Cam gear

After several years of a odd noise on my 450 I decided to tear into it .I found cam gear nut was loose ,causing key way to round out and gear is loose on key way. It looks like I will need a new cam.My question is this a normal problem? Will I need a heavy gear if mostly using hydraulics for steering and rear 2 point lift.Where would you find a heavy gear? The plate that has 2 bolts holding cam
in place has wear on it.Do yall ever replace this plate,if so where from?

Same thing happened to my Super M; also to a buddy's 400. Replacement heavy gear (#6760DB) is available from Carter & Gruenenwald - about $170 as I recall. Also if you get a new camshaft nut, be sure to get the one with correct thread hand! (Both right and left hand threads were used at various times).

When I got my SM apart I found the camshaft keyway badly chipped out; only one side of the key "pocket" remained. Rather than replace the camshaft I held the key tight against the good side of the keyway then tack welded it to the camshaft. I then installed the new gear and old nut as usual.

This works since the camshaft key only needs to hold the gear aligned while the nut is being tightened. Once torqued, it's friction between the gear hub and the camshaft boss that drives the camshaft - the key is now "just along for the ride".

Be sure to purchase/install a new camshaft nut keeper too so the nut doesn't come of again! Also I used Locktite Red Threadlocker (#271?) on the camshaft threads as added insurance.

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Can't help you with the cam gear thrust plate. Mine showed only slight wear. So I left it as is.

Since I did the repair that ominous knock from the front end disappeared. That was about 10 years ago; tractor still runs perfectly!

450 tractors came with the best cam gear IH made. 450 tractors engine serial number 9860 and lower used a cam with right hand threads and 9861 and higher used left hand threads without a lock plate to help with the nut comming loose problem. Left hand thread cam and the late cam gear is all thats sold for years now. Unless someone has a new old stock laying around. Aftermarket parts should be patterned after the later IH replacement parts.
Can't remember the specs on cam end play without looking it up.

The replacement camshaft was only furnished with left hand threads, it was same that was listed in higher serial in 450 series, it is correct substitution in parts, IH also sent a left hand nut, the gear was made of steel with no holes on the web of hub, original were cast iron with 3 holes in web, if it came loose and/or busted these were used on M, Super M, Super M-TA, 400 & 450. The live hydraulic pump drag was the cause usually, IH engineered it too close strength obviously in originals.