Is it time for a new transmission

[The Leppy]

Hi all, if there;s anyone with a better understanding than I maybe you could help this decision role a little smoother...I have a '66 with a 289/three speed auto. but it's either time to rebuild the tranny or throw a 4 spd. manual in. what with gas @ the price it is, will I truly save by having the extra gear? suggestions are greatly appreciated

[KiltedBanshees93GT]

You will save, as far as gas goes, but the difference wont be anything mind-bending. Probibly 2-3mpg maybe more if you do a lot of highway driving. (But it adds up, and I tend to be conservative) The biggest single gain will be wear and tear on the engine. My 66, with 3.25's and a c-4 runs at near 2.5k on the highway, as opposed to the 93, which at the same speed is ticking along at like 1700 in 5th. Another option you can consider is swapping in an AOD, you'll be able to cruise in overdrive, and it'll be the same car on the surface streets. Best of both worlds, and you dont have to screw with the conversion to stick. (Sorry, I forgot to mention this option in your other thread )

[Gearhead999]

Unless you change the tranmission to a 5 speed with O/D or an AOD the fuel mileage will be almost exactly the same as your C-4.

The four speed and the C-4 both have a 1:1 or direct drive high gear.

[The Leppy]

thanks a lot fellas, it sounds like the AOD is probably the way to go! i'd rather not toy too much with the car,,,most of it is orig. this sounds like there's the ability to put back to stock?