Member Project: Swingarm Bushing

Stats

• Made By: Steve
• Status: Finished
• Tools used: 3-in-1 lathe, 16mm reamer, Arbour Press

Description

I have a Honda Grom and like any good motorcyclist I take pride in modifying my bike. This modification involves replacing the standard steel swingarm with a Tyga aluminium over braced item. This is a straight swap however I wasn’t happy with the new arm as it had like the OEM arm rubber bushing at the pivot instead of roller bearings that I would expect.

Bought replacement Swingarm

The problem here was that despite my best googlefu and the help of a local bearing suppliers I couldn’t locate a set of roller bearings at the correct size that being 12mm ID and 24mm OD by 42mm length. So having already removed the rubber bushing I decided the best solution here would be to turn some bronze bushing to size to remove the flex of the rubber bushes.

So I ordered some oilite bronze stock and headed to the 3-in-1 lathe. Checking my feeds and speeds I turned the rpms down on the lathe and set about turning the outside of the stock down to fit. With that set it was time to drill the internal diameter to 16mm to fit a pair of needle roller bearing internal sleeves.

Bronze stock on the 3-in-1 Lathe

And this is where I made a mistake. Drilling the centre out to 16mm resulted in the internal sleeve simply slipping through the hole. Turns out twist drills are not that accurate. So I started again, this time drilling to 15mm and then finishing off by hand with a 16 mm reamer. The sleeve now fitted perfectly.

Two attempts to drill

Next was to put the bush into the swing arm where by I found the next problem. While one hole was 24mm the other was around 23.5mm so was to big to fit. I solved this by putting the bush back into the lathe held by a live end in the tail stock and dead end in the chuck to enable me to hold the part while being able to work the length of the piece.

Retry on the diameter

Finally with both bushes the right diameter I used the Arbour press to insert them securly into the arm and then fitted the arm to the bike.

Bushes inserted into Swingarm

These were made in a few hours over the course of a couple of visits to the space. I could have completed this in one evening if I didn’t have to wait for my new reamer to arrive.