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Triple gear pins pressed into flywheel

Posted: Fri May 22, 2020 11:49 pm
by Arnie
MTFCA transmission booklet on page 16, Figure 13, states "Standard triple gear pin diameters are as follows: bushing segment is .675, press fit segment, .680, tapered head .697-.689.
In that same booklet in the paragraph titled Triple Gear Pins, it states: "The magnets directly behind each pin must be remove in order to properly remove the triple gear pins as the pin are tapered with the large end to the magnet side. The taper is only about 1/8 inch long and measures about .687, so if you push it the wrong way you're forcing a .687 through a .680 hole.

My questions are:
A. Do the holes in the flywheel have any taper? If so, how long is the taper and the angle of the taper and at which end?

B. According to the above the triple gear pins have a taper but it seems to be at the end. Would the taper conflict with the straight press fit segment in the flywheel. Or is the taper act like a shoulder and limit the travel of the pin pressing. I do not understand if there is taper on the pin but not taper in the hole in the flywheel hole how does it properly mate? Would not a pin with a shoulder and a counter bore in the flywheel hole (larger than the shoulder diameter of the pin) eliminate the conflict of straight bore and taper bore of the triple gear pin when pressed together?

C. Is there a taper portion of the hole and press fit length in the same hole? I would think this would be a conflict as two elements are fighting one another ( a straight press fit on part of the pin and then a taper on another part of the pin).

Please explain!

Re: Triple gear pins pressed into flywheel

Posted: Sat May 23, 2020 10:13 am
by Dan McEachern
The pins are not tapered. The bore is not tapered. The book is correct in that the pins must be pushed out toward the magnet side of the flywheel.
There is no counterbore in the flywheel to accommodate the slight shoulder on the end of the pin. The pin gets driven in or pressed in until the shoulder begins to embed itself in the flywheel material. Look at the bore in the flywheel after you remove the old pin and you can see the deformation from the pin shoulder.

Re: Triple gear pins pressed into flywheel

Posted: Sat May 23, 2020 2:07 pm
by Arnie
Further research seems to indicate that the pins were not tapered. Perhaps the MTFCA transmission booklet information needs to be revisited!


Re: Triple gear pins pressed into flywheel

Posted: Sun May 24, 2020 12:41 pm
by OilyBill
it might also depend on the year of production. Hard to tell when they started doing something, or stopped doing it. Someone posted on here, and they had actual documentation that they started doing something on July 6th, and then ceased doing it on August 8th, the same year. So there are just a few thousand "T"s with that particular feature. (Nothing to do with these pins, just an example of how often things could change in "T" production.)

Re: Triple gear pins pressed into flywheel

Posted: Sun May 24, 2020 2:08 pm
by Ron Patterson
That information can be found on the ROC (Record of Change) Cards for the flywheel (factory #T-701) and triple gear pins (factory #T-715) and associated Ford drawings depicting each change.