ECO Hubs Who needs 3:07 gears?

[CallMeColt]

From the discussion here, seems these are better in every scenario that's been tried. Really makes me wonder why the gear reduction exists if direct drive results in better performance. Obviously there is half the torque in 1st gear but beyond that, seems the shifts would just be later to somewhat compensate. Am I missing anything?

It probably had to do with the fringe end of requirements. Such as a truck at fully loaded capacity, fully occupied, their gear, turret with M2, ammo, at max incline, highest elevation, dead stop start. Basically, worst case... being able to do what it was supposed too. With the EcoHub, it wouldn't I'd guess, without a skilled driver.

 

[Ronmar]

What Colt said, These trucks were not built for highway efficiency, they were built to meet a military specification(milspec). In this case I think it had to be able to overcome a 18” curb at max weight? Weird things happen in the land of milspec, like the grossly oversized battery to meet a -40F CCA specification. That in itself wasnt the issue, only providing a 60/40, 12/24v dual volt alt to support such a large battery was the problem. The kind of problem class action lawsuits and recalls are made of in the real world, but perfectly acceptable in the land of milspec. Uncle sugar just whistles up a warehouse of new batts and alternators as needed

No you are not missing anything. It is just that these can deliver so much torque to the wheels that unless you are grossly overloaded, and trying to do something extreme like climb a 18“ curb, it would never all be used. You are dropping the 2:1 at the hubs, but for our typical use, you were never fully getting the 2:1 that the torque converter is capable of delivering out of the transmission. Minus the 2:1 at the hubs, the TC is stepping in and actually delivering some conversion(up to 2:1 as needed), so for our typical use, people are reporting same or better performance minus the 2:1 hubs.

For our typical use, dropping the engine back to peak torque at highway speed, removing the 10% gear losses at the hubs and bringing the driveshaft RPMs back inside the max RPM vs angle curve on the chart are all HIGHLY desirable changes from efficiency and safety standpoints…

 

[DeMilitarized]

Has anyone installed these on a 3116 engine?
Any real word experience?
Taking off on a hill is already pretty slow even with an empty truck.


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Look up the 3116 governor adjustment on Abel the lmtv on YouTube and there is a video of how to increase that off the line jump and works great. These are fine on a 3116 due to the torque converter actually increasing torque at low rpm in 2nd gear


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[Ronmar]

Look up the 3116 governor adjustment on Abel the lmtv on YouTube and there is a video of how to increase that off the line jump and works great. These are fine on a 3116 due to the torque converter actually increasing torque at low rpm in 2nd gear


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It wasn't just a governor adjustment, it was a governor and turbo replacement. There is an adjustment that you can do that will roll on the fuel a little earlier off idle, but that is not going to effect Peak torque output or HP. The governor is matched to the turbo, you replace them both and adjust the rack to the 290 spec…

The TC does the same variable 0-2:1 conversion, matching engine output to load on all of these trucks with the 2:1 hubs gone you will actually get to use the TC, instead of it acting like a simple slip clutch with enough delivered torque at idle to move the truck…

 

[Xengineguy]

From the discussion here, seems these are better in every scenario that's been tried. Really makes me wonder why the gear reduction exists if direct drive results in better performance. Obviously there is half the torque in 1st gear but beyond that, seems the shifts would just be later to somewhat compensate. Am I missing anything?

I think one of the parameters in the design of the trucks is the speed limit of 57 MPH. Keep young soldiers alive and out of trouble.

 

[GeneralDisorder]

I think one of the parameters in the design of the trucks is the speed limit of 57 MPH. Keep young soldiers alive and out of trouble.

Not since before the Afghan war. The latest HMMWV's coming out of depot are 6.5 turbo's with 4L80E's that will do over 80 MPH. The HEMTT A4 based chassis like the PLS, the LET, etc will all do 75 MPH or so with their CAT C15's. The JLTV will cruise at 75 MPH all day long. They found out in Iraq and Afghanistan they need convoys to MOVE not be slow targets.

The FMTV's - even the A1P2's are about the slowest thing they have. The A1R and A1P2 trucks will do about 62 MPH.

The speed "limit" of the truck was due to it's engine redline and gearing. It was a consequence of a series of choices and requirements - not a requirement in itself. The military wouldn't mind if they would do 75 MPH. That's why the MRAP's with the same axles got the 3.07 gearing.

 

[juha_teuvonnen]

I can not get that low in weight, we have an M1083 6x6. Even with a 20' composite box, proper subframe, we start at 22k before interior of box is built out.

We have removed the bed from my m1083a0 (3116 engine, 3.07 gears), added approximately 5 feet of length to both frame and subframe and installed a Winnebago 1700BH on top using a spring mount. I had to weigh it to get it registered in Texas. It weighs 22200 lbs and I have a CAT scale receipt to prove it. According to Winnebago to trailer is 3200 lbs. Since we removed the triangular section of the frame in front of the trailer and the axle, the habitat probably weighs less that 3000 lbs now. I am guessing that the bed weighs about as much as the Winnebago.

 

[juha_teuvonnen]

Has anyone here installed ecohubs in the three axle truck with a 290 Hp 3116 and 3.07 gears? My truck is an M1083A0. It has 290 HP 3116, three axles and weighs 22200 lbs with habitat and quarter tank of fuel (I have ab 85 or 90 gallon tank from m900 series 5-ton).

I am worried about losing torque on the low end, I just drove the truck from Boston to Dallas with a 20 ft enclosed trailer full of furniture, books and tools behind it. The trailer weighs 4000 lbs empty. I didn't weigh it full, but I am guessing that I was pulling 10000 lbs. The truck struggled to stay on 7th uphill, dropped in to the 6th going uphill and even into the 5th on steeper hills. With 3.07 gears, when it's empty it tops out at 60-62 mph. It will do more downhill. With stock tire pressure at 62-65 psi and worn out shock absorbers, it's unwise to go faster than 65-70, IMHO.

If anyone has a similar rig with Ecohubs in the greater Dallas area please let me know.

 

[wheelspinner]

Has anyone here installed ecohubs in the three axle truck with a 290 Hp 3116 and 3.07 gears? My truck is an M1083A0. It has 290 HP 3116, three axles and weighs 22200 lbs with habitat and quarter tank of fuel (I have ab 85 or 90 gallon tank from m900 series 5-ton).

I am worried about losing torque on the low end, I just drove the truck from Boston to Dallas with a 20 ft enclosed trailer full of furniture, books and tools behind it. The trailer weighs 4000 lbs empty. I didn't weigh it full, but I am guessing that I was pulling 10000 lbs. The truck struggled to stay on 7th uphill, dropped in to the 6th going uphill and even into the 5th on steeper hills. With 3.07 gears, when it's empty it tops out at 60-62 mph. It will do more downhill. With stock tire pressure at 62-65 psi and worn out shock absorbers, it's unwise to go faster than 65-70, IMHO.

If anyone has a similar rig with Ecohubs in the greater Dallas area please let me know.

62-65 tops out? You have other issues. Should easily top 70. How is your fuel system (filters, lines etc) have you confirmed 100% throttle on the linkage?

 

[CallMeColt]

Not since before the Afghan war. The latest HMMWV's coming out of depot are 6.5 turbo's with 4L80E's that will do over 80 MPH. The HEMTT A4 based chassis like the PLS, the LET, etc will all do 75 MPH or so with their CAT C15's. The JLTV will cruise at 75 MPH all day long. They found out in Iraq and Afghanistan they need convoys to MOVE not be slow targets.

The FMTV's - even the A1P2's are about the slowest thing they have. The A1R and A1P2 trucks will do about 62 MPH.

The speed "limit" of the truck was due to it's engine redline and gearing. It was a consequence of a series of choices and requirements - not a requirement in itself. The military wouldn't mind if they would do 75 MPH. That's why the MRAP's with the same axles got the 3.07 gearing.

Well yeah, these trucks had the outlines for their designs made in the late 80's. Most interstates in the US were 55mph still. Not comparable to vehicles 30 years newer.

 

[Tortuga]

If I was to install eco gears how would I get my speedo to read correctly? Before you say adjust the dip switches my 1993 A0 does NOT have dip switches. Possibly a replacement speedo that is adjustable? Thanks

 

[Ronmar]

Hmmm it should have dip switches, got apic of the backside of it?

 

[Tortuga]

Hmmm it should have dip switches, got apic of the backside of it?

Ronmar here is a shitty picture but it is what I have right now. Maybe they are under that plate marked 319 now that I look at this picture again

 

[Ronmar]

Wonder who made that one.

 

[coachgeo]

Ronmar here is a shitty picture but it is what I have right now. Maybe they are under that plate marked 319 now that I look at this picture againView attachment 903625

IMHO....... pull it out..... put a Tach there and somewhere else put a GPS based speedometer.

 

[juha_teuvonnen]

62-65 tops out? You have other issues. Should easily top 70. How is your fuel system (filters, lines etc) have you confirmed 100% throttle on the linkage?

The fuel system was serviced last month, tank clean, filters new, fresh oil change, etc. Fresh oil in the transmission also.

 

[Tortuga]

Wonder who made that one.

I think my 93 may have have been very early off the line. When I get a chance I will have to pull the speedo out and look for more information or branding on it.

 

[Tortuga]

IMHO....... pull it out..... put a Tach there and somewhere else put a GPS based speedometer.

Not a bad idea. I do already have a tach (winch truck), but maybe they make a round GPS based unit. I will have to look. Or just a universal programmable unit.

 

[Ronmar]

Or a more recent lmtv speedo that is switch programmable...

 

[tennmogger]

Ronmar here is a shitty picture but it is what I have right now. Maybe they are under that plate marked 319 now that I look at this picture againView attachment 903625

I also had a speedometer that had no dip switches, so they certainly exist. I swapped mine out for a programmable one.

Another option that gets mentioned rarely is a GPS speedometer. Depending on which reseller you try to buy a speedometer from, the GPS one might be economical.