Wear limits on the O.D. of rollers and idlers. (420c)

[joeturner1977]

I just purchased a 5-roller 420c. The undercarriage needs some work. The previous owner had to remove a track link to get the tensioners to work.

On the left side the first four rollers have the R.H. flange wore off and the front idler bushing is completly wore out. It is so bad the track does not stay on.

The right side is in better shape. The idler bushing is wore just as bad as the other. Rollers look good and have no play.

Now I am wondering what the stock size the O.D. of the rollers and idlers should be? How much wear is tolerated? What makes the roller flanges wear completely gone? Is the material steel or iron? (for welding purposes)

I am a Machinist that works in a job shop. I am new to the crawler world as far as owning one, but I repair/rebuild parts for heavy machinery daily.

I like your website and have found lots of helpful information already. My questions are most likely repeat for you guys, but I would greatly appreciate any and all information.

Thanks - Joe

[JimAnderson]

Joe,
If the previous owner had to remove a link to adjust the tracks then
the pins and bushings are shot.If you keep running them expect to
see the pins through the bushings as holes will show up where the
sprockets contact the bushings.Side flange wear on the rollers is
caused by side hill running.The rollers are steel and can be welded.
JimAnderson

[JimAnderson]

Joe,
I need to amend my previous post.Roller flange wear normally
occurs during turns and is more severe on loaders.It can rapidly
increase with lots of sidehill operation with one track lower than the other.
The front idler is steel and can easily be welded but the upper
roller is cast iron.JimAnderson

[joeturner1977]

Thanks Jim, knowing the material is very helpful.

Now I am wondering what the stock size the O.D. of the rollers and idlers should be? How much wear is tolerated? The right side rollers look o.k.. I will have to mic. them for wear and decide if I want to build them up as well.

I was also considering making my new rollers from scratch and putting them on the deere pins and end castings. I am toying with the thought of making them double flange rollers like the modern dozers have to reduce side flange wear. Is this a bad idea??? Is the deep undercut between the diameters the track runs on there for any reason???

Any feedback or thoughts are always welcome.

Thanks - Joe

[JimAnderson]

Joe,
Based on NOS parts the front idler is 19 1/4 " with a width of
1.800 across the vertical guide flanges.This part is as cast so a tape
measure was used to obtain dimensions.Bottom roller is 7.187 "in
diam with a flange thickness at the root of .375".These measurements
are based on NOS parts.
Be advised that the two bellows seals needed for each roller or
idler is roughly $150.00 each and only availble from Deere.
I can get new Berco rollers from Deere for about $150.00 ea
ready to bolt on.These rollers are for the 350 machines but can
be used as a replacement for the 420 rollers.If you are not
interested an accurate restoration of your machine then these
rollers are a much cheaper route to go.JimAnderson

[joeturner1977]

Jim,

Are berco rollers available thru any deere dealer, or do I have to go thru your dealer??? I am going to need at least one roller assembly. One rollers i.d. bearing was so bad it ate the seals and half of the pin. There is noticable wear on the end castings. The other pins and end castings look good. I was going to make new rollers.

How do I know If my old seals are bad??? The seal looks o.k. but the steel plate they run on have a noticeable groove. My first thought was to make new plates and re-use the seals. Maybe this not a good idea.

I guess that if the seals are not re-usable then I would be better off with the berco rollers.

Honestly, what do you think about the seals. I am open minded and want to hear what eveyone thinks. All advice is welcome.

Thanks - Joe

[Lavoy]

I am working on new seals, but it will be a while before we have anything. I think they are well over $150 now from Deere. I have new aftermarket rollers in the $120 range for sealed lifetime rollers. You do not want to replace one roller, the outside diameter will be larger than the used rollers you are running it with, and it will put more stress on things.
Lavoy

[joeturner1977]

Lavoy,

I intend to replace all 5 rollers on the left side. It is just one assembly is so bad I don't have any parts to re-use/work with. The other four rollers are good except the roller flanges are wore off. I am a machinist and was considering making my own rollers to put on the deere pins and castings. That means turning the roller, making bushings, making new seal plates, possibly re-place seals, reassemble.

If I can get new rollers for $120 each. then maybe it is not worth rebuilding my old ones. I did not realize that affordable new replacement parts are still out there.

Can you shoot me a rough price for 5 rollers with shipping to Wausau, WI 54401.

Thanks - Joe

[Gil]

The early crawlers like the MC did not have roller seals, as I learned from Lavoy. I assume that your JD420 has seals similar to my JD440s. What I find in looking at many rollers is that the seals fail eventually from age, wear, or over filling. When you pump them with grease it oozes out the sides.

I have become rather religious at greasing them whenever I plan on do a reasonable amount of work that would generate heat in the track components, especially in the summer.

The seals not only keep things in - the grease; but they keep things out – dirt, but especially water. If your run your crawler through water or mud, the moisture can get inside and significantly damage the wear surfaces.

If you want to test your old seals, pump them with a hand grease gun. If the grease oozes out, they are blown. That makes them a good candidate for frequent greasing. Do not use too much grease gun pressure on a good seal or you can pop it inadvertently.

[JimAnderson]

Joe,
I don't know if your local Deere dealer can get Berco rollers for you.
Lavoy would probably be your best bet.I am lucky in that I have an
outstanding parts guy to deal with.Recently I had him look up a part
and it came up obselete in the computer.He did an additional search
and found the parts.They were the last two to be had anywhere.
According to my parts guy Berco makes track components for Deere.
I thought that was neat information.JimAnderson

[Lavoy]

Joe,
Sure can, send me an e-mail, I am out of town tomorrow through the weekend, off to cub scout winter camp. Going to see if I can break something on the sledding hill. I will get back to you next week sometime.
Lavoy

[joeturner1977]

Joe,
Based on NOS parts the front idler is 19 1/4 " with a width of
1.800 across the vertical guide flanges.This part is as cast so a tape
measure was used to obtain dimensions.Bottom roller is 7.187 "in
diam

Left rollers are shot. I am measuring 19 1/8" x 1.73" on both front idlers and 7.15" on the right side bottom rollers.
I do not think they are bad enough to replace... I will replace the left side rollers and top & front idler bushings.

I know I need to repin & bush the tracks, but how you gage the sprocket wear??? By the Root Dia. or O.D.?

[JimAnderson]

Joe,
New sprockets are 1-3/4" wide at the base of the gullet.Each gullet
has approximately 5/16" to 3/8" of thickness up to the tip of the tooth.
As the sprocket width decreases at the wear points then there is less
metal to carry the load and wear accelerates.If your sprockets have
worn out a set of pins and bushings my guess is that they need to
be replaced as well.They can be built up with welding rod.I have
a welded up set on my Dad's 420c that were done several hundred
hours ago and they work well.JimAnderson