TR2/3/3A TR3 transmission clutch fork & shifter removal?

[AHS]

I've got 2 TR3A transmissions I'm cleaning and checking over. On the first transmission, the clutch fork shaft slid out easily and the steel dome over the base of the shifter came off with some minor persuasion. On the second transmission, neither one wants to cooperate.

The square headed bolt is out of the clutch fork and the shaft now freely rotates about 30 degrees in the fork and slides back and forth 1/8" or so, but the fork won't slide off the shaft. The shaft retention bolts have been removed and the shaft will slide as far as the fork hitting the inside of the bell. I've both tapped on the shaft and put moderate torque on the clutch release lever. I'm suspecting a large burr, but I don't want to force it.

Both the long and short bolts have been removed from the shifter dome, but it still won't budge. I've also sprayed a lot of penetrating oil in there. I've already broken a large strap wrench trying to get the dome to move. There is enough of a gap underneath the dome to get a pry bar in, but I've only put a little force there so as not to damage the aluminum shift extension casting. It didn't want to move that way either.

Any suggestions would be greatly appreciated.

Thanks,
Andy

 

[TR3driver]

That square headed "bolt" is supposed to have a tapered section on it, long enough to go all the way through the shaft. My guess is that it is broken near the base of the threads and the broken end is still in the shaft.

With some finesse, it's possible to drill a hole through the fork in-line with the bore for the pin, and use a pin punch to drive out the broken end.

As you can see, the surface of the fork is at an angle to the direction you want to drill. What I did was to center punch and start the hole perpendicular to the surface, then once it had penetrated by 1/16" or so, start turning the motor to drill the direction I wanted.

The article at https://www.buckeyetriumphs.org/technical/clutch/ClutchShaft/ClutchShaft.htm has some suggestions for how to prevent future breakage. I used the "additional bolt" method. Assemble the fork, shaft and taper pin with the shaft out of the gearbox (being sure to get the fork the right way round) then drill through the fork and shaft. I used a drill that was slightly smaller than 1/4", so the bolt had to be tapped into the hole. I also picked a 1/4" Grade 8 bolt that was long enough for the unthreaded section to extend into the fork on the other side, then cut off the excess threads (so it didn't foul on the gearbox). It's still working fine after some 15 years; but that doesn't prove much since the original taper pin lasted a lot longer than that

For the shift cap, you may have to cut the cap, but I've always been able to get the reluctant ones off with a pipe wrench. It chews up the surface, but the damage is only cosmetic. Once you can force the cap to turn, just keep turning while you pull up to work it off.

 

[bobhustead]

I used the method described by TR3 Driver. As I recall, I had to cut the shaft with an angle grinder to get the fork out so as to access the fork at the correct angle to drill it. Make sure a new shaft is available. Bob

 

[TR3driver]

I used the method described by TR3 Driver. As I recall, I had to cut the shaft with an angle grinder to get the fork out so as to access the fork at the correct angle to drill it. Make sure a new shaft is available. Bob

I was able to do mine with it still in the bellhousing, and theoretically save the shaft. But when I got it out and saw how badly it was worn, I replaced it anyway. TRF has them listed on sale at the moment, so they probably have some in stock.

 

[AHS]

Randall, you were 100% corect that part of the square headed bolt was sheared off. It wasn't at the base of the threads, there was some of the pin shaft remaining, but it was substantially shorter than the bolt from the first transmission when I compared them. It was very easy to use your method of drilling a hole & driving out the remainder of the pin with a punch. It tapped out so easily that I wonder why it sheared off in the first place.

The shifter dome came off eventually by using a punch bearing against the steel at the holes for the long cross bolt. It took hundreds of small blows and that sort of squared off the top of those 2 holes, but that won't matter. There was some corrosion on the steel causing a lot of friction.

Thanks,
Andy

 

[TR3driver]

It tapped out so easily that I wonder why it sheared off in the first place.

It didn't shear because it was too tight. Every time you step on the clutch, it applies a strong bending motion to that pin, causing it to flex a bit. Eventually it work hardens and breaks at the point where it flexes. The link above to the Buckeye Triumphs site has some cutaway diagrams showing the problem.

Evidently some long-ago engineer thought it would be stiff enough to work harden ... or else just didn't care as long as it lasted until after the warranty period.

It's also possible that someone did a clutch job in the past, and replaced it with one of the "too-soft" aftermarket pins.