Just wanted to share a success I had today with the removal of the cush-drive bushings from the rear hub of my K3 350. Kudos to the AHRMA Facebook group for proving that there is more than one way to skin a cat!
It began with my inadvertent damaging of the existing bushings when I became overly eager with cleaning parts in my new sandblast cabinet.
Hard to see in the photo, but there is significant erosion of the rubber in the bushing. So much so that I didn't feel comfortable leaving them in a hub that will potentially see a race track.
The first attempt at removal consisted of a cold chisel and a ball-pien hammer carefully trying to tap out each of the bushings from the rear. I only came up with steel shavings and several busted knuckles.
Second attempt came from a friends suggestion to heat the hub and use the expansion of the aluminum to release the corrosion bond on the steel of the bushing. Lots of heat and lots of wafting soot of burned rubber left me nothing but a blackened hub.
Posting to the AHRMA group presented several alternative solutions:
1. Using an oven to accurately control the heat to a point where the aluminum would expand but not the steel
2. Pressing out with a hydraulic press and a custom fabricated split punch that would clear the interior hub supports
3. Drilling out with a carefully centered drill bit.
4. Progressive drilling to thin the wall of the bushing sleeve, until a cutting chisel is used to peel the remaining layer out
Since all but the first required more tooling that I was equipped for, I opted for more controlled heat. The first problem was encountered when considering that the burning rubber smell that could still be strongly detected in my garage would not be a pleasant addition to our kitchen. So I attempted to burn as much rubber out as possible with a hand torch. Strangely enough that when you actually want to burn something like this, it ends up being a bear to get going. Needless to say I resorted to mechanical means of trying to remove the rubber completely so as to reduce the possibility of smelling up the house. This quickly led to a realization that I was spending way to much time in a precautionary step. Why not use an outdoor cooking surface instead!
By suggestion from the AHRMA group, I purchased an IR temp gun from Lowe's and used it to know when the hub had reached between 250 and 300 degrees. Alas, progress!
A few heat cycles on the grill to work each bushing out and the 4 them were out with verily little sign of the effort inside the bushing ports of the hub. I had been very concerned about damaging the interior surfaces to the point that a new bushing would no longer fit.
Takes 5 minutes with a 1" hole saw in a drill, preferably with a drill press.
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