View Full Version : Master Link Problem

ed d2
12-11-2006, 09:38 AM
I am new to this crazy hobby so please forgive the stupid questions.
After working my new (to me obviously) D2 for a few hours one of the tracks derailed. I found that the master link was joined together with a simple pin that is peened over on one end. Of course it had partially backed out and allowed the track to derail. I see in the parts book that the correct fix is to replace the two links with links that will accept the tapered pins that Cat designed. That sounds like lots of work and expense. What is the downside to simply welding a "peen" on the other end of the pin until I have to fix it right?

12-11-2006, 12:48 PM
I have seen lots of them welded over the years at the shop so you can weld yours till you decide to fix it correctly.

Al Letts
12-11-2006, 01:27 PM
On my ole junkyard relic D2, the master link PIN on the right side was replaced with an equipment hitch pin with flatwasher and cotter key retention. It's held for a bunch of years.


ed d2
12-11-2006, 04:58 PM
Thanks to all for the ideas.

12-11-2006, 07:03 PM
if it were me i would weld a washer to the end of the pin rather than try to weld the pin to the link, like others have said the link is hard so the weld will not usualy hold to it very well

12-12-2006, 12:58 AM
Ed - Never seen a worn, welded pin, stay in a track for very long, if given some serious amount of work.
The main reason being, that the constant rotating/twisting action of the links is like twitching a piece of wire .. sooner or later it breaks, with the constant working back and forth.

Here's a neat trick that works, and was shown to me, well over 40 years ago, when I ran a beat up ole-A-C, that had more pins falling out of its 120% worn undercarriage, than would fall out of an open dressmakers kit.

Run 4 beads of weld lengthwise on the pin, the same length as the pin boss is thick.
Take the pin to your big bench grinder, and with your best bench grinder sculpting skills .. grind the beads of weld into wedges that taper each side about 30 .. and which taper from the full height of the bead, down to nothing at the inside end.
If you're a pro at sculpting with a 4" angle grinder, you can use that instead. Just ensure the pin is held firmly.

Once you have those 4 beads sculpted to neat wedges .. drive the pin in flush.
It might take a bigger hammer than normal, but that pin will stay there longer than any welded pin, due to the tight wedging action of those weld beads. It will come loose again eventually, as nothing will keep a worn pin tight forever .. but it is by far the most successful method of keeping loose pins in.

ed d2
12-13-2006, 02:59 PM
Thanks for the idea.
Let's see if I got your solution correct.
The welds run from each end of the pin and they are ground lower toward the middle of the pin?
That will take a big hammer!


P.S. My daughter lives in Melborne, she married a Aussie and moved "down under". You have a beautiful country!

12-13-2006, 06:20 PM
ed - You only need to run the beads of weld on the one end of the pin .. the outside. And yes, the beads are highest at the outside edge, and taper down towards the center of the pin.
No need to have them too high, at the outside end .. about 1/8" - 3/32" at the outside will be plenty.
Make sure the beads end up, a smooth and even wedge shape, right along their length .. and that they are all parallel.
Use a low hydrogen 7018 rod for the welds .. and if you're not satisfied with the wedges alone .. you can still run a couple of short beads on the end of the pin and pin boss, to assist with securing it.

AJ - You must have been working with some crap aftermarket undercarriage, to have links that shattered .. or the weld bead wedges were huge.
Cat links are made of extremely tough steel, that are deep induction hardened on the wear areas .. such as the rail .. but the pin hole area isn't hardened, and that tough metal will stretch to accomodate the wedges.

12-15-2006, 05:14 PM
If anybody has a photo of a welded-up pin like you're describing ( taper weld ), I'd be much obliged to see it.

12-15-2006, 06:25 PM
I worked 11 years in the track shop of a Cat dealer and have seen plenty links crack in the press When the rollers are badly worn and the flanges have been hammering on the link bosses and distort the link and pin so they go sort of D shape they can even crack the link when been pressed out and stand no chance of going back in when turned without cracking as there is very little give in the link and i often had the odd one crack for no apparent reason When tracks are shot they are shot and out of the options posted to keep the pin in I would go with Ajs it is the simplest and best method and is on the same principle as the old tapered plug spreading the pin to tighten it in the link a bit of heat and a few blows of a heavy hammer is all thats needed

Old Magnet
12-16-2006, 11:50 AM
Hi GoCat,
Thanks for the info, I totally agree.

As far as the variety of undercarriage out there I like to quote "halftrac", lifetime track shop owner/operator from his "I B Dozing" website.

"Now days you don't know where undercarriage components are made and whether they are from China, Korea, Italy, or..... they are all OEM equipment for someone and even Cat undercarriage fails"

Also would like to ask your advice on the following.
I have a D4 that came with welded master pins (full circumference weld). The rails are in good shape but are due for a P & B turn. What technique would be best to remove the welded pins with minimum damage to the links? Thanks

12-16-2006, 05:07 PM
Usually the tracks coming into the shop would be off the machine and the m/pins out Any pins that were welded in would not be used again or the link either To get them out the end would be torched off down to the link and the press would push them out we kept a pile of used links for the purpose of replacing any one we had to scrap A new link would be to high A new set of master pins would be supplied with each set of tracks going back to the customer You could try grinding the weld off as low as you can and it may brake away easy enough