ECO Hubs Who needs 3:07 gears?

[Xengineguy]

i'm trying to wrap my head around what you are saying. Lets say my engine puts our 1000 FT LBS TQ. If you do a 2 to 1 reduction is it now 2000 FT LBS TQ at the wheel? if you go to a direct drive at 1 to 1 are we back to 1000? is there a way the TQ can be amplified through gearing to exceed the component capability? I will buy this for my MTV if its safe and at least as reliable as the factory setup. I wonder about stripping out the splines in the axel end adapter ...

The hub or axle adapter as you call it is made of 4140 steel hardened to Rockwell 55 to 60. Then the inner splines are wire edm
cut to a tighter tolerance than stock apx 20/30 percent tighter…. Should be much stronger than what looks like a powder metal oe gear thats
hardened to 67 Rockwell. Time will tell.

 

[coachgeo]

The hub or axle adapter as you call it is made of 4140 steel hardened to Rockwell 55 to 60. Then the inner splines are wire edm
cut to a tighter tolerance than stock apx 20/30 percent tighter…. Should be much stronger than what looks like a powder metal oe gear thats
hardened to 67 Rockwell. Time will tell.

are the designers of this hub system looking at it like the whole axle is tuff enough to eliminate (nominally) one half of OEM design; that was figured to be part of how the force's get shared thru out all the components?? ... or are they figuring the new hub will share the forces similarly as those outer gears once did? Sounds like hubs would be strong enough if the design has that intent in mind.

Concern in the past in Unimog World was when discussing similar designs; including numerous engineers (including NASA engineers), is that the R&P and other parts associated is not designed to carry the applied forces alone. (nominally) Maybe these Meritor's are strong enough if that is the proposal?? Also, in a portal axle you can't take those gears out of the equation without just removing the portal and loosing the lift so might as well just swap to conventional axles.

Since our outer gears are not portal thusly can be swapped with a hub design such as this; especially if designers see it would in affect carry/share forces same as the gear reduction system, it replaces..... don't see any argument against it in that respect.. Temperatures of the pumpkin and hubs will be most telling I guess.

ya'll go for his inventation and take your trucks with you for comparision.... keep us posted

 

[RRaulston]

The hub or axle adapter as you call it is made of 4140 steel hardened to Rockwell 55 to 60. Then the inner splines are wire edm
cut to a tighter tolerance than stock apx 20/30 percent tighter…. Should be much stronger than what looks like a powder metal oe gear thats
hardened to 67 Rockwell. Time will tell.

well, I'm interested. Is the MTV intermediate axel the same part as the front and rear axel? Thanks..

 

[Xengineguy]

are the designers of this hub system looking at it like the whole axle is tuff enough to eliminate (nominally) one half of OEM design; that was figured to be part of how the force's get shared thru out all the components?? ... or are they figuring the new hub will share the forces similarly as those outer gears once did? Sounds like hubs would be strong enough if the design has that intent in mind.

Concern in the past in Unimog World was when discussing similar designs; including numerous engineers (including NASA engineers), is that the R&P and other parts associated is not designed to carry the applied forces alone. (nominally) Maybe these Meritor's are strong enough if that is the proposal?? Also, in a portal axle you can't take those gears out of the equation without just removing the portal and loosing the lift so might as well just swap to conventional axles.

Since our outer gears are not portal thusly can be swapped with a hub design such as this; especially if designers see it would in affect carry/share forces same as the gear reduction system, it replaces..... don't see any argument against it in that respect.. Temperatures of the pumpkin and hubs will be most telling I guess.

ya'll go for his inventation and take your trucks with you for comparision.... keep us posted

well, I'm interested. Is the MTV intermediate axel the same part as the front and rear axel? Thanks..

The other members can answer this best, but if the outside reduction is the same then the hubs and adapters will fit.
My best guess is Yes!

 

[serpico760]

well, I'm interested. Is the MTV intermediate axel the same part as the front and rear axel? Thanks..

I think that the only difference between the intermediate and rear axle lies in the differential components. I'm going to check the part numbers later but I think everything outside of the pumpkin is the same

 

[coachgeo]

.. should work on each 6x6 axle too. pretty sure Outer hubs are same

 

[Xengineguy]

Todays update
tried to haul stone unfortunately the pit was closed. The truck pulled the empty dump trailer like it wasn’t there..
I did find out that my pigtail adapter I purchased for the trailer locks the brakes solid when plugged in! Glad I looked back
was dragging the trailer down the drive with all 4 locked.

Now the fun part, filled the truck and jumped on interstate 69 North for 50 miles. Outside temperature 40 degrees
bucking a little wind going north 10 mph + - . Travelling at 61 to 63 most of the time. Pushed it to 70 a couple times.
The tires seem to warm up and the little bounce goes away. Turned around stopped at a rest area checked rear diff temp
was barely warm to the touch maybe 75 or 80 degrees. The hubs were cold to the touch… Returned to the same place and
filled the truck again. Same pump. Took. 9.79 gallons…. 108 miles. Checked miles with gps app and Speedo x2. They were very close to each other less than 2 miles difference…. So if I’m not mistaken that’s 11.031 mpg at let’s say 63mph……….
Not to bad! ( The fuel mileage test was done w/o trailer. Got to correct the pig tail adapter…)

 

[Skyhawk13205]

How does the hub nut lock without the gears? The torque is less then 20ft lbs

Also the torque from the axle is transmitted through the hub splines. Looks like your design the torque is applied directly to the wheel hub gear carrier attach bolts. I would imagine the design may be strong enough to take normal driving loads but not sustained heavy loads if used in an industrial for heavy duty application.

 

[Xengineguy]

How does the hub nut lock without the gears? The torque is less then 20ft lbs

Also the torque from the axle is transmitted through the hub splines. Looks like your design the torque is applied directly to the wheel hub gear carrier attach bolts. I would imagine the design may be strong enough to take normal driving loads but not sustained heavy loads if used in an industrial for heavy duty application.

The nut is locked with a single split collar, the collar is machined to fit over the splines on the axle tube. The collar has two holes that line up with the existing pins on the spindle nut Slide the collar up tight to the nut tighten the Allen bolt. You remove the inner gear but leave the shims in place.
If you’re hauling huge loads or using the truck for military off road you might want to reinstall the reduction for that. It only
takes 15 to 20 minutes per wheel including clean up…. No shimming required….
Let’s face it, these trucks will never see the severe off road they were designed for in civilian hands. If you want to beat the trash
out of it put the reduction back on.

 

[RRaulston]

The nut is locked with a single split collar, the collar is machined to fit over the splines on the axle tube. The collar has two holes that line up with the existing pins on the spindle nut Slide the collar up tight to the nut tighten the Allen bolt. You remove the inner gear but leave the shims in place.
If you’re hauling huge loads or using the truck for military off road you might want to reinstall the reduction for that. It only
takes 15 to 20 minutes per wheel including clean up…. No shimming required….
Let’s face it, these trucks will never see the severe off road they were designed for in civilian hands. If you want to beat the trash
out of it put the reduction back on.

How about a 20-minute installation video??!

 

[Xengineguy]

How about a 20-minute installation video??!

I’m sure A video will be posted at a later time.. Right now I’m concentrating on getting all the quotes for production, very different than
one set at a time. Looking good so far, I’m holding my price point. Thank you for your input .

 

[1stDeuce]

Ok, I'm following this thread more from an engineering/interest point, since I haven't yet been able to pick up an M1078 yet, and with mileage reports of ~5mpg, I'm not sure I want to... Kudos to Xengineguy for figuring this kit out and producing!! That is a lot of work, and a lot of cost for prototype parts, and then testing, which means a lot of time too!! I hope he manages to get this into at least limited production and make enough to justify his expenses!!

In considering the workings of the FMTV driveline, it seems there might be another possible "opportunity" for these reduction hub eliminators...

The F/LMTV "transfer case" is claimed to have a torque bias of 70/30. This bias is achieved through a planetary differential in the transfer case . If the transfer case diff could tolerate the front output speed being double the rear output speed without burning up the interface between rotating planet gears and their pins, then theoretically you could go with 1:1 hubs on the rear axle only, and leave the reduction on the front axle... This would give an overall torque split close to 50/50, and instead of going from 7.8:1 to 3.9:1 gearing overall, you would effectively be going to 5.85:1. The big downside is that you would NEVER be able to use MODE to lock the center diff, as the ratios would be wrong. For everyday use though, you would save 50% on the kit, and likely gain most of the mileage improvement from running the full kit, with a theoretical top speed around 72mph instead of the stock 58mph or the fully 1:1 kitted 116mph, providing better gear ratio splits and allowing the use of 7th gear overdrive.

The limiting factor for going this route would be getting the differential planet gears in the transfer case to handle constantly spinning under power... Looking at the exploded view in the TM, the planet gears in the center diff do not appear to have bearings or even bushings to their shaft. This is not surprising, since in normal driving there is very little rotation of the gears on their pins... Given a front shaft speed of 2900RPM's, and a rear of half that, the planetary carrier would be revolving at 1450rpm's at top speed instead of 2900, but by my guesstimation, the little planet gears would be spinning around 1.5 times faster on their shafts, so around 2100 rpm's. If you open up the planet gear ID and put needle bearings in there, it has a chance... By comparison, the front wheel end pinion gears spin about 1100rpm's on their needle bearings at road speed, so I don't know how the t-case gears would hold up at almost double the speed...

 

[Ronmar]

Ok, I'm following this thread more from an engineering/interest point, since I haven't yet been able to pick up an M1078 yet, and with mileage reports of ~5mpg, I'm not sure I want to... Kudos to Xengineguy for figuring this kit out and producing!! That is a lot of work, and a lot of cost for prototype parts, and then testing, which means a lot of time too!! I hope he manages to get this into at least limited production and make enough to justify his expenses!!

In considering the workings of the FMTV driveline, it seems there might be another possible "opportunity" for these reduction hub eliminators...

I dont think the center diff would survive this... I think you still wont be able to get into 7th, and without mode you are a 1 wheel drive vehicle(any single wheel spins means you are parked). That 70/30 split serves another purpose and is common on AWD vehicles. For driveability/control, you want the rear end to spin/slip first.

not getting to 7th(second overdrive) isnt a real big deal IMO. In a lot of applications Alison did away with it/programmed it out of the 6 speed 3060 and limits the trans to 5 forward gears. I have a freightliner ambulance configured like that where I work.

 

[olly hondro]

A simple minded view: when I look at the M35 deuce n half pumpkins then look at the Meritors, well, the Meritors look tiny. " There is gear reduction at the hubs so R & P do not have to be so big," is the response I get.....

 

[Ronmar]

You can only make a pinion so small. In order to get a taller ratio, you need to make the ring(and pumpkin) a lot larger...

 

[GeneralDisorder]

You can only make a pinion so small. In order to get a taller ratio, you need to make the ring(and pumpkin) a lot larger...

Exactly. Higher numeric ratios require a lot of small teeth on the ring gear, or a really big ring gear. Lower numeric ratios tend to have big chunky teeth and big chunky teeth are naturally stronger. So on the deuce - which doesn't have the reduction hubs - the R&P ratio is 6.72:1. Compared to the FMTV R&P of 3.90:1

It's not at all a fair comparison really. The deuce has a larger ring but that's because it's got a MUCH lower ratio (higher numeric) and thus if it didn't have a HUGE ring gear it would have tiny, weak teeth.

 

[Xengineguy]

You can only make a pinion so small. In order to get a taller ratio, you need to make the ring(and pumpkin) a lot larger...

Yes! Exactly correct…. We used to set up 12 bolt Chevrolet rear ends with 6:13/1 for circle track racing very small pinions!
and driveline speeds of 6500 to 7000 rpm! Sometimes we would even shorten the driveshaft at home. Cut the weld at the yoke
shorten the tube, weld it back together. Those were the days!

 

[Xengineguy]

Had a chance to pull some weight today. Hooked a 24’ tilt deck equipment trailer on the back of the 1078.
pulled it empty about 35 miles picked up my tractor at the dealership and returned home.
I would guess the trailer to be 2500 lbs maybe a bit more and the 5010 Kioti cab tractor with loader another
5000 lbs. So 7500 lbs give or take. It pulled the combination absolutely no problem thru rolling hills at 55 to 60 on back roads.
No downshifts were needed, and pulled it 65 on the highway no problem. The shifts were nice, could be lowered a bit.
When it upshifts you lift your foot a little unless you want to go faster. It’s not working hard at all.
I would like trailer brakes next time!

 

[Ronmar]

I had actually thought about this several years ago and worked up some numbers way back when. The numbers looked acceptable back then but I didn’t have any time to pursue it and shelved it for later. I am glad someone else is exploring the possibilities.

Here are the numbers I came up with for 395/85R20 tires(~146.6” circumference).
MPH for 7.8:1 axle ratio:


*= lockup. The TCU initiates lockup somewhere in 3rd gear, which is probably why the 2-3 shift feels a little harsher than the rest(Its also a bigger % jump). if accelerating, the TCU maintains lockup continuously 3rd thru 7th both up and downshifting. Before lockup the Torque converter gives you an infinite slip until you reach TC stall(1400-1600RPM) at that point you have an added 2+:1 torque multiplication. As the turbine unstalls/starts to accelerate(truck moving) The torque multiplication decreases from ~2:1 back towards 1:1. This added variable torque multiplication is the true magic of the Allison automatic config.

Here is the same breakdown with a 3.9:1 axle ratio(minus the 2:1 hubs).
MPH for 3.9:1 axle ratio:


Driveshaft RPM @ ~60MPH cruise in 6th gear with the 3.9, will be ~1685RPM down from ~3333RPM@60MPH with the 7.8 final ratio. That is significant!

7th gear will probably no longer be used automatically(i think cruise speeds in excess of 65 or so are not wise), but it is still there, and under certain conditions you may be able to use it, although the shift point criteria may need to be changed to get it to stay there. With a 3.9 final, ~60 MPH in 7th would be 1314 engine RPM. Wether that produces enough torque to be sustainable would need to be tested. I have seen different numbers between mid 1450-1550 RPM for peak torque point so…

Not using 7th is insignificant IMO as Allison programs 6th gear(our 7th) out of many applications using the 3060 transmission(the core of our 3070). I occasionally drive one(old FL-50 ambulance with 5 speeds and a cummins engine) “How can I get 6th gear back” is a popular topic on the “Skoolie” forums as many school busses were programmed for only 5 of the 6 available speeds from the 3060. The transmission simply doesn’t care…

As mentioned the axles are gross milspec overkill even for one of our trucks grossly overloaded. Because of the weights we typically do run, I do not think loosing the 2:1 hub final will significantly effect their operation.

I think the benefits of dropping the engine RPM closer to engine peak torque at highway speed(60MPH with 3.9 in 6th gear will yield 1517 engine RPM) and cutting the driveshaft RPM IN HALF on these very steep driveshafts far outweigh any possible downsides that I can see… Thats why I was attracted to the concept way back when…

The only place I would be curious to see final performance is in slow speed wheeling. The low speed torque manipulations provided by the torque converter in the Allison are where this combination really shines though. I am sure it will be different, but I do not think that difference will be significantly different/unusable at slow speed Because we have that added 6.93:1 first gear.

Would love to come wheel your truck, but don’t think I am getting to Indiana anytime soon…

You can put me down for a set though

edit: Easier to read the tables as screenshots. Forgot how difficult it was to do columns in HTML

 

[buffalohunter]

I had actually thought about this several years ago and worked up some numbers way back when. The numbers looked acceptable back then but I didn’t have any time to pursue it and shelved it for later. I am glad someone else is exploring the possibilities.

Here are the numbers I came up with for 395/85R20 tires(~146.6” circumference).
MPH for 7.8:1 axle ratio:
View attachment 892322

*= lockup. The TCU initiates lockup somewhere in 3rd gear, which is probably why the 2-3 shift feels a little harsher than the rest(Its also a bigger % jump). if accelerating, the TCU maintains lockup continuously 3rd thru 7th both up and downshifting. Before lockup the Torque converter gives you an infinite slip until you reach TC stall(1400-1600RPM) at that point you have an added 2+:1 torque multiplication. As the turbine unstalls/starts to accelerate(truck moving) The torque multiplication decreases from ~2:1 back towards 1:1. This added variable torque multiplication is the true magic of the Allison automatic config.

Here is the same breakdown with a 3.9:1 axle ratio(minus the 2:1 hubs).
MPH for 3.9:1 axle ratio:
View attachment 892321

Driveshaft RPM @ ~60MPH cruise in 6th gear with the 3.9, will be ~1685RPM down from ~3333RPM@60MPH with the 7.8 final ratio. That is significant!

7th gear will probably no longer be used automatically(i think cruise speeds in excess of 65 or so are not wise), but it is still there, and under certain conditions you may be able to use it, although the shift point criteria may need to be changed to get it to stay there. With a 3.9 final, ~60 MPH in 7th would be 1314 engine RPM. Wether that produces enough torque to be sustainable would need to be tested. I have seen different numbers between mid 1450-1550 RPM for peak torque point so…

Not using 7th is insignificant IMO as Allison programs 6th gear(our 7th) out of many applications using the 3060 transmission(the core of our 3070). I occasionally drive one(old FL-50 ambulance with 5 speeds and a cummins engine) “How can I get 6th gear back” is a popular topic on the “Skoolie” forums as many school busses were programmed for only 5 of the 6 available speeds from the 3060. The transmission simply doesn’t care…

As mentioned the axles are gross milspec overkill even for one of our trucks grossly overloaded. Because of the weights we typically do run, I do not think loosing the 2:1 hub final will significantly effect their operation.

I think the benefits of dropping the engine RPM closer to engine peak torque at highway speed(60MPH with 3.9 in 6th gear will yield 1517 engine RPM) and cutting the driveshaft RPM IN HALF on these very steep driveshafts far outweigh any possible downsides that I can see… Thats why I was attracted to the concept way back when…

The only place I would be curious to see final performance is in slow speed wheeling. The low speed torque manipulations provided by the torque converter in the Allison are where this combination really shines though. I am sure it will be different, but I do not think that difference will be significantly different/unusable at slow speed Because we have that added 6.93:1 first gear.

Would love to come wheel your truck, but don’t think I am getting to Indiana anytime soon…

You can put me down for a set though

edit: Easier to read the tables as screenshots. Forgot how difficult it was to do columns in HTML

Seems to me the ideal gear ratio might be around 4.30 , makes 7 gear usable and a little lower first. You can put me down for a set for a 1083.