SN PAB 06638 2006 DOM We are in the midst of replacing some of our undercarriage. Machine has 7000 hours on it. I bought it last November, 2022, and have been using it to dredge our 70 year old, 20 acre pond. The sprockets had gotten sharp, one bottom roller froze and flat spotted, another is just frozen, etc. I got an undercarriage inspection by the CAT rep (and it was free as some of you said it would be) and they gave a pretty detailed report of wear and recommendation of what to replace. My son and I are replacing: sprockets, 4 carrier rollers, 3 bottom rollers, rebuilding the track adjuster units. I bought a new chain/link assy. and CAT has swapped my pads to the new tracks. I pick up the rebuilt tracks tomorrow. Today while pressure washing the adjuster assemblies, I noticed the large tensioner spring is broken at one end. It has been working so far...the break is near the end of the spring. What is the recommendation on continuing to use it "as is" since it works so far?
If the machine is for your own use then leave it if it hasn't caused problems before. Definitely don't weld it.
Some shots of prepping the CAT for the work.
More prep.
Delivering tracks to CAT. Lots more picts but you get the idea.
The top carrier rollers and the sprockets I have been able to remove. So far, the bottom rollers are not cooperating. A new Rigid heavy duty cordless impact driver, PBlaster and patience got the sprocket bolts and top carrier rollers loose...not so the bottom rollers. I have also used a torch on the bottom roller bolts but to no avail so far. I tried heating the area around the bolts to expand it at first...no joy. Then I heated the bolt itself to loosen/break any locktite..nope. I have cleaned the area of bolts/threads and used PBlaster several times...hit the bolt heads with a 3 pound sledge...still cannot break them loose. I am going to try a 3/4 inch drive socket tomorrow with a breaker bar to see if it will work. Any suggestions on what to try to loosen these 12 stubborn bolts I will be glad to hear.
I've always used a 1" impact wrench or a 3/4" ratchet or breaker bar and a long pipe for the bottom roller bolts.
Thanks, John. I have a 3/4" breaker bar...headed to NAPA now to pick up the 30mm 3/4" socket I need. I already wrung off the 1/2" adapter I had on the 3/4" bar. I'll let you know how it goes.
Second the long pipe suggestion. 8-10ft would be my thought. This is another case in point where length is your friend…….. It also enables you to control much better how much force you apply to the socket.
Sounds like you are already on it, but get the reducers/adapters out of there. Ideally a short socket strait to the bar or impact. The extensions, reducers and such in there eat up torque.
It's less than half a coil of the spring that is broken off. I'd leave it like it is. If it was broken in the centre it would be a different story. As an insurance policy I think I'd be using 1" drive one those track roller bolts.
I put all new rollers on my 320DLRR, when it had 10k hours. Over a 1/3 of the bolts broke, almost all at the head. Tried torch heat, fast cool, torch heat slow cool, induction heater....nope, only got one out. Cut the rest flush and torched them out, in 10°F weather, on a muddy jobsite. It can be done, but, just like anything else, there is skill and a learning curve involved. Sometimes, they're just stuck. Since it's getting new rollers, and the bolts are still there, couldn't you torch away enough of the roller housings that the bolts are no longer in tension?
You guys ARE very good...thanks for the suggestions. It was the 3/4" drive socket and LONG bar that made the difference. I had a 4' bar but per John and Nige, I put a long sleeve/pipe over that one to get about an 8' bar. ALL the bolts came free...most "popped" as they let go...2 or 3 eased loose and I thought I was wringing the bolt head off. But, nope, all bolts came out, none broke. I did use a good bit of PBlaster yesterday, several times, so maybe that helped. Thanks for the tips...no broken or rounded-off bolts is awesome.
and a few more -- working solo until my son gets here tomorrow sometime. Had to rig up a second man to hold bars for me -- and belays to catch the rollers when I dropped them:
Congratulations on getting all the bolts out without breaking any but I hope that you are going to use all new bolts for the track rollers.?
I THOUGHT I was but when I picked up my parts they only had 4 new bolts for me. I pointed out that I needed 8 more and they said it would be OK to re-use ones that looked "OK". My instinct was to go with new ones. I will call them in the AM and see if they have 8 more in stock. I am only replacing 3 of the 16 rollers...they were frozen. All the others still turn (albeit not easily) and supposedly still have good life in them per CAT. The ones that came out had a white residue on them...not red like the sprocket bolts. I assume it was red Loctite on the sprocket bolts. Should I also use red loctite on roller and carrier bolts?
I think the white is what’s left of the nickel plating of the original bolts. If they are not corroded I’d suggest to give them a thorough cleaning with a wire brush and refit with a liberal coating of copper anti-seize all the way down the bolts, not just the threaded portion. Seeing as you only have 4 new bolts then pick the 4 that are in the worst condition and replace them maybe.?
I like that idea. I plan to put a wire wheel on the shop grinder and use that to clean the bolts. Good thought on the nickel residue. The bolts seem decent enough to use them again (except the one that had a burr on the head).
When reusing the old bolts, I go by the condition of the heads. The corners are what corrodes away and if thin now, there won’t be enough left when you go to take them out in the future. Then it’s torch time.
Maybe its just the pictures, but the cribbing beneath that undercarriage looks pretty scary. The round logs under the timbers . . .
It can be an attention getter, I agree. The logs do not roll, the earth is sandy and soft enough that they sink into a trough and won't roll. The boom stick bucket was always in place as support. I did have the full weight on the cribbing, but the bucket was always in contact with the ground also in case the cribbing failed. I never had the cribbing hold the full weight unless the bucket was there as the backup. I just didn't want the full weight of the excavator on the bucket for days at a time. I'm not sure if that's acceptable for hydraulics. So the cribbing held the excavator and the bucket was backup.
Pretty much "Shake hands with danger" HEF Homeowner edition. Bad Bob