MTFCA Forum

I know I'm getting old, but I can't find the allowable amount of wear for the transmission triple gear pins. I checked the Ford Service book and can't find it! The flywheel I'm working on shows .002" which seems acceptable.

Paragraph 275 in the service manual states "Triple gear shafts are inspected for wear by measuring the diameters of the shafts with micrometers. If the shafts show more than 0.002" wear they should be removed and new shafts installed as described in paragraphs 288 and 289.".

My first question is what are your plans for this project?
If only a few miles locally then just use them!
If further then I would replace them now while it is easy.
Personally I virtually ALWAYS replace the pins and almost never replace the bushings in the triple gears unless they have serious problems.
Just my philosophy!

It has been debated many times on the forum on clearance, if you set up with only .002" they tend to give trouble, .002" each side, pin .004" smaller than bush hole is the minimum.

I do .0035 to .004. Gear is bored on a lathe. thats a fine BORED finish. .004 with a hand reamer will grow to .005 or more after break in. i NEVER use reamers.
drums same spec. they are turned in an accurate lathe chuck. held on the gear or shaft. bushings are bored. drums turned the same way. could be honed after bushing bore centered in the lathe.
First cut, you will notice bushing is not perfectly centered. You will typically notice the drum is not running perfectly true & requires a small clean up cut to square up.

That's some good advice John. I bet lots of guys aren't as particular as you but I'd bet your work is running still without issues.

I will third John’s method. Of course he, Gene, and I, are all Califunny guys so take us for what you think we’re worth. Back when I used to do this fun stuff as my "regular" job, I had a Sunnen Honing Machine and liked finishing off the bushings the way John describes. We’re not talking about using a little brake cylinder honing tool here. Good to see your presence here, John. This is the best forum on any subject on the interglut. Your contributions will be of value to many and the people here are awesome.

For a while there, the largest of the drum bushes were a problem. Machining them in the lathe often did not clean them up totally. A couple of times I had to be satisfied with a small cup or two of un-machined surface to run the gears on slightly worn shafts. There was enough meat in the bush to machine it to fit a new shaft, but leaving a bit to make a better fit on a worn shaft was problematical.

Allan from down under.

know what you mean allen. likely as not the reverse drum bushing does not clean up 100%. thats one reason why i think reaming is less than ideal. As you point out, custom sizing your bore makes up for mating shaft wear. Low drum bushing normally cleans ok, but, bushings are never perfectly centered to start. the reamer will follow the off center. Sean, if i owned a sunnen hone, i would close bore all the bushings & finish hone. A careful, fine bore finish is otherwise excellent.

I think Larry is asking about wear on the pins, if you have .002 wear on the pin, check and see if the wear is all the way around the pin, if not .002 out of round wound make a big difference on how the gear runs and I would replace the pins if that were the case. My .002 cents.

one consideration is how far around is the wear pattern. look at the pin. the non load side will have no wear. the pins can be removed & turned 180 degrees. same as replacing with a new pin. this assumes pins are tight & no other issues & go back in tight. added bonus - allows better lubrication from the non load side gap. bushing clearence of less than .006 should be maintained with used bushings. clearence is checked in the tangential direction of the flywheel. .002 wear is not so bad, but, with everything apart i would either replace or turn the pins, leaning heavily toward replacing. i have been accused of being picky. for a putter, no big deal. for a long distance & tour car, i would fix it.

P.S. If original bushings are still in spec with new or oversize pins. stay with the original bushings & change pins. general wisdom is original bushings are better than new ones. Both pin wear & bushing wear should be considered in the decision.