TheDrashStash
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Could the transmission tcm be programmed to bring back 1st gear? It would give you some much needed low end
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ECO Hubs Who needs 3:07 gears?
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Ronmar
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Its not so much bringing back 1st gear, that low 1st range is the add-on gear to the 6 normal speeds found in the 3060 core transmission. The 2nd gear that it starts in is actually the normal 1st ratio for the 3060 trans + the fixed 1.2:1 transfer case ratio… You could always down arrow to reach it if you were trying to get something really heavy moving…
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Could the speedo be changed to show the correct speed after eliminating the gear reduction?
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Currently 65mph. It will go much faster…
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1st gear is still there and now you can use it. I know it’s hard to believe but low end power is great. Remember you also have
mode for lower first as I understand.
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If I understand correctly the Speedo in an AO uses dip switches to change the calibration, the A1 is set thru the transmission ecu.
will know more this week. I have an appointment with an Allison guru this week.. To this point I’ve been using gps speedometer
works very good!
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Are your recorded acceleration times starting out in 2nd or manually selecting 1st?
How is the acceleration from a stop starting out in 2nd?
What generation is your truck and what HP/TQ are your currently running?
Due to the unfortunate aerodynamics of these chassis (and mine is a 1079 so even worse) I stick to about 50 MPH regardless. Would the trans even make it to 7th gear at 50 mph? Being peak toque and thus efficiency is @ 1400 RPM and 7th would put the engine below that.... hopefully it would just stay in 6th??
If I were to consider this - I'm running a 2008 with the Gen IV Allison 3700SP and I also have a 370 HP, 931 Ft/lb fuel map loaded on the C7. Peak torque is up (compared to stock) by about 200 Ft/lbs at 1400 RPM.
How is the acceleration from a stop starting out in 2nd?
What generation is your truck and what HP/TQ are your currently running?
Due to the unfortunate aerodynamics of these chassis (and mine is a 1079 so even worse) I stick to about 50 MPH regardless. Would the trans even make it to 7th gear at 50 mph? Being peak toque and thus efficiency is @ 1400 RPM and 7th would put the engine below that.... hopefully it would just stay in 6th??
If I were to consider this - I'm running a 2008 with the Gen IV Allison 3700SP and I also have a 370 HP, 931 Ft/lb fuel map loaded on the C7. Peak torque is up (compared to stock) by about 200 Ft/lbs at 1400 RPM.
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That's actually what I was thinking of asking earlier today. Where the vehicle knows it speed from and apparently looks like it's the transmission. Because I believe various modes limit you based upon speed and tire pressure
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Acceleration times were not in “mode” so yes 2nd. Not from a stop just to make things a little more consistant. The acceleration from a stop 2nd gear is very good! I’m letting the transmission shift on its own in all tests. My truck is a stock A1 274 hp….
The tranny will not shift to 7th at 50mph. I think I will try to lower shift point of second OD so it is at 65 mph.. if it can be done?
the idea would be to lug it a little at 60 to 65, the tranny seems to hold gears very nice allowing you to gain some more fuel mileage.
Thru town you can force an up shift by going a little faster then slow down to allow a little lug, the engine is very happy doing this
and accelerates good with out downshifting.
Ronmar
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Yes vehicle speed sensor is in the transfer case at the output, same as any other vehicle. I do not know if the TCU can alter/scale the output, but the speedo dip switches will need to be changed to display correctly. CTIS uses the raw speed pulses so will also be out of wack and not sense overspeed untill you double its programmed setting(probably wont ever indicate overspeed ever again
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RRaulston
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uh yeah, I drove my 1083 100 miles and I swear I burned half a tank. I need to do a more scientific test.... So what is the new ratio as compared to adding 307 gears?
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Exactly half the current ratio of 7.8 which is 3.9. 3.07 gears with the reduction hubs give you 6.14
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You mean 3.4 not 3.9? Or is that common core math!
DeMilitarized
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I believe he meant to write 7.8/2 is 3.9 which is the ratio before 2:1 reduction.You mean 3.4 not 3.9? Or is that common core math!
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Correct - I meant 7.8. My bad on the Typo. The ring and pinion is 3.9
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Here is an invitation for anyone that owns one of these trucks to come test drive mine and report the good or bad.
Im in north east Indiana, you can pm me to make arrangements. My Allison guru dropped the ball, so will probably be next week for speedometer adjustment etc. I think I’m going to haul some gravel this weekend if the pit is open. I have a nice tandem
dump trailer to overload and pull. Will report.
Im in north east Indiana, you can pm me to make arrangements. My Allison guru dropped the ball, so will probably be next week for speedometer adjustment etc. I think I’m going to haul some gravel this weekend if the pit is open. I have a nice tandem
dump trailer to overload and pull. Will report.
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coachgeo
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Since an axle with outer gears, be it portal or gear reduction.... it is said the forces from the drive system are "shared" heavily between R&P and the outer gear system. Could be the hub design of this new setup may create that same effect????
Thusly, take measure with a temp gun your pumpkin and hub temperatures in various circumstances that others can duplicate..... like heavy loads in a bed.... or long up hill difficult-highway route where you know the grade of the climb and how long it is.
Comparing these temp measurement s of the hub system and others of their OEM system; might be a good potential way to evaluate forces on ring and pinion and if they remain similar to OEM or of if they are being worked harder (get hotter). Maybe some of the OH folk, or the IL folk with LMTV's and you can get together and do some same test on a weekend for real good comparison? Maybe you can go to the SC FMTV meet up in hmmm Sept or Oct . I forget the dates at the moment.
As @tennmogger alluded to... he and I have been around years of discussion on this topic via our life in the Unimog world. This is going to be in interesting experiment.
RRaulston
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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 ...
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It's all good it'll be exciting to hear what the results of the tests are!
coachgeo
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has nothing to do with gear reduction. Just strength of individual components.
there is a 5 gal pail of sand.. if you pick it up with one hand to walk it 1000ft.... its not fun unless that hand is BEEEF strong...... if a buddy grabs the handle with you.... its less work on each person's hand than on the one person/one hand.
In this case the drivetrain force = the weight of the sand. one person/one hand, carrying it is how standard axle moves the pail of sand and they are built beeefy. Two people's hands sharing the weight of the pail is how the force is sorta divided up between gears in the pumpkin (person #1) and gears at end of axle (person #2) is how our axles are designed. Yes that is not an exact scientific explanation...... but conceptually sorta gets the point across.....
Two people do not have to be as strong as one person... manufacture design strength of things with that in mind. Two places to help carry load then they dont make each of them as strong as they would if it was only one place that had to carry the load . "Typically that is"
If this hub ends up acting like a second person's helping hand, just like the outer gears in the OEM axle do ..... then all good. Orrrr if these axles are not "typical" and are so over built strong in the first place (which is the proposal if I understand correctly) then you dont neeeeeed the help in carrying the load in reality, so you can cut off the helping hand cause its not needed.
OEM= Original Equipment Manufacture.