.

[Derrickl112]

.

 

[diverman555]

If you don't have the same size tires Derrick, when you engage your front axle it will tear the gears out of the transfer case. Mark

 

[350TacoZilla]

that or twist driveshafts off, on a light 4x4 on soft ground you can get away with it. i have seen some mud trucks run taller front tires so they are spinning faster to "pull" truck through mud, but on something this heavy or that you run on rd's no way breakage and also tire wear if it doesnt break something right away.

 

[emr]

All is true , But with an air shift you and you know what you are doing, and dont run it on hard pack, meaning black top or such, it is fine, I have run 1100s for years on the front of an M 35 and the 900s on the back dueled, I never had a problem , and if you did run it for a second on hard pack it would not explode,

 

[ProPower]

Derrick112 If its only 2'' Dont worry about it ! We have 14/20s on the front of a 936 and 395 XZLs on the rear and it works great! We use our 2 936s as intended for heavy recovery and towing and havent had a problem yet! Just the truck loaded with all our tools and hardware weighs 38000# ,So if we haven't twisted a drive shaft it probably wont happen.

 

[Scarecrow1]

I know it can be done but I will never do it myself . I know that the front is geared different because if not you would never be able to turn the truck in all wheel drive . I know there are some guys on here that have the numbers in there head to back up what I am trying to say , but just I,m not My main concern aside from the gear ratio is the fact that now you have to carry two spares if your going out of town or anywhere for that matter. I just don't see the need for this change to the truck but , it's to each there own......

 

[Csm Davis]

Scarecrow all the gears on these trucks are exactly the same front and rear, as are most factory built civi trucks.

 

[Csm Davis]

Derrick if you have a air engaged Transfercase you will be okay if you don't engage it. But if you get it in a bind on some hard pack or pavement it can break things. This will have to be a personal call on your part.

 

[Bolkbich]

Hey Derrick Im sure you remember how the tires on the m923 were cupped and worn with a really bad pattern. Remember how it used to bind up and almost try to stop. The stress on a truck that heavy locked in all wheel drive is crazy, its a miracle it didnt break. It was really bad and that was with the same tires on the front and rear. If you dont plan on engaging the front axle , tire size doesnt mean a thing....but if you think you might need all wheel drive, i wouldnt do it.

 

[Derrickl112]

.

 

[supermechanic]

To csm Davis. Front drive ratio in 5 ton transfer case is 1.06 to 1. Scarecrow is correct in the fact a different ratio exists front to rear, the difference is in the T-Case.

 

[patracy]

Thanks for the imput everyone. After looking more, I found a combination that I think will work. The front tires will be 42.5" and the rears will be 42.3". Now All I have to do is find a set of them for sale...

Sounds like someone is thinking about 12.5's on the front and 11.00's on the rear?

 

[Derrickl112]

.

 

[patracy]

I've got a set I'll be removing soon from my 931. If it doesn't work out with the buyer I have lined up, would you be interested in the 177s?

 

[Derrickl112]

.

 

[Bolkbich]

To csm Davis. Front drive ratio in 5 ton transfer case is 1.06 to 1. Scarecrow is correct in the fact a different ratio exists front to rear, the difference is in the T-Case.

If the T- Case front drive is 1.06 to 1, what is the rear drive ?

 

[patracy]

I think someone is confusing the sprag operation. Which would engage when there's 1.07 to 1 from the rear over the front.

 

[73m819]

If the T- Case front drive is 1.06 to 1, what is the rear drive ?

The rear is 1

I think someone is confusing the sprag operation. Which would engage when there's 1.07 to 1 from the rear over the front.

It is 1.07 to 1, front to rear, the transfer internals have the front going faster then the rears that is why they are called over running clutchs (sprag)

 

[Bolkbich]

If the front was geared faster than the rear the sprag would lock as soon as you started driving. The only way a over running sprag would work is if the front and rear drive the same speed..... when one slips , it goes faster and locks the sprag.

 

[73m819]

If the front was geared faster than the rear the sprag would lock as soon as you started driving. The only way a over running sprag would work is if the front and rear drive the same speed..... when one slips , it goes faster and locks the sprag.

the front IS geared faster, when the rears spin, they are turning FASTER then the fronts because the front has slowed down and the sprag grabs.