Sprocket inserts

[Theweldor]

John C
You are correct in the fact that you have to weigh out your options. It basically amounts to do you spend that money today or do you prolong it until a later date. It is inevidabley (sp) coming, just depends on how long you want to keep the cash in your pocket.

 

[oceanobob]

Updated an old thread -

No progress was made since this post started due to work not requiring the dozer. Seems as though I should have busted the track and changed the sprocket some time ago. Now it appears the track adjusters seals are also needing attention - allowing the grease to leak and the tracks go back loose.

At this time the sprocket is worn to sharp points. Also learned the sprocket insert fabricator is no longer producing the inserts because the raw material a "fine grain high carbon steel" is cost prohibitive. Somehow I got the idea the inserts would help the sprocket mesh with the worn chain compared to a new sprocket with the worn chain.

Thinking I will measure the pitch on the chain and compare it to the specs in the manual and decide to what extent the repair should be accomplished. Will update.

 

[Tones]

Bet you a $ to a knob of goat styt the chains are stuffed and the ldler is over extended causing the adjusters to leak.

 

[oceanobob]

I shall get the section outta my manual and measure the chain for the stretch. Many thanks for this suggestion. Using a round bar to fit tween the sprocket and the chain to pull the track taught, yes?

Have been to the local JD dealer and their recommendation for chains etc is a company called ITR. Seems to me rebuilding the tensioner gets me deep enough in it that I have priced the chains, sprockets, roller set, etc.

 

[Tones]

The adjuster seals are off the shelf parts at any good bearing shops. With the ldler out of the way there's only about an hours work to do both sides. ITR make a good product.
Dealers are stealers, save some bucks and give them a swerve .

 

[oceanobob]

Put a pipe in the sprocket and tightened the chain....didnt have the manual. Wrote down the number but it doesnt mesh with the dimension attained. Redo in order.

 

[oceanobob]

Brought the manual and did the measurements.

Chain pitch 25.2" thru 25.7", measured 25.3
Chain link ht 3.5" to 3.26", measured 3.3 to 3.4
Carrier roller 6.0" to 5.5", measured 5.772
Front Idler .96" to .77", measured .836"

So far, so good....yes it is worn but within the specs.

Then this: the Roller / Pins, FYI feel like a egg (or maybe a pear). New is 2.010. Reverse direction is 1.885, Forward direction is 2.002.
The spec for 'high impact' is 1.890 and for 'normal' is 1.820. Bumping into a limit.

Seems like a roller turn would alleviate the concern of "old pin in that worn chain on the new sprocket".
However am not sure about location of track press shop. Is it true that track press shops dont always perform the "sealed and lube", they do a "greased" turn? And the cost for a new chain may not be that much more than trucking the assemblies a long ways and then paying for the turn.

Or....since the pitch measurement shows that is aspect is not near worn out, maybe throw a sprocket into the mix although the rollers look like an egg and delay the inevitable?? Ergo try to discard the chain when all worn out.

~~~~~~~~~~~~~~~~~~~~~~~~~~~

As far as the track tension adjuster not holding, thinking the area should have been cleaned more often but never did take off the covers and attended to that, but yes belly pans are regularly cleaned out but didnt think of the track adjuster - this problem is seals fer sure, and maybe the chrome damaged on the rod too.

Marker some black lines on the roller where worn (looking upward at roller)

Chip on tooth (thin)

Pointed and one side worn more than other

Pipe in sprocket to pull track tight for measurement of pitch


Thanks for all the wisdom, tips, and suggestions.

 

[Welder Dave]

Those sprockets are pretty much toast. If 1 tooth chipped more will follow. With the price of aftermarket undercarriage there are very few shops that do pin and bushing turns. I think it's somewhat common for the reverse side of the bushings to wear faster than the forward side. That's how mine are wearing and have seen it on a couple other machines. I couldn't get a real answer from the supplier on why but I know driving in reverse especially at high speed causes the fastest rate of wear. I'm thinking maybe because the sprockets are pulling the chains from the top which tightens them. I also think the backhoe being about 4000lbs. adds a lot more resistance when backing up. On hard ground it isn't bad but on softer ground where it sinks in a bit it takes a lot more power to back up because it's basically trying to climb out of the depression at the heavy end. Going forward with the front end much lighter is much easier and takes a lot less power.

 

[OzDozer]

Oceanobob - The items you've marked with black marker are called bushings, the pins go through them to hold the track together.
The bushings are very worn, probably because of abrasive soil. In the old days of track shops everywhere and expensive undercarriage, we'd pull the track chains off at the wear point yours are at, take them to a track shop, and get the pins and bushings pressed out, turned 180 deg, and then pressed back in.

This then presents a new wear surface to the sprocket and takes the wear out of the track chain pitch.
We'd install new sprockets and go on to get another 1500-2000 hrs out of the other side of the bushings and pins. The undercarriage would then be scrap.

Unfortunately in todays world, there are very few track shops left, and very few people turn pins and bushings any more, because labor costs have gone ballistic, and new undercarriage has become much cheaper.

Your easiest option today is to keep driving until the sprocket teeth just become bumps and the sprocket starts jumping inside the bushings. That will still take a while. Then just buy all new aftermarket undercarriage.

 

[Nige]

@oceanobob - this is the process that @OzDozer is describing. As you can see it requires expensive hydraulic tooling that many track shops had in years gone by but today is nowhere near as common. It is a labour-intensive process which is why it isn't cheap, and probably one of the reasons it fell out of favour. First the complete track chain has to be disassembled, then reassembled again with each bush having been rotated by 180 degrees. Usually new seals for the bushings are also installed at the same time.

 

[Vetech63]

I haven't seen bushing turns in 20 years or longer. It isn't cost effective any longer.

 

[CM1995]

Bob we put ITR chains, sprockets and pad bolts on our 321DL a couple of years ago. We've had zero issues and much less than Cat.

 

[Nige]

It's only cost-effective IMHO if you are in a market that has a low hourly labour cost, or if your time costs nothing then build a track press and you do it yourself - like this guy on YouTube.

 

[Shimmy1]

As far as the track tension adjuster not holding, thinking the area should have been cleaned more often but never did take off the covers and attended to that, but yes belly pans are regularly cleaned out but didnt think of the track adjuster - this problem is seals fer sure, and maybe the chrome damaged on the rod too.

Do you have the capabilities to work on this undercarriage yourself?

 

[Tones]

Another way of getting a little more life out of the sprockets is to swap them from side to side. One side will be worn more than the other and believe it or not it's all to do which hand you write with.

 

[CM1995]

Another way of getting a little more life out of the sprockets is to swap them from side to side. One side will be worn more than the other and believe it or not it's all to do which hand you write with.

Since it's a small tractor no sense in going through the labor and not just buy new segments IMO. Aftermarket segments are very reasonable for a 450.

 

[oceanobob]

We did get a repair quote for each track or chain "bushing turn" at around $1400 to $1500 plus parts (half a set of bolts or all the bolts to the pads).
ITR chains are about $2000 and I was assured this is notably less than JD OEM.

The turn process will also not be a true repair per se because the new "seals" are not those like new with the vacuum grease application - this is not attempted: some grease is manually applied to the roller instead. Nicknamed a 'wet turn'.

When comparing new chains to having these bushing turned: Not possible to save the difference due to the fuel and delivery cost to haul track back and forth to their shop, plus the misc parts reduces the difference a bit.

In conclusion: let's say there are three or four parameters that were in spec and one parameter was end of life. Had I not been thinking 'bushing turn', that [now] olde skool technique (for that one parameter): I would be less pained. Clearly am aware of the 'gotta do it this a-way cause the cost of labor otherwise is a worse idea'.

Always known and been reminded "if you keep that machine make sure you save for the undercarriage day!"

Looks like we are off to the races! Kicking the can no more.

I presume: if doing the rebuild, include all the rollers and the idler and of course the sprocket.

As to this 1998 JD 450G model:
The chain and the sprockets are about half the part bill: the idler, top roller, bottom rollers .... comprise the other half the bill. Budgeting $9k for complete list with an unknown is the condition of the chrome rod for the grease seal.

It is interesting because of the logic quandary - if turning the bushings? then one keeps all the existing rollers and idler; but if putting new chains? then one must/should do "all new". Therefore while the bushing turn may not be the less cost method when looking part by part, but it allows further usage of additional old parts which in turn lessens the overall repair bill and staves off a notable amount.

Hmmm....

 

[Vetech63]

You could just throw new sprockets on it and have at it.

You have to remember that here on this forum, most of us are trained to put out the best final repair. We usually don't recommend short cuts...........it's not our nature. As a self-employed tech, I can only consider a short cut if asked and approved by my customer..........outside of that it gets what I say.

Could you possibly run your undercarriage out longer just by changing the sprockets? Sure, you can.............it's been done many times. It's just not something I can recommend as a solid repair that will last you for years.