M813 repower

[Str8Jacket]

I used the advanced search on here and looked through every thread I could find on this so if I missed it I apologize.

But has anyone dropped in an 8.3/auto out of a 939 series into their 813 or the like? I like the look of the 813 but the engine/trans from the later models. Seems like it would work just fine.

 

[sandcobra164]

I have not read a thread on here concerning such a conversion. I'm quite certain a good fabricator could pull it off with no trouble. If you decide to go that route, I'd get an entire donor truck so I could swap the backing plates on the axles out and rob the components to add air brakes to your truck while you're at it. You will also need the transfer case as the Allison trans is a direct drive in 5th and the M939 trucks have an overdrive transfer case to make up for the lack of overdrive in the trans. Just don't drive the M939 truck prior to doing it. I love the looks of the M809 series trucks and M35 series trucks but look to your left at a picture of me and my big ole' square hood! They are nice and comfy trucks in comparison. I've had plenty of seat time in all 3 but I prefer the overall comfort of my M923.

 

[wreckerman893]

Derek Taylor (Taylortradingco on here) had a truck with an 8.3 that he is parting out. If he still has it you would have an ideal donor truck. PM me for his phone number if interested.

 

[Str8Jacket]

I have not read a thread on here concerning such a conversion. I'm quite certain a good fabricator could pull it off with no trouble. If you decide to go that route, I'd get an entire donor truck so I could swap the backing plates on the axles out and rob the components to add air brakes to your truck while you're at it. You will also need the transfer case as the Allison trans is a direct drive in 5th and the M939 trucks have an overdrive transfer case to make up for the lack of overdrive in the trans. Just don't drive the M939 truck prior to doing it. I love the looks of the M809 series trucks and M35 series trucks but look to your left at a picture of me and my big ole' square hood! They are nice and comfy trucks in comparison. I've had plenty of seat time in all 3 but I prefer the overall comfort of my M923.

Looks like I have some gathering to do. I am contemplating a Crew Cab upgrade for the 813 too. This site is gonna get me in trouble with the Wife.

Do you think it would be easier to just swap the sheetmetal over from the 813 to the 923 (for example) instead of changing out the running gear in the 813? I havent looked up the dimensions of the frames yet, just spitballing ideas here.

 

[Jbulach]

Do you think it would be easier to just swap the sheetmetal over from the 813 to the 923 (for example) instead of changing out the running gear in the 813?

Yes

 

[adamsoffroadperformance]

There is a guy from Brazil on the 5ton facebook page that has an 813 with an 8.3L. says it was built rebuilt that way by the government for the Marines if I remember correctly.

 

[fuzzytoaster]

There is a guy from Brazil on the 5ton facebook page that has an 813 with an 8.3L. says it was built rebuilt that way by the government for the Marines if I remember correctly.

That is correct, it was a model for export only to Brazil.

 

[Str8Jacket]

I guess sometimes living outside the US has it's perks.

Anybody think I'll have a problem fitting the 8.3 with an intercooler under the hood of the 813? From the pictures it looks more narrow in the nose that a 923. Thinking about it though, since it fits the 855, I don't think I'll have an issue.

 

[dk8019]

It would be a nice repower. I would love to do one and keep the manual transmission though.

 

[Str8Jacket]

Yes a stick would be great but my wife will use the truck to pull the horse trailer too. So I want to keep it "user friendly". That's also the reason for the crew cab. I've been figuring out a plan for ultimate sound deadening to go along with the stereo and possibly Super Duty seats.

 

[red]

With the smaller 8.3 you could move the radiator back from the grill and fit an intercooler in there without much trouble.

The frame is the same between the series, different body mounts and some more accessories bolted to it on the 939 trucks.

If you don't have the 813 yet I'd buy an 923a2 or 925a2 in your position. Much cheaper to buy the cab/front body of the older 809 series and less work than buying basically 2 complete trucks to meld into 1.

 

[brianrbull]

I have been thinking of this myself to Repower my M816... would the 8.3L Bolt up to the 5 speed?

 

[red]

same SAE2 bellhousing bolt pattern. Flywheel for the 8.3 and a new clutch might be needed.

 

[Str8Jacket]

With the smaller 8.3 you could move the radiator back from the grill and fit an intercooler in there without much trouble.

The frame is the same between the series, different body mounts and some more accessories bolted to it on the 939 trucks.

If you don't have the 813 yet I'd buy an 923a2 or 925a2 in your position. Much cheaper to buy the cab/front body of the older 809 series and less work than buying basically 2 complete trucks to meld into 1.

You and I are on the same page. Either a 923 or a 931, sell the body and find an 813, 814, 818 etc cab/nose. I'd like to put a 8' drop side bed behind the crew cab. I bet I could even keep the steering column and shift tower from the 923 and make it work in the 813

 

[sandcobra164]

You and I are on the same page. Either a 923 or a 931, sell the body and find an 813, 814, 818 etc cab/nose. I'd like to put a 8' drop side bed behind the crew cab. I bet I could even keep the steering column and shift tower from the 923 and make it work in the 813

Awesome idea sir! I think there would be alot less work involved with swapping sheetmetal from an M809 series truck. There will still be some fabrication work involved but likely alot less if you start with a solid chassis and drivetrain. You wouldn't even have to find a running M809 series truck, you just need the cab, fenders, hood and grill. For what it's worth, M35 cab tubs are interchangeable with the M809 series trucks when it comes time to do your swapping.

 

[Str8Jacket]

Awesome idea sir! I think there would be alot less work involved with swapping sheetmetal from an M809 series truck. There will still be some fabrication work involved but likely alot less if you start with a solid chassis and drivetrain. You wouldn't even have to find a running M809 series truck, you just need the cab, fenders, hood and grill. For what it's worth, M35 cab tubs are interchangeable with the M809 series trucks when it comes time to do your swapping.

Good to know. Not to sound too much like an FNG but by cab tubs you mean?

 

[fsearls92]

The m809 series cab and m44 series cabs are the same. Tub, doors, windshields, and roof are the same. Fenders and hoods are different though.

 

[Str8Jacket]

The m809 series cab and m44 series cabs are the same. Tub, doors, windshields, and roof are the same. Fenders and hoods are different though.

I thought that was the answer but I don't like assuming anything. Once I gather all my pieces for this Frankenstein project I'll either need to build a hoist next to my garage or convince the wife I need an 816 too

 

[wreckerman893]

IMHO the flip nose of the 900 series 5 ton trucks beats the crap out of standing on your head to work on stuff under the hood. I've had both series of vehicles and barring an MV rat rod project will never go back to the 800 series.

 

[fuzzytoaster]

So what I'm hearing from this thread is M939 base, M809 fenders, and make the M809 hood a tilting hood like the M939. DO IT!!