final drive with big tow?

twalker294 · 06-17-2005, 12:57 AM

Simple question here guys -- what is the final drive ratio with the big tow package? I was noticing on the way home from Tyler, TX this afternoon that at around 77 mph in 5th I was turning about 2100 rpm, so I would guess it's around 3.90 or so?

Thanks
Todd

RockyMtnTitan · 06-17-2005, 02:11 AM

Quote:

Originally Posted by twalker294

Simple question here guys -- what is the final drive ratio with the big tow package? I was noticing on the way home from Tyler, TX this afternoon that at around 77 mph in 5th I was turning about 2100 rpm, so I would guess it's around 3.90 or so?

Thanks
Todd

3.36 gears, but equal to 4.10 because of the 5 spd tranny. 2.94 gears w/o BT package, equal to 3.73. I have the latter, and at 80 mph, I'm at 2K.

**loufish** · 06-17-2005, 04:36 AM

Quote:

3.36 gears, but equal to 4.10 because of the 5 spd tranny. 2.94 gears w/o BT package, equal to 3.73. I have the latter, and at 80 mph, I'm at 2K.

That's only partially correct, when in 1st gear it's equal to a set of 4:10's, but in in 4th, and 5th(overdrive) it's still only a 3:36 gearset.

SUBTITAN · 06-17-2005, 06:14 AM

Quote:

Originally Posted by loufish

That's only partially correct, when in 1st gear it's equal to a set of 4:10's, but in in 4th, and 5th(overdrive) it's still only a 3:36 gearset.

If that was the case wouldn't they be turning the same rpms in overddrive?

RockyMtnTitan · 06-17-2005, 10:21 AM

Quote:

Originally Posted by loufish

That's only partially correct, when in 1st gear it's equal to a set of 4:10's, but in in 4th, and 5th(overdrive) it's still only a 3:36 gearset.

Thanks for the clarification....I was lazy (and lacking expertise) so I went for the short answer...lol!

**loufish** · 06-18-2005, 12:31 AM

Quote:

If that was the case wouldn't they be turning the same rpms in overddrive?

A 3:36 rear end gear is a 3:36 rear end gear, in 4th which is 1:1, it's still a 3:36 gear, and will pull and tach accordingly. Our trannys have such a low 1st, 2nd, and 3rd gear ratio, that the 3:36 rear end gear doesn't seem too high a gear, but in 4th, and 5th, you're back to a 3:36 gear....

SUBTITAN · 06-18-2005, 08:21 AM

Thanks loufish.

RockyMtnTitan · 06-18-2005, 01:44 PM

Quote:

Originally Posted by loufish

A 3:36 rear end gear is a 3:36 rear end gear, in 4th which is 1:1, it's still a 3:36 gear, and will pull and tach accordingly. Our trannys have such a low 1st, 2nd, and 3rd gear ratio, that the 3:36 rear end gear doesn't seem too high a gear, but in 4th, and 5th, you're back to a 3:36 gear....

Thank God for that, I guess. Imagine what our mileage would be like running true 4:10 (or even 3:73) gearing in 4th and 5th gears! Seems like a good balance to me.

**loufish** · 06-20-2005, 07:51 AM

Since installing my 315 tires, I'd love to run a 3:70 - 3:90 gear, and I don't think I'd lose any milage, but pick up all sorts of power for towing.
This isn't mentioned much, but running a tall rear gear puts way more stress on the tranny, so a gear like what I suggested above would really give our trannys a break.

*JayDee* · 06-20-2005, 09:56 AM

To answer the original question...

Final drives at the axle shaft:

3.36:1 in 4th gear

2.80:1 in 5th gear