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

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.

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.

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

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.

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!

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?

Gearing always depends on:
- Use; long straights, DE, street
- Tire and wheel package
- Engine power band/engine type

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.