Cam Chain Replacement

[Mcgyver74]

Well, I have a while yet before i have to worry about CCT's but after reading all the issues, and being at EOM listening to Drew telling us how his motor grenaded I think I will be slightly modifying my FJR's maint schedule, I am adding "Replace CCT" every 30k Miles

Overkill? Probably, but I figure I'm not going risk grenading my motor over a 75 dollar part!

Of course this in my mind begs the question, is there an interval when Mamma Yamma says you need to replace the Cam Chain?

 

[RadioHowie]

Well, I have a while yet before i have to worry about CCT's but after reading all the issues, and being at EOM listening to Drew telling us how his motor grenaded I think I will be slightly modifying my FJR's maint schedule, I am adding "Replace CCT" every 30k Miles
Overkill? Probably, but I figure I'm not going risk grenading my motor over a 75 dollar part!

Of course this in my mind begs the question, is there an interval when Mamma Yamma says you need to replace the Cam Chain?

Direct quote from the FSM:

CHECKING THE TIMING CHAIN

TENSIONER

1. Check:

• timing chain tensioner Cracks/damage/rough movement - Replace.

---------------------------------------------------

a. While lightly pressing the timing chain ten-

sioner rod by hand, turn the tensioner rod

fully clockwise with a thin screwdriver.

b.Remove the screwdriver and slowly release

the timing chain tensioner rod.

c. Make sure that the timing chain tensioner

rod comes out of the timing chain tensioner

housing smoothly. If there is rough move-

ment, replace the timing chain tensioner.

That's it. The whole 9 yards. Pretty much "if it's broke, replace it." No mention at all of a service interval. And no mention that if it's broke, so are 12 of your 16 valves. <_<

Quite honestly, I wouldn't pick an arbitrary figure like "30k miles" unless you just want to.

However, if it starts making rattling, grinding noises at 29K, park it and fix it.

For a suggested replacement interval, assuming no rattling, grinding noises up to the time, I'd recommend changing at the 2nd valve clearance check at 52k.

But what the hell do I know? I just put a new CCT AND cam chain in a perfectly good motor with only 42,000 miles on it.

'Howie

 

[wfooshee]

. . . like silk panties sliding down a supermodel's leg. Smoooooth.

You know this how, exactly ? ? ?

Seriously, thanks for taking the trouble to show us what you're doing in all this. Will be very useful in the future, I'm sure.

 

[RadioHowie]

. . . like silk panties sliding down a supermodel's leg. Smoooooth.

You know this how, exactly ? ? ?

MissusHowie wasn't ALWAYS old, cold and grumpy. :fuck:

 

[Patriot]

Well, I have a while yet before i have to worry about CCT's but after reading all the issues, and being at EOM listening to Drew telling us how his motor grenaded I think I will be slightly modifying my FJR's maint schedule, I am adding "Replace CCT" every 30k Miles
Overkill? Probably, but I figure I'm not going risk grenading my motor over a 75 dollar part!

Of course this in my mind begs the question, is there an interval when Mamma Yamma says you need to replace the Cam Chain?

part of the fun is the apparent lack of quality control on a new CCT

some have fixed the problem of noise for many thousands of miles...some, the noise came back in less than 10k

that's a big part of the attempt to find an aftermarket unit that is destined to work every time for a long, long time

the pin in that grenade is the POS spring that the engine depends on in a stock CCT

 

[Fred W]

Here's a little theory I have on these CCT failures running around in the back of my head.

Suppose the clock spring they are using to actuate the tensioner is weakening as it ages. Maybe heat cycles, maybe it's something else. All is well with the ol' FJR engine when you don't mess with it because the tensioner has been in the same position for a long time. The actual amount of chain, guide and sprocket wear that would require the CCT to move and take up slack has to be very little, so the CCT stays (somewhat stuck) in the same position and the engine remains quietly together with straight valves.

Now along comes the required valve clearance inspection. If the clearances are all good then the valve cover gets thrown back on and the engine continues life as before, CCT still suck in a good place.

But suppose one or more valves need to be re-shimmed. This requires retracting the CCT to pull the chain off the cams sprockets. Maybe that heat cycled spring has taken a set. Or becomes hardened, who knows. Or maybe it's just because we move it from the previous position. But after retracting the CCT it may not have enough spring force to hold it in place when the engine whips that chain around. The tensioner backs off and bad sounds emanate. Valves are brutally crushed. Trips are missed.

So, you guys with the exploded engines; How does this hypothesis fit in with your actual experience? Had you (or a shop) ever retracted the CCT before the engine went tits up?

 

[SkooterG]

So, you guys with the exploded engines; How does this hypothesis fit in with your actual experience? Had you (or a shop) ever retracted the CCT before the engine went tits up?

My FJR has been re-shimmed on several of the valve checks. No prolbems with my CCTs.

 

[Fred W]

Understood, Greg. I don't mean to say that every CCT that gets de-tensioned will then do it.

But it would be of significant interest if all the blown engines had been.

 

[RadioHowie]

Fred, your analysis is, I believe, right on target. I think your conclusion of a spring that loses its ability to "spring" is the crux of the matter.

As many know, my CCT spring broke in half inside the housing. After dissection of the CCT and discovery of the source of my catastrophic cam chain tensioner failure, I took a long, hard look at the system. And close inspection of the spring revealed that where the spring broke, right in the middle, the metal coil itself was what I could only describe as "brittle". The ends of the spring, where they engage the screw mechanism and the outer body, were strong and flexible, in that I could grab the spring with needlenose pliers and, with some effort, bend the spring.

However, if I attempted to bend the spring metal at the broken end, then a piece of spring would snap right off at the fulcrum point of the pliers.

There's no rust or corrosion on the spring, since it gets regular oil from the motor, but the spring itself, in the middle of the spring, was brittle and broke easily.

Now it's impossible to determine if that's the cause of a spring that came from the manufacturer in bad condition, or 5 years and 46,000 miles worth of heat-cycling ruined the temper of the metal, turning it from spring steel to cheese whiz.

However, my CCT, in the 4 years I'd owned it prior to CCCTF, had never been retracted, so that part of your theory doesn't apply to my situation.

 

[Fred W]

However, my CCT, in the 4 years I'd owned it prior to CCCTF, had never been retracted, so that part of your theory doesn't apply to my situation.

OK, that shoots a big hole it my hypothesis, but helps shed a lot of additional light on the failure.

So, what we do know:

Howie's spring broke in the middle and was never retracted.

Ionbeams' spring was unbroken, but very wimpy. He had recently been fiddling with it because he had the marbles in a can sound. The new one he receive had considerably more spring tension, though he thought the tension was still kind'a wimpy

All 4 are MY 2004s.

There have been other 1st gens with marbles in a can noise. Owners have generally had the CCTs replaced before failure. Presumably this is just an artifact of insufficient sampling and that eventually other 1st gens will fail.

What we don't know:

Is this limited to 1st gens?

Is the CCT spring defective upon install?

Is it entirely mileage dependent or is there something else involved, like maybe number or intensity of heat cycles, etc.

 

[Geezer]

My CCT followed the exact sequence Fred described. It was fine until I wound it up to change shims and started making noise immediately afterward.

I believe Howie's experience is more of an anomaly in that his is the only one I know of where the spring actually broke. In my case, when I released the spring after timing the cams I left the screwdriver on the CCT plunger and unwound it slowly by hand rather than letting it fly. The shock of letting it fly would be the time for it to break if it's going to. I still had to go back and add a little tension later, so mine was obviously not working automatically at that point.

 

[Patriot]

Here's a little theory I have on these CCT failures running around in the back of my head.
Suppose the clock spring they are using to actuate the tensioner is weakening as it ages. Maybe heat cycles, maybe it's something else. All is well with the ol' FJR engine when you don't mess with it because the tensioner has been in the same position for a long time. The actual amount of chain, guide and sprocket wear that would require the CCT to move and take up slack has to be very little, so the CCT stays (somewhat stuck) in the same position and the engine remains quietly together with straight valves.

Now along comes the required valve clearance inspection. If the clearances are all good then the valve cover gets thrown back on and the engine continues life as before, CCT still suck in a good place.

But suppose one or more valves need to be re-shimmed. This requires retracting the CCT to pull the chain off the cams sprockets. Maybe that heat cycled spring has taken a set. Or becomes hardened, who knows. Or maybe it's just because we move it from the previous position. But after retracting the CCT it may not have enough spring force to hold it in place when the engine whips that chain around. The tensioner backs off and bad sounds emanate. Valves are brutally crushed. Trips are missed.

So, you guys with the exploded engines; How does this hypothesis fit in with your actual experience? Had you (or a shop) ever retracted the CCT before the engine went tits up?

not here...in 100k miles, it has had only 2 valve checks with no adjustment - 35k and 75k miles by a Yamaha dealer shop

CCT had never been touched when the "anomoly" happened

Jeff_Q and I played with the old part and with the new part and could barely, if at all, feel any difference in tension

I wish I had had the forthought to keep the old CCT.

 

[Fred W]

Hmmm.... Are you positive they never "tested" the CCT at the stealership, Mike? I thought you bought your bike used with a lot of miles already accumulated? But if you are sure, then I would say that definitely negates my hypothesis. I could have excused Howie's, since his broken spring seems to be an anomaly, but if your valve crash happened with no broken spring and no beforehand messing with the tensioner, then that would seal it.

Your observation that the spring tension of the new vs old was indistinguishable also shoots a big hole in my second theory of the springs losing torsion with age being the root cause.

Which leads us to this final conclusion:

[SIZE=12pt]The Yamaha FJR1300 Cam Chain Tensioner is a completely shitty design and can not be trusted!! [/SIZE]

 

[ionbeam]

I've played with several 'failed' CCTs, a couple of replacement CCTs that were either DOA or 'failed' in <10k miles and a few new CCTs. In casual inspections I haven't observed anything that is definitely heat related like bluing or embrittlement. I haven't got enough CCTs to make any meaningful comparisons of actually measured plunger force at 50% extension, the standard service length. I have been sent two CCTs that were removed due to cam chain noise that had better spring tension than one of the new CCTs.

I have noticed inconsistent plunger force between units, be they new, used or 'failed'.

Technically, I don't think the design of the CCT is flawed but the execution realization of the design needs work. Some engineer someplace knows how much force it takes to keep the cam chain properly tensioned. The force would have range limits where too much causes premature wear and too little causes noise or worse. The CCTs should be built to achieve this range of max/min force in the real world plunger extension range in the FJR engine's application. I believe 100% of the CCTs would meet the requirements if the plunger only extended from 5% to 35% of total travel. I believe 0% of the CCTs would meet requirements with plunger extensions from 75% to 100%.

Anyone that has played with a CCT will notice that it is easy to vary final spring tension during assembly. Due to the design of the end cap it forces the assembler to install the circlip in increments of 180° rotation of the adjuster screw. If the assembler installs the circlip at the first opportunity the spring is not wound up as much and there is low plunger force at 50% extension. If it is rotated another 180° there is more force at 50% extension and given a full 360° of rotation there is strong plunger force at 50% extension.

Fred, I've still got one CCT at home and JamesK has my other tensioner, if you want one to play with I will give you the one I have when I return your Fieldsheer riding suit

Edited to add:

When someone does a valve check or adjustment and removes the entire cam chain engine cover (vs just the timing cover with the big ass screw slot) they move the slipper pivot bushing and that may change the alignment of the slipper, even if by just a little. Jeff Ashe has noticed some galling and flaking of the slipper pivot bushing. Perhaps this is why some engines start to have noise after playing with the CCT or especially after a valve check.

 

[Zorlac]

With that said Alan, would you go with the APE manual CCT?

 

[RadioHowie]

With that said Alan, would you go with the APE manual CCT?

You know you don't have to ask ME that question.

 

[ionbeam]

Actually, I would go with an OEM adjuster but check the 50% plunger force. I'm getting pretty good at gauging that force with my calibrated finger. If I felt the force was less than what it should be I would remove the end cap and add either 180° or 360° more turns to the spring. During rapid engine speed changes there is extra force applied to the cam chain that you wouldn't find with the engine off or idling. If that force caused any slack in the cam chain an auto adjusting CCT would take care of it.

If you read back through some older posts where people have brought their FJRs to a dealer complaining about chain noise the dealers 'fixed' the problem by repeatedly whacking the throttle. This forced the CCT to extend because the cam chain would wind up, and possibly the engine vibration assisted the plunger to move.

Howie is the exception with a broken CCT spring, I can see why he would be interested in a fully manual adjuster. He just needs to keep in mind that setting the adjuster in a static condition *might* not prevent chain wind-up during major engine speed transitions.

 

[Fred W]

Fred, I've still got one CCT at home and JamesK has my other tensioner, if you want one to play with I will give you the one I have when I return your Fieldsheer riding suit

Awesome. I'd definitely like to see it. I'm pretty sure mine is coming out one way or another (for inspection or replacement) this winter.

And based on what you say, maybe we could get just the springs, to be replace say every 30k miles, rather than having to buy the whole friggen CCT assembly?