Slick 60's

When I put my 66 togather I figured the 460 should be able to handle the 2.75 gears but with 31 inch tires on the rear it was a little slow to take off so today it got 3.00 gears and much better,now I have to figure out why the C-6 wants to shift into third too soon and I think my speedo is now much more closer to be correct.

When you say "too soon" how too soon is it shifting? Mine varies depending on how far my foot is buried in it. Under "normal" take off it comes in at about 50mph..

EDIT: Heres something I read on FTE that might help.
https://www.ford-trucks.com/forums/9107 ... ost8317914

If I recall correctly, the shifting in the c-6 is actuated by the vacuum modulator. Check this out: http://www.network54.com/Forum/260730/t ... oo+early--

Related to the spedometer, a free program such as Waze for your phone included a GPS based speed indicator.
Paul

Its in third by 20,I fought this trans since I put it in and when it had 3.54 gears it was in third by 10 so I adjusted the modulator until it was all the way in and adjusted the loose intermdiate band which helped and was ok with the 2.75 gears but I need to do something about it now. I was told use use a modulator with a purple stripe and will look into longer push rods too if that does not work.

66camperspecial wrote:Its in third by 20,I fought this trans since I put it in and when it had 3.54 gears it was in third by 10 so I adjusted the modulator until it was all the way in and adjusted the loose intermdiate band which helped and was ok with the 2.75 gears but I need to do something about it now. I was told use use a modulator with a purple stripe and will look into longer push rods too if that does not work.

That is the reason you're getting slow takeoff, not so much to do with the diff ratio as with your shift points. The 460 should pull strong even with the 2.75 if it has a chance to get into its torque range b4 shifting. If you wanna get off the dime quicker, a torque converter swap, one with a higher RPM engagement, would help.