Seeking Transmission advice

Most speedster owners who want lower rpm on the highway go with a 3.88 ring and pinion gear (also know as a freeway flyer).  This will space out all of your gears.  In most cases the 3.88 works fine.  I have a 3.88 in my tranny, but I'm swapping it out for a 3.44, because I want even lower highway cruising rpm.  My 2276 has the torque to handle the 3.44 gearing, but I wouldn't recommend it for a 1915.

So, leave your 1 through 4 gears alone and change the ring & pinion to a 3.88.

Have you looked into a porsche 5 speed transmission

Might as well put this all in one place....

With a low revving (5000 or so rpm peak?) 1914 you have 2 options-

 1- Stay with the 4.12 ring & pinion and stock gears - 3.78 1st, 2.31 2nd, 1.31? 3rd and .89 4th. You could install an aftermarket 1-2 mainshaft and gears to get what you want, but they run about $500 or so just for the parts.

2- Change the r&p to a 3.88 (would solve the low 1-2 gear issue), but your 1914 won't develop enough torque to cruise comfortably with the .89 4th without overheating, so change 4th gear to a .93. This will get you back to a final drive of about the same as the 4.12/.89 combo. The .93 is the 4th gear VW used with the 3.88 r&p.

This is a great conversion, but not an easy or cheap option.

I used a 3.88R/P and .84(?) fourth in my Spyder..... Did very well....  Spyder weighed under 1500 lbs....   MY latest (CMC) weighs 1730 lb. and uses a stock IRS tranny w/ 4.12 R/P....

The Spyder had the performance over the CMC due to weight and higher H.P.   Both used engines in the 1.9 L. size....

If I did the Spyder over again, I would use the .92 fourth gear to keep from diving into third so often when driving in the mountains...   My .02....

I've got a 915 trans (911 5 speed) in my speedster and will never use anything else again. well worth the money....

Leon, I had a similar experience with my 3.88/.84 combo.  To keep the momentum up, while accelerating, I had to really wind the engine out in 3rd gear.  Even with a 2110 engine 4th gear was a bit of a dog.

Coolryde, I'd love to go with a Porsche 915, or Subaru transmission, but for me the cost of buying the tranny and completing the conversion would be more than I'd willing to pay. 

I imagine the cost of purchasing and installing a 915 or Subaru, with a flipped r&p, would be about the same?  The Subaru tranny is fairy pricey, at around $4,000.

I like my 901 five speed.  It has a 914 tall fifth, so the jump between fourth and fifth is a little steep, but it is great for cruising.

First gear is really only good for getting you going.

I am running pretty much Stock gears.  I think mine look like this:

915/70

911 Carrera 3.2 Turbo-look (USA/Japan) 1984-86

5-speed synchronized transaxle

Manufactured by Porsche (ZF)

Plate-type limited-slip differential available

Rod shift

Single-plate clutch

Gear ratios:

1st gear: 3.18 (11/35)

2nd gear: 1.83 (18/33)

3rd gear: 1.26 (23/29)

4th gear: 1.00 (26/26)

5th gear: 0.79 (38/30)

Ring and pinion: 3.88 (8:31)

How did we get from changing the R&P to installing a Porsche 5 speed transmission?

I have a 1776 but with CB heads and balanced crank.  It is no beast but can get out of it's own way just fine.  I have the 3.88 and gearing is perfect for the amount of power.  I bought it used so I can comment on gears but it was a 2007 Vintage build if that helps.

4th gear could be .93 (stock with the 3.88 r&p), .89  (stock with the 4.37 and 4.12),  a .82 (stock bus; I forget what years), or any one of the aftermarket 4th gears made. I believe there is a .77, 1.04, 1.12, 1.19, 1.21.... Sorry for getting carried away; the point is, unless you open the transaxle up or chart the rpms at highway speeds you won't know. If I were a betting man I'd go with the .93 or .89.

~3,200 RPMs at 70 MPH in 4th.

Rear tire size?