M813 low range slippage

[markgjsquires]

hello all. I have a 1970 M813 it is in good shape and has served me well for the last 10 years I’ve had it. But about two years after I started using it on my farm when in low range it slips. It sounds similar to either a shaft is worn down grinding or its not fully engaging and has worn off the outer edge of a gear inside the transfer case. The transmission and engine shift and act fine. And when the transfer case is in high range there is no signs or sounds of slippage and it performs completely fine. I do have the front drive shaft removed from the transfer case only because i Was trying to rule out any chance of it being to increased resistance from the front wheel drive engagement. I have seen threads of where guys suggest to drain the gear oil and run diesel through it for a while to clean the internals. Would the low range slippage be from a ”dirty” sprague clutch. Or from other internal defects. Just looking at possibilities it can be before I go for removal and replacement.

thanks

 

[NDT]

Power from the transfer case input shaft to the output shaft is all through gears in both ranges. Any "slippage" would be heard as horrible grinding. Check to see that the high/low range shift rail is adjusted properly.

 

[Mullaney]

hello all. I have a 1970 M813 it is in good shape and has served me well for the last 10 years I’ve had it. But about two years after I started using it on my farm when in low range it slips. It sounds similar to either a shaft is worn down grinding or its not fully engaging and has worn off the outer edge of a gear inside the transfer case. The transmission and engine shift and act fine. And when the transfer case is in high range there is no signs or sounds of slippage and it performs completely fine. I do have the front drive shaft removed from the transfer case only because i Was trying to rule out any chance of it being to increased resistance from the front wheel drive engagement. I have seen threads of where guys suggest to drain the gear oil and run diesel through it for a while to clean the internals. Would the low range slippage be from a ”dirty” sprague clutch. Or from other internal defects. Just looking at possibilities it can be before I go for removal and replacement.

thanks

.
Agree with @NDT .
Draining and looking at the gear oil would be good.
If it really was "slippage", the higher gears would (should?) might show clutch slippage.

Don't really think you need to try to wash out the internals on the gearboxes... IMO