Gearbox chain tension spec for 2162 and 2152 headers in manual
The manual of our slightly older 2162 recommends a torque of just 20 inch-pounds (and then turn back 1.25 turns) on the tensioner drawbolt that's under the fill port of the main gearbox. Our 2152's manual (which is for the newer 2142, 2152, and 2162 headers) calls for a torque of 20 foot-pounds and then back off 1.25 turns! A fair bit of difference between the manuals.
This fall, not noticing which manual was which, we applied this fairly hefty torque to the tensioner on our 2162, which is way way over-tightened. Ended up friction-welding the idler sprocket to the shaft it spins on (no bearings, but bathed in oil). Broke the drawbolt and wratched up the idler's swing bracket before the chain fell off. Replaced the sprocket, stub shaft, bolt, and swing bracket. This time we tightened the chain while the cover was still of so we could see that it was properly tensioned. And yes indeed 20 inch-pounds minus a turn and a bit is about right (turn until you feel it start to go tight, then back off is enough).
We figured the old-style gearbox required the smaller torque, and the new style aluminum gearbox was the higher torque, since the the newer header's manual really does say 20 foot-pounds. However about a week after the 2162 failed so spectacularly, the chain in the 2152 broke. It was clearly over-tensioned as well. Luckily the idler was fine. After replacing the chain, I left off the round cover so I could see the chain as I tightened it. Long and short is the manual is wrong. Someone goofed and changed inch-pounds to foot-pounds.
So maybe just a warning that the Case manual seems to be wrong here. The drawbolt should not be overtightened! We learned this the hard way.
Also should anyone break this chain, or if it just gets old and stretched, you can use standard #50 chain in a pinch, but the OEM part is a one-piece chain with no connector links. We replaced the chains with MacDon-supplied chains.
Last edited by torriem; 10-01-2015 at 10:41 PM.