M880 rear axle selection

[maddawg308]

M880 axle selection

Planning on future builds, getting my mental ducks in a row (hard to do, since most of those ducks are suffering massive hangovers at any one time). Plan to build a quasi-M880 truck, on a more modern frame. Engine would be a 6BT Cummins. The stocks axles on the M880 series were Dana 44 front axle and Dana 60 rear, with a 4.10:1 gear ratio in each. These were "pretty weenie" (as Uncle Floyd used to say) and weren't that stout. This truck would be used for heavy-duty off-roading, towing and offroad recovery, so I would be trading up to something a LOT more beefy.

Here's the options:

Front axle:
Dana 60
Dana 70
Rockwell 2-1/2 ton

Rear axle:
Dana 70
Dana 80 (non-dually)
Corporate 14-bolt
Rockwell 2-1/2 ton

The Rockwells are tough enough, but are fairly heavy and I'd rather not go with them because the Rockwell gear ratio is too steep and would suck as road speed would suffer. The other options are all tough and you can get gear ratios in pretty much anything you want.

What is your opinion?

 

[ODdave]

60/80. Upgrade the 60 shafts to 1.5 in outers and be good to go.

 

[maddawg308]

I've heard the Dana 60s used on the M715 series of trucks front axles are not as good as other Dana 60s used in other commercial trucks. Can someone care to elaborate on why?

 

[ODdave]

They may have had the corse splined axles. Where they closed knuckle?

 

[maddawg308]

For some reason I want to say they were open knuckle.

 

[Dave_1972]

I would go 60/70 - the 70 will handle a larger gearset (up to 7.70) if you want later on.

That's what came with the 92' W250 that I will be dropping an M880 body on in the future.

(along with 6BT - A518 - and NP205)

 

[MidnightDuramax]

Well if you wanted to go all out and run the 2 1/2 tons there are gear sets for them. Overson Engineering :: Ouverson :: Hardcore Off-Road Parts has 4.90 gear sets. I think there is another company making gear sets as well. Overson also has everything to make them completely bullet proof.

 

[ODdave]

You can get 5.13 for Dana 80s. Overson stuff is great, but not bullet proof.....

 

[nattieleather]

Not much differnece IMHO between the Corp 14 bolt and the Dana 60 rear axles. But a Dana 60 front and Dana 70 like stated above would be a good combination with out going to the heavy duce axles.

 

[MidnightDuramax]

14 bolt is stronger it has 3 pinion bearings instead of 2 like all others. The pinion has the 2 standard pinion bearings but it has a third as well. The third one is on the snout of the pinion gear. It gives more strength in keeping the pinion engaged with the ring gear under extreme load.

 

[ODdave]

The 14 bolt is more compareable to an 80. A 60F & 70 rear are pretty much equal in strength as they use the same yokes/ splines (weak piont). Your going to find that the 14 & 60 dont have many ratios in common. If you have access to an 80 it is Stronger than the 14 or 70.
Here is some food for thought,
Pic #1- 14-70-60.
Pic #2- 14-70
Sorry i did not have an 80 here, but the splines are bigger than the 14.

 

[imbobbbb]

the easiest thing to do is just buy an early 90's ctd truck and stick the front clip,doors and bed off of a '75-'78 on it.You can keep the early '90s cab,its pretty much the same.You have to get a bit creative to get the hood to latch but its easier than swapping all the drivetrain parts. A '76 grille works better with the intercooler than a '77.The dash won't look like 'real' m880,but you wont have to adapt anything wiring wise and the average guy wont know the difference.

 

[maddawg308]

I've already come to that conclusion about the body, bob, we've discussed that before in a different thread. What I was interested in knowing is to get the most bulletproof components, even if I start with an early 90s platform, I might have to swap out major components such as the axles anyways.

I saw a Dana 80 on a Dodge W350 the other day, very beefy. I'll have to look around at the Chevy dealership and see what I think of the Corporate 14-bolt compared with it...

 

[ODdave]

2 things your not gonna see on the 14 from the outside. The axle shafts "neck down" between the splines and the flange, and the carrier brg caps have a bolt in the middle of them that has been known to compromise the strength of them. Both easily remidied but just food for thought.

 

[Wy-m880]

imbob, one problem with your idea, back of top cab is different but it only noticable to most dodge users lol and i think some bed holes went from out side frame to be up thru in back behind springs, but only difference i think i have ever encountered, i have a diesel frame from 92 my buddy bought it for engine and trans i hauled away rest of frame ps box and axles