CCT Issue, do I need to worry??

[WoodyNZ]

Hi All

I have read a lot about the CCT failures. I believe there is a fix that you guys recommend?

I have a 2003 VTR Firestorm with 12,000 km's on the clock. Do I need to worry about this issue?

If so can someone please share the link with me as to where I can see how to do it.

Thanks in advance!

Daniel.

[AMCQ46]

Yes you should do something, it is a time bomb

At least do the stopper mod
http://www.vtr1000.org/phpBB3/viewtopic ... 31&t=19416

[VTRDark]

CCT's can go at any time, it's a gamble!

You can either go for the stop mod http://www.vtr1000.org/phpBB3/viewtopic ... 31&t=19416
Which is the Honda auto CCT's that are converted to a fail safe. So when it does fail, it don't send the valves crashing.

Or

You go for the full manual conversion, your options are here
http://www.vtr1000.org/phpBB3/viewtopic ... 16&t=22720

Then with regards to fitting View Topic
http://www.vtr1000.org/phpBB3/viewtopic.php?f=31&t=8326

(:-})

[sirch345]

Then with regards to fitting View Topic
http://www.vtr1000.org/phpBB3/viewtopic.php?f=31&t=8326

(:-})

Daniel, definitely follow that link Carl posted on setting up the valve timing if you intend to carry out any CCT modification,

Chris.

[Trainraider]

I couldn't find any explosion pictures of the CCT from the workshop manual or from the forum this far, so I had to do my own.

I tried to figure out the CCT, but no luck this far. Possibly because it is tweaked or I don't actually understand what it is supposed to do...

As I have understood, it should push cam chain "slider" towards the cam chain and if there are some movement into any direction it should go back and forth...

Possibly the movement is rather minimal, but I would expect at least something visible to eye and feeling of movement.

Well. Here is a picture of everything I found from CCT - in order how they are placed inside the system.


Starting from the left
- Bolt and locking washer
- Cover
- spring
- worm (I understood that this is the name of this part)
- some kind of shell
- And the tensioner head (or what ever called)

I have here couple of problems. Why there is this spring if it doesn't do anything and even if it does, is it really supposed to be so "weak"?

The second problem is the "shell" as it is so long that when everything is put together, it blocks completely the movement of the tensioner. Maybe it is intentional and this is how it is supposed to be. at the same time, this could actually work as a manual tensioner because depending how much I screw the "worm" - the length of the tensioner is set.

Also I don't really understand why I would need locking tool because the piece is rather solid... But maybe there is something completely wrong here.

[Edit]
Ok. I think I figured it out now. So when you reattach the CCT, you need to screw the tensioner head all way to down (or at least a bit). Keep it still for a while, then add the locking tool so it won't "eject". Then when placed in theory the tensioner has correct tension towards the cam chain. And since of the build of the CCT, in theory it shouldn't allow the cam chain loosen.

So the next question is, how this is supposed to fail? Does it break to parts, or will the spring get loose/snap?

And to the bitheads of the forum. How I am supposed to use the search function. If I search "CCT" I get 0 hits. Possibly it will take some days to figure out the search function as well.

[Edit 2]
It seems that both of the CCT's are intact. So they have failed because the spring has just worn out. I would assume. I wonder how much pressure you are supposed to have against cam chain slider. Because if that is know, it should be possible to make more robust CCT. Not that I am any better than Japanese engineer (from the top of the post you will see that I am actually far from one), but...

So the idea is, that when the cam chain slackens, the tensioner pushes bit forward to avoid the "rattle". When again at place it does not actually give much pressure for the chain itself. Repeat this until CCT is too "loose" to push the cct rod enough to avoid rattle and bang - you have a failed CCT and expensive workshop visit ahead.

Or another option for failure is that for some reason the "worm" can, because of the tired spring, actually move backwards with a help of the vibration and pressure. It only needs one faulty stroke and the valves are bent...

and off topic. It might be time to stop or "fixing" the bike. Because it is Friday night and I don't think I get much further today in any case. Tomorrow I'll need to buy sealant pasta and then I can start putting the engine together. I guess I still need to buy also new springs for the CCT's...

[tony.mon]

You're correct with the locking tool, it's to hold the adjuster locked so that the plunger stays retracted while fitting the CCT, or while removing the cams to reset valve clearances, etc. (Actually it's easier just to remove the CCT altogether for that job, and refit it later).

The spring is only there to stop the worm drive undoing under the pressure from the chain pushing on the tensioner blade as it rotates- the chain will try to fly into a round shape if it can, while it's turning at speed, and therefore pushes back at the blade.
The tensioner will also try to retract under a closed throttle, and it saves a little engine energy by slackening off the chain a little when the throttle is closed and the engine is slowing down.

But if the spring weakness enough it will allow the tensioner plunger to retract under that pressure.
If the tensioner backs off a little, that's normal, but if it backs off enough to allow a rattle it is also likely to be slack enough to allow the chain to ride over the teeth on the cam sprockets, usually on the exhaust side, and the cam-to-crankshaft timing is no longer correct.
Two teeth or more and you will get bent valves, because they are still open as the piston rises to tdc.

Back to your original question, yes, probably you need to worry, but better yet, you need to do something to prevent it happening. Or you can take a chance, plenty do and most get away with it. Depends if you like a gamble.
For me I don't want to be stranded and face another expense, and possibly completely ruin the engine. This is rare, but can happen, if the valve damages the piston crown then realistically it's going to be cheaper to get a 2nd hand engine and change them over rather than go for a full rebuild, due to the cost.

[sirch345]

Well put Tony, and it saves me from having to explain that

Chris.

[Trainraider]

Now there comes couple of extra questions. Failsafe will be done soon as the engine is back together, but before that:

It seems that also other Honda's have the same kind of CCT. CBR1100 CCT looks like it is bit upgraded version of the same system. Would that fit?

And is there a difference between front and back CCT's? (dummy question, but I didn't check while fooling around with them ).

I understand the basic principle of the CCT and the need of it, but I have my doubts that it is actually slackening when you close throttle (or I understood something wrong from the explanation, which is also highly possible)... I have to do still some testing and tinkering but:

If you take the CCT off and screw the tensioner all way in (shortest possible position). The spring is now under tension and when
you release the tensioner it will push itself back to full length.

If you let the tensioner release half way and try to press it back, it should not go backwards. When again you release the tensioner it continues pushing itself until full length.

So when the cam chain is rolling high revs it pushes itself towards the tensioner and it should not move anywhere. When again closing the throttle, thus slackening the cam chain, the tensioner should try to push a little bit forward.

The only way I see the tensioner moving backwards is because the spring is too weak and the vibrations from the engine (and push from the cam chain). And this can happen when you rev the engine (lot's of push from cam chain) and when closing the throttle (chain slackening and the weak tensioner doesn't push the chain enough forward). And of course a small movement because of the tolerance of the parts and the rubber at the end of the CCT.

I can now clearly see the problem why it is very difficult to "redo" the tensioner. Possibly the one way would be to do a "half manual" tensioner as there was in Honda CX. So when you release the "fixing bolt" of the tensioner it will press itself with a spring against the cam chain blade. Then you fix it again with bolt and it won't slacken. Then you simply open and close the fixing bolt every now and then and in theory the cam chain is ok all the time. With correct spring you don't need to worry about how much you put tension to the manual tensioner which I think is the biggest issue with those.

I hope you don't mind me continuing this discussion in this thread... There could be better place for this.

[Stratman]

The Blackbird has a similar problem with the tensioner failing, but being an IL4 doesn't cause the same damage when it goes, apparently. I changed mine to manuals several years ago - the originals popped at 35,000 miles with no warning. Given the lack of regular adjustment needed, I can't see why the original design wasn't for manual CCTs in the first place.

[tony.mon]

That's correct. The Blackbird has the same tensioner, and in common with most engines the cct can fail, but when it does the chain can't become slack enough to allow the chain to ride over the teeth of the sprocket and allow the sprocket to "move" under the chain.
With Storm engines, it can do this.
That's why tech's/mechanics with no experience of these engines often get it wrong, taking the CCT out without setting the engine to a position where there is no ramp pressure on the cams from the valve springs, which means that when you take out or slacken the cct the cam won't move by itself as soon as it can.

The front and rear cct's are the same, except with one type of manuals, which have different length bolts, as one cylinder needs less bolt adjustment than the other- can't remember which way round atm, someone will chip in, I'm sure.

Also you're right about the semi/manual version with a locking screw acting against the plunger, which means you release the plunger and then it resets itself, do that again if it starts to rattle in a few thousand miles.
It would prevent catastrophic failure, but you might as well fit a manual, and adjust it properly each (rare) time you need to.

[VTRDark]

someone will chip in, I'm sure.

as one cylinder needs less bolt adjustment than the other

Not heard of that one. Well that would be even more of a reason for removing each cam cover and measuring each independently rather taking the measurement from the rear.

Some manuals do have a longer thread just to make adjustment easier. The front is a little harder to get to so a longer thread helps.

(:-})

[sirch345]

So when the cam chain is rolling high revs it pushes itself towards the tensioner and it should not move anywhere. When again closing the throttle, thus slackening the cam chain, the tensioner should try to push a little bit forward.

The only way I see the tensioner moving backwards is because the spring is too weak and the vibrations from the engine (and push from the cam chain). And this can happen when you rev the engine (lot's of push from cam chain) and when closing the throttle (chain slackening and the weak tensioner doesn't push the chain enough forward). And of course a small movement because of the tolerance of the parts and the rubber at the end of the CCT.

The standard Honda CCT's do self adjust when the engine is in use, they are designed to work that way. I have written this before on here as some will know, and my findings were taken with new standard CCT's fitted. If you remove the front CCT end cap and fit a small screwdriver (flat blade type) down inside the CCT so it drops down into the slot of the worm, then with the engine running you will see it turns at approx. 3,000 revs, better still hold you hand lightly over the screwdriver as you watch the rev counter and you'll feel it turn. It turns clockwise approximately 1/4 of a one complete turn (90 degrees). This action slackens off the tension on the cam chain. Once the revs drop back down again the CCT will turn back that 90 degrees putting back the same tension on the cam chain that was there before you started the engine. The engine vibes along with the pressure against the tensioner are what allow the plunger to retract. I agree trying to make a CCT retract by hand is almost impossible.

Chris.