Hello all, I have a D8H with about 7K hours on it and it is time for a new UC. I’ve never tackled a project of this size. Could use some advice or if anyone has a pdf or video that offers tips and tricks. This isn’t my first rodeo with UC so I’m not a newb but definitely don’t think I know it all. I have these items new ready to go sitting in the yard. New Wet track sets 24in grousers I believe. All new top and bottom rollers, new idlers, new sprocket’s segments on a set of spare new hubs. Also replacing the rubber “suspension” pads on the track frames. new bolts and hardware. Machine has a single shank ripper on it. Got multiple other pieces of equipment, excavator, workers, wife and such to aid in install. Gonna be some country fun where I’m doing the in the barn yard. I appreciate any advice specifically on stuff you would do differently if to do it again. Use the machine for clearing woods in the northeast, and probably one day reclaiming fields from failed green energy projects.
I guess the first thing would be figure out which tractor I really have? And maybe dry the tracks out. Bob
Drying the tracks out won’t be a problem got some paper towels. 46A 1972 machine power shift. Thank you! Good stuff.
In the Cat world we have this thing called serial numbers to identify tractors . That tractor had several undercarriage updates And in 48 years who knows what has been replaced other than the hour meter. Since you have to remove track frames any way they are turned upside down to replace rollers and wear strips. You will have to round up a 100 ton sprocket press and tooling. The best way to do it would be hire some one who knows how to do this work. Bob
46A27283, does this help
Easier to replace segments than entire sprocket hubs unless are loose or leaking profusely, easier yet to pull track trucks and visually inspect everything on the machine based on age and having upside down for serious impact use or heat and beat to remove stubborn to broken roller attachments. SALT or Lubricated Rails are not referred to as 'Wet' where the age of your machine could have dry pin or also have had SALT rails previously installed as a replacement type. Good time to inspect recoil system, better time still to replace Idlers and rebuild/reseal the track tensioner pistons, inspect truck assemblies for cracking or the main attachment points for wear or damage. LOADS of Cribbing materials will be essential to support the frame of the machine as perform said work. Also HIGHLY recommend the belly pans come off at some point and cleanout performed if has been 'Awhile'.
A professional undercarriage assessment should have been done before you bought the "farm".......so to speak. If this is anything like mine.........all she is going to help with is telling you that you are not doing it right. My advice would be to have your existing undercarriage evaluated. You may have bought a whole bunch of stuff you didn't need for farm dozer use. Unless of course, you like to spend your wifes shoe money
The best thing you can do to get the most life out of your undercarriage is to block out 3rd gear on the powershift. I've been running my old 46a that way ever since i got it almost 40 years ago. With any undercarriage, speed kills
I'm old enough to have thankfully lost the memory of most of those that I have had the misfortune to have had to do.
I am heretofore working to kill those very braincells in my own head!!
Wife insists I need some brain cells to kill.
I don't have a wife..... or a d8.......steps of life say I need a d8
Ide be glad to send mine to you. She will have you lined out in a week! LOL
An old d8 may cause you less problems
Your UC may not be as worn as you think. Years ago,, I bought a 14A D8, 1958 model and the track was so worn on it that the place it came from took out 1 link in the track chain on each side so it would be tight enough for use. The UC was no longer available, so they made it work and it did. Your project is a big one.
The worst thing about shortening a chain is that the chain is so stretched that there is no gearing with the sprocket. This not only increases the wear of the sprocket, but also puts heavy load on the drive. Been there, done that.
Yeah , my old D7 was walking out of her tracks but still in pitch measurement by a squeak , took a link out on both sides and stopped her slipping out of the tracks on sidelings . Hard cold economic choice .
If memory serves me correctly, the other consideration is that when you take a link out, it runs on the same sprocket teeth every revolution instead alternating between teeth. For example an even number of sprocket teeth and an odd number of links. Modern crawlers only drive on every second sprocket tooth but wear evenly on every tooth. Somebody correct me if i'm wrong
you wrong, if a sprocket is a hunting tooth design ie, a odd number of teeth then the number of links don't matter because a track chain is a double pitch chain. A sprocket with even number of teeth only runs on every other gullet ,these are not used any more. Bob
Ok, my memory is a little foggy, i remember the odd number of links but didn't multiply it by 2 for the number of pitches
Its the number of teeth on the sprocket And any more they are almost all odd. the number of chain links don't. Bob
Ya, ok thanks for the refresher
There was a local D82U with small bits of steel between every second tooth so no bush could sit in the gap , tracks would have had to had some stretch in them to take two links out aside .
That is a even tooth sprocket a true double pitch sprocket. When the track stretched to the end of the adjuster one link could be removed. Bob
Chains don’t stretch they wear and expand. Pins to bushings grind into each other and increase the distance pin to pin. If managed to get to a full link of wear are well beyond design life risking throwing rails at bad times putting too much side stress on rollers or idlers and sprockets or just breaking pins or link ends. Harder on machine than not unless running it into destruction.
Track wear is a science in it's self. If you are talking a newer production machine verses a homeowner lots of difference . A D 8 track link 9 inch pitch sealed track at 100% worn is a 1/2" over 4 pins. You stretch the track to take this measurement. A 7 roller chain is 41 links so total wear is 5 inches. That's well within adjuster range. when the tracks are at 150% the wear is at 1 inch so 10 inches will allow a link to be removed . This is a homeowner fix to keep from buying $50 thousand in parts. generally pins wear twice as fast as links. All that said short tracking is more often done on excavator tracks on mid size machines . Bob
If you have SALT tracks, there is little to no internal wear between the bushings and pin. What little bit of adjustment that you have to do is from the external wear on the bushing and the throats between the sprocket teeth plus the wear on the idlers. Side wear on the rollers and idlers is almost always from the track frames being out of alignment with the sprockets. Worn chains usually equate to all the rest of the components to have the same amount of wear. Lots of people talk about pulling a link, but few ever do it.
Hey, here's a question for you guys. I've never had anything to do with high-drives, but a guy i know who's owned various dozers told me the high-drives are harder on segments and rails because the rails only wrap around the sprockets approx 100 degrees as opposed to low-drives which are approx 180 degrees. So, given the same operating conditions, and SALT rails, on the same size and weight machine, is he right? Theoretically he should be right. Is there a vast difference between service life of the two types( high-drive compared to low-drive)?
The people selling the stuff years ago pushed the theory that only three teeth exerted a pull on the chain no matter which type of drive. The quality of the metallurgy on chains made today has largely made any arguments moot. That and the fact that they make the bushings thicker. High drive stuff lasts as long and any conventional drive stuff. It does cost more up front and in cost per hour. What isn't addressed is the double idlers on high drive undercarriage and the additional wear being put on the rails of the links. Look at any worn high drive chains and you will see a belly worn in the middle of the links. Two idlers means double the wear per revolution of the chains. It is a big reason Cat is trying to push the System 1 undercarriage over the conventional SALT undercarriage.
Seeing as how the rails don't touch a drive sprocket that is a no starter. The bushings have a shorter wear pattern but the plus to this is they can be turned twice on bigger tractors. I thought Cat gave up on system 1 on big tractors some time ago? And the big tracks are made in heavy duty versions as are bushings. Like I said there are dozens of factors on track life. Bob
I didn't find it an easy job .With the right gear for removing pins be easier .Then there was the moment of doubt about the tracks being long enough after the links off and in bits .
I got most of the new undercarriage from various equipment auctions and sellers who had them as spares for their D8.. I figured my stuff was pretty worn out. Since I got a complete undercarriage I might as well replace it all. And start fresh again. See pictures for what my machine looks like now. Bottom roller are hidden behind rock guard… they appear to have similar wear. Pin are exposed…. Bushing worn through