couple of questions on the 5 tons

[mm73]

I am about to purchase a 925 but have a few questions.
Is the gear ratio different in the axles between a truck with super singles on it and a truck with smaller duals on it. what size are the stock duals that come on the 923-925's I ahve read through all 15 pages of threads in this particular forum. any help is appreciated.

Thanks

 

[porkysplace]

A google search of " M 925 specs" brought this up in the wiki .

Specifications

U.S. Marine Corps M923A1


All models of the M939 share a common basic chassis, motors, armory, etc. The basic truck is a 6x6 (three axles, six sets of tires, all six powered) medium truck. The vehicles have a wide variety of configurations and weights. [1]
Note that the motor and tire specifications, along with other improvements, apply to the A2 versions (and A1 versions) of each base model listed below. There is an M928, an M928A1, and M928A2.
[edit] Engine

The M939 and M939A1 models use a Cummins NHC 250 diesel engine, producing 250 hp.(685 ft·lbf@1500 rpm). The M939A2 models use a smaller Cummins 6CTA8.3 engine producing 240 hp.(745 ft·lbf@1500 rpm). All models have the same automatic transmission.
[edit] Tires

The M939 uses 11:00 R20 tires with two tires per side per axle in the rear (rear tandem duals). The M939A1 and M939A2 series use oversized 14:00 R20 tires and rear tandem singles. M939A2 series vehicles use a centralized tire inflation system.

Link to wiki : M939 Truck - Wikipedia, the free encyclopedia

Rear Axle Ratio6.44

 

[M813A1]

Yes to your question all the model trucks use the ame gear ratio of 6:44 to 1 !! Wether it has early 1100:R20 tires or the late 1400:R20 tires the axle ratios are all the same

 

[mm73]

I thougt those super singles where 395 85 20 or 385 95 20's? so are they actually 1400r20's instead? I am not like most people, I dont want the biggest tire I can fit on the truck but I would like some bigger tires than the stock 1100r20's that come on some of them. Oh and thanks for the info on the gear ratios. that helps out a bunch.

 

[fsearls92]

The A1's and A2's came with 14.00's and the others came with the 11.00x20's. Mine came with 11.00's on it, and I went ahead and added 395x85 20's not long after purchase.

 

[mm73]

My next question would be, If the truck is doing 55mph with the 1100r20's comfortably, meaning not reved out, what will the truck do with 1400r20's not reved out and what would it do with 395's not reved out? Also if you have 395's on it, is the truck constantly changing gears when going over overpasses etc.

 

[fsearls92]

I ran mine at 60 with the 11.00's comfortably just below 2000 rpm's. Now with the 395's I have run it at a top speed of 68 just above 2000 rpm's and that was with a GPS not the speedometer. Grant it thought I don't run it at 68 mph since it usually is following my duece we normally run it around 50mph. Not sure on the 14.00's yet, I might stick on an extra set i have laying around this winter just to see how they feel on the truck.

 

[mm73]

Let me know how it runs. I am curious so I know what to start looking for.

 

[poorman4x4]

1400r20's are a 49" tire, have them on my 923 i can do 63mph all day long at 2000 rpm

 

[poorman4x4]

I run mine all over lafayette, up to colfax for mudfest, drive it anywhere, overpasses arent bad, you have a grandmother-powered cummins 250, you cant really expect much, a cummins 400 swap is coming as soon as it cools off around here, then im going to upgrade to the 1600r20's(53") to lower my rpms back down after the power increase

 

[M813A1]

A good choice of tire is the 1200R20 it is 44 inches and it will pull better then the 1400R20 and you will not loose as much pulling power as you will with the 1400R20 tires . Now in the M939 truck it may not have as much pulling power loss as the M809 trucks because of the automatic . But I had 1400r20 on my M813A1 for a while and it run out well at 63 on level ground but died when pulling a hill with the 1400R 20 tires

 

[mm73]

all goog information. however I still have to get a truck, i thought I would have one by now but every truck i was looking at went for 5k and over. Last week I saw some sale for 2k-3k. So Im still looking for a truck rt now.