ECO Hubs Who needs 3:07 gears?

[Ronmar]

The comparison I am interested in is the crawl ratio. In a vehicle this big a crawl ratio over 50 would be helpful on difficult trails (7+). Moving methodically and steady through obstacles is easier on the equipment and the occupants. For example: I'd like to have ECO HUBS on our rig and take the Road to Hite to camp at The Doll House. The low crawl ratio is giving me pause.

Now if I could reprogram the throttle control in MODE to make it less punchy that would be helpful.

You have much more experience than I do running 48's on a rig. I value your comments—

So put them on, if you don’t like them you can always put the spiders back on… unless you are contemplating a LOT of weight, I do not think you will be disappointed

 

[hike]

So put them on, if you don’t like them you can always put the spiders back on… unless you are contemplating a LOT of weight, I do not think you will be disappointed

I agree, and our rig hopefully will remain light and agile—

 

[GeneralDisorder]

The comparison I am interested in is the crawl ratio. In a vehicle this big a crawl ratio over 50 would be helpful on difficult trails (7+). Moving methodically and steady through obstacles is easier on the equipment and the occupants. For example: I'd like to have ECO HUBS on our rig and take the Road to Hite to camp at The Doll House. The low crawl ratio is giving me pause.

Now if I could reprogram the throttle control in MODE to make it less punchy that would be helpful.

You have much more experience than I do running 48's on a rig. I value your comments—

You will be able to crawl as slow as you like. I have yet to reach for 1st gear so all the crawling I've done to date with the ECO hubs has been in 2nd gear at "only" 16:1. I could arrow down to 1st and be at 27:1 but I haven't found the need yet. You can move as slowly and methodically as you like with the Allison and diesel combination.

Again - you have to remember that we have useable torque at REALLY low RPM. Idle even. So your experience with ultra low crawl ratio's on Jeeps isn't really applicable - yeah you have to rev them up quite a bit to get any movement out of 86:1 crawl ratio but that's the only way to get any power out of the engine. You get that punchy throttle feel because of the transition from engine manifold vacuum where the gas engine is actually being choked and is working against a closed throttle plate to free flowing when you pop open the throttle. Diesel engines like ours don't have throttle plates (we don't have EGR) and they are very different animals under similar conditions.

Have you taken a stock LMTV off-road?

 

[hike]

You will be able to crawl as slow as you like. I have yet to reach for 1st gear so all the crawling I've done to date with the ECO hubs has been in 2nd gear at "only" 16:1. I could arrow down to 1st and be at 27:1 but I haven't found the need yet. You can move as slowly and methodically as you like with the Allison and diesel combination.

Again - you have to remember that we have useable torque at REALLY low RPM. Idle even. So your experience with ultra low crawl ratio's on Jeeps isn't really applicable - yeah you have to rev them up quite a bit to get any movement out of 86:1 crawl ratio but that's the only way to get any power out of the engine. You get that punchy throttle feel because of the transition from engine manifold vacuum where the gas engine is actually being choked and is working against a closed throttle plate to free flowing when you pop open the throttle. Diesel engines like ours don't have throttle plates (we don't have EGR) and they are very different animals under similar conditions.

Have you taken a stock LMTV off-road?

Nothing more than a forest road as yet. We have a development project with some good inclines (25°), though rocks or ledges. That would help me get a feel for the throttle response and steep climbing.

You all make me think, I appreciate it—

 

[hike]

Took me a bit to get my brain around your table, and your gear ratios are a bit off.

1- the transfer is not shiftable. It applies a fixed 1.2:1 to all the input ratios using 3 large gears. They took a 3060 transmission with its 6 speeds(our 2-7) + R and hung the 1.2:1 off the back end. In the upper rear of the transfer they put the C6 clutch pack that brakes a shaft that runs up thru the middle of the trans output shaft and transfer primary gear to the sun gear in the last planetary gear set. This allowed them to squeeze an additional gear out of the 3060 core and provide us with that very low 1st gear.

The only thing selecting mode does is to lock the center diff down in the bottom, and of course limit the top gear to 5th.

here are the final ratios including the fixed 1.2:1
GEAR RATIO CLUTCH

1st 6.93:1 C3-C6
2nd 4.18:1 C1-C5
3rd 2.24:1 C1-C4 + LU
4th 1.69:1 C1-C3 + LU
5th 1.20:1 C1-C2 + LU
6th 0.90:1 C2-C3 + LU
7th 0.78:1 C2-C4 + LU
R -5.00:1 C3-C5

Here is a photo of the google doc I found the gearing information in. I do not recall though I think this belongs to a member here? It is titled: FMTV LMTV Common Issues & Fixes



I may have misunderstood the discussion (and implications of the table "N/A" entries) on how the granny gear was added and/or its final ratio. Perhaps the final is 6.93, though that is after the 1.2 in the transfer case. That would make the base ratio for 1st 5.78 and reverse -4.24. Though the crawl ratios and speeds at rpm would remain unchanged, no?

 

[Ronmar]

The third planetary carrier turns the hollow transmission output shaft. The c6 clutch all the way in the back brakes the third sun to develop an additional ratio. I spent a day home sick once working it all out and had all the interactions in my head, but have since brain dumped that info

The fixed 1.2:1 in the transfer is applied to ALL transmission outputs, 1st thru 7th and reverse. That 6.93 is the published final output for first which includes the 1.2:1.

The Ratio for R has always bothered me in that it did not add up mathematically with the ratio published for R for the 3060 +1.2 for the transfer, like the other gears do. Its final ratio may indeed be 5:1, making the actual trans output something less. But since both 1st and R are derived from the last planetary, it may have been altered to produce that really low 1st, and those alterations also set it up so our R stayed around 5:1 i will measure it eventually, but I got a lot of stuff to “get around to”…

crawl ratio is interesting information, but it is only strictly applicable to manual transmissions when hard coupled/clutched into the engine output.

As general alluded to, in 1st and 2nd we are hydraulically coupled to the trans with a variable 0-2:1 torque multiplier which helps to match engine output to load… in that configuration we can apply anything from idle torque to peak engine torque, and we can override even engine idle torque using the brakes, so we have from 0 to double peak torque available to apply at any speed we choose From inches per hour to feet per second… The trans wont lockup/hard couple until 3rd gear…

 

[hike]

As general alluded to, in 1st and 2nd we are hydraulically coupled to the trans with a variable 0-2:1 torque multiplier which helps to match engine output to load… in that configuration we can apply anything from idle torque to peak engine torque, and we can override even engine idle torque using the brakes, so we have from 0 to double peak torque available to apply at any speed we choose From inches per hour to feet per second… The trans wont lockup/hard couple until 3rd gear…

This is the piece I have been missing. The way the torque converter plays in the drive line. @GeneralDisorder mentioned it, too, I just kept walking past it. Thank you all for helping my Jeep brain get here. ECO HUBS are on the mod list now–

 

[hike]

You cannot apply twice the torque to anything, because you do not have it available. With 2:1 hubs, if you are VERY heavily loaded in a max traction situation and against an obstacle/slope you cannot surmount you will apply all your available torque until you reach TC stall. All the drivetrain components had to be able to withstand this force(TC Stall test). The driveshafts are typically the weak link, and they are clearly specced to more max torque than we can deliver. General disorder with his tuned up C7 is closing in on the limits though The only thing the ecos do is reduce the possible force you can apply to the wheel by 1/2…

I agree the axles are over spec'd and the likely reason for the 2:1 wheel hubs is to keep the pumkins smaller with larger RP teeth. I do not doubt the axles can carry the stresses our use cases are likely to encounter, even off road on challenging trails.


I disagree the torque on the axle shafts are not doubled when at the same RPM.

Conservation of energy says if we remove the 2:1 hub we are essentially doubling the size of the wheel and tire. We can see this simply by looking at the formula for Torque: t(small tau) = F (force) x r (radius) [these are the vectors that show an instant of the rotating mass and angular acceleration]. The math says the torque is doubled, while the force stays the same. [what?] While we are not changing the tire size the 2:1 reduction hub effectively does. This changes the radius the force is applied across. We can check this by changing the tire size to 23.3", changing the wheel hub to 1:1 and doing the crawl ratio or MPH calculations. Comparing 2:1 hubs with 46.6" tires to 1:1 hubs with 23.3" tires; we see the math matches. But this all requires the engine and driveline RPM's to be the same, thus applying the same force.

In practice folks should not be running through the same challenging location at the same RPM (or twice the speed) as with the 2:1 hubs. Since the RPM's are lower the force being applied is lower. And removing the 2:1 reduction also reduces the loss from added heat in the gears along the entire driveline, especially at the wheel hubs. We know this because folks who have these installed are reporting less fan use to cool the engine and transmission.

Pragmatically, with the torque converter in the lowest gears being variable, hopefully the reasonableness of the operator in the upper gears, and the driveline overspec'd as it is, the ECO HUBS reduce the rpm's on the engine and driveline enough to make the very unlikely event of axle shaft damage minimal. In addition, the lower stresses and rpm's OTR should more than make up for some occasional short lived stress off road.

I have known folks who broke axle shafts on their Jeeps, though I never have. The difference may just be luck, though some folks go out looking for "send it" opportunities any time they can.

I think I just repeated everything @Xengineguy @GeneralDisorder and @Ronmar have been saying. Thank you for your patience with me, some times I just need to say it outloud myself to understand it all–

 

[hike]

Ordered a set. They may ship tomorrow–

 

[hike]

The third planetary carrier turns the hollow transmission output shaft. The c6 clutch all the way in the back brakes the third sun to develop an additional ratio. I spent a day home sick once working it all out and had all the interactions in my head, but have since brain dumped that info

The fixed 1.2:1 in the transfer is applied to ALL transmission outputs, 1st thru 7th and reverse. That 6.93 is the published final output for first which includes the 1.2:1.

The Ratio for R has always bothered me in that it did not add up mathematically with the ratio published for R for the 3060 +1.2 for the transfer, like the other gears do. Its final ratio may indeed be 5:1, making the actual trans output something less. But since both 1st and R are derived from the last planetary, it may have been altered to produce that really low 1st, and those alterations also set it up so our R stayed around 5:1 i will measure it eventually, but I got a lot of stuff to “get around to”…

The corrected worksheet with crawl ratios and speeds:

 

[GeneralDisorder]

I'm 21,000 lbs and running 3.90's, ECO hubs, and 370/931 tune. I typically run 65 to 75 mph on the highway and usually I just pin it from every stop. I own and operate a performance shop with an in-ground DynoJet and consequently I'm no stranger to very high performance vehicles and I don't drive slow no matter what I'm driving or where I'm driving it. I have a lead foot and a full send mentality and not many f*cks about what I break - I will figure out how to fix it and reinforce it on the back end and chalk it up as a learning experience when and if I break stuff.

I have not had any issues in that regard and the boundary conditions under which these vehicles perform in the military are so ridiculous that I'm genuinely not concerned about breaking any parts of the axles. I'm more concerned about the C6 thrust bearing on the transfer case at the high driveline speeds of the reduction hubs and the engine being run at WOT for hours and days on end. I would take a broken axle shaft over either of those any day. And if that happens I'll have stronger axles made.

 

[Ronmar]

I disagree the torque on the axle shafts are not doubled when at the same RPM.

Conservation of energy says if we remove the 2:1 hub we are essentially doubling the size of the wheel and tire.

I think you may be overthinking this a little. RPM has little to do with this, other than in determining torque output at the engine.

To perform a specific task, say pulling a 40,000# truck up a 30 deg slope, yes by removing the 2:1 at the hubs, you are doubling the torque applied to all the components along the path to do that same task.

Now lets say you are attempting to pull 60K up a 60 deg slope, a task so great you run out of torque regardless of wether you have 2:1 hubs or not. At that point, where you reach engine peak torque and converter stall, and are still just setting there, thats is all there is available. This condition can happen with or without 2:1 hubs, so all the components must be designed to withstand all the force you are capable of producing. we have done nothing to increase available torque from our source, just reduced the amount of thrust it can produce from the tires.

of course in most any condition with 2:1 hubs, and even without the 2:1 hubs, except that of extreme load, we typically run out of traction before we run out of torque anyway, so component loads are low, but they were designed to take all the power plant can produce.

unfortunately the 2:1 config yields driveshaft RPM that at our shaft angles, are way past the acceptable range.

 

[hike]

I think you may be overthinking this a little. RPM has little to do with this, other than in determining torque output at the engine.

I may be. You all know much more about these vehicles and systems than I likely ever will. I appreciate all you share. Now that I have ordered the ECO HUBS I am on to how to best replace my bricked (5 steady lights) CTIS with a manual system based upon your design that suits my asthetic for matching—

 

[DeMilitarized]

that

I may be. You all know much more about these vehicles and systems than I likely ever will. I appreciate all you share. Now that I have ordered the ECO HUBS I am on to how to best replace my bricked (5 steady lights) CTIS with a manual system based upon your design that suits my asthetic for matching—

Arduino CTIS controllers are my favorite. Half the cost of a ebay time bomb replacement.

 

[hike]

First test drive with the ECO HUBS went fabulously. Much quieter, smoother, cooler (hovered near 200, fan did not kick on), and she cruises at 60 like she is walking diligently. When the transmission hits that next gear at 60+ she leaps forward like she wants to run.



Thank you @Xengineguy. I haven't had her off road yet, though first steps are pointing toward awesome adventures ahead.

And thank you to @GeneralDisorder, @Ronmar, @Third From Texas, and all the others for helping along the way—

 

[GCecchetto]

First test drive with the ECO HUBS went fabulously. Much quieter, smoother, cooler (hovered near 200, fan did not kick on), and she cruises at 60 like she is walking diligently. When the transmission hits that next gear at 60+ she leaps forward like she wants to run.

View attachment 907041

Thank you @Xengineguy. I haven't had her off road yet, though first steps are pointing toward awesome adventures ahead—

Nice! I'm on a plane headed for Maryland to pickup my truck next Thursday. Can't wait.

 

[CallMeColt]

First test drive with the ECO HUBS went fabulously. Much quieter, smoother, cooler (hovered near 200, fan did not kick on), and she cruises at 60 like she is walking diligently. When the transmission hits that next gear at 60+ she leaps forward like she wants to run.

View attachment 907041

Thank you @Xengineguy. I haven't had her off road yet, though first steps are pointing toward awesome adventures ahead.

And thank you to @GeneralDisorder, @Ronmar, @Third From Texas, and all the others for helping along the way—

Sorry to derail a bit, but looks like you are not far from me. I'd love to see the difference first hand, as well as get together with another LMTV owner. If you are up for it, reach out. If not, not hard feelings!

 

[hike]

Sorry to derail a bit, but looks like you are not far from me. I'd love to see the difference first hand, as well as get together with another LMTV owner. If you are up for it, reach out. If not, not hard feelings!

Sure. Wife is out of town this weekend, where shall we meet?

Hondo would be good. I have a client developing a project in Natalia and visiting the site would be good for me, too—

 

[Skyhawk13205]

I noticed before I changed to eco hubs, my truck would get up to temp pretty fast less than 5 min of driving at highway. Now my truck has a harder time getting up to 200 deg. I wonder if the heat production is from the transmission having to spool at such a high rpm. It would be nice to see a temp that the transmission runs at now with eco hubs.

 

[hike]

I noticed before I changed to eco hubs, my truck would get up to temp pretty fast less than 5 min of driving at highway. Now my truck has a harder time getting up to 200 deg. I wonder if the heat production is from the transmission having to spool at such a high rpm. It would be nice to see a temp that the transmission runs at now with eco hubs.

I am not sure about whether the engine or transmission generates the most heat. Though I read here (on the forum) that A0 units had the transmission cooling loop routed in to the cooling system differently than later units. I have wondered if there is a convenient port to add a temp sensor to the transmission. Or adding one before the the transmission cooler would be staight forward—