M880 part time conversion question

[chriskonen]

Hello, I'm a new member, first time post. I recently acquired a 1977 Dodge M880. The truck starts and runs strong and is in fairly good shape despite being stationed in upstate NY and being subjected to harsh winters and salt conditions, then being put in service for 8 years for the DOT.

I plan to restore the vehicle, do an engine rebuild (on a spare 318 then tranplant) as well as a few upgrades and changes like adding a stereo plus a small lift and slightly larger tires either 33s or 35s. I've been looking into the Mile Marker 603 part time conversion kit as it will upgrade the hubs, aid in the steering (truck has been converted to power steering already) and hopefully add to the fuel economy.

My question is, what, if anything, can I expect as far as increasing my gas mileage? Will I jump up 2-3 miles per gallon or will I not really notice any gains? If not, what can I do to increase fuel efficiency for daily driving short of converting to fuel injection. I'm not looking to do anything incredibly expensive since I only paid a flat grand for the truck. Thanks for any help, Chris.

 

[Elwenil]

No, you really will not see much difference and it will take you a long time to recoup your investment in the Milemarker kit. Also note that the Milemarker kit doesn't really "upgrade" the front hubs, it just adds a locking hub that is very similar to what Ford used on some Rangers and Bronco IIs. Many consider the hub design to be very weak and not much of an upgrade. If you really want part time 4WD, find a cheap '80-'93 Dodge W250 and swap the transmission, transfer case, drive shafts and everything from the knuckles out on the front axle and that will get you part time 4WD for probably about the same price as the Milemarker kit if you shop around and will be much more reliable. Personally, although I do not like the full time 4WD system and can't stand the front wheel bearing design, I'd just drive it and maintain it properly and it will probably be fine. If you plan on beating on the truck off road or adding big, heavy tires, then I would at least upgrade to the later style hubs or a D60 front axle.

As far as MPG, about the only thing you can do is make sure it's in good tune and drive like there is an egg under the gas pedal. It's a 34 year old truck with 4.10 gears, an underpowered engine and the aerodynamics of a brick. It's not going to get much better unless you swap in a diesel engine.

 

[goodbrewing]

I converted my M886 many years ago. I got a newer dana 44 from a scrap yard and swapped from the ball joints out to the newer locking style hubs. I used the milemarker kit in the transfer case. It all works great and only set me back about $500. including new brakes and joints.
You won't notice much gain in gas mileage but I do allot of highway driving and was wearing out front end parts and driveshafts. I get between 10-11 mpg if I'm not towing but for what it is and what I use it for I think that is reasonable.

 

[diesel583]

Haven't drove my 885 much in the last few years but it was my main transport for 20 years. Got it with 12 miles on it, it has 137000. It got 10mpg loaded empty, or pulling a 24ft trailer. Never had any problems with 4wd, drive shafts, or front ends. I personally wouldn't change a thing.

 

[goodbrewing]

Haven't drove my 885 much in the last few years but it was my main transport for 20 years. Got it with 12 miles on it, it has 137000. It got 10mpg loaded empty, or pulling a 24ft trailer. Never had any problems with 4wd, drive shafts, or front ends. I personally wouldn't change a thing.

I wish I had that kind of luck. I had a little vibration 1 day driving down the interstate next thing I heard was a loud bang and a sudden jerk. The CV joint in the front driveshaft gave suddenly and the result was the driveshaft folding at the joints, catching the crossmember and snapping a front inner axle shaft. Yes it was my fault for not stopping immediately when I felt the vibration but haven't had any problems since. It was worth it to me but your results may not be the same.

 

[chriskonen]

Thank you all for the input, sounds like I should skip the conversion kit as it won't correct any of the issues. Guess I'll look into hub upgrades and roll with it. Glad I asked!

 

[Cucvnut]

cool M880 in your avatar!

 

[m880 unimog]

your truck looks great,love the original paint ones,sounds like you were lucky to avoid the rusty curse in that part of the country.
if 4 wheel drive is not vital to your plans-i would go for a diesel set up.
welcome to SS

 

[Elwenil]

Not sure I completely understand that last comment. Why would he need to give up 4WD for a diesel swap? Maybe I'm just not catching your meaning.

 

[m880 unimog]

putting a 2wd diesel engine and trans into a different vehicle is generally a much easier job than hooking up a 4wd-no adaptors,prop moves,etc.
with the hub options he mentioned,and wanting good fuel mileage,thought this would be a valid option.
my current build on a m880 has 4wd-would have saved many hours of work if i didn,t need 4wd-

 

[Bob H]

Thank you all for the input, sounds like I should skip the conversion kit as it won't correct any of the issues. Guess I'll look into hub upgrades and roll with it. Glad I asked!

hub upgrades?????????????
I've had M880's for several years & I have not had any hub issues.
Sure most of my trucks are babied but not all, this un works

 

[chriskonen]

As the hubs go, I'm just going by what I've read in other posts and forums that the bearings wear out quickly. I plan to lift the truck 3-6" to accomodate 33 or 35 inch tires on 16 inch rims. No off roading is planned but this will be a daily driver for 20 miles a day so I can't take the chance of something breaking regularly and I want to keep the truck as cheap as possible thus the question about fuel efficiency

I got it cheap, it runs strong, had the power steering added and even has a cherry bomb glasspac muffler installed so my girlfriend and I bought it as a project truck to fix it up and have a fun toy for weekends and such. It has some rust, floor pans are pretty bad and the quarter panel wells are shot, but I can get replacement panels for a couple hundred bucks from rustrepair.com so no big. I also wanted it because I remember seeing these vehicles at McGuire AFB here in Jersey when my dad used to take me to the runway as we used to love to watch the jets take off and land.

For anyone interested I'll post a few more pics of our toy. And thanks again to everyone. I'm going to have lots of questions and need a number of parts in the coming months.

 

[Elwenil]

putting a 2wd diesel engine and trans into a different vehicle is generally a much easier job than hooking up a 4wd-no adaptors,prop moves,etc.
with the hub options he mentioned,and wanting good fuel mileage,thought this would be a valid option.
my current build on a m880 has 4wd-would have saved many hours of work if i didn,t need 4wd-

True but over here at least, the 4WD components are readily available to swap in a complete 4WD Cummins drivetrain from a '89-'93 Dodge truck and later Dodge models can donate the engine and transmission though require an older transfer case.

As far as the hub swap goes, many people have used the '75-'79 Dodge full time 4WD trucks without issues for many years but I doubt many will argue that the wheel bearing design is weaker than the normal spindle and bearing design that was used prior to '75 and then again after '79. It's definately more of an issue with the small bolt pattern 1/2 ton trucks but it is something to watch out for. I personally would swap the hubs, mainly to convert to part time 4WD since I prefer more control over my drivetrain but as long as you don't use cheap discount parts store bearings you can usually get by with the stock full time hubs. But piece of mind may be worth the swap just to not ever have to worry about it.

 

[Bob H]

As the hubs go, I'm just going by what I've read in other posts and forums that the bearings wear out quickly. I plan to lift the truck 3-6" to accomodate 33 or 35 inch tires on 16 inch rims. No off roading is planned but this will be a daily driver for 20 miles a day so I can't take the chance of something breaking regularly and I want to keep the truck as cheap as possible thus the question about fuel efficiency

I got it cheap, it runs strong, had the power steering added and even has a cherry bomb glasspac muffler installed so my girlfriend and I bought it as a project truck to fix it up and have a fun toy for weekends and such. It has some rust, floor pans are pretty bad and the quarter panel wells are shot, but I can get replacement panels for a couple hundred bucks from rustrepair.com so no big. I also wanted it because I remember seeing these vehicles at McGuire AFB here in Jersey when my dad used to take me to the runway as we used to love to watch the jets take off and land.

For anyone interested I'll post a few more pics of our toy. And thanks again to everyone. I'm going to have lots of questions and need a number of parts in the coming months.

Stock hubs should do ya fine then
here's another of ours my kid with 33 x 11.50's
& the next one with 36 x 12.50's
and one showing how we baby it

 

[rnd-motorsports]

Nice lookin truck! had one as a grass rig on the fire dept for years. Never had any problems with it !