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Hello all. Back again since I finally have the parts to rebuild the '72 TR6 in hand. Most of you prolly have forgotten that I had an alternator explosion that finally took out the TR6 over a year ago. The crank nose was slightly damaged (galled) and I have had it cleaned up and will attempt to use it. I got the package of parts from MAP today including .020 pistons, stator (I had a spare rotor left over from the bobber project bikes) new rotor stud and nut, gaskets, seals etc.

It took a while to re orient myself to the old girl when we (my son and I) started looking it over to order parts but it seems to be coming back to me. I just wanted to let you all know that I'll be back in reassembling mode soon and may be posting questions again. Spending too much time lately in old inline 6 Mercury outboards....

Anyhow, the fondest hope is the TR6 will ride again at TSMR 11.

Thanks, Bernie

Hi Bernie,

Good to have you back!

w/b Bernie!

Cheers,

Steve

Ooo....been there before. Had the rotor on the '73 Bonnie simply disentegrate in a grinding, clunking explosion that sounded like a washing machine tumbling down a flight of stairs. Not pretty.

Opened the primary and lo and behold, the rotor was missing but a powdery mess including chunks was scattered throughout.

Best of luck with the 6. It'll all come back to you once you're inside. It does to me, especially after the third time of closing the primary only to find a clutch disc nut or similar smiling at me from the parts tray.

Richard

Richard, Yes you HAVE been through this. You forgot to mention the amazing stench of burned electrics when the primary cover was removed.

I have attributed this failure to myself not centralizing the rotor correctly when I last replaced the stator. I'll be paying close attention on this one. I thought it might have been a worn main bearing but the engine internals are almost like new. It's getting new std big end shells and .020 pistons, although I believe it could have been honed and std pistons replaced. The rings were cracked and a piece of ring got on top of the timing side piston and dinged it somewhat, but the bore looks very nice.

I've had the ol girl for over 25 years and I hope I can do her justice with this rebuild.

Bernie

Ah yes. I'd forgotten the aromatic scents of burned metal, powdered rotor, and hot oil that permeated the garage and surrounding neighborhood.

The idea of not having it centered sounds good to me. When I ordered a good used one out of Alabama, he said he'd never heard of a rotor coming apart such as this.

But upon this longtime Triumph guy's advice, we used a feeler gauge to get the correct gap all the way around to center it in the stator.

After the first of the year, I'll be back at my own rebuild. New bearings -- mains and con rods -- and cleaning the sludge trap, of course.

My dad bought this bike in 1993. It's funny how Brit bikers hang on to their bikes for life.

Keep us posted on how you're doing and how "the ol girl" is coming along.

Merry Christmas!

Richard

Hi,


Fwiw, first time I fitted a new alternator, I tried measuring the gap that way but became frustrated with a normal feeler gauge, 'cos you're trying to get something that's straight (across the gauge blade) into a narrow gap that's curved.

That time I managed to find a piece of wire that was the correct thickness, but imho the better advice I got after was to find a steel or aluminium can with the desired wall thickness, cut a strip from that long enough to wrap 'round the rotor, fit the rotor and stator with the shim strip in place, then pull out the shim strip and - voila - gap set and rotor centred all in one go. :bigt

Only thing to remember when you use a shim strip is leave a little of the strip protruding all the way 'round ... or, how're you going to get hold of it to pull it out? Damhikt ...

Hth.

Regards,

Hi Bernie,

I just read a great article in Vintage Bike (1999-2), that John Healy wrote about making sure the gap is correct. You must keep rotating the rotor in increments. "it is just as important to rotate the rotor in 60 degree steps, and do the checking six times." Do this to check if the crank's mainshaft is bent. "The stub holding the rotor could have bent over the years." .008 gap is what you are looking for.

"There is more to installing a new rotor and stator than checking for the minimum air gap. It is possible to have both the rotor off .004" in the same direction as the stator is off .004" durig initial assembly. You will measure the proper .008" inch minimum clearance, but when you rotate the motor 180 degrees they wil touch. If you failed to catch, and correct this, you could have a catastrophe in the making. It is important to realize that the cranks in these vertical twins flex, and as they do the clearance between the stator and the rotor is compromised."

Careful, and very slight, realignment of the studs if it is necessary, must be slight and careful. "Very little force is required to crack or break the studs. If the crank's mainshaft is bent further work by an expert is required. One can machine the outer diameter of the rotor, but you will loose some output." Quotes = John Healy

Bob, Thanks for posting that...I remember reading it probably just before the alternator blew....but I don't have a copy, thats very helpful and a little scary, 8 thou is kinda small if I need to 'adjust' the studs, I'll likely enlarge the mounting holes in the stator a little.

Hi Bernie,

Back copies are available through John's TIOC site. Wish I had every one of them. Maybe someday.

I do not want to say what Kevin Cameron said about the flexing/breaking cranks. Yikes. Leaping Lizards. Egads. It seems Kevin went through a "dark period", in a few of the Vintage Bike issues, where he listed the inherent design flaws in our engines, that one can do little about with a rather large fortune.

I think he was just tring to get people to adjust their expectations downwards.

Bob, yes there are limitations to all mechanical things and the frailties of Britbikes not the least, but mine have put many miles and many smiles between hi school and AARP eligibility. I have arguably the least desirable of all Brits and it still never fails to draw a positive comment and a nostalgic smile wherever it parks outside the garage.

Hi,


Aiui, that's a bad idea - the stator can then move down (especially over time) on any stud where the top of the hole in the stator isn't restin on the top of the mounting stud.

Bear in mind that, if you apply a very small amount of force to a stator mounting stud, it's orientation can be changed. That is another advantage of the 'shim strip' method - fitting the rotor and stator as one unit by definition orients the stator mounting studs correctly to the crank centre. Only additional thing I'd agree is that, once the strip's been removed, as per JH's advice, you need to rotate the crank/rotor and check that you still have at least the minimum clearance with the rotor in different positions relative to the stator.

Hth.

Regards,

"I think he was just tring to get people to adjust their expectations downwards."

Good plan, that's why I never thrash my old girl. Back at the 50th Anni, there were blokes old enough to know better THRASHING the pants of their bikes like they were 18 year olds again - it must've been some kind of mass hysteria.

Not sure what you mean by thrashing the bikes. Did they break down?

What I had in mind with that statement, is that people were finding modifications which produced more horse power, and I think he was just pointing out that there were limits, to safe changes. And it was an engineers, assessment of design, with a history of why what is, is, and what had changed in engine design and why.