I my have a speedometer problem, does anyone know what speed your going (highway cruiseing in 3rd gear) when the engine is at 3000 RPM's. I have a 3 speed auto 1973 w/454c.i.

Also at 2500RPM's & 3500RPM's
Thanks.

Haha... well, if your gears are the same as mine, same transmission, then 3000rpm is a shade over 70mph, I'd guess 71 or 72. I have a 71 with a 350 however. So the transimission is a th350, while i assume yours is a th400. I also have the stock 3.08 gears. I'm pretty sure the ratio's are the same in the th350 and th400, and i'm also sure that your rear end is also a 3.08... at least stock:) I'm pretty sure of the numbers.... i was just testing this out myself today!

Brandon

Head on over to this site: http://www.idavette.net/tech/ratioc.htm

It will let you know your speed at different RPMs. Average tire size for Vettes is 27", you can go to the manufacturer's site for your tires to find an exact measurement. Using this site I discovered that I have a 3.36 rear instead of the 3.08 I thought I had.

That calculator doesn't work....
What transmission is it supposed to work with?? It can't work with every vette transmission ever made, and it doesn't specify on the page. It showed me at a 3.348 rear end.... lol, and i know its a 3.08.

Brandon

To Contrail,
Great web site you gave me, I wrote down some rpm's and speeds they producted and will try it tommorrow. It will help me stay semi-legal on the roads and with traffic flow.
Thanks

BrandonS, It worked for me. I double checked it against a radar gun.

Both the TH350 and TH400 have a 1:1 RATIO for 3rd gear. Check you tire size. I thought mine were 27" and found it to be 26" (big difference).

That calculator works for all trannys that came in vettes because they all had 1 to 1 high gear ratios. Well, except for the ones with overdrive, but even those were 1:1 in Drive. Joe