The Ford Barn - View Single Post

P.S. · 12-31-2019, 07:56 AM

The drilled shaft (with a small hole from the drilled out center to the outside of the shaft, of course) seems to be all the rage. So, I did a little experiment.

With the stock shaft, as Kurt said, oil from the spring loaded filler does make it to the top bushing. That spring is there for a reason. The question is, how much oil makes it to the upper bushing vs. the bottom bushing? Well, as it turns out, the answer is: Plenty. I have never seen a worn out upper bushing with a good lower bushing. They are always worn the same.

So, is there any harm in drilling the shaft? Maybe.

You see, when the shaft is not drilled, oil wicks to the upper bushing. There is no airflow between the upper bushing and atmosphere, so the oil tends to hang around there after wicking into the space between the shaft and the bushing. If the shaft is drilled, then oil can easily flow from the hole in the shaft, past the upper bushing, to the lower bushing and stay there. Long story short, the drilled shaft might actually be worse.

This all assumes that you oil the distributor shaft as frequently or more frequently than every 500 miles. If you're the forgetful type, then the drilled shaft might be a good idea.

I experimented with a newly rebuilt distributor by putting oil in an otherwise dry fresh rebuild that did not have the drilled upper shaft. I only put oil in the spring loaded oil cup. I spun the shaft a few times, then removed the shaft. The upper bearing surface was just as wet with oil as the lower. Then, I re-cleaned the housing, swapped to the drilled shaft, and repeated (no oil in the shaft, just the oil cup). This time, only the lower bushing surface area was wet with oil, the top was still dry. That means, only the oil actually dripped down the hole in the shaft lubes the upper bushing surface. So, what happens when gravity drains the oil from the upper bushing area? I suspect it runs dryer than the lower bushing, and at some point, the upper bushing will show more wear than the lower bushing. Something that doesn't happen with the stock shaft and proper lubrication.

12-31-2019, 07:56 AM	#12
P.S. Senior Member Join Date: Jul 2012 Location: California Posts: 1,696	Re: distributor shaft The drilled shaft (with a small hole from the drilled out center to the outside of the shaft, of course) seems to be all the rage. So, I did a little experiment. With the stock shaft, as Kurt said, oil from the spring loaded filler does make it to the top bushing. That spring is there for a reason. The question is, how much oil makes it to the upper bushing vs. the bottom bushing? Well, as it turns out, the answer is: Plenty. I have never seen a worn out upper bushing with a good lower bushing. They are always worn the same. So, is there any harm in drilling the shaft? Maybe. You see, when the shaft is not drilled, oil wicks to the upper bushing. There is no airflow between the upper bushing and atmosphere, so the oil tends to hang around there after wicking into the space between the shaft and the bushing. If the shaft is drilled, then oil can easily flow from the hole in the shaft, past the upper bushing, to the lower bushing and stay there. Long story short, the drilled shaft might actually be worse. This all assumes that you oil the distributor shaft as frequently or more frequently than every 500 miles. If you're the forgetful type, then the drilled shaft might be a good idea. I experimented with a newly rebuilt distributor by putting oil in an otherwise dry fresh rebuild that did not have the drilled upper shaft. I only put oil in the spring loaded oil cup. I spun the shaft a few times, then removed the shaft. The upper bearing surface was just as wet with oil as the lower. Then, I re-cleaned the housing, swapped to the drilled shaft, and repeated (no oil in the shaft, just the oil cup). This time, only the lower bushing surface area was wet with oil, the top was still dry. That means, only the oil actually dripped down the hole in the shaft lubes the upper bushing surface. So, what happens when gravity drains the oil from the upper bushing area? I suspect it runs dryer than the lower bushing, and at some point, the upper bushing will show more wear than the lower bushing. Something that doesn't happen with the stock shaft and proper lubrication.