Triumphrat

NHOJ from Maine

hello all.
newbee to this forum.
i've owned my t100 for many years.. blew it up once, (timing to far advanced)..
but have not had it on the road for 5 years.. when i first bought this bike, it was after the prievious owner had thrown the primary chain... fixed it.. but a constant hassle has always been the piviot rod for the primary chain adjuster. when first purchased, i had seen a repair at the base of it on inner case. adjuster kept coming loose. when i had the engine a part, had a new boss welded in.. lasted two seasons before it fractured. Last weekend engineered a new design that bares the load on inner case lip.

have any of you fellow 500 owners experinced the same frustration?
it seems like a flawed design.
if my new design dosen't work, i think i will go to belt drive.
any thoughts?
if interested, i can post details of my modification, that dosen't entail splitting the cases, or welding aluminum.

thanks a bunch, looking forward to meeting all in cyber-space.

john

ps if you are wondering why 5 years to fix,
my other bike is a 1964 BMW R60/2.

McQueen

If I'm not mistaken, the primary chain adjuster threads into the boss in the primary cover, not the case. Could be as easy as finding a new primary cover on ol' eBay.

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GrandPaulZ

Nope, it threads into the case.

Not much you can do without ingenuity.

Engine-new-it-ty?

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McQueen

Weird. What year did it switch to the primary?

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GrandPaulZ

I'm thinking of the 650s, 500s may be different, but they never changed on the 650s; the primary chain and adjuster setup has always been in the inner primary (left crankcase half).

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GrandPaulZ
Author of "Old Bikes"
Born Again Bikes
My Photos

McQueen

Only reason I dispute is that my 750 has it in the case. When I was removing the primary cover on the 500, it wouldn't come free...that's when I noticed the d@mn chain adjuster threaded into the cover.

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Mecchanica

Sure, we'd like to see the modification, but since I haven't heard that this is a problem, it may not get much use. Also show the original repair, maybe we can suss something from that.

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Triumph old, Triumph new, any Triumph will do.

DAGAD

Get the metal slipper as fitted to the BSA C15. It will fir ALL 'C' range especially the 3TA & 5TA which didn't have a tensioner fitted until '59. It fits on the alternator studs and works really well.
Roy.

NHOJ from Maine

yup..
there is an aluminum boss on the inner left hand crankcase, right below the stator. a pivot pin juts out from this boss providing the anchor point for the front of the spring steel/rubber adjuster. the inherent problem I see with this set up is that as you adjust the chain adjuster, Pushing chain up from underneath,
it transfers a lot of load to the boss that holds the pin. Imagine the differance between holding a 10 pound sack at arm's length, compared to holding the same weight close to your chest.
over the years i tried to reinforce this boss with JB weld. Then when I had the cases split, I sent the left side to have the boss properly replaced, (new one welded in to recieve pin).. I thought I had it licked, but alas, after 2 seasons, this new boss fractured.
so last weekend we executed a re-engineered design.
I didn't want to split the cases, and felt it might just end up failing again.
We ground down the remnants of the boss, which still left the hole for the end of the pin. Then with some careful measuring, we took a piece of angle iron, and proceeded to make a 'foot' underneath the pin that sat on the lower inner lip of the crankcase. the upper part of the angle iron sits against the inner crankcase with a hole in it to allow the pin to run through it and sit in the original crankcase hole. then we welded the pin to the angle iron foot.
then drilled two holes through the bottom of the lip of the inner crankcase to recieve bolts and secure foot to the inside crankcase lip. Now the load as the tensioner pushes up, the stress is transfered directly underneath the pin, as opposed to the end of pin.

I am hoping this works. I think the design is sound, and it seemed very strong on installation. I will let all know how it works out.

I would love to know if any other 500 owners have had the same hassle.

Mecchanica

Good idea, Roy. I installed one of the late 441 items into an early 441 which was sans adjuster. Never considered fitting to a 500, but it's certainly a very similar primary set up. Should work fine.

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Triumph old, Triumph new, any Triumph will do.