Dyno - 4th gear, why?
Thread Starter
Instructor
Joined: Dec 2000
Posts: 107
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From: Frankfurt/Main, Germany, Europe
Dyno - 4th gear, why?
Well, a few days ago we went to the dyno for the first time and unfortunately they did the testing in the wrong gear. Instead of using 4th (1,00:1) they used 5th (0,74:1). We do know that the results are wrong, however, we wonder how much off they might be. Any ideas? Can the error be calculated? Anything else I need to know?
Btw.: Why should one use the gear with the ratio 1:1? Could anybody explain this to me?
Thanks in advance
Mike
Btw.: Why should one use the gear with the ratio 1:1? Could anybody explain this to me?
Thanks in advance
Mike
Melting Slicks
Joined: Feb 2002
Posts: 2,613
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From: Winston Salem NC
Re: Dyno - 4th gear, why? (noC5yet)
If every car is dynoed in 1:1 the results can be compared. Except of course for rear gear differences. If they made the mistake they should do it over, free of charge.
Drifting
Joined: Apr 2001
Posts: 1,763
Likes: 24
From: Austin TX
Re: Dyno - 4th gear, why? (noC5yet)
Lets see if I can explain this. With most (probably all) manual transmissions, they have an input shaft, a counter shaft and an output shaft.
The input shaft is geared directly to the counter shaft. The synchronizers spin with the output shaft, while the gears on the output shaft free wheel on needle bearings. When the transmission is put in gear it engages one of the synchronizers onto one of the output shaft's gears. Therefore, in 1,2,3,5,6 there are two gears sets through which the power must travel.
In the 1:1 gear, our 4th gear, the synchronizer connects the input shaft directly to the output shaft. Power does not travel through any gears in the transmission. The counter shaft free wheels with no load placed on it.
Eric
The input shaft is geared directly to the counter shaft. The synchronizers spin with the output shaft, while the gears on the output shaft free wheel on needle bearings. When the transmission is put in gear it engages one of the synchronizers onto one of the output shaft's gears. Therefore, in 1,2,3,5,6 there are two gears sets through which the power must travel.
In the 1:1 gear, our 4th gear, the synchronizer connects the input shaft directly to the output shaft. Power does not travel through any gears in the transmission. The counter shaft free wheels with no load placed on it.
Eric
Racer
Joined: Sep 2002
Posts: 483
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From: Austin Tx
Re: Dyno - 4th gear, why? (66ImpalaLT1)
I will add that there are lots of transmission that do not have a 1:1 straight through arrangement. Almost all of these are found in foreign cars (Prosches, Ferraris,...)
Thread Starter
Instructor
Joined: Dec 2000
Posts: 107
Likes: 0
From: Frankfurt/Main, Germany, Europe
Re: Dyno - 4th gear, why? (66ImpalaLT1)
Thank you for this very helpful explanation! Now I guess I got that! I do really appreciate that you guys take your time to help me!
Cheers
Mike
Cheers
Mike
