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TR2/3/3A The big brass drain plug on the OD does not thread in easily


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The big brass drain plug on the OD does not thread in easily. I might get ¾ of a turn by hand then I need to use a wrench. I am using a piece of angle iron with a notch for the wrench. I would feel better about tighten the big bolt up if I could get it to go in by hand then do the last with the wrench, but it is not happening. I guess I am looking for some ideas and suggestions. I could by new for 115.00 or maybe file the threads on the big plug a little sharper and see if that helps. Or just go for it and wrench it in most of the way then tighten up until it stops. I just hate fits that are not smooth. Perhaps these big plugs always feel difficult--- I just do not know.

Also the configuration of the screen looks different than the Moss sales book. I basically have the screen and the plug, but there is a bolt up in there that could come out and also no magnets at least none that came out with the screen and plug.

Also I am replacing the home made gasket of leather I made because it leaked with one or 2 of the store bought gaskets, but it looks one might all there is room for because there only 3 threads on the plug, but I could fit it I guess and maybe I should because of the difficulty of the plug.

I noticed a metal plug off to the side of the big plug that is leaking also. Do these things leak like on all Triumphs or I am lucky. Incase no one had this one. Do you know why Triumph never built a toaster? Answer: because they could not figure out how to make it leak oil.


Great Pumpkin - R.I.P
The early plug with the hex and the bolt did not originally have magnets. There might be room for one, but on mine, it interfered with the screen.

BTW, there should also be a flat washer, and a spacer inside the screen. The bolt tightens down against the spacer, so it doesn't crush the screen.

The plug should go in all the way easily. I'm guessing you have damaged threads, which might show up with careful inspection.

It can be a challenge to seal them up, but it can be done. On the other plug (which I'm assuming is an expandable dome, kind of like a freeze plug), I might clean the area thoroughly, apply some mild heat, clean again with solvent, butter the outside with JB Weld (the slow setting kind) and then slap a piece of fiberglass cloth over it. JB Weld by itself probably won't hold the pressure, but fiberglass soaked in JB Weld might hold.

The main gearbox will take a magnetic plug. I like the hex socket plugs from MMC, but it's a standard pipe plug.


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I figured there was some damage also, but with the large size of the plug I just did not know. The threads look good in the aluminum case. The plug looks banged up on the outside and maybe bent, but mostly bent superficially around the notches, but the notches are bent up in a couple of spots, and maybe it is out of round. It actually looks like it should go back together easier than it does. Nothing jumps out at me. I might file the plug tomorrow and see if I can knock anything off that is too dull and not crisp. I also will look into the other sources for a new plug. I like the look of the brass and your idea with the soft plug is good. I feared the fluid was leaking too much around my home made gasket, but plenty of fluid came out. It is the old story of a couple drops looks big on the floor. I think I will make a better tool out of a cheap sock ,if I can find one, to tighten it down with also.The plug has a nice maybe ½ inch tall brass numb that sticks up in the center that matches a hole in the screen well, so I do not know. it should be correct.


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Either the photo is making the plug look distorted...or it is distorted in the first pic. Definitely don't torque it until you are able to get a good turn and a half by hand first! Part of the problem may be that when the threads are going straight, the plug looks tilted. If you thread with the plug straight, then the threads will be crossed. Try starting with the threads straight and by holding pressure on the plug as you turn backwards. Yes, backwards! This will align the threads, and then you can reverse the turn without removing the pressure and screw it in normally.

In the first pic you can see the large space between the threads and the outer rim of the plug. Go to ACE Hardware and find an O-ring that fits well into that notch. Then so long as the surface of your tranny is not damaged, you will have no more trouble with leakage.


Great Pumpkin - R.I.P
Whoops, sorry, I didn't (can't) see the photos on my phone. You've got the wrong plug! The screen with the retaining bolt only fits with the early hex head plug. The later plug with the notches has a peg that fits into the larger hole in the later screen, so the plug holds the screen in place.

In order to use the later plug, I believe you have to also source a later screen, and lose the bolt, flat washer and spacer. I'll bet that's why it doesn't want to go in; it's hitting the screen.

PS, yeah, that plug looks too chewed up to seal well. Looks like someone has been beating on it. You can try to dress the sealing surface flat with a file.

Graham H

Jedi Warrior
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Your OD is the early model which has a deeper filter and was held in with a center bolt. If your drain plug has the center peg as Randall said you need to take the filter bolt out so the peg fits in the end of the filter and the plug should screw in without hitting anything.
The oil dripping from the other side of the casing and the welsh plug area could be coming from your selector shaft seals, have a look under the gear shifter for oil running down the side of the box.



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Sorry I did clarify sooner these 4 year restoration combined with my youthful mind, I forget. The transmission came out of 1961 tr3. I was able to get the plug to go in and out smoothly by filing the edges of the brass threads with a triangular file. The screen and plug look correct and I am going with it for now. In many ways, I wished I would have rebuilt this trans before I put it in, but I wanted to hear it sing and the OD intimated me a little, but we are becoming friends.

I tried to find a square O ring-- even went to the large commercial store downtown, but all I could find was a round one, and I chose the medium thickness because it fit the grove and looked correct. I should get the fluid in today some time---plus crawling under cars is not as easy as it once was--- I never completely refit the OD cut out switches on the top with the dip stick, so I hope I can handle that standing up and sitting down. Anyways, I used some high heat orange silicone on the soft plug and I will see what happens. Basically blasted brake clean on the plug and waited and wiped. There is also a little ball bearing coming out of the casting. My thoughts are some kind of pressure release valve or something.


Great Pumpkin - R.I.P
The little ball bearing is a plug. Just like the larger plug, the hole was used during manufacture to drill an internal passage, then at least in theory permanently plugged off.
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