420C idler bushing and shaft dimensions

BLS · Post by **BLS** » Sat Nov 07, 2009 4:50 pm

can any one tell me the (new) dimensions of the front idler shaft (both journals) and the bushing dimensions in the idler and support? I have looked in my manual and can't seem to find them. I know something is worn, just not sure what needs to be replace...
I pulled the idler off (without splitting the tracks), don't know if i'll do that again...
thanks for your help
Brian

Mark Birdeau · Post by **Mark Birdeau** » Sat Nov 07, 2009 7:13 pm

I have no idea what the diameter would be, but if the shaft is wore any amount it will have a shoulder. The shoulder would be more evident on the front of the shaft. Mark:

BLS · Post by **BLS** » Sun Nov 08, 2009 10:21 am

Mark,
There isn't much of a ridge on the shaft or the edges of the bushing.
Here are the following measuremetns:
Support bushing: .992
Shaft: .980

Idler bushing: 1.995
Shaft: 1.970

There is quite a bit of gap on the idler side (.025 inch), and a little on the support side (.012 inch), combined they don't add up to what I was seeing when everything was together... the tracks would go from too tight to loose enough to drop the track off. When looking at the idler and the support, you could see that they weren't concentric with eachother (almost by .25 inch).

Also, I didn't find a bushing part number for the idler bushing in the manual, are they available from Deere?

Lavoy, do you have bushings and shafts available, if so, what's the price.
Thanks
Brian

Ray III · Post by **Ray III** » Sun Nov 08, 2009 9:34 pm

I have more than 1/4" wear in my idlers and my tracks are nowhere near falling off. Not that I don't need to fix it but you may have problems elsewhere.

BLS · Post by **BLS** » Sun Nov 08, 2009 11:15 pm

Ray,
i lost a track in a sharp turn going up hill, i knew the tracks were loose, but i thought i could fix it later... (i was 100 miles from home on a saturday and the nearest store was half an hour away) I spent 2 hours getting the track back on then realized that the front idler bushings looked warn... and i didn't have a 1-1/2 inch wrench with me, when i tightened the tracks up, i probably got them too tight (to make sure they wouldn't fall off again).

i will definately look at the final drive sprockets and bearings.

i found a good Idler shaft to replace the old one.

can anyone provide the new or servicable dimensions of the idler support bushing inside diameter? the replacement shaft O.D. measures 1" and the old idler bushing measures .992". I'm planing on honing out the bushing to match the shaft, unless anyone has a better idea.
Brian

Gil · Post by **Gil** » Mon Nov 09, 2009 6:16 am

I would not discourage you from tightening up the idler shaft, but I doubt that it is what caused you to lose your track. There would not be enough play to cock the idler enough to walk the track off. If the front idler is the problem, it may more likely be wear in the frame rails where the idler slides, allowing it to angle more radically.

If your track came off from the front, this is an indication of idler problems. If the track first came off from the rear drive sprocket, there is more indication of problem with the sprocket, rollers, or chain. If the sides of your front rollers are worn more than the back rollers, this would also be an indication of idler problems. Of course rollers get replaced over time and the long term wear pattern may not be evident, especially since the worst ones are usually the ones replaced first with better ones.

Mark Birdeau · Post by **Mark Birdeau** » Mon Nov 09, 2009 5:55 pm

Brian I don't think there is a bushing in the support. At least I have never seen one. I wonder if somebody didn't turn the shaft and install a bushing in the support. The parts book lists M 2266T as the bushing number for the idler and rollers. I was able to get them from Deere about 8 years ago. Mark:

BLS · Post by **BLS** » Tue Nov 10, 2009 9:52 am

Mark,
I've only pulled apart two idlers and both of them had bushings, so my knowledge is limited. Looking at he parts manual, it does list 12 bushings per side refering to the bottom rollers, so I was assuming that 10 were for the bottom rollers and the other ones were for the idler support.

It does look like someone turned the shaft at one time, because it is smaller than the replacement shaft that I found.

Who knows how many field repairs have taken place over the last 50 years. I'm going to try to hone out the existing bushing tomorrow and get it back together.
Brian

Mark Birdeau · Post by **Mark Birdeau** » Tue Nov 10, 2009 5:38 pm

Brian it is surprising what one runs into for repairs on these things. I've made a few along those lines myself. Mark:

JDcrawlers Messageboard

420C idler bushing and shaft dimensions

420C idler bushing and shaft dimensions

bushing I.D.

Who is online