So I'm getting ready to mate the new trans to the new motor before I drop them in as a pair. Time to decide if I want to monkey around with the 5th on the trans going in or not.
Here's some info:
1997 Mustang V6 T5
Input length: 7.85 inches
Pilot diameter: 0.668 inches
Input shaft: 23 teeth
"Bigger" input shaft bearing
Steel throw-out bearing tube on input retainer
1988 Turbocoupe 4cyl T5
Input length: 7.41 inches
Pilot diameter: 0.590 inches
Input shaft: 19 teeth
"Smaller" input shaft bearing
Aluminum throw-out bearing tube on input retainer
Input shaft length measures from the face of the transmission to the end of the shaft, so when it is installed.
To make this work, I had a machine shop cut down the V6 input shaft to 4cyl specs. Even though this will cut through the case hardening on the shaft, I don't think it will make much difference since the area makes contact with roller bearings. The guy that machined it seemed to agree and I found a few other cases around the internet that seemed to agree. If the pilot bearing goes bad, that might be another story. At least these input shafts are abundantly available. Looks like I'll find out first hand.
Fifth gear - I needed the following info to crunch some numbers:
4cyl T5:
Teeth Input/Countershaft: 19/33
Teeth Fifth/Countergear: 27/59
Ratio: 33/19 * 27/59 = 0.7948
V6 T5:
Teeth Input/Countershaft: 23/34
Teeth Fifth/Countergear: 25/51
Ratio: 34/23 * 25/51 = 0.7246
I could have swapped fifth gears, and this would've given me a ratio of 0.598... quite a low ratio/high gear. Using 3.55s and a 26.2 inch tire:
Ratio - RPM @ SPEED
0.598 - 2125 @ 77.8 (swapped)
0.725 - 2567 @ 77.8 (stock v6)
0.795 - 2815 @ 77.8 (stock 4cyl)
0.598 - 1640 @ 60
0.725 - 1980 @ 60
0.795 - 2173 @ 60
So, I think if I'm going to run 3.55s, which I am not changing for the near future, I should probably stick with the stock 5th gearing for the V6 trans.
Just for fun, running a 4.56 rear gear would put 60mph back at 2100 rpm.. so marginally better than stock. Final 1st ratio would be 15.276, compared to stock's final 1st of 14.094.
Oh, forgot to add, if nothing else, I needed to dive in to swap the speedo drive gear. Tbird's is 6 tooth and the Mustang's is eight tooth.
Here's some info:
1997 Mustang V6 T5
Input length: 7.85 inches
Pilot diameter: 0.668 inches
Input shaft: 23 teeth
"Bigger" input shaft bearing
Steel throw-out bearing tube on input retainer
1988 Turbocoupe 4cyl T5
Input length: 7.41 inches
Pilot diameter: 0.590 inches
Input shaft: 19 teeth
"Smaller" input shaft bearing
Aluminum throw-out bearing tube on input retainer
Input shaft length measures from the face of the transmission to the end of the shaft, so when it is installed.
To make this work, I had a machine shop cut down the V6 input shaft to 4cyl specs. Even though this will cut through the case hardening on the shaft, I don't think it will make much difference since the area makes contact with roller bearings. The guy that machined it seemed to agree and I found a few other cases around the internet that seemed to agree. If the pilot bearing goes bad, that might be another story. At least these input shafts are abundantly available. Looks like I'll find out first hand.
Fifth gear - I needed the following info to crunch some numbers:
4cyl T5:
Teeth Input/Countershaft: 19/33
Teeth Fifth/Countergear: 27/59
Ratio: 33/19 * 27/59 = 0.7948
V6 T5:
Teeth Input/Countershaft: 23/34
Teeth Fifth/Countergear: 25/51
Ratio: 34/23 * 25/51 = 0.7246
I could have swapped fifth gears, and this would've given me a ratio of 0.598... quite a low ratio/high gear. Using 3.55s and a 26.2 inch tire:
Ratio - RPM @ SPEED
0.598 - 2125 @ 77.8 (swapped)
0.725 - 2567 @ 77.8 (stock v6)
0.795 - 2815 @ 77.8 (stock 4cyl)
0.598 - 1640 @ 60
0.725 - 1980 @ 60
0.795 - 2173 @ 60
So, I think if I'm going to run 3.55s, which I am not changing for the near future, I should probably stick with the stock 5th gearing for the V6 trans.
Just for fun, running a 4.56 rear gear would put 60mph back at 2100 rpm.. so marginally better than stock. Final 1st ratio would be 15.276, compared to stock's final 1st of 14.094.
Oh, forgot to add, if nothing else, I needed to dive in to swap the speedo drive gear. Tbird's is 6 tooth and the Mustang's is eight tooth.
1988 Turbo Coupe
- 0.020 Diamonds w/stock rods, T3 w/stock IC, BoPort 1.5 cam, LA3 w/QH on MAF, water/meth
- 5-lug swap, 31-spline, 4.10s, vacuum brakes, PBR front brakes, 2000 Mustang GT 17" rims
- 0.020 Diamonds w/stock rods, T3 w/stock IC, BoPort 1.5 cam, LA3 w/QH on MAF, water/meth
- 5-lug swap, 31-spline, 4.10s, vacuum brakes, PBR front brakes, 2000 Mustang GT 17" rims