M1078 with 225hp and high speed gears: pro's and con's

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Awesomeness

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so at $2500 for the gears you're looking at $22500 in fuel, 7500 gallons @ $3/gal, or about 45000 miles @ 6MPG average. For $4500 gears, $40500 in fuel, 13500 gallons @ $3/gal, 81000 miles @ 6MPG average.
I updated my math above, because something wasn't looking right in the morning light. It's not 3750-7000 miles you'll need to drive to pay for the gears, it's 45000-81000!
 

coachgeo

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I updated my math above, because something wasn't looking right in the morning light. It's not 3750-7000 miles you'll need to drive to pay for the gears, it's 45000-81000!
yeah this is why I hesitated for a bit...... but decided to go all out (higher HP, gears swap and taller tires). All in all will not make funds back while I use it.. butttt... will be less wear on the engine and tranny which will extend its life...butttt..... When selling it down the road... when Im too old to use it or my wife; to be, shoots me.... whichever comes first- a big chunk of that money will be made back then.
 

ramdough

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One thing I have seen several people mention.

Some throttle pedals need adjustment causing the pedal to not allow full throttle on some trucks. That would also be something to look at.


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Ronmar

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Well lack of pedal travel or pedal not rotating the governor bell-crank to the high speed stop, would = not reaching full speed. They call it a throttle, but a more accurate description is speed selector. The pedal tells the governor what RPM to run at, the governor controls the throttle/fuel rack...
 

ramdough

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Well lack of pedal travel or pedal not rotating the governor bell-crank to the high speed stop, would = not reaching full speed. They call it a throttle, but a more accurate description is speed selector. The pedal tells the governor what RPM to run at, the governor controls the throttle/fuel rack...
I was trying to differentiate between the hand throttle and the pedal. Maybe my post sounded off on wording. My understanding is the issue has to do with the pedal.


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Ronmar

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There is only really one "throttle" the hand lever and pedal are interconnected so the lever basically depresses the pedal to actuate the single cable that runs down to rotate the governor bell-crank.

In the end though, a mis-adjustment of the throttle or the high speed stop on the governor will limit peak governed RPM/top vehicle speed.

It might also hamper performance a little as the governor in part decides how much fuel to deliver based on the difference between commanded RPM(governor bell-crank position) and actual RPM. It still has to wait for boost to build to deliver full fuel, so this would probably not be all that noticeable...
 

88atlas07

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Not to thread jack, but has anyone tried to change out the ring gear and pinion themselves instead of ordering the whole assembly from an mrap? I haven't looked at part numbers yet but a 3.90 Meritor ring gear and pinion can be had for $300 (I realize this is the stock gear ratio-this is just an example). Even if you took the assembly to a differential specialist to assemble and shim, it'd be cheaper than the $4k+ that ebay and other surplus suppliers want for mrap assemblies.
 

Reworked LMTV

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Not to thread jack, but has anyone tried to change out the ring gear and pinion themselves instead of ordering the whole assembly from an mrap? I haven't looked at part numbers yet but a 3.90 Meritor ring gear and pinion can be had for $300 (I realize this is the stock gear ratio-this is just an example). Even if you took the assembly to a differential specialist to assemble and shim, it'd be cheaper than the $4k+ that ebay and other surplus suppliers want for mrap assemblies.
New or used price?
 

coachgeo

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double post..... moderator please delete this post

PS.... with the change over ......... why the heck are they staying with a user not able to delete their own post???
 
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coachgeo

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Not to thread jack, but has anyone tried to change out the ring gear and pinion themselves instead of ordering the whole assembly from an mrap? I haven't looked at part numbers yet but a 3.90 Meritor ring gear and pinion can be had for $300 (I realize this is the stock gear ratio-this is just an example). Even if you took the assembly to a differential specialist to assemble and shim, it'd be cheaper than the $4k+ that ebay and other surplus suppliers want for mrap assemblies.
if you can find the gears separate...... with the raise in cost of used thirds out there; you may be correct that it is cheaper, but have doubts one can find new or this would have been process most have taken. Post here if you find new. Thus, for same reason as expressed before; still looks like shipping a used 3.07 ratio third is less costly compared to just shipping a used R&P due to added labor expense.

99% of the R&P are used... inside an axle.... so options are

both scenarios (ship gear only / ship whole third member )
>pay labor to remove third
>Pay labor to install third

Ship gear only
same above plus
>pay labor to dissasemble donor third
>Pay labor to disassemble users third
>pay labor to assemble users third with donor parts

Thus so far gear only is more expensive due to additional labor

ship
here is where the ball game plays most.... with rise in price of the cost of thirds out there.... add on the shipping of that heavy third you begin to bring the margins of the two scenarios closer to one another. Right now; suspect labor of "Gear Only" scenario still comes out more expensive than shipping cost of heavy third used in that scenario.

Iffff one has the knowledge to install R&P themself then this lowers the margin between gear only and ship whole third scenario even more... though you still pay cost of seller disassembling donor third . Again though if one can find "new" R&P then you cut out some labor cost on seller end... but you have higher cost of "new" sooooo????
 

88atlas07

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if you can find the gears separate...... with the raise in cost of used thirds out there; you may be correct that it is cheaper, but have doubts one can find new or this would have been process most have taken. Post here if you find new. Thus, for same reason as expressed before; still looks like shipping a used 3.07 ratio third is less costly compared to just shipping a used R&P due to added labor expense.

99% of the R&P are used... inside an axle.... so options are

both scenarios (ship gear only / ship whole third member )
>pay labor to remove third
>Pay labor to install third

Ship gear only
same above plus
>pay labor to dissasemble donor third
>Pay labor to disassemble users third
>pay labor to assemble users third with donor parts

Thus so far gear only is more expensive due to additional labor

ship
here is where the ball game plays most.... with rise in price of the cost of thirds out there.... add on the shipping of that heavy third you begin to bring the margins of the two scenarios closer to one another. Right now; suspect labor of "Gear Only" scenario still comes out more expensive than shipping cost of heavy third used in that scenario.

Iffff one has the knowledge to install R&P themself then this lowers the margin between gear only and ship whole third scenario even more... though you still pay cost of seller disassembling donor third . Again though if one can find "new" R&P then you cut out some labor cost on seller end... but you have higher cost of "new" sooooo????
Makes sense. It seems the only way it'd be worth it if the R&P could be bought new as single parts with no disassembly required. Ill look into it as am in the market for 3.07's but turned off by the ridiculous price
 
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