Cam Chain Tensioner any thoughts ?

SussexTre · May 15, 2008

Found this company that makes/supplies manual Cam Chain tensioners, a area of concern to some unlucky Tre riders with skipped timing snapping etc.

"APE manual cam chain tensioners are designed to replace the automatic and hydraulic tensioners on high performance engines. The automatic adjusters can back out when the throttle is closed suddenly at high rpm. This allows the cams to go momentarely out of time, and can result in bent valves and/or serious engine damage. Hydraulic tensioners have a tendency to put too much tension on the chain guide under high rpm/high oil pressure conditions, resulting in premature wear."

At least with a manual tensioner you would be sure of good tension and the limit of wear without relying the unpredictable standard part.Of course during my searches did find stories of some owner having it so tight the engine would not turn over hhmmm :doh: :doh: any thoughts or comments ? Errol ?

FiBlues · May 15, 2008

Good for racing dudes, not for road use.
Tre tension looks good to me, the only problem has been too short spring.
Everyone must check the spring, not a big job.

W: Pekka

SussexTre · May 15, 2008

FiBlues said:
the only problem has been too short spring.
Everyone must check the spring, not a big job.

My engine (when I get it back) has been fitted with various recalls including a new (modified ?) different tensioner according to Brian Harris at KJM.The standard tensioner is a non service part and automatic self adjusting device but (BIG but here) one that needs monitoring is then no longer trustworthy.....or very automatic :doh:

here are the adjustment instructions for the manual tensioner....not very technical thou :

"How I was told to adjust the APE cam chain tensioner. Back the bolt out (won't take much) until you just start to hear the cam chain knocking. Now turn the bolt back in until the knocking just goes away, then go another 1/8 to 1/4 turn more. I went about 1/8 turn plus after the knocking went away and seems to be perfect. Once you have everything the way you want it, lock the locking nut in place so the bolt will not turn."

Obvious drawbacks would be issues like forgetting to tension the chain, over tensioning causing premature Cam Chain wear and under tensioning the Cam Chain.But at least it would be in your own control

Engenia · May 15, 2008

I think there is / was 2 issues with the cam chain tensioner.
1. the original spring is uncomfortably short.
2. the guide it works against may be fitted too tightly, making it difficult for the adjuster spring to move it

My spring has nearly run out of puff when the chain needs replacement.

My last guide wouldn't fit in at all. I had to file the sides down before it would work. If that wasn't done properly, there would be problems.

I'm all up for manual adjustment, but how you would measure the chain tension, I have no idea. I'm not keen on adjusting on the presence or absence of 'knocking'.

I had a Fiat 124 Coupe, years ago, that used an idler wheel against a toothed belt. To adjust it, you unlocked it, let the spring set the correct tension, then you locked it back up again. Much more positive method. It's locked, so can't move back, and the tension is correct at setting. If the manual system you show had a similar arrangement, I'd jump at it.

Solution to the problem is easy though. Monitor the depth. It should move about 1mm every 10,000 km.

Cam Chain Tensioner any thoughts ?

SussexTre

FiBlues

SussexTre

Engenia

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