MTFCA Forum

I removed the magnets from my 11's flywheel to check for cracks (found two bad ones) so I I'd like to replace the triple gear pins as they have about .001 to .0015 out of round condition. I found a set of new pins in my stash but I think they are factory size. They measure .686 at the 1/8" step and .679 below that. I've seen conflicting post about actual pin size. I understand the pin hole will be opened slightly when the old pins are pushed out. Will these pins work? I'm not sure the pins that are in the flywheel are original or not, should I just leave them alone?

.679 is the official Ford stock size. IF they were reasonable snug coming out and your new ones go in with some effort, you should be ok. From my experience .0015/.0020 " interference is just about perfect.

Just went through this with J&M Machine. I had been waiting on pins from Bob's Antique Auto, who I have to say has been such a great guy to deal with. Unfortunately the guy who sets up the machine to cut the pins can't come in and they are out of them. J&M Machine ended up having a set in their shop for me. He told me there were some pins out there that were made a bit too big and when people used them they ended up cracking the flywheel. J&M had to make a tool to make the hole bigger so they could use them. If you are worried about cracking another flywheel send the pins and flywheel to J&M. I bet they could make them work. If you can wait for a bit buy your pins from Bob's. Same with your bushings.

The pins should be pressed out the opposite way they were pressed in. You should able to be pushed in with limited pressure until the enlarged end enters the flywheel then the pressure is somewhat increased. I would not recommend pressing them through from the rear, only press them in from the rear. There are some after market oversize pins, you have to measure and be sure you have the right pins. Unless the pins have come loose in the flywheel they shouldn't need to be replaced. New bushings usually require to be reamed or honed to fit, a bit loose is far better than too tight.

Just to be the devils advocate and also learn something, is it necessary to replace these pins with this out of round .001-.0015? Thanks

Should pins with 1 1/2 thou be replaced - My opinion:

From an engineering standpoint, the answer is "yes"
If you're paying an enormouse amount of money to have it remanufactured, the answer is "yes"
If you're doing it yourself, the answer is "it depends"
I have had excellent success using pins like that on my own work and have put many thousands of hard miles on them, but I understood the limitations presented by this choice and made repairs that would not conflict or be deleterious to that choice

I will use triple gears with needle bearings as an example: Using those pins and Dan McEachern's excellent needle-bearing triple gears would be a terrible combination of parts; the gears thus fitted must have a perfect pin, therefor that would be a bad choice. Conversely using his gears with new pins would be an excellent choice. This is but one example, but the most extreme I could come up with.

Life is a long series of compromises and this is one where excellent results can be had with less than perfect parts just as easily as a "perfectly" repaired transmission with pins and bushings at factory specs can result in a destroyed assembly in less than 20 miles.

Just to clarify one point in Scott's post above. The pins I provide with my needle bearing triple gear conversion can not be replaced with an aftermarket replacement pin or a Ford original pin. My pins are ground to a +/- 0.0002" tolerance based on a size the bearing manufacturer recommends. This size is nowhere near the size of a Ford pin. In addition to the size issue, I've found that some of the after market pins are not ground to the Ford specs, and the material and heat treatment is not sufficient to endure long term use with the loads a needle bearing places on the pin surface.

Scott's points above are well made.

Dan, glad you made that clear. I sure didn't and am sorry that I didn't. It makes complete sense as you control the finish, toughness and size that way, which is important in that you are supplying a "system" that would be incomplete otherwise. I hear nothing but good stuff about those things, and from people I trust.

Thanks, understand the finish and size requirements when needle bearings are used, but I can't get the image from my head of a reamer held vertical in a bench vise with someone turning the triple gear to ream a new bushing. The "black" Ford Service manual says replace if the pin is worn .002 and re-bush the gear if more than .005 play and aim for a .002 running fit. The MTFCA comprehensive guide to transmission repair says replace the pins if the wear exceeds .005, with bushing clearance of .002 for a new job and .005 for a repair. In my case the choice to replace is how much disposable cash I have at the time and how many miles I plan to drive the car. Just my humble opinion, enjoy.

Well, if I read your post correctly, you have .0005 (half a thousands) out of round on your pins. For a loose-fitting bronze bushing, that's not a lot, but it is some. IF the pins are nice and smoooth, I wouldn't worry about a bronze bushing with enough oil clearance on those pins. One could even "shoeshine" the pins to make them smoother (and you could even, though it is a lot of work, reduce the ovalness), I would want to see something like 1,500 grit finish oh them So time, or money (or both???). And it also somewhat depends on what kind of driving you will be doing. casual occasional, or cross country long distance.
this advice is, of course, worth every cent you paid for it!

david_dewey wrote: ↑

Fri Mar 27, 2020 5:52 pm

Well, if I read your post correctly, you have .0005 (half a thousands) out of round on your pins. For a loose-fitting bronze bushing, that's not a lot, but it is some. IF the pins are nice and smoooth, I wouldn't worry about a bronze bushing with enough oil clearance on those pins. One could even "shoeshine" the pins to make them smoother (and you could even, though it is a lot of work, reduce the ovalness), I would want to see something like 1,500 grit finish oh them So time, or money (or both???). And it also somewhat depends on what kind of driving you will be doing. casual occasional, or cross country long distance.
this advice is, of course, worth every cent you paid for it!

David,

I see where you're coming from with your .0005 statement. I think the OP may mean that one pin is maybe .001 out of round, while another may be .0015. Still, I don't believe that's too excessive. However, since it's apart now, it'll never be a better time to do it.

I was not planning to take the flywheel apart but I had to re-magnetize the magnets, in doing so I found two cracked magnets. So I said if I have the flywheel apart I might as well replace the pins. Either they were replaced in the 50's when G'pa rebuilt the engine or they are original from 1911. To be honest I doubt G'pa replaced them, he wouldn't have spent the money.

You may not need to, either. An awful lot of very early cars never saw the service necessary to wear out a transmission.