M818 Making ODD noise while driving

[atvcat33]

ok the truck is a 818 cummins the truck when starting out 1st gear it seems like the brakes ar applied and there not and the parking brake is released. then goes away when moving and makes like a rumble noise when driving then goes away and when stoped at a light does the same thing again????? what is going on??????

maybe bearings in rear end, not hot though??
or transfer case???

no issues slipping or not going in gear either

help is needed

 

[wsucougarx]

Have you checked to make sure there is light b/w the e-brake pads and the braking surface?

 

[dm22630]

It is your sprag.

Before you move the 818, shift into reverse, THEN shift into 1st. You should hear a "hiss/pop" noise. Then you are good to go. I think what you are experiencing is your sprag case being in reverse & then being forced into the forward position. If you dont follow the steps above, you will break it soon.

Also, after you initially do this, you do NOT need to do it again while driving/stopping/moving, unless the 818 drifts backwards at all. Then you will need to shift into reverse & then back to 1st.

I have a 818.....and a wiiiiiiiise man (doghead) told me about this. I would have surely broken my truck otherwise.

 

[atvcat33]

what the H%ll is that

ok if its the sprag thats transmission or t-case??? and i take it replacing one of those would be in best mannor or try to fix it?? i am familar with m35's and never heard of a sprag belive it or not

bp
big help thanks

 

[m139h2otruck]

Forward and reverse sprags are in the transfer case, and operated by an air cylinder which in turn is controlled by valves attached to the transmission shifter. Strongly suggest that you drain, flush and refill transfer case to cleanup any sludge in the case that may be affecting the shifting of the sprag coupling. Also make sure air cylinder is working, and the couping shifts back and forth correctly. Have been through this, and managed not to break anything, but did get a number of big bangs out of it prior to cleaning.

 

[dm22630]

ok if its the sprag thats transmission or t-case??? and i take it replacing one of those would be in best mannor or try to fix it?? i am familar with m35's and never heard of a sprag belive it or not

bp
big help thanks

Sprag is what engages the front wheels (just like the on/off switch does in most M35s w/airshift). It senses slippage & auto engages the front axle. Some of my deuces have sprag. I hate it. BUT......for 818s, there is no other choice.

 

[98hd]

Sprag is what engages the front wheels (just like the on/off switch does in most M35s w/airshift). It senses slippage & auto engages the front axle. Some of my deuces have sprag. I hate it. BUT......for 818s, there is no other choice.

You could do the MWO to add a valve to the air supply line. Then you only have to worry about it when you need 6 wheel drive.

 

[alphadeltaromeo]

I personally like both the air shift and the sprag...they both work very well when you understand how to use them.