FMTV High Speed Gears

[Guruman]

You can do the 3rd member on a bench.

You will need a bearing splitter, dial indicator. Mark compound. Shims. Pinion seals. If you have not done it before chances are you will f it up

At $1800 a pair versus $5k a pair, I can afford to screw it up twice and still be money ahead. Provided I eventually actually succeed, rather than screwing up $1800 worth of new gears, then going back to buying pulled 3rd members anyway. Finding the shims might not be an easy task though.

 

[Keith Knight]

Set up bearings are also very useful. In my local town I’m the guy everyone wants to have do there ring and pinion set up for their Jeeps. Been doing them for over 20 years. But those are new gears with new bearings and shim kits. I would be nervous about doing these gears not having spare shims and bearings and my bearing puller would probably be to small for this set up.

 

[simp5782]

At $1800 a pair versus $5k a pair, I can afford to screw it up twice and still be money ahead. Provided I eventually actually succeed, rather than screwing up $1800 worth of new gears, then going back to buying pulled 3rd members anyway. Finding the shims might not be an easy task though.

I dunno where you are getting your prices from but I just paid 1200 ea per axle whole hub to hub. So... maybe shop around

 

[Guruman]

I dunno where you are getting your prices from but I just paid 1200 ea per axle whole hub to hub. So... maybe shop around

Maybe you can drop me a PM with where you are shopping? I've been looking for a month, best I've found the take out 3.07 center sections that actually has them was 4.5k for the set, plus freight, making it pretty close to 5k to my door. At half that, I'd pull the trigger today.

Edit: Also hub-to-hub would be great, as I KNOW at some point I'm going to need some of those parts.

 

[B-Dog]

A big hurdle is that the pinion nut requires 900-1100 ft lbs. You might be able to use a torque multiplier braced against the yoke but I would be concerned about damaging the yoke. If your press doesn't have a gauge, you have to torque the pinion nut to check the bearing preload which is adjusted with shims. Translation: You will likely have to press bearings, torque the pinion nut, undo and repeat multiple times. To adjust the pinion location, you completely assemble and adjust the carrier, check the wear pattern then take it all apart to change out shims as required. Lather. Rinse. Repeat.

Suffice to say, in addition to the tools Simp suggested, I would add; patience. I would also add a press, something to hold the yoke and a carrier stand. Maybe you can do this on a bench but this isn't a 65lb carrier out of a Tacoma.
Setup bearings aren't necessary. Instead of shims on the diff bearings, there are adjusting rings.

 

[NDT]

If you are not familiar with setting up R&P in a heavy truck, take/send your pumpkins along with your new R&P to a competent shop like MTP drivetrain Many, LA.

 

[Guruman]

If you are not familiar with setting up R&P in a heavy truck, take/send your pumpkins along with your new R&P to a competent shop like MTP drivetrain Many, LA.

That's an option, and I still might be able to save a bit, depending on how much they would charge me for the work. Freighting those pumpkins back and forth eats into any potential savings pretty quickly.

I was kind of hoping to hear about those $1200 complete axles... Ready to heat up my credit card.

 

[simp5782]

That's an option, and I still might be able to save a bit, depending on how much they would charge me for the work. Freighting those pumpkins back and forth eats into any potential savings pretty quickly.

I was kind of hoping to hear about those $1200 complete axles... Ready to heat up my credit card.

Pretty sure I am not going to divulge that. Some folks on here know the location of them.

If I need them I know where to get them. I am not going to give that away so I can't get em a month from now cause word got out. If I want to buy 50 at a time like some people do and folks be sad about it calling people scalpers cause they get em for cheap well then they should invest their money and buy 50 at a time too.

 

[Guruman]

Pretty sure I am not going to divulge that. Some folks on here know the location of them.

If I need them I know where to get them. I am not going to give that away so I can't get em a month from now cause word got out. If I want to buy 50 at a time like some people do and folks be sad about it calling people scalpers cause they get em for cheap well then they should invest their money and buy 50 at a time too.

I kind of figured you'd not be sharing. I kind of get it. I don't tell everyone about my favorite fishing spots in Montana.

But then again, I don't get on public forums and bust peoples' chops because they cannot catch a fat trout.

While I'm making fishing analogies, I have been known to hire a guide or two when fishing unfamiliar waters. Maybe you'd take a small finders fee for hooking a guy up?

 

[Guruman]

So. I found some MRAP takeout diffs, but I'm not convinced they are the correct ones to swap into a FMTV. How can one positively identify the correct ones?

Here's some pics of what I found, not sure if they'd work as they have some actuator or sensor on the side (locker maybe? yes, please!), and the yoke is wrong.

I've asked for more info, but I'm not convinced they would know.

 

[coachgeo]

So. I found some MRAP takeout diffs, but I'm not convinced they are the correct ones to swap into a FMTV. How can one positively identify the correct ones?

Here's some pics of what I found, not sure if they'd work as they have some actuator or sensor on the side (locker maybe? yes, please!), and the yoke is wrong.

I've asked for more info, but I'm not convinced they would know.

View attachment 857627View attachment 857628View attachment 857629

would be awesome if they fit .... yes locker .... but likely no does not fit. They appear to be from "axle tech 4000" version of axle

AXLETECH 4000 FRONT OR REAR AXLE

AXLETECH 4000 PLANETARY STEERING AXLES, 9 TON RATING, AIR LOCKING DIFFERENTIAL, HEAVY DUTY ZERO HOUR AXLE.FRONT AND REAR AXLE AVAILABLE, AS WELL AS WIDE AND NARROWTHESE ARE ALSO AVAILABLE IN A TANDEM REAR CONFIGURATION WITH A 6.84 RATIO WIDE AXLETECH AXLES 6.84 GEAR RATIO, 90" WMS, 45°...

westerncanadianrockwell.ca

 

[Guruman]

would be awesome if they fit .... yes locker .... but likely no does not fit. They appear to be from "axle tech 4000" version of axle

AXLETECH 4000 FRONT OR REAR AXLE

AXLETECH 4000 PLANETARY STEERING AXLES, 9 TON RATING, AIR LOCKING DIFFERENTIAL, HEAVY DUTY ZERO HOUR AXLE.FRONT AND REAR AXLE AVAILABLE, AS WELL AS WIDE AND NARROWTHESE ARE ALSO AVAILABLE IN A TANDEM REAR CONFIGURATION WITH A 6.84 RATIO WIDE AXLETECH AXLES 6.84 GEAR RATIO, 90" WMS, 45°...

westerncanadianrockwell.ca

I'm pretty sure it's still wrong for what I need, but I noticed that the pic you posted has the actuator in the 3 o'clock position and the top 12 o'clock has part of the bolt circle chopped off.

The one I posted seems to be round, without the chopped off flange. ??

 

[Mullaney]

So. I found some MRAP takeout diffs, but I'm not convinced they are the correct ones to swap into a FMTV. How can one positively identify the correct ones?

Here's some pics of what I found, not sure if they'd work as they have some actuator or sensor on the side (locker maybe? yes, please!), and the yoke is wrong.

I've asked for more info, but I'm not convinced they would know.

View attachment 857627View attachment 857628View attachment 857629

.
Any chance any of the materials with or near it might have the NSN number? With that number, you could know what it fits into...

 

[Guruman]

Now that my winch is in, and my A/c is mostly done, I'm circling back around to gears.

Still waiting to get the hook up on those $1200 take outs....

Speaking of...

I'm trying to determine the effort required. Swapping in a chunk (or just the R&P) on the rear seems straightforward, but the front seems much more involved.

Would it be easier to just swap the whole front axle with one already having the highway gears?

 

[DiverDarrell]

Now that my winch is in, and my A/c is mostly done, I'm circling back around to gears.

Still waiting to get the hook up on those $1200 take outs....

Speaking of...

I'm trying to determine the effort required. Swapping in a chunk (or just the R&P) on the rear seems straightforward, but the front seems much more involved.

Would it be easier to just swap the whole front axle with one already having the highway gears?

It's alot easier just to swap in the third member, then to swap axles. I did the swap and added a rear locker in 2 days of work. Also adjusted the reduction hubs correctly while I had everything apart.

 

[Guruman]

It's alot easier just to swap in the third member, then to swap axles. I did the swap and added a rear locker in 2 days of work. Also adjusted the reduction hubs correctly while I had everything apart.

Good to know, thanks.
I thought if it were easier I'd just get a whole axle, but if it's not I'll save the freight and get just the centers.

 

[m-35tom]

You will save the most by just getting the ring & pinion, easy to install by any good mechanic. $875 each set includes shipping.

 

[Guruman]

You will save the most by just getting the ring & pinion, easy to install by any good mechanic. $875 each set includes shipping.

This is a good point, and I've considered it. At the time I did not really have a place that would work on it, but now I might.

 

[coachgeo]

You will save the most by just getting the ring & pinion, easy to install by any good mechanic. $875 each set includes shipping.

yup..... there was a time when take out MRAP 3rds; already with the higher ratio R&P, were not that expensive and even with shipping it was cheaper to swap in a whole MRAP takeout...... even when calculating labor. But that is not the case anymore. R&P swap is way to go now.

 

[m37charlie]

Around here Highway Speed starts at 75 in some areas. If 75 sounds like 58 does know then I will back out of throttle to at least 70.

Thanks

You want a FMTV to drive on the interstate at 75mph? That’s not what they’re for. Think about the planetaries; the tires exploding; the fuel consumption.
From my perspective these things are for bad road camping vehicles or whatever. 60mph on the highway is more than fast enough. Yeah fast gearing is great to get rpms down. Especially since the bolt on Marmon Herrington MVG-1150 transfer case has an unfortunate high range ratio of 1.09.