Wondering what the easiest way to tell what my truck has for gears in it. I think they have been swapped out so I want to check but I really dont feel like pulling off the diff cover just to find out.
Thanks
Evan

 

I guess the tag is gone also...There is a formula where you turn the drive shaft and count how many turns the wheel rotates.I just can't remember the formula.Its been years since I've done this....Anyone have the formula.??What is your RPM at 60MPH or 70MPH???We may have a close idea on the ratio...

 

If you are running about 2000 RPM at 70, you have 3.55
If you are running about 2200 RPM at 70, you have 4.10

Ronnie

 

Yea at 70 its exactly 2k rpms But the tires are up to 285's so that should also make a little bit of a differance. I dunno i just expected the rpms to be lower when I installed the 5spd. BUt I guess I was wrong.
Evan

 

5spd's have less of an O/D than the auto do

 

that sucks but the trade off is still worth it. having a max cruising speed of like 75 is kinda limiting my bad driving habits
Evan

 

I am turning 2100-2150 rpms at 60. I have a 5 speed and 4.10s. I am also running 285/75-16s. Does this sound right?

 

Bump... please help

 

Mark a spot on your driveline.

If you have an open rear differential, jack up one tire and turn it two revolutions.

Have a friend count how many times the shaft spins during your two turns of the tire.

The number of drivelline revolutions is your ratio.

Just over 4 turns = 4.10

3.55 turns = 3.55


See a pattern?


With a locker, you'll have to lift both tires, and you'll only spin the tire once.

I think it's the same for a limited slip, but have never tried one.

Chad

 

5spd really hurt rpms, with the auto i was at like 67@2000, with the 5spd 4.10's and 235/85/16 tires im at like 59@2000, i checked that yesterday. 70+ is just way to high rpms to want to cruise at for any period of time so it sucks for any roads above 55 pretty much.

 

Ok, I am seeing the same speeds you are. I just wanted to make sure there was nothing wrong with my truck. I guess I could go to 3.73 or 3.55 diffs. I will just have to see I guess.

 

Get your vin# and call the dealer. With it he can pull your "build sheet" on the computer. From that he can tell you EVERYTHING about your truck, unless a PO has changed something.