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FMTV High Speed Gears

Awesomeness

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You can save the gear oil and reuse it if it is clear and clean. Otherwise, front 2 gal, rear maybe 2 1/2 gal. front no need to remove big hub nut in front so no oil loss. Rear must remove nut so very small loss but hub oil in rear comes from diff oil so it will refill itself. You will need some gear oil RTV. No other parts needed, just clean the kingpin seals and grease the kingpins when done.
Front Axle Differential: SAE 75-W90, 9.5 qt
Rear Axle Differential: SAE 75-W90, 18.05 qt
Front Axle Planetary Hubs: SAE 75-W90, 11-13 fl oz (each)

The total is almost 7 gallons. Mine took every bit of that.
 

Awesomeness

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That rear figure includes the hubs which you do not need to drain.
I'm not sure what you're suggesting. As soon as you pull the large plug to get the shaft out, most of it comes out. Plus, since they are the same as the front hub, that would only save you 11-13oz each, which isn't really much savings when you have to buy almost 7 gallons of fluid.

When I did mine, I didn't "drain" the rear hubs - I just pulled the large plug to get the shaft out. I bought a 5 gallon bucket of gear oil, plus a six pack of quarts, giving me a total of 6.5 gallons on hand. During reassembly, I put all of that in, and was a little short. So I ran to the store, bought 2 more quarts, and put about 1.5 quarts in (e.g. I have about 1/2 quart left in one bottle still). So call it 6.75 gallons, or 7 gallons, if you want, but the TM's numbers are very close.
 

ramdough

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Austin, Texas
Does anybody know how to re calibrate the speedometer for an A1 ? We installed the high speed gears but off course the speedo is way of now. In the front we took off the whole hub. Took us about 1 hour to get both front hubs of. Installing both diffs took us about 5 hours in total with 2 persons. It's an easy job with the right tools.

View attachment 782222View attachment 782223
Did you ever figure out how to calibrate the speedometer?


Sent from my iPad using Tapatalk
 

Berend

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Yes it's very easy , you have to do it with the CAT ET software. The pulses per mile have to be changed in the settings for the ECM.
 

m-35tom

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eldersburg maryland
I'm not sure what you're suggesting. As soon as you pull the large plug to get the shaft out, most of it comes out. Plus, since they are the same as the front hub, that would only save you 11-13oz each, which isn't really much savings when you have to buy almost 7 gallons of fluid.

When I did mine, I didn't "drain" the rear hubs - I just pulled the large plug to get the shaft out. I bought a 5 gallon bucket of gear oil, plus a six pack of quarts, giving me a total of 6.5 gallons on hand. During reassembly, I put all of that in, and was a little short. So I ran to the store, bought 2 more quarts, and put about 1.5 quarts in (e.g. I have about 1/2 quart left in one bottle still). So call it 6.75 gallons, or 7 gallons, if you want, but the TM's numbers are very close.
The hub level is at the bottom of the big center nut I think so yours were over full maybe. Rear sets its own level, just the fronts need to be filled but there is no need to do anything to the front to change the diff.
 

Awesomlmtv

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California
I’ve got a 94 1078, will these work on an A0? Anyone have a set for sale? I’m really excited to get a bit more highway speed and calm the motor down.
Thank you
 

PFH

Member
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Location
Kona, Hawaii
Getting ready to finally install my locker and gears, but I would like to check the lash before. Anyone know what the lash measurement is on these? TIA
 

epicmotorsports

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ST GEORGE/UTAH
I blew up my front diff transporting to dock on tbe h1 in hawaii. Gonna fix it in st george ut. I need a set of h speed diffs please for a starving mechanic. Lol had to pull front shaft and pinion on the freeway and limped in with the mode selected to force the drive to work was limited to 30mph max and 5th gear. But made it. Was my fault cuz it was drained and i forgot to check it.

Need to find turret cover and some high speed diffs, i got a couple of used rear diffs in standard config but would prefer to go to the 3.09 diffs
 

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fuzzytoaster

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I blew up my front diff transporting to dock on tbe h1 in hawaii. Gonna fix it in st george ut. I need a set of h speed diffs please for a starving mechanic. Lol had to pull front shaft and pinion on the freeway and limped in with the mode selected to force the drive to work was limited to 30mph max and 5th gear. But made it. Was my fault cuz it was drained and i forgot to check it.

Need to find turret cover and some high speed diffs, i got a couple of used rear diffs in standard config but would prefer to go to the 3.09 diffs
I've got a set of 3.07s for $4500, taken from new MRAP axles in the crate. I'll toss in a turret cover to help you out.. I've got a green one here somewhere.
 

epicmotorsports

New member
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18
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Location
ST GEORGE/UTAH
I've got a set of 3.07s for $4500, taken from new MRAP axles in the crate. I'll toss in a turret cover to help you out.. I've got a green one here somewhere.
Can contact at 43566nine one55eight
I've got a set of 3.07s for $4500, taken from new MRAP axles in the crate. I'll toss in a turret cover to help you out.. I've got a green one here somewhere.
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My direct is 4356691five58 tyler
 

Guruman

Not so new member
Steel Soldiers Supporter
So....

Say I was to buy a couple new sets of 3.07 ring and pinions instead of just getting a whole center section. How hard would it be for the average Joe to get the new gears set correctly? Special tooling? Parts (shims and such) ? Would the gear pattern need to be set in the truck (pulling the center section back out to check the gear pattern would not be fun.) ?
 
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