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Triumph TR6 - Bolt securing Crank shaft extension

I am having a wee problem dismantling the engine 1971.
The part in question is: the bolt (TRF PLATE AJ54) that secures the crank shaft extension and damper wheel to the crank shaft. My question is which way does it turn to loosen it off? Is it a bastard thread? I ask this because of the direction of rotation of the engine. I have tried both directions and well it just does not want to budge. The shop manual just calls it a special bolt.
My current situation is engine on the stand, head off, and back end stripped down/off. Obviously the crank turns as I try to loosen the bolt.
Any thoughts and suggestions appreciated.
Rick C
Rick Crawford

That's a left hand threaded bolt. Only a left handed monkey wrench will loosen it. If you don't have one, ask the guy that loaned you the engine lift and stand. I'm sure that he'll know what you're talking about:)
Doug Baker

Doug- That's not nice.
Rick-Use a bigger braker need something to stop the crank from turning,if I remember my journey. Why are you working on your car,shouldn't you be at your desk?


I'm probably late on this. You probably have it solved. If not:

I ran out to the garage to have a look since mine is still apart and mine is definately NOT left handed thread. It does not need to be left handed becuase the big key in the nose of the crank keeps the pulley from wanting to spin and thus loosen the bolt. I remember mine came of easily. I think I just put a wrench on it and gave it a slight whack with a hammer and off it came. Once I got that off I thought the timing gear and sleeve would just slide off. Not to be! I had to run to Sears to buy a small gear puller. Came right off then.

Since all this is still fresh with me feel free to ask any questions. There are many little things I found out along the way. Did you ever try to decipher the Bentley manual on how to time the crank and cam together....where they mention the valves being "on the rock"? After much pondering and looking at the minimal spec's I finally figured out what they are talking about. With the stock cam there are no timing spec's so that's all there is to go on. Just one of the few things I have learned.

Good luck

HP Henry Patterson

Yep - it's a normally threaded bolt. I'd recommend a B.A. pipe wrench on the fan extension to keep it from turning, and a B.A. breaker bar to turn the bolt.
Brent B

Rick, Air impact wrench! normal thread just tight
Clive P

Something you might check in the archives: Fan Extension 'Special Bolt' . BTW, I think that turns the same direction as a 'lyte' bulb!

Rod Nichols

Thanks guys. As usual the definitive answer and some good advice. I think I will try the air first then B.A. stuff. I was kinda hoping I would be getting the crank back by now.
Henry, You will probably be getting an e-mail or 2 from me. Thank you..I will need the help. I (like most:) got the manual out after and saw the procedure about marking the fly wheel for TDC. I did not do that. ( if you look at the manual, It says put the dial indicator on piston #1' and find TDC...why does the picture show the dial indicator on #6???...ya gotta love those Brits:) Is this step important? Shoud I put the block back on the engine hoist and reinstall fly wheel and do this? This procedure deals with timing the crank and cam.
Don, one has to get his priorities straight. After all, spring is upon us and Cheryl said "no way" to the Barney Rubble thing.
I will let you know.
Rick C
Rick Crawford

I had a hell of a time undoing mine by myself. Even though I had more breaker bar than needed I still couldnt get it undone because even with the car in gear, blocked and with parking brake on the leverage I would apply would make the car want to roll up the blocks. Success for me involved using a propane torch to heat that bolt -after expressing my disatisfaction with ample application of heat the bolt came undone with only a little effort of the breaker!

Of course it helps to know you are turning it in the correct direction. I got if off with just my 1 1/8" wrench and a couple of pieces of hard wood to keep the crank from turning. Really not that much effort required. Front plate is off and the mains are loose. Gotta clear a spot on the shelf for the parts to kept in order and location. Crank goes in tomorrow.
Thanks guys
Rick Crawford


Glad to hear you got past that little problem.

Cyl#1 and #6 are "paired" cylinders. When #1 is at TDC compression #6 is at TDC exhaust. So it doesn't matter which one is used for finding true TDC. You may not have to do this if you trust the timing marks on the cam and crank sprockets. I'm going to do it to be sure everything is timed as best as possible. The true TDC is used to do the cam timing check where you may adjust the cam relationship to the crank. Ideally when you have the two marks on the sprockets lined up the cam and crank are perfectly timed. If not you may have to adjust it a tooth or two. It is that adjustment that is very confusing in the Bently manual.

Let me know if you need my email address. I still have to go back and put in those @ symbols you guys taught me.


HP Henry Patterson

Talk about a can of worms. #3 crank bearing cap was broken right off at the bolt exit. The 2 bearings had been worn down to almost flat that side of the bearing. I might have been into a little more work if I had not decided to do this now. Crank and pistons out. Thrust washer end play measured more correctly at .0130". Cylinder walls look very clean but need to be honed to de-glaze for new rings. All thats left on the engine is the Dizzy and cam. I think I will remove and have the block hot dipped.
Rick C
Rick Crawford

Bet your glad you did this now eh Rick ?
Charlie B.

Wow! Is the main bearing cap broken? Or is it the bolt that is broken? Any idea what the underlying cause might be?

Some hot tank solutions eat aluminum. The oil gallery plug on the front of the engine under the plate is aluminum. I have heard of people loosing that plug. The solution that was used on mine must have been aluminum friendly.

HP Henry Patterson

This thread was discussed between 15/03/2005 and 18/03/2005

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