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TR2/3/3A Mills Pins??

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deuce

deuce

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Hi Folks ..Back again..I'm trying to remove the gas pedal and pedal shaft from my tr3. The book mentions mills pins. What are they? I'm thinking like a spring pin but are these tapered or what? Are they one way? Only coming out one way. I tried tapping on what I thought was the pin with a pin punch. I didn't want to get too violent with it. Anyone with experience with these?
 
Well, a Mills Bomb was a popular type of Hand Grenade used by the British army in WW1. The pin was the locking device. Remove it and throw....

Seriously though, in this context I think a Mills Pin to be a slightly tapered pin with one or more grooves in it. Should be one-way as I remember.
 
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Yup, what Roger said. A tapered pin with grooves in the sides, to allow it to crush slightly in the hole. After all these years, they can be stuck pretty tight, too. I had a devil of a time even though some of mine had worked loose. Finally wound up making my own punch about 12" long so I could bang on it with a BFH and not hit anything else.

Don't forget there are (at least) two different configurations of the pedal linkage for LHD. The diagram in the workshop manual is the early configuration, the later configuration only has 2 Mills pins instead of 3. Mine was a bear to get apart even after getting the pins out.
 
It was a real bear on mine too. The only thing harder was the forward leaf spring mount.
I ended up destroying one of the bushes to get it off--RevingtonTR are the only ones that have them, and used ones at that. My problem was bends in the shaft, after I found and drove out the Mills pins with a heat wrench and punches. Had to cut the bush in half.
 
FWIW, since the holes were damaged anyway on TS13571L (DPO had used bolts instead of pins), I reamed them until they were round and straight, then installed split pins instead of Mills pins. I don't recall the size offhand, but I bought new pins from MMC (the ones from HF are junk) and reamed to the minimum size that they would fit. Seems to be working out fine.

MMC also sells standard taper pins (without the groove). I didn't check to see if there was a standard pin that matched the original holes, though. The taper should be enough to lock them in place, but a drop of Loctite certainly wouldn't hurt anything.
 
Thanks for the input..so..on one side of the shaft the pin is flush..almost invisible. The other appeared..in a mirror..to be dimpled. Would you say the flush end is the wide end of the taper? And how about just drilling out the pin and replacing it with a spring pin? Though replacing is definitely down the road.
 
You usually have to study both sides, then make an educated guess which is the big end. If it won't tap out the way you guessed...try the opposite side, as you likely guessed wrong. What's a spring pin? Is that like Randall's split pin, often called a roll pin...i.e. Hollow rolled steel?

When I ordered the pins from Moss and TRF they both sent roll pins. They may work, but are not as strong as a mill pin.
 
deuce said:
Thanks for the input..so..on one side of the shaft the pin is flush..almost invisible. The other appeared..in a mirror..to be dimpled. Would you say the flush end is the wide end of the taper? And how about just drilling out the pin and replacing it with a spring pin? Though replacing is definitely down the road.
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The problem with drilling is that it won't make a round hole, especially if you start with a hole that is not round. Very prone to chatter when you are enlarging an existing hole by just a bit. Regardless of the type of pin you use, it's important that it be a tight fit when installed, in all 3 sections of the resulting joint. That's why I used a reamer (actually several of them in stepped sizes but one would probably have done if it was the right size to begin with).

And in case it's not clear, a split pin is a variety of spring pin. Roll pin is the other variety. In my very limited experience, a roll pin works better in a joint that has to have some "give" in it; a split pin works better when the joint doesn't move. Hopefully, my usage falls into the latter category. I agree that neither is as strong as a solid pin, but hopefully it's strong enough. Too soon to say, really, but it's been some 5 years and no signs of distress yet.

I also have the linkage adjusted so the pedal hits the stop just slightly after the throttle plates do, so the force on the linkage is limited even with the pedal to the metal. If you're running without an effective pedal stop (as my DPO apparently was), then IMO no pin is going to last for very long. Even a solid pin will be the weakest link.
 
Thanks for the valued insight. I'll try to get the mills pins out . Seems almost like a two man job. One with a drift or pin punch and one on the opposite with a backer of some kind. I don't know why I get impatient sometimes. Thanks again to all PS Would the mills pins be reusable ?
 
They're about 50/50 on reusing. Often they come out bent after trying to punch them. Often they can still be straightened by tapping with a hammer on an anvil or similar iron surface.
 
I am just guessing as usual, but if the pin is not lose it should be fine and the lose ones know what why to come out. I would just sand blast the whole thing and paint it black. Like Randall said there are a couple of variants and plus a real good picture in the Moss catalog on reassembly. I remember taking out a pin years ago are that I never should have and it freed up something that was more trouble that it was worth. The split pins work fine for reassembly.
 
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