[Jiffy]

I'm swapping a 2003 drive train into my 2001 Cobra next week. The rear gears are different from memory - 3.27 vs 3.55?

So, I'm interested in understanding what the gear ratios are in my old trans (1-5) and comparing them to the new trans (1-6) to understand what the comparison on top gear ratios is like....

Anyone have those details?

Cheers
Jeff

[Eagle2000GT]

I'm assuming its a 2003 Cobra drive train and not a 2003 GT drive train because you indicated the transmission would be a six speed. Here are the spec sheets on the two cars. The '01 had 3.27 gears. The '03 had 3.55 gears. Fifth gear in the '01 transmission was 0.67:1. Fifth and six gears in the '03 are .80:1 and .63:1, respectively. If we were to compare drive trains in the highest gear, the '01 was 2.19 (.67 x 3.27). The '03 is 2.23 (.63 x 3.55). That isn't enough difference to matter to anything. Other gears: (transmission gear ratio x rear end gear ratio)

'01 Cobra.........'03 Cobra
...1st: 11.02..........9.44
...2nd: 6.51..........6.32
...3rd: 4.35...........4.62
...4th: 3.27...........3.55

The combination of transmission and rear end makes the '03 1st a lot higher, 2nd a little higher, and 3rd and 4th a little lower.

Mustang Specs - 2001 Ford Mustang Cobra
Mustang Specs - 2003 Ford Mustang Cobra

[Jiffy]

Eagle2000GT - love your work buddy!

Thanks again - looks like 1st will be a little taller (1st in my 2001 Cobra seems a little low anyway, plus with a load more grunt, it should make it stand up and haul ass), after that they'll be fine and the 6th gear will mean a little less revs on the freeway....

Running 275/40/18's on the rear so it'll be a fine ride at speed...

[Jiffy]

Just realised that I didn't describe the changes very well! D'oh
So - the drive train is being swapped with the exception of the rear end! The original 31 spline 3.27 geared IRS remains - which means that the gearing changes to this:
2001 Cobra 5 speed w/3.27 2001 Cobra 6 speed w/3.27 gears 2003 Cobra 6 speed w/ 3.55 gears
1st 3.37 x 3.27 = 11.0 2.66 x 3.27 = 8.7 2.66 x 3.55 = 9.4
2nd 1.99 x 3.27 = 6.5 1.78 x 3.27 = 5.8 1.78 x 3.55 = 6.3
3rd 1.33 x 3.27 = 4.35 1.3 x 3.27 = 4.25 1.3 x 3.55 = 4.6

So, 1st gear gearing will be much taller than original in my 2001, and a little taller than a normal 2003, but probably not too much of an issue. The 1st gear in the Cobra today is quite low and it does work the motor hard to get up and off the line, but once it's moving it should be ok....

Interesting, 5th gear and 6th gear are 2.2 and 2.06 so pretty darn close I think...

Will report back and describe what it's like....