FMTV High Speed Gears

[DiverDarrell]

Probably Diesel Brothers bought them all.

 

[sjohn116]

Steve is out. Premiere is out. Bryce is out. Hmmmm...

 

[ramdough]

Anyone with the 3.07 gears have any issues with not enough torque for hill climbing, off-road, towing, etc? I have heard that without hp upgrades higher speed gears can cause everything to be sluggish when you would naturally need more torque.


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[tburk49760]

I was one of the first to regear one and it is hands down the best mod I've done so far. Basically the same as adding another gear on top... I was worried that 1st gear would not be low enough for real grunt work. Not the case. Mine is nearly a daily driver and I keep up with traffic fine. Want not need more power...

 

[PowerstrokeNC]

Anyone with the 3.07 gears have any issues with not enough torque for hill climbing, off-road, towing, etc? I have heard that without hp upgrades higher speed gears can cause everything to be sluggish when you would naturally need more torque.


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My LMTV accelerates faster.... doesnt have to row through a bunch of close ratios, its way more drive-able and responsive in my opinion.

 

[PowerstrokeNC]

I agree with tburk, definitely the best mod I have done, totally changed the truck for the better.

 

[cybindustries]

Now I just need to find a set of gears so far no luck in my search

 

[Adventure Driven]

What gear ratio did you go with ?

Seth

I agree with tburk, definitely the best mod I have done, totally changed the truck for the better.

 

[coachgeo]

What gear ratio did you go with ?

Seth

Pretty sure there is only one option beyond OEM. so he must have same as all the others who did the upgrade (3.90 is OEM, 3.07 is upgrade / Before 2:1 reduction at hubs)

 

[Tex68w]

I am in the "still looking" camp as well. Fingers crossed some more will come available.

 

[Reworked LMTV]

I agree with tburk, definitely the best mod I have done, totally changed the truck for the better.

Any struggles setting the lash?

 

[DiverDarrell]

Lots of good info in the planetary hub set up post, for gear lash at the hubs. The center sections themselves are like A ford 9". And will be pre set up for ring and pinion lash

 

[Reworked LMTV]

Lots of good info in the planetary hub set up post, for gear lash at the hubs. The center sections themselves are like A ford 9". And will be pre set up for ring and pinion lash

Sorry, not sure what you mean by "pre set up" : )

 

[blhar15]

Has anyone been able to recalibrate their speedometer once they convert to the higher speed axles?

 

[DiverDarrell]

Pre set up, as in people have been getting the entire center sections. The gers are already factory set up.

 

[ramdough]

Has anyone been able to recalibrate their speedometer once they convert to the higher speed axles?

By chance does anyone know what type of signal the speedometer uses?


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[Keith Knight]

if you have an A1 with the computer controlled ECM its just a matter of having Caterpillar change the settings in the ECM.
I had them change my ECM settings and now reads correctly.
Now the vehicle tops out at 74mph according to the speedometer. After a 250 mile trip loaded with a 1951 M38 Jeep with the cruise control set at 60mph, I calculated the MPG at 6.5 MPG compared to before the gear change with no load and driving 55mph only getting 3.5mpg.

 

[DrillerSurplus]

if you have an A1 with the computer controlled ECM its just a matter of having Caterpillar change the settings in the ECM.
I had them change my ECM settings and now reads correctly.
Now the vehicle tops out at 74mph according to the speedometer. After a 250 mile trip loaded with a 1951 M38 Jeep with the cruise control set at 60mph, I calculated the MPG at 6.5 MPG compared to before the gear change with no load and driving 55mph only getting 3.5mpg.

Wow! that's a big improvement in mpg.

 

[coachgeo]

Im curious..... most info I've read was the 3116 got around 6.5-7mpg. Why do you think your's was at first getting half what has been suggested as the norm? Or is my recall of the "norm" way off base?

 

[scottmandu]

if you have an A1 with the computer controlled ECM its just a matter of having Caterpillar change the settings in the ECM.
I had them change my ECM settings and now reads correctly.
Now the vehicle tops out at 74mph according to the speedometer. After a 250 mile trip loaded with a 1951 M38 Jeep with the cruise control set at 60mph, I calculated the MPG at 6.5 MPG compared to before the gear change with no load and driving 55mph only getting 3.5mpg.

3.5 mpg is hard to believe I got 4 mpg doing 45 mph for 65 miles leaving tracks in the sand a foot deep.