Eco Hubs and 3.07's - in a 2000 M1088 with a 3126 (~24k pounds)

[coachgeo]

Keith, that wasn’t really the point I was trying to make, he could have gone a lot slower, even down to a crawl, because it appears he had the torque he needed to do so on that slope. Like in sand and snow, a little momentum can help you, but it doesn't last long…

I took some of the torque figures listed here and crunched some numbers. Now of course traction and a myriad of other variables like if they chose the TC stall to correctly coincide with PK torque not withstanding, here are some rough capability calculations:

Of course my 3116, 225@620FT/LB. At peak torque/TC stall and 3.9:1, should deliver 13,200lb of force, It should be able to drag 20K up a 41.3deg slope.
DS Torque 3652FT/LB. 60%

Stock 3126, 274@~800FT/LB. With 3.9:1 at peak torque/TC stall should deliver 17,035lb of thrust. It should be able to drag 24K up 45.2 degrees.
DS Torque 4712FT/LB. 78%

Ckoubas Tweaked 3126, 330@860FT/LB. @3.07:1 and peak torque, you should have 14,414lb of thrust, or enough to drag 24K up a 36.9deg slope.
DS Torque 5066FT/LB. 84%

And Generals C7, 370@931FT/LB. With 3.9:1 and peak torque, thats a whopping 19,823lb of force or enough to drag 21K up a 70deg slope…
DS Torque 5484FT/LB. 91.4%

Found my old notes on driveshafts, anyone know what wall thickness tube ours uses?

Based on 279 U-joints we use type 16 driveshafts(Rockwell/Meritor 16R, Dana-Spicer 1610?) with 4” tubes, they make weld yolks for .109 and .134 wall thickness. The two different thickness shafts are rated at 6000 and 6500FT/LB max torque(peak) respectively. The U-joints have a rated yield of 7100FT/LB.

The percentages I listed above are load related to the 6K shaft rating…

YMMV…

290 hp M1079 3116??

 

[Ronmar]

290 hp M1079 3116??

Got a peak torque spec For the 290? Oh and a target weight?

 

[Lostchain]

like many times while traversing very technical terrain you can’t just fly up it. Most of the time you are controlling the speed just barely enough momentum to get over the obstacles without throwing everyone and everything all over the place. Inevitably we miss calculate and don’t overcome the obstacle and have to hit the brake let everything settle down and not roll backwards then hit it again with a little more throttle to get over it.

The thought didn’t cross my mind to completely stop, but It would’ve been no problem. In 1st the truck has a huge amount of torque available. 1st is basically a granny gear, I could have started and stopped on a steeper hill even. Next time I am out and about I will try that.

In regards to MPG the drive out there and all of the off-roading was 268 miles, I crossed the Cascade Mountain range via the Santiam Pass, stayed between 55 and 60 on the Highway and did just under 100 miles of off-roading and got 8.72 MPG

On the way home I crossed the range again at the same pass, 174 miles total and I stayed mainly 55-60 again on the Highway and got 10.19 MPG

 

[Keith Knight]

Lots of great information Ron, thanks for all the number crunching. I’m seriously considering this swap primarily for the better fuel mileage. That would be a huge savings in the long haul.

 

[Ronmar]

290 hp M1079 3116??

Yea I havnt found that spec either

I have seen a GM spec, 300HP@2600 RPM and 732FT/LB. So guessing ~715FT/LB for the 290hp...

The 1079 curb weight is 18,834, but that includes 1000# of crew and fuel weight. Fitted out for camping maybe just over 20K? Lets say 22K...
715FT/LB nets you 15,225# of thrust. That should be enough to pull 22K up a 43.8deg slope. That engine torque means the driveshafts could see a maximum of ~4211FT/LB, or ~70% of a 6K max rated driveshaft...

With some of these calculated angles, especially offroad, it is likley you will run out of traction before you run out of torque

 

[ckouba]

A very brief update: Had a wet tank leak which I remedied and wanted to validate, so I used the truck for some errands today. If I had never had the reduction hubs, I would never even think about them. The rig feels normal... I think my trans is still re-learning shift points but I still see no practically negative impact to performance, and I can't wait to see how far a tank of gas will take me now.

If you're thinking about this and your use case is similar to mine, my experience remains extremely positive so far. Thanks Mike!

 

[Xengineguy]

Thanks Chris for the update. Sounds good. Also thanks for trying something untested on a heavier rig with the 3:07.
We really didn’t know how that would work out. So glad it worked for you!

 

[olly hondro]

I purchased a set for the Gladiator LMTV. I am estimating it will weigh in about the same as an overweight HUMVEE, so, say, maybe 10 000 lb at the most. I am anxious to get it on the scales when it is done. I see no downside to the hub conversion: if the low speed crawl technical stuff requires more torque, then the conversion is reversible.

 

[ckouba]

I purchased a set for the Gladiator LMTV. I am estimating it will weigh in about the same as an overweight HUMVEE, so, say, maybe 10 000 lb at the most. I am anxious to get it on the scales when it is done. I see no downside to the hub conversion: if the low speed crawl technical stuff requires more torque, then the conversion is reversible.

Thread drift: We need a new thread about whatever that is!!!

 

[RRaulston]

I purchased a set for the Gladiator LMTV. I am estimating it will weigh in about the same as an overweight HUMVEE, so, say, maybe 10 000 lb at the most. I am anxious to get it on the scales when it is done. I see no downside to the hub conversion: if the low speed crawl technical stuff requires more torque, then the conversion is reversible.

View attachment 899496

I need to stop by and see this! I'm in Sahuarita....

 

[olly hondro]

Thread drift: We need a new thread about whatever that is!!!

Yes, sorry, I meant to post in the original eco hub thread.

 

[Camel Driver 1]

There is now at least one truck with 3.07 gears and the Eco hubs. Rick came over last yesterday and we spent a LONG quality day together doing a CTIS service in addition to the hub swap. MASSIVE(!!!!) thanks to him for his assistance!

The verdict? I have only driven about 7 miles with it due to the hour we finished but I think it's going to work out just fine. It moves off a stop differently than it did with the reduction drive, but I don't think it's any slower. Acceleration was a bit "softer" at some points in the gear/rev range, but the interesting thing is it appears to pull the mild hills better than with the reduction gears. I was able to maintain ~60 MPH up a hill where previously it would drop down gears and spin the motor while dropping into the low 50's.

I am back to work for a few days so I don't have time to do a fuel burn run, but I can tell you that my anxiety over "will this work" is gone. I know this might not be everyone's cup of tea, but I can tell you for my build's mission statement, this mod feels great.

More impressions will be shared as we log more miles.

Thanks for the ECO HUB review. I just ran across them the other day. I have an M1083 with stock gears but, any and all real world info on these is appreciated. From what I've seen so far I believe I will be putting myself on the list for a set before the year's end. I have to laugh, it sounds like the 1083 will be getting 2+ MPG better than my Ford F350 DRW. Guess which truck will be my daily driver after a set of ECO HUBS?

 

[ckouba]

Last weekend, we had our first "real" trip in the camper, and one of the things I was most curious about was how the truck would do with the Eco hubs.

I've already shared that I never did log extensive mileage with the truck prior to the conversion but I can honestly say it doesn't feel much different power-wise than it ran prior to the delete. The difference is in the drivetrain calamity- or lack thereof. I had a gear whine which has gone away (presumably the bevel gears). The drivetrain is spinning at half its prior speed. When I get to 65 on the freeway, the trans shifts into what I believe to be 6th gear and the motor starts to just lope down the road. I'm at probably 25k #'s now and the minor hills I did fine with, some of them able to keep just rolling on at 60-65. The steeper ones would slow me down, but based on the one shakedown trip I did last fall, I don't think it's any worse than with the bevels installed. I think my Eco hubs will be permanent residents, and they play very well with their neighbors- the 3.07 gears. Not going to change anything at this point.

I know the question is now, "What was your mileage??!?!?" Unfortunately, I screwed up the refill and need to redo it. I thought the pump would have stopped on the card before the tank was full, but I know it ended up with more fuel in it than I started with. I thought I had a solution to that and had noted the mileage and fuel used from the ECU, but even that was jacked up. It indicated that I had used 44 gallons over the trip, whereas I only put 35 gallons in at the pump, so something isn't correct there. Doing the math on the overall MPG's, prior to the trip, it had gone 8662 miles using 2619 gallons of fuel (according to the ECU) for an average MPG of ~3.3 MPG. Adding the 279 miles for the weekend using the 44 gallon figure from the ECU would get me ~6.3 MPG.

I assume that original MPG is heavily weighted for non-highway/military use and probably not accurate objectively. But in comparing results using the same yardstick (ECU miles and ECU fuel gallons consumed), the mileage has almost doubled. Does this mean the actual mileage doubled? Seems too good to be true but I will be doing some math as I gather more data. I know that I only put 35 gallons in it and that was over the initial fill line I started with, so the ECU telling me I used 44 gallons seems way too thirsty for the rig. Using 279 miles and 35 gallons gets me to ~8 MPG, but I also think I may have been off by as much as 5 gallons. If that was the case, 279 miles using 30 gallons will be >9 MPG and I would be very content with that- the cargo van this vehicle replaced only got ~12 MPG, so yeah, I'll take the 9+ for the level of comfort and capability this brings!

The Clif notes version is: Driveability is realistically unchanged. Mileage is "improved". Drivetrain wear and tear is halved. Cruising speed is pleasant. Noise is dramatically reduced.

 

[ckouba]

As an aside, I am pretty happy with how the odometer is reading. It matched extremely well to the mileage that Google Maps told me that I travelled. I think the distance covered side of the equation is pretty accurate.

 

[Ronmar]

Thanks For the report.

The only place 2x hubs are a benefit is if you are trying to start and move a VERY heavy weight up a very steep incline In 1st gear. Everyplace else they really are a hindrance.

Removing them also removes the ~10% of power transfer loss those gearboxes incur in getting engine torque to the tires…

 

[tennmogger]

I haven't seen this mentioned, the speed sensor that warns of CTIS overspeed is now at half speed. There won't be a warning or an auto bump up to HWY speed at '40' mph. Guess it would happen at 80, ha ha.

And my odometer reads exactly half what it used to read. i have to double odometer number to calculate mileage. That is logical of course.

 

[Ronmar]

I haven't seen this mentioned, the speed sensor that warns of CTIS overspeed is now at half speed. There won't be a warning or an auto bump up to HWY speed at '40' mph. Guess it would happen at 80, ha ha.

And my odometer reads exactly half what it used to read. i have to double odometer number to calculate mileage. That is logical of course.

Yep, no ctis warnings anymore untill ypu hit warpspeed. The CTIS controller may be able to be reprogrammed.

I forget what year/model truck do you have?

 

[GeneralDisorder]

CTIS gets it speed signal from the ECM if you have a 3126b or C7 engine. You will still get HWY mode overspeed unless you reprogram the CTIS controller. ..... Not sure where CTIS gets its VSS from on an A0 but it is easy enough to reprogram the CTIS controller for the new PPM (pulse per mile). You will still get HWY mode overspeed unless you reprogram the CTIS controller.

CTIS reprogram is super easy - the software is free from Dana and you can use any RP1210 adapter and windows laptop..... On the A0 though I believe this requires a special interface cable that plugs in-between the controller and the truck to give you the coms breakout unless you do it on a bench. I've only done the A1 black controllers.....

 

[Ronmar]

The A0 CTIS uses the same pulse signal as the speedometer.

I suspect it is un-conditioned pulse info right from the xfer case sender as i have seen nothing in the little bit of WTEC 2-3 programming i have seen that indicated that it was adjustable/scaleable in the TCU.

 

[tennmogger]

Yep, no ctis warnings anymore untill ypu hit warpspeed. The CTIS controller may be able to be reprogrammed.

I forget what year/model truck do you have?

1994 A0, the one with the ECO Warp Drive.