How to Fit Girder Fork Bushes
- Andy Marks
- Jan 27
- 2 min read
Updated: Jan 29
On this page you'll learn how to fit girder fork bushes on vintage and post-vintage motorcycles with this step-by-step technical guide. We explain how to prepare the forks, make and fit bronze bushes, check alignment and ream to size — essential skills for restoring Webb, Norton and other period fork sets.
Some manufacturers used bronze bushes in their forks from new. However many didn't, neither Norton or the Webb forks used for the images on this page did. If bushes were used it is a simple case of getting the old ones out and pressing new ones in.
Top Tip: When getting the old bushes out, use a tap that's 1/16'' bigger than the spindle to put a thread in the old bush, then screw a bolt in and you have something to tap with a drift from the other side.
When bushes were not fitted from standard the repairs are a little more involved. Here’s how we have done it.
Set the Fork Up on the Milling Machine
In this picture the top yoke is being set up on our Bridgeport using a length of silver steel in a collet to line the yoke up with the quill. It is important to use the correct size silver steel and run it all the way through. Any slight miss-alignment here will make the forks reluctant to move.
It is important to bore, bush and ream one side before boring the other side. This makes sure you have the 2 bushes in line with each other.
Bore the Fork to Take the New Bush
We always aim for a bush with a wall thickness of around 1/16''. In this example a 5/8'' cutter is being used in the yoke designed for a 1/2'' spindle.
The longer the bush is the better, we usually aim for around 1''.
Make a Bronze Bush
Sintered and oil filled bronze bushes are available off the shelf in a range of sizes and are relatively inexpensive. However we have found these don't last very long. A proper bronze bush turned up from the solid, with the correct sized hole drilled and reamed, is a far better option. It also allows us to ensure a proper fit in the freshly bored fork.
About 0.002'' oversized on the outside diameter is ideal.
Press the Bush in and Ream to Size
A fly press is ideal for this job, but if you don't have one, a piece of studding with a washer and nut on each end will also work.
Once the bush is pressed in you will need to ream it to size again as the interference on the outside will close the thin walled bush in slightly. Fortunately most forks come with standard size spindles (3/8, 1/2, 5/8 etc) so the reamers are relatively east to get if you don't already have one.
Once this has been completed on one side, the yoke can be put back on the milling machine and lined up to bore the other side out and repeat the process.
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