If you've spent any time operating heavy machinery, you know that annoying clunking sound when you've got too much play, which is exactly where excavator bucket shims come into the picture to save your pins and bushings. It really doesn't matter if you're running a brand-new mini-ex or an old 30-ton workhorse that's seen better days; eventually, things start to loosen up. That side-to-side wobble might seem like a small deal at first, but it's actually a sign that your equipment is eating itself alive from the inside out.
Why that little bit of play is a big deal
When there's a gap between the bucket ears and the dipper arm, every time you curl the bucket or pick up a heavy load, that metal slams back and forth. You might think a few millimeters of wiggle room isn't a problem, but in the world of heavy hydraulics, that's a massive amount of "slop." This movement creates a hammer effect on your pins and bushings. Instead of the force being distributed evenly, it's concentrated on small points, which accelerates wear.
If you let it go too long, you're looking at more than just a noisy day at the job site. You're looking at oval-shaped holes in your bucket ears. Once those holes lose their roundness, a simple pin replacement won't fix it anymore. You'll be calling in a mobile welder for a line-boring job, and trust me, that bill is going to be way higher than a handful of excavator bucket shims.
What exactly are these shims anyway?
At the end of the day, an excavator bucket shim is basically just a very specific, heavy-duty washer. They usually look like a flat ring with a hole in the middle that matches the diameter of your bucket pin. They come in different thicknesses—usually ranging from 1mm to 3mm or so—and they're designed to slide onto the pin to fill that empty space between the bucket and the arm.
Most people prefer hardened steel shims because they can handle the literal tons of pressure being exerted on them. You might see some "soft" shims or even nylon ones floating around, but for most digging applications, you want something that isn't going to crush or disintegrate the first time you hit a rock.
Figuring out the right size
You can't just grab any shim and hope for the best. You need to know your pin diameter first. If you've got a 45mm pin, you need 45mm shims. It sounds obvious, but it's easy to get wrong if you're just eyeballing it.
Once you've got the diameter right, the next step is figuring out how many you need. The goal isn't to make the bucket so tight that it won't move; you want it "snug." Usually, a good rule of thumb is to stack them until you can barely fit the last one in. You want to leave just a tiny bit of room for grease to move around, but you definitely want to kill that side-to-side slide.
The process of shimming a bucket
Installing excavator bucket shims isn't exactly rocket science, but it is a greasy, heavy job that requires a bit of patience. First, you've got to get the bucket off the ground and supported safely. Please don't rely solely on the hydraulics while your hands are in the danger zone—use some jack stands or heavy blocks.
Once you've knocked the pin out (usually with a big sledgehammer and a drift), you'll want to clean the area. Wipe away the old, crusty grease so you can see what you're doing. Slide the bucket back into place, align the holes, and then start checking the gap. Most guys like to put the shims on one side, but if the gap is really big, it's better to split them up between both sides to keep the bucket centered.
A pro tip: if you're struggling to get the pin back through the last shim because it keeps dropping down, use a little dab of thick grease to "stick" the shim to the bucket ear. It acts like a temporary glue and saves you a lot of frustration.
Knowing when to call it quits
There comes a point where excavator bucket shims can't save you. If you've stacked five shims on one side and the bucket is still rattling like a can of spray paint, your bushings are probably shot. Shims are great for taking up lateral (side-to-side) play, but they won't fix vertical play. If the pin is bouncing up and down inside the bushing, you need new bushings and pins, period.
I've seen guys try to weld shims directly to the bucket ears as a permanent fix, and while it works for a while, it usually makes it a nightmare the next time you need to do actual maintenance. It's better to keep them as "floating" pieces that can be replaced or adjusted as the metal naturally wears down over the seasons.
The cost of ignoring the problem
It's easy to say, "I'll get to it next weekend," but those weekends turn into months pretty fast. Every hour you operate a "loose" machine, you're losing precision. If you're trying to grade a flat trench or do some fine landscaping, that extra wiggle in the bucket makes it nearly impossible to be perfect. You end up over-digging or having to go back over your work, which wastes fuel and time.
And let's talk about the pins. A set of high-quality excavator bucket shims might cost you less than a lunch at a decent diner. A new main pin for a mid-sized excavator? That can easily run you several hundred dollars, and that doesn't even include the labor of cutting out the old one if it's seized or mushroomed from all that banging around.
Keeping a kit on hand
If you're running a crew or even just maintaining your own machine, it's a smart move to keep a variety pack of shims in the truck. They don't take up much space, and they're one of those things you'll be glad you have when you notice a gap opening up during a pre-shift inspection.
Since they come in different thicknesses, having a mix of 1mm, 1.5mm, and 2mm shims allows you to "tune" the fit perfectly. As the machine works and the metal wears, you might find that you need to add another thin shim every few hundred hours to keep everything feeling like new.
Final thoughts on maintenance
At the end of the day, using excavator bucket shims is just good old-fashioned preventative maintenance. It's one of those small tasks that separates the guys who keep their equipment for twenty years from the guys who are constantly complaining that their machines are "junk."
A tight machine is a quiet machine, and a quiet machine is usually one that's going to keep making you money instead of costing you a fortune at the repair shop. So, next time you hear that metal-on-metal "thump" while you're digging, don't just turn up the radio. Grab a tape measure, check your pin size, and get some shims in there. Your equipment (and your wallet) will definitely thank you down the road.