4.10 to 3.73 DONE

[rjwest]

Completed conversion of 96 1 ton 4x4 to 3.73 gears.
( from 4.10)
Seems to be faster off the line, and shifts at higher rpm's, I think the lower gear ratio allows
turbo to spool up faster....
Drives nice 2000 rpm at 65mph ( speedo recalibrated with dip sw's )

Torque Converter now locks up at 51-52mph....
use to be at 46-47....

I guess the Tran only knows transmission speed not
actual MPH......

WOuld reprogram of PCM to 3.73 gear ratio lower lock up speed....

Anyone with 3.73 gears , What is your lock up speed??

[richard7]

Mine locks at 50 mph.

You should get shift speeds (vehicule) increase in a ratio of 4.10/3.73=1.099, so 10% increase.
So you numbers are normal.

[Uncle Wally]

RJ,

How did you go about your ring and pinion change? Did you get different gears and install in original housings, or did you buy used units in 3.73 ratio and swap.

I am thinking about doing the same thing with ours. I want to try the larger tires first though before I spend that kind of cash.

Waldo

[rjwest]

UNCLE WALLY, Went as big as I could on tires
( Duelly) got about 7 % , still to much rpm at 65..

I found a complete front IFS drive unit with 3.73 gears from a guy who converted to a solid axle
( Lift Kits are IN in Jax Fl. ) swapped front..

Same guy had 3.73 rear ring/pinion with very low miles.. NO REAL WEAR, Had 4x4 shop install with all new bearings.. total cost about 700 US....
(Replace front unit and change out ring and pinion)
If I did not get the front unit I probably would
not have done the conversion as I am told the front gear change is a hard job to do. ( Expensive.)
Had an extimate of 1500 to have gears changed in
front and rear ( to expensive )...

It does drive a lot better unloaded.....
Only down side is Lock clutch now at 51 mph vs 45 before.. Always unlocked in 45 speed zones...

I now get 2000 rpm at 65 mph. Use to get 2000 rpm on my 1/2 ton gasser, at 70mph..

Will see how it runs with my truck camper ( 3000lb.) let you now results in Dec ( Go'in hunting in 2 weeks )