aftermarketer for track use.
I would still prefer control at all times (I guess I'm kind of a mechanical control freak).

[josh912]

If your paranoid, sell your Porsche and buy a new one with a tiptronic!

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Joshua Harrison
1968 912 Coupe
www.geocities.com/jkh912

[wayne savage]

To Josh 912, I would never sell my 72 911 S. And when I am dead they will have to pull my cold dead hands off of my leather sterring wheel, before any body can have a chance of owning my 72 911S

[wayne savage]

To Josh 912. I will never sell my 72 911 S. Infact, when I am dead,they will have to pull my cold dead hands off from my leather coated steering wheel, before any one will have a chance of owning my 72 911 S. Buy a new one with a tip. How could you insult me that way.