Pin and bushing bore repair
Worn Pin Bore Repair: Weld and Rebore, Sleeve or Oversize Bushing
When a pin bore on an excavator, backhoe or loader wears out of round, there are three common ways to fix it. Here's how each one works, when to use it, and how portable line boring fits into all three.
- Repair the bore on the machine
- Every method starts with a straight, true bore
- Written by the Chicago shop that builds IRM line boring sets
Why bores wear
Why a new pin alone won't fix a worn bore
Pins and bushings at pivot points carry heavy, shifting loads. Dirt, missed greasing and shock loads slowly wear the bore out of round. Once it is oval, the pin moves around, wear speeds up, and you get slop in the bucket, boom or linkage. A new pin in a worn bore wears out quickly, so the bore itself has to be brought back to round and in line.
Signs a bore needs repair
- Visible play or clunking at the pivot
- New pins or bushings wearing out quickly
- A bushing spinning in its bore
- Bores that are out of round or out of line with each other
The three methods
Three ways to repair a worn pin bore
All three methods rely on line boring. A portable line boring machine cuts the bore straight, round and in line with the bore on the other side, right on the machine.
1. Weld and rebore
Build up the worn bore with weld, then line bore it back to the original size so the original pin and bushing fit again.
Best for
- Bores worn too far for a simple cleanup
- Keeping the original pin and bushing size
- Parts with enough material to weld
Watch out for
- Heat from welding can distort the part, so weld evenly
- Leave enough weld for the bore to clean up fully
- Takes welding time plus boring time
2. Sleeve the bore
Line bore the worn hole oversize, install a steel sleeve, then bring the sleeve's inside diameter back to the original size.
Best for
- Parts where welding isn't practical
- Restoring the original pin size
- Bores with heavy or uneven wear
Watch out for
- Needs enough wall thickness around the bore for the oversize cut
- The sleeve needs a secure fit so it can't spin
- You need a sleeve made to size
3. Oversize bushing
Line bore just enough to clean up the bore and make it round, then fit a bushing with a larger outside diameter.
Best for
- Moderate wear
- The quickest of the three repairs
- Machines with oversize bushings available
Watch out for
- You need the oversize bushing in stock or made
- Each repair leaves less material for the next one
- Only works when the bore can clean up within the bushing size
Choosing a method
How to choose the right repair
- Measure the wearCheck how far out of round the bore is and whether the bores still line up with each other.
- Check the material around the boreMake sure there is enough wall thickness for an oversize cut, or enough material to weld.
- Decide on the pin sizeWeld and rebore or a sleeve keeps the original pin and bushing. An oversize bushing changes the bushing you'll need next time.
On time: an oversize bushing is usually the fastest repair, while weld and rebore takes the longest but brings the bore back to its original size. Not sure which one fits your job? Send us the bore size, the amount of wear and the equipment, and we'll help you choose.
Equipment
What you need to line bore the repair
Every one of these repairs needs a straight, true bore. That is what a portable line boring set is for.
- Line boring setBoring bar, bearings, plate or channel, centering cones and hardware. Complete sets from $2,900.
- Power FeedHands-free, steady feed for a smoother finish. Or use your mag drill.
- Boring bars0.875" to 1.75" in diameter, 21" to 100" long.
- BoreRightSet the tool bit precisely for the final size.
Need a sleeve or bushing made?We're a Chicago machine shop. We can make custom sleeves, bushings and other parts for your repair.
See our machining servicesNew to line boring? Follow our step-by-step line boring guide.
FAQ
Common questions
Can I just replace the pin and bushing?
Only if the bore is still round and in line. If the bore is worn oval, a new pin and bushing will move around and wear out quickly. The bore needs to be repaired first.
Do I always need to weld before line boring?
No. Welding is one option. If there is enough material around the bore, you can bore it oversize for a sleeve or an oversize bushing instead.
Can the repair be done on the machine?
Yes. Portable line boring is made for on-site repair. The set mounts on the equipment, so you don't have to remove the part or haul the machine to a shop.
How much should I bore oversize for a sleeve or bushing?
It depends on the sleeve or bushing you're fitting and how much the bore needs to clean up. Measure the bore and check the part's specs. If you're unsure, call us at (224) 435-6999.
What equipment do I need for these repairs?
A portable line boring set, a drive (our Power Feed or a mag drill), and a boring bar sized for your bore. For weld and rebore, you'll also need welding equipment.
Get the right setup for your repair
Tell us the bore size, the distance between bores and the equipment. Anguel will get back to you.
Ask about your bore repair
We’re ready to start as soon as you are. Fill out the form below, and a representative will be in touch shortly to kick off your next line boring project.
- Prefer to talk? (224) 435-6999
- Helpful to include Bore size, distance between bores, and the equipment you're repairing.
- Built in Chicago Designed and manufactured by IRM. Works with standard handheld drills.