Reading all the "heartbreak" about this issue has got me thinking (dangerous I know). As earlier stated, rarely have I found significant wear on Ford bushings. The pins are always badly worn on one side. So I'm thinking that if new pins with a ground finish and probably hardened were available in a couple of different oversizes (maybe std, .005, .010, and perhaps up to.015). Might provide a superior solution for quite possibly less cost.
Let the argument begin!!
Since triple gear pins have to be installed from the magnet side of the flywheel, it might be a little bit difficult to get an oversize triple gear pin into place.
I suspect there is a way around that. With the current design that is the easiest way but a couple of options come to mind
I think the replacement pins are already oversize. On the last set of triple gears I did, I had to bore the existing bushings to achieve 4 thou clearance after installing new pins. To reestablish the flange thickness, I simply pressed the bushing the out the gear just enough to wrap a piece of wire under the flange and push it back in. There was enough of the flange sticking out to face them on a lathe to get the required thickness. It worked well.
You may well be correct. I have reused Ford bushings for quite a few years and have never had to do any refitting, but this might just be good luck!!
Another solution to the worn flange might be to just buy a suitable thickness "machinery bushing" shim washer. Might consider getting them nitrided (likely get them to about 53 Rc) so they would wear longer.
In the blind study of dozens of used pins and bushing pairs done a few years ago that none of you guys other than RDR wanted to see the results of , the results on...and I stopped the research because of boo-bear indifference...
The secondary part of the initial study was to include a new pin and bush for reference tested to the same parameters and that showed that a replacement pin (in this case the one with the live center...not the blind 'center'produced by another...yes...there are two manufacturers), came in at true to drawing size along with near absolute roundness, and the bush was only checked for ID as I was looking into manufacturing a swedging-like tool for insert.
Both were from the same vendor...brand L from Massachusetts.
I post the QC 'map' of 'as-received'. The parts were measured with the right of the decimal accuracy shown with in -calibration NIST traceable metric mics and the conversion to imperial was to same decimal point.
A 32 micro inch finish in my view is on the rough side. If the pins were ground they should be more like an 8.
Interesting stuff. I probably was away at the time of your study
I don't suppose you have the data relating to the used bushings you encountered? That would be relevant to my idea. From your study I see the "bar" is set pretty low on the pins. Won't be hard to make better ones!!
Indifference? I doubt it. How many folks do you figure understand what these numbers represent. I fancy myself and a pretty fair hands on machinist and I don't have a clue as you what you mean. Perhaps you might lower your standards and speak plain English to us morons.
Richard, I apologize if you took offense. The above chart was as received format from my QC department...I'm not that creative. Further, wordiness is a DNA flaw I have always had and on deep matters like metallurgy I have pleaded for an editor ... Want to volunteer? . I may even be passing through Sacramento on Monday or Tuesday and we could chat it up?
Les, I'll go PM with you on the past work. I actually think I have an electronic report on the sets that RDR supplied. Unfortunately it is really blind as I have no idea what they came off of, and Ralphie has since passed on.
Ted, I'd agree that a better finish is needed. As good as these seem to be dimensionally, I was surprised at the number for finish. I guess/suspect that they are ground near dry?
Oh, As Richard says...decoder ring might help....
1- The test was done by 5 different inspectors all using certified mics. They of course did not pick up the exact same place to measure and the differences show waviness or inspector 'feel' differences.
2- The tests were all done in the same plane by all 5 (called 12-6, referencing the clock), then the pin rotated 90 degrees (now 9-3 with reference to the clock) and measure taken again.
3- The inspectors used metric mics...USA/Imperial derived
4- The bush hole means nothing as this was pre- insert/pre-bore and recorded there for my own info.
On my '13 roadster, one of the gears was just starting to kiss the flywheel, so I took one of my empty Coors cans and made three shims to place under the flange. Rather than press out the bushings all the way, I pressed them out about a 1/2", and snipped the shims with a pair of dykes so I could get them over the bushings, and then pressed the bushings back down. Worked.
Reading your post makes me think there might be a market for case hardened shim washers (although nitrided would be cheaper and would probably do the job too). 1/16 thick maybe
George sent me a picture of the foundry he was or is an engineer at. I always thought it might have covered a square block. That foundry is huge with every testing tool known to man.
If you look carefully the early fly wheels have three fins inside the cup or recess in the rear. The fins are placed to deflect oil under the edges of the triple gear that also has a cup facing the fly wheel the twist direction of the oil groves in the bushing pulls oil into the bushing.
That makes spacing the flange end of the triple away from the flywheel important, other wise the cup or flange end on the gear will not load the cup and the gear will contact the fly wheel slinging oil away from the gear.
Late fly wheels do not have those fins. Guess Henry decided they were not necessary.
If I understand your chart, it appears to suggest that the triple pins are .677 dia. at the bushing end, while the bushing I.D.'s ("yellow metal I.D.") are at about .6755, on average. Seems to suggest a press fit of .0015.....?
Jerry, that is correct for a replacement bush right out of the bag, before insert, before bore/ream/hone.
I threw that at my QC guys with the pin for a different reason but since I bought pins and bushes same day, they went over to QC together and the boys reported them together.
The reason was I wanted to make an insert tool to hold ID (and keep true centerline maybe???) while pressing a bush in a gear. I also had an idea of ball pressing to final size and the insert tool was also going to be the "ball" holder.
Big idea based on a pending retirement that never happened. Board refused my letter...then bought the robotics company that assembles iPhones...then reminded me my contract was for life, so now I play with robots small to large. Should have paid attention when my kids were into "transformers". Those things that looked like one thing but unfolded to something else
How about drilling a small hole in the flywheel mounted pins to supply oil to the triple gear bushings. The hole would be drilled from the back side of the pins and angled upward to exit the pins at about the center of the triple gear bushing. This would allow centrifugal force to supply oil into the bushing on it unloaded side.
Just an idea.
Definitely a valid idea. Just bouncing ideas around at the moment
We tried the lube hole thing years ago from the other direction, drilling holes in the root of the gear teeth thru into the bushing, hoping the gear mesh would force oil into the bushing. This did not seem to make much difference.
You can't change the laws of physics. Even in original engines where there are no doubt Z bronze bushings, the triple gear pin is always worn on one side. Why? Because there is metal to metal contact caused by failure of the oil film. The loads are simply too high for a non pressure fed plain bearing to support. Yes, .005" clearance solves the seizing issue in most cases, but we still see bushing failures- because the extra clearance makes it impossible for the bearing to develop the oil wedge it needs to maintain an oil film.
Just food for thought.
Dan's needle bearings for hardened triple gear pins is a good solution. John W. Stoltz in Tx uses a similar solution on his T:s with two std 6203 ball bearings in each triple gear - the gears has to be ground to 40mm holes for the bearings. The pins has to be turned down slightly to 17mm.
(Message edited by Roger K on May 15, 2016)