Sprag Clutch 5 Ton

[m139h2otruck]

Not trying to beat a dead horse to death, but want to make sure the transfer case in our truck is OK to continue operating.

The operators manual I have talks about being able to tow in reverse IF the sprag is released. To release, it says to jack up one front tire, open the air drain valve and remove all air from the system, and check to see if the wheel can be moved in both directions. Our truck does this as described in the manual. Also, this confirms what rizzo is doing with his Mopar powered truck (looked at his video again).

I will again drain the gear oil and replace, and maybe wash the inside of the case out with some fuel oil mixed with ATF. Hopefully, the banging we heard has not hurt anything yet. I still shifts and drives on the road alright, and in hard going locks up like designed.

If anyone has any other ideas or recommendations, please let us know. Thanks

 

[DDoyle]

I'll jack one of mine up in the morning to verify this. If I'm wrong, it won't be the first time - and its unlikely to be the last!

Best,
David

 

[m139h2otruck]

I hope to have found & corrected any potential problems in the transfer case this last weekend.

Ordered and changed out the speedo cable, and while checking things with the engine running and the transmission cover open, found that the transfer shift air valves on top of the transmission were all loose and leaking air at the gaskets. This explains the air leakdown rate and maybe the poor shifting of the sprag clutch in the transfer case. Also drained the case again and refilled with half ATF and half fuel oil. Drove around the neighborhood at no more than 20 mph and ran the transmission forward and reverse 6-8 times to work out all the sludge in the air cylinder/shifter linkage. Drained again and refilled with 80-90 gear oil. Gave it the finger wave in the drain hole and wiped out 3 or 4 finger fulls of sludge! No chance to try on the road again, but it seems that the air shifter clunks in stronger now (may be my imagination). No loose extra parts/pieces and things look real good inside. Hope this works.

Lessons learned:
1) Change the oil!! and then change it again. In our case, this is a 45 year old truck, and the gear oil looked original! Old style gear oil can turn into almost a solid at this age.
2) Flush the case to remove as much sludge as possible.
3) Check for air leaks in the shift system. If full air pressure is not delivered to the air shift cylinder, this may cause the sprag not to engage right and hurt the transfer.
4) Watch the oil level and condition!! This is a big case full of gears and bearings and it only holds just over 5 quarts. That's not a lot of oil, compared to the transmission with a PTO which holds over 11 quarts and is much smaller in size. If you let the oil level get down 1 or 2 quarts, you are now 20 to 40% low on oil.

It is my opinion (for what that's worth) that some of the transfer case failures that occur are a result of the problems or lack of maintenance that I have outlined above. For the price of the gear oil and the time it takes, it is well worth it to make sure that the case is as clean as possible and the the sprag shifter is receiving full air pressure.

Thanks for listening.

 

[dumptruck]

where is the drain/fill plugs on a 5 ton tranfer case.thanks.vg