T56 swap speedo

[ZekeStang]

For those who have swapped to a T56, was your speedo off? By how much?

 

[tjm73]

For those who have swapped to a T56, was your speedo off? By how much?

Depending on your car, it may cause no change. Which T56 are you refering too? The FRPP one's? What's your car?

 

[Mgt351]

What year is your car? what did you switch from? The T56 if it is a Ford unit should have a 7 tooth gear in the trans (assuming yours is manual and not electric) If you have a 90-93 car you need to get the correct speedo gear for a 87-89 that goes with the rear gear you are running.

 

[ZekeStang]

I'm referring to the Tremec T-56 made for the 5.0. I didn't know FRPP made the T-56 though. This is a 94-98 Turbocharged Mustang with 2.73 stock gears? I'm willing to upgrade my rear end gear to whatever the T-5 was calibrated for or just speedo gears.
But even with the 'correct' rearend gear(don't know if 2.73 came on 5.0s&what speedotooth?) i figured the speedo would be off anyways since the T-5 has slightly different gear ratios than the T-56.

Also, maybe i'm not understanding how the speedo gear works (mechanical)? What would it now do in 6th gears or are there differently matched pinions for each gear in the tranny that turn the speedo gear?

If your speedo is correct, please advise on the rear end gear you're using with the T-56 as well as speedo gear tooth.

Note: This isn't the viper T-56, mine has the .62 6th gear ratio.

Help is much appreciated

 

[1990FoxLX]

I'm referring to the Tremec T-56 made for the 5.0. I didn't know FRPP made the T-56 though. This is a 94-98 Turbocharged Mustang with 2.73 stock gears? I'm willing to upgrade my rear end gear to whatever the T-5 was calibrated for or just speedo gears.
But even with the 'correct' rearend gear(don't know if 2.73 came on 5.0s&what speedotooth?) i figured the speedo would be off anyways since the T-5 has slightly different gear ratios than the T-56.

Also, maybe i'm not understanding how the speedo gear works (mechanical)? What would it now do in 6th gears or are there differently matched pinions for each gear in the tranny that turn the speedo gear?

If your speedo is correct, please advise on the rear end gear you're using with the T-56 as well as speedo gear tooth.

Note: This isn't the viper T-56, mine has the .62 6th gear ratio.

Help is much appreciated

I have the same gear ratios in my T-56, but the gear ratios of the transmission have no effect on the speedometer calibration. The speedometer drive gear is attached to the output shaft of the transmission, which is directly connected to the rear wheels via the driveshaft, rear diff and axle shafts. So, the ratios prior to the transmission output have no effect on speedometer calibration.

To help you choose your a new rear gear, you should reference the Speedometer Gear Usage Chart in the FRPP catalog. The T-56 in my 1990 Mustang LX uses a 7-tooth drive gear. I believe you probably have the same drive gear in your T-56. My driven speedo gear is a 20-tooth gear which is the proper relationship when using a 3.55 gear ratio, which is what I have in my Mustang's rear axle. This is considering that you are using the same diameter tire as stock on the rear of your Mustang.

The chart in the FRPP catalog shows all of the correct drive/driven gear relationships for gear ratios ranging from 3.08 to 4.30. Personnally, I really like the 3.55 gear set. They added plenty of torque without hurting my highway cruise RPM too much. Remember, the T-5's fifth gear is nearly identical to the T-56's sixth gear (0.68 vs 0.62) so don't think you can go with a deeper rear gear because you have a T-56. The real benefit of the T-56 is the added ratio of the fifth gear. It's really nice for light cruising around town and gives you a "between" for accelerating on the highway without having to redline in fourth gear (direct drive).

Hope this helps.