Combines R40 Back Feeder Chain Keeps Jumping a Cog

There are two good tips on the HYPER MODS site (left hand menu bar). One is under the feederhouse section and the other under the tips section. They both apply to your R40. There are other tips under the feederhouse section that may interest you also.

There are strippers available that should keep cob from getting between rear sprockets and chain. This will jump the chain. Some guys will just leave chains on fast to help eliminate need for strippers. Have you did any helical modificationsIJ What shaft is wrapping upIJ If front you may need to fill in area between sprockets and square tube. If rear you may need to adapt corn head to bring material more toward center of chain to prevent following the side wall. Otherwise the things that come to mind about rear is is there an oversize triangle supporting helical over feeder opening, rock sump installed, or cylinder bars are not pulling material from feeder. I suppose the material wrapping is tough and or green.

What style rear feed have chain spkts do you have. Origional had a solid drum, later ones had 3 half shields that float. If the shields do not move freely this is a problem. IF you have the solid drum, as Dan stated I think you have a feeding problem. Make sure there are no setscrews protruding or nicks on the shaft, drum, or shields. If a chain consistantly jumps and looks skewed, it needs to be loosed at the 4 bolts that hold the slats on and rolled loose and then retightened. Worth the effort.

I have done all of the other hyper mods but have not done anything with the helicals over the concave. I have the concave set at 3_4". Do I need to close so it grabs the material better. I have a 3 year old sunnybrook rotor that does a fine job. The one thing that has changed from last year is I went to a 6 row 3000 hugger head. There is a lot more material going into the combine now. The material is not tough or green. Took all the bolts lose yesterday and rolled the chain and it did straighten out. Only ran for a couple hours after that but material was still building up around the sprockets. I will need to look where the head is feeding into the feeder. We did not make any modifications to the crossover auger on the head. Is there a part number for stripper plates for the rear drum. Also drum with sprocket on rear feeder chain is a closed drum.

Around '90 the drum with sprockets welded to them was changed to hex shaft with separate sprockets. Side shields are stationary and center anti-wrap floats between sprockets. I'm still assuming it is back shaft you are having wraping with. This shaft kit can be found in thresher bulliton 0009. You would need this shaft kit first for the factory stippers to work. Otherwise you would have to fabricate your own. The stripper kit P_N can be found in Main tab bulliton 0019. I don't know about your Sunnybrook. Does it have bars similiar to your old rotor or similiar to the N6's. Bars might be wore to point of not sucking material away but I believe that is a long shot. Most guys will suggest tightening concave to slightly less than diameter of a threshed cob so you might phisically check this clearance. Good luck