clearym

Does anybody have figures on what RPM the 2005-6 GT runs (manual trans) at 65mph (or somthing close to this) with the following Rears:

3.55 (stock)
3.73
4.10

thanks

Blackman

I have 4.10 5-speed, 80mph at 2800 rpm

Tik_Tok

I've still got stock 3.55's, on the highway at 65mph, It's about 1900 RPM.

clearym

Anybody with 3.73's out there?

MikeVistaBlue06

Look at your tach now at 65mph and see what the rpms are. To figure what they will be with a new gear do this:

New RPM = Old RPM X (new gear ratio/old gear ratio)

Now I have an automatic (stock rear was 3.31), but it works the same way. In OD I was taching 2000 @ 70mph. With my 3.73s I now tach:

2000 x (3.73/3.31) = 2253. My tach now sits on the first mark above 2000 @ 70mph, which is 2250rpm.

If you have a manual transmission, get the 4.10s; if you have an automatic and wish to keep some overdrive, get 3.73s.

BTW, with your car your rpm would change as follows:

1900 X (3.73/3.55) = 1996rpm (might as well say 2000 @ 65 mph)

1900 X (4.10/3.55) = 2194rpm (might as well say 2200 @ 65 mph)--note how close this is to my automatic with 3.73s when I'm at 70mph. This is why you should do 4.10s IMHO...

Hope this helps.

sonicblue05

funny, iv heard 3.73 for manual and 4.10 for autos is the way to go???

MikeVistaBlue06

Final drive ratio for an automatic with 3.73s = 0.75 X 3.73 = 2.7975; OD on an automatic is 0.75:1


Final drive ratio for a manual with 4.10s = 0.68 X 4.10 = 2.788; OD on a manual is 0.68:1 (taller) so you want more gear in a manual when compared to an automatic.

Thx,

Mike

grasshopper

http://www.8bsp.com/mystang/trans_mustang_manual.xls
http://www.8bsp.com/mystang/trans_mustang_auto.xls

clearym

Thanks guys. This spreadsheet is exactly what I was looking for.

mustangman02232

your both wrong, 4.10s or nothing