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Rotor Button

Why do I keep breaking rotor buttons?

This makes 2 in 4 months, they install just fine, no obstructions inside the cap, they work for 500+ miles and then break. A piece of the button breaks off.

This should never happen, right?

First we need to be clear on what actually you are breaking. A “rotor button” is mounted inside the center post of the cap, it it usually part of the cap and is not removable except on some GM V8’s with the coil on cap. The rotor button makes contact with the center of the rotor which mounts on to the distributor shaft. Which part are you breaking, the button mounted inside the cap, or the rotor itself which presses on to the distributor shaft?? Either one of these two items could break due to a worn out distributor. Does the distibutor shaft have excess side to side play in it?? If it does you might end up replacing the distributor.


Where are you getting the cap and rotor? Aftermarket?
I recommend you get OEM (Autolite?) parts.

I’d go with Transman with the shot distributor. It might not be bushings, per se~, but whatever prevents vertical climbing as the helical cut cam driven gear would want to… is shot. I’ve always associated lateral run out with primary ignition problems, but I guess it could work to hammer the button.

Check to see if there is any sideways movement in the distributor shaft. If so, the dist. shaft bushings are worn out and this can lead to the rotor making contact with the cap terminals. The cap terminals are stronger than the rotor terminal so it will give up first.

As to why they’re worn out it’s probably due to coked oil on the dist. housing. The car is 20+ years old and has a measly 65k miles. This means skimpy use and likely very irregular oil changes. This will coke oil around the small holes on the housing that allow lube oil to the shaft bushings. Once the oil holes coke over the bushings won’t last long.

The distributor is driven directly from the camshaft, no gears involved…

Has the distributor been removed lately? Has the head been worked on lately?