Tech question on 46 chief primary chain

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Tech question on 46 chief primary chain

Post  scruloos61 on Fri 25 Dec 2009, 8:53 pm

Merry Christmas--I have a tech question on my primary drive--46 chief--I believe that I have been sold a primary drive chain that is too long. In order to get the 3/8 inch up-down play called for in the old repair and overhaul manual, I have the adjustor foot pushed way-way up so that the foot is actually up slightly above the lower curve of the engine sprocket, and the bottom leg of the chain is seriosuly hourglassed up. The chain was sold me as new and it only has about 50 miles on it. Has anyone else dealt with this? If so can the chains be shortened? Pictures on the Kiwi site of an adjusted primary drive seem to clearly indicate less play in the chain. My sense as a mechanic tells me that the chain is too long, the adjustor is too maxxed out, and I am likely to have a potentially catastrophic problem if I run it like this. I will attempt to attach a pic, and any information, tips or war stories would be much appreciated. Thanks, Paul

PS: After posting this, I don't see the pic I attempted to add, but I have one I can send in a direct email to anyone who wants a look. Thanks again, Paul


Last edited by scruloos61 on Fri 25 Dec 2009, 8:59 pm; edited 1 time in total (Reason for editing : Unsuccessful post of related picture)

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Re: Tech question on 46 chief primary chain

Post  indianfrank on Wed 03 Feb 2010, 9:24 pm

I have a used one in my barn., I can measure it if you think that would help

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Re: Tech question on 46 chief primary chain

Post  Micmac on Sat 06 Feb 2010, 11:53 pm

Frank, you ain't got an extra speedo in that barn, do ya? Laughing Laughing Laughing
Pete
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Re: Tech question on 46 chief primary chain

Post  indianfrank on Sun 07 Feb 2010, 12:53 am

sorry no

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Re: Tech question on 46 chief primary chain

Post  Yellow53Chief on Sat 01 May 2010, 1:07 pm

Hi,
Please send a picture of your primary chain. I'll check it out. All of the post-WWII Chiefs run the same primary chain. I have a very used old one and a new one. Both have 76 pins and 38 outer side plates. Both are 'endless' meaning no master link. As far as shortening a chain goes, that would probably mean that a master link would be needed. A master link is not the best idea because if that chain breaks and comes loose it will ball-up inside the primary drive and proceed to explode similar to a grenade sending pieces of aluminum everywhere including possibly your left leg. On top of that, the engine, transmission, and primary drive cases will be ruined if not heavily damaged. On a very used chain, with the primary cover off and the chain adjusting shoe removed, lift up on the bottom of the chain between the sprockets. The distance is around 1 7/8 inches from the highest lifted pin to the bottom lowest inside surface of the inner primary case. On a new chain there should only be about 1 3/8 inches. If the primary drive cover is off, the easiest way to tell if your chain is shot is to try and lift the chain off of the clutch drum teeth. If the chain is adjusted and you can lift the chain off 1/2 the height of the clutch drum teeth, the chain is shot. On a machine that is running a chain that is very used you will notice that the chain is hitting the inside of the primary case on the clutch drum side, where the cover retaining bolts go through. This cannot be adjusted out and the chain must be replaced. When trying to diagnose a loose chain, be sure that the clutch drum bushing is not worn out. A good bushing should only have about .001 to .0015 clearance on the transmission mainshaft. A left side transmission main bearing that is badly worn can also appear as a loose chain. With the transmission mainshaft end-play set at .005 or so, there should only be barely perceptible bearing play. The bearing should be quiet if spun. A bearing that 'rumbles' should be replaced. If you do replace the left side main transmission bearing be sure to use an original thrust-type bearing or a high-quality angular contact bearing. This bearing is installation direction sensitive and must be installed to that the balls have full contact when the inner race in pulled to the left relative to the outer race. I hope some of this information helps. Send the photo to Steven Bailey baiste@sgu.edu

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