901 5th gear

[setho]

Along the way, the transaxle in my '66 was rebuilt with shorter gears... Unfortunately, that includes 5th, and it makes highway driving no fun. (4,000 rpm around 75-80mph)

Can anyone recommend a good 5th gear ratio? I'm thinking a Z or a ZA, but I'd like to hear from someone with experience.

Thanks!

[304065]

What wheels and tires? Exact model of tire.

[beh911]

4000 rpm in 5th at U.S. highway cruise is basically Z as well, just as an FYI. These small displacement engines are geared to keep RPMs pretty high for access to the peaky power.

Do you know what gear was used for 5th in your rebuild

[Flieger]

I have AMFSX and am at 4,000 rpm at 70-75mph cruise. It actually runs well there. Fuel economy is relatively good and it fires nice and smooth. Tires are 225/50-R16 Advan A048's.

[kenikh]

Stock (standard) gearsets in '66 came in two variants:

A F M S X
AA GA O U Y

Your experience could evidence an X or Y 5th, depending on tires, but if 4K at freeway speeds bothers you, a Z 5th would likely be the least jarring from 4th for both of these combinations.

The split to ZA isn't bad, for either, but would only consider a ZD if the trans was 901/0 with U 4th.

[setho]

Thanks all -

I guess the key is going to be opening it up and seeing what's inside first and foremost and make some decisions from there.

I'll have to look at the tire size, but I seem to remember it being a 195/70-14. Those will be getting replaced in the not too distant future.

beh911- Thanks for the chart.... Very helpful.

[Bill Simmeth]

Are you sure you're on 14s? If so, just changing to 15s will help you drop RPMs some.

[Chris Pomares]

I run A,GA,N,U,ZD with a TBD in my 901 transmission with 205/55/16's at 25 inches. That's about the same as a 195/65/15. At 80 mph I'm running about 3200 rpm and get 32 mpg. My 2.4 POLO has a lot of torque and plenty of power so I don't know how those gears would work for a small 6. In my case the only gear I would like to change would be 1st. The engine has so much torque I would like to go to a B or C 1st. U to ZD is a pretty big jump on long uphill grades if you don't have the power. If you live at altitude (I'm in Colorado) or deal with long uphill grades all the time like Phoenix to Flagstaff or the like a ZA might be a better choice.
Chris

[davep]

I have V & ZD sets available.

[setho]

I have V & ZD sets available.

Sending PM!