any one Revers 3 and 5 gears, Transmission gearing |
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any one Revers 3 and 5 gears, Transmission gearing |
wes |
Feb 28 2013, 02:30 AM
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#1
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wes Group: Members Posts: 1,588 Joined: 8-December 07 From: Ukiah Ca Member No.: 8,436 Region Association: Northern California |
I am looking for thoughts on reversing 3 & 5 gears, was at Sonoma raceway today and talking to a 914 racer back in the years who offered this info. Any one have thoughts or info on this idea would be of interest! Thanks
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Luke M |
Feb 28 2013, 07:22 AM
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#2
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Senior Member Group: Members Posts: 1,372 Joined: 8-February 05 From: WNY Member No.: 3,574 Region Association: North East States |
I have a side shift gear box that has the 3 rd & 5th gear swapped around in it.
It makes for a short 3 rd & 5 th gears. I had it in my 70 914 1.7 in the early 90's. It was ok for the auto x and short race tracks. I feel that it wasn't good for street driving. I recall having to shift from top of 2 nd to 4 th gear on street driving. 5 th gear was short and gas mileage suffered on the highway. I guess it depends on what you're doing with the car too. Like I said on the track it was ok but not so great on the street. |
pcar916 |
Feb 28 2013, 10:09 AM
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#3
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Is that a Lola? Group: Members Posts: 1,523 Joined: 2-June 05 From: Little Rock, AR Member No.: 4,188 Region Association: None |
I ran this way for 11 years. Loved it. Like stated above the highway mileage takes a hit, but it makes third gear a lot more useful in my book. You'll hear at least one other thing too, that the gear angles are reversed in the third gear pair.
That forces the shafts in the opposite direction. If your bearings are good then it's not an issue because they're double row balls and designed for that kind of thing. If they're worn however then you could get a slightly different R&P gear mesh pattern from the difference in pinion depth... may or may not be a problem. Regardless, and especially in a high horsepower car, I'd want to verify the condition of the bearings. I'd do it again but prefer, in a street car just leaving 5th alone and getting a second 5th gear pair to replace third. |
brant |
Feb 28 2013, 10:48 AM
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#4
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914 Wizard Group: Members Posts: 11,624 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
It creates what is called a "Ka" ratio.... close to an M gear for third.
very commonly done for decades.. I have one box like that. or you can buy an M ratio |
McMark |
Feb 28 2013, 10:54 AM
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#5
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Leave the stock fifth for freeway use. I've got spares and they're not hard to come across. If you plan on doing big track racing, getting a lower fourth would be a good plan.
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wndsrfr |
Feb 28 2013, 08:00 PM
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#6
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Senior Member Group: Members Posts: 1,429 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
Definitely do it if you really want to enjoy DE events. It was one of the best things I've ever done to my car.
I did the swap on mine after finding that at the DE events the stock tall gearing just wasn't doing it for me even with 165rwhp on my 2316 engine. The overly tall ZD 5th just doesn't allow for any acceleration, so 5th is simply useless other than to maintain. Flipping 3rd & 5th and putting an "S" in 4th position created a wonderful set of ratios...use 3/4/5 for entire track at Summit Point, VIR, Roebling & CMP. The engine loves it--you're always in the best torque band, just great. Is there a downside? No. Not really. Sure, you'll be seeing higher revs on the freeway--who cares? Fuel mileage? Really? For a car that you're tracking? When 100 unleaded is $9/gallon at the track? No big deal in reality. Cruising around town is excellent--can use 5th in the ubiquitous 45mph zones even. Again, get an "R" or "S" to put in for 4th to get proper spacing....you'll love it! (IMG:style_emoticons/default/driving.gif) |
brant |
Feb 28 2013, 09:30 PM
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#7
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914 Wizard Group: Members Posts: 11,624 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Also we should note...
MSX or Ka, S, X is great for a 4 cylinder on most tracks..... not great for a 6 cylinder. think about it.. if your readline is 6250rpm.... its a whole different gearset from 7250rpm... and don't even consider it at 7800 rpm.... msx is the common 4 cylinder gear set, but not a 6 cylinder set up for most tracks.... (RA may be an exception) |
wndsrfr |
Mar 1 2013, 08:47 AM
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#8
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Senior Member Group: Members Posts: 1,429 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
Also we should note... MSX or Ka, S, X is great for a 4 cylinder on most tracks..... not great for a 6 cylinder. think about it.. if your readline is 6250rpm.... its a whole different gearset from 7250rpm... and don't even consider it at 7800 rpm.... msx is the common 4 cylinder gear set, but not a 6 cylinder set up for most tracks.... (RA may be an exception) Hmmm......not to hijack, but what's the sweet spot for a /6? |
Dr Evil |
Mar 1 2013, 09:58 AM
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#9
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Send me your transmission! Group: Members Posts: 22,999 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region |
Gearing always depends on:
- Use; long straights, DE, street - Tire and wheel package - Engine power band/engine type |
campbellcj |
Mar 2 2013, 11:51 AM
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#10
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I can't Re Member Group: Members Posts: 4,545 Joined: 26-December 02 From: Agoura, CA Member No.: 21 Region Association: Southern California |
I have a box set up this way too - Ka, Q, V - good for short technical tracks and/or with an engine that can rev. Not streetable.
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