SWB Short Gears

[jaudette3]

My '67 rally car has a good gear box in terms of performance, but it's really loud. I'm going to remove it and have it rebuilt it in order to quiet things down. It's noisy across all gears and I suspect it's the ring and pinion.

While I'm at it, I'm flirting with the idea of going with shorter gears. German Transaxle here in Bend has a lot of gears on hand (they tell me that the 901 in the 911 used the same gears as the 914), so this is the perfect time to change things. It's currently got the stock short gears, A-F-M-S-X, which I really like. But I think I recall Kenik and others here recommending an even shorter set for these cars, something like A-E-I-O-U (the so-called "vowel set"). That seems *really* short, but I love the pop. This car isn't used as a highway cruiser anyone.

The engine is the original case built to 2.7 specs with PMO's, the original Solex cams and other goodies. The car has dyno'ed at 220HP.

Any recommendations would be appreciated.

Best Regards,
John

[kenikh]

As far as gears go, I’ve run the gamut and if you still want to do an occasional trip on the freeway, there is no better gearset than this: AA-F-K-Q-X

I can honestly say that this is the gearbox Porsche should have put in these cars. You get the same road manners as your AFMSX, but unbelievable gear splits all the way up. The drop from 4th to 5th isn’t as quick as S to X, but realistically, who needs to speed shift at redline in 4th? This gearset gets the performance shift right where you’ll use them. The other nice thing is that you don’t have to go searching for a bunch of esoteric gears since, you already have 3!

I compromised and went with A-F-Ka-Q-X, since I couldn’t find a AA 1st and the K 3rd was too expensive. KA is a flipped ZD 914 5th; nothing wrong with it, but some people grumble about axial loads…blah, blah, blah – never met a 901 guy that has ever seen an issue with flipped 901 gears. Given that you are a details man, I figure you’d want to know all of the options.

I’ve driven 2000 miles in one trip on this gearset, half of which were on some of the twistiest roads in California. This was in a Solex cammed 2 liter SWB and it is the most responsive, fun and quick gearbox I have ever driven in a small bore car. If you don’t have an LSD, might as well add one while you’re in there since it sounds like the R&P has to come out.

I guarantee you’ll love it!

[Allen Henderson]

Well, I just put a ZD 5th in my 901. Going to go with the '67 stock-look 2.4E/S engine I'm building for freeway cruising and better gas mileage. All other gears remain stock. I'm tired of 4,000 rpm+ just to keep up with freeway traffic these days. Should go down to about 3,200. I'll let you know in a few months.

Yes, this is counter to what you want to achieve John but is what I'm doing.

-Allen-

[kenikh]

I'm with you Allen - the 4th to 5th split is really inconsequential, as long as the other 4 gears play nice. I'd be tempted to even try A-F-K-Q-ZD one fo these days. If you really wanna fly, try flipping a 4 speed 'H' in 5th (I call it ZH below). That gear has 200 MPH potential!

[Allen Henderson]

I'm with you Allen - the 4th to 5th split is really inconsequential, as long as the other 4 gears play nice. I'd be tempted to even try A-F-K-Q-ZD one fo these days. If you really wanna fly, try flipping a 4 speed 'H' in 5th (I call it ZH below). That gear has 200 MPH potential!

On the way home today, I was thinking how fast a SWB with ~210 hp could go? And...I decided that if I'm to find out EVERYTHING needs to be in tip top shape. I'll have to upgrade to a three point harness and a helmet

How do I read the bottom chart? Along the X axis, is that RPM and, if so, how many per division. Regardless, I think you talking about a REALLY tall gear.

-Allen-