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PostPosted: Tue Nov 17, 2009 3:23 pm 
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Howdy, Y'all
One of my drive units (I have 2 boats with the v2 drives) is driving me crazy. It makes a semi-loud "thunk" sound with almost every pedal stroke. It doesn't seem to do it if I'm pedaling really softly/slowly or really hard, but does it every time when I'm cruising along at a moderate level of effort. It happens when my right foot is traveling forward, just after the pedal masts have passed each other (so my right foot is a little bit ahead of my left, in other words). This drive unit is pretty new, it came on a 2010 boat and I've put maybe 10 days of use on it. It has the Turbo fins which I installed right after getting the boat (I think I went on one outing with the stock fins) and the fin tension adjusters seem to be adjusted well, and changing their adjustments doesn't appear to help with the "thunk" sound. Anyone have any ideas as to what might be causing this noise? I'm sure it's spooking the fish, which is the last thing I need since my fish-catching skills are bad enough already. Help!
-Richie

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PostPosted: Tue Nov 17, 2009 5:05 pm 
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If nobody else has any suggestions, let me ask a few questions.

1. Can this be duplicated out of the boat or in the other boat?

2. Has this occurred on every use or just once?

3. Do you think it might have something to do with your shoes or pedals as they swipe across the crank arms?

4. Looking at the fins from the front with the Drive upside down in your hand (double checking that the pedals are even and in the same pin position), are the fins together or split significantly? Are they sticking straight up or are they leaning over to one side more than 2 or 3 degrees?

5. How does your cable tension look? (looking for about 1/8" squeeze for the front two and about 3/16" on the rear)

6. No obvious kinks in either chain as you slowly operate the Drive by hand?

7. Looking from the side of the Drive, do your fin masts look parallel with each other (same separation at the tip as at the base) and do they appear to extend straight out the sprocket (not bent back)?


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PostPosted: Tue Nov 17, 2009 7:18 pm 
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Heya Roadrunner, nice to hear from a definitive expert! I'll take a stab at your questions:


1. Can this be duplicated out of the boat or in the other boat?
-- Same in the other boat, can't get it to happen out of the boat, seems to require some resistance. Moderate pedaling does it, with really light or hard pedaling I can make it not happen.

2. Has this occurred on every use or just once?
-- Hard to say as I usually use the other boat and drive unit. It probably wasn't happening the first time I took the boat out with the stock fins, but may have been happening since I put the Turbos on.

3. Do you think it might have something to do with your shoes or pedals as they swipe across the crank arms?
-- Definitely not.

4. Looking at the fins from the front with the Drive upside down in your hand (double checking that the pedals are even and in the same pin position), are the fins together or split significantly? Are they sticking straight up or are they leaning over to one side more than 2 or 3 degrees?
-- They look very straight/plumb/perpendicular, etc. All lined up nicely, in other words.

5. How does your cable tension look? (looking for about 1/8" squeeze for the front two and about 3/16" on the rear)
-- Seems fine, matches the tension on my other drive unit as close as I can tell.

6. No obvious kinks in either chain as you slowly operate the Drive by hand?
-- Not that I've noticed, but I will check that again closely.

7. Looking from the side of the Drive, do your fin masts look parallel with each other (same separation at the tip as at the base) and do they appear to extend straight out the sprocket (not bent back)?
-- They look OK to me, but I will check again and compare with other drive unit.

Thanks for all the suggestions for troubleshooting this!

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PostPosted: Tue Nov 17, 2009 9:23 pm 
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OK Richie, if everything else is looking normal, perhaps we should look at the clew outhaul (pictured).
Image

Normally, depending on now much slack you've allowed with the adjustment screw, the fins pull it back and forth. If it were binding on the shaft, it could be frozen at low pedal efforts, but you might be overcoming the resistance at medium efforts. It might be slamming across at mid stroke with "almost every stroke". Presumably it would operate normally at high pedal efforts. So you might check this out to make sure that it rotates without catching or too much friction. A little break free might help if it's sticking.

Next, notice in the picture above, the fin sits in the outhaul groove a good 1/8" at the back. If less than this, it could be popping out when flexed and you would likely feel it.

Neither one of these gives a "thunk" per se, but certainly merits looking into anyway.

Sorry I can't be more help. If all this comes out negative, it might be time to consult your dealer. He can call the factory for assistance if necessary. In any event, it would be nice to find out what it is. Keep us appraised! 8)


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PostPosted: Wed Nov 18, 2009 8:22 am 
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Location: Fort Walton Beach, Florida
Eecher wrote:
Howdy, Y'all
One of my drive units (I have 2 boats with the v2 drives) is driving me crazy. It makes a semi-loud "thunk" sound with almost every pedal stroke. It doesn't seem to do it if I'm pedaling really softly/slowly or really hard, but does it every time when I'm cruising along at a moderate level of effort. It happens when my right foot is traveling forward, just after the pedal masts have passed each other (so my right foot is a little bit ahead of my left, in other words). This drive unit is pretty new, it came on a 2010 boat and I've put maybe 10 days of use on it. It has the Turbo fins which I installed right after getting the boat (I think I went on one outing with the stock fins) and the fin tension adjusters seem to be adjusted well, and changing their adjustments doesn't appear to help with the "thunk" sound. Anyone have any ideas as to what might be causing this noise? I'm sure it's spooking the fish, which is the last thing I need since my fish-catching skills are bad enough already. Help!
-Richie


I have the EXACT same problem...well HAD the problem.
Mine only came from a single side though....i.e. my right foot going forward is when it thumped.
I figured out that mine was coming from the chain rolling onto one of the flipper cams was slightly mis-aligned....but only at the extreme end of the stroke.
What I did was figure out which "tooth" was hanging it up and ground it to a bit of a point.
The chain now rolls onto the cam without the thump now.

This may not be your problem, but thats what worked for me.

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PostPosted: Wed Nov 18, 2009 3:45 pm 
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Hey Synovis-- thanks for the tip! I have the exact same symptom (only thunks when my right foot is going forward) so I will check out the issue you described and see if I've got the same problem.

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PostPosted: Thu Nov 19, 2009 5:27 am 
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I pulled my drive out.....went through the motions while I was looking closely at the chains.
I found that at the end of the stroke on one of the chains, that it didnt "drop/fall" onto the gear tooth like it should.
Now; it did not thump in my hands at all like it did in the hull under pressure.
I really wasnt sure if that was actually the problem or not, but since I filed that one tooth a little, the problem is gone.

Good Luck

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PostPosted: Thu Nov 19, 2009 6:04 am 
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Had the same problem. In my case it was the hole
in the peddle shaft was elongated. The pin was moving in the hole.
Dealer changed the shaft.
The new shaft is slightly elongated too but the thunk isn't nearly as bad.


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PostPosted: Thu Nov 19, 2009 4:21 pm 
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Location: Banana River , Fl
Ok, I'm a little confused. I have this pboblem too, but it goes away if I lenghten my stride to the max allowable. I thought the fins were slapping against the hull. i have to admit, I haven't investigated the issue, but having read this thread, I'm beginning to wonder...is it fin slap or not?!

Thanks


TC

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PostPosted: Thu Nov 19, 2009 6:03 pm 
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Hey Folks
After examining my troublesome drive unit, it seems like I have the same problem as Synovis-- the rear chain isn't seating onto its sprocket quite right, causing a kind of ratcheting effect as it moves through its range of motion. There's one spot on the chain that's particularly "sticky" that matches up with exactly the spot in the pedaling range where I feel and hear the "thunk" most of the time. I'm 99% sure that it's the chain snapping fully down onto the sprocket that I'm feeling. So I'm going to disassemble the whole business, do some light sanding/grinding and apply some BreakFree and see what happens. Thanks for everyone's help with this! My next question will be about how to keep your feet warm out on the water in the wintertime...
-Eecher

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PostPosted: Thu Nov 19, 2009 6:10 pm 
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@Rockets-- it doesn't sound like you've got fin slap to me. In my experience, it can only happen on some models (the Revo seems especially prone to it) and it happens precisely when you lengthen your stride to the max allowable. If you've got a thunk/thwap/thud kind of sound happening at some point in your stride other than the very end, you've got something other than fin slap going on. I've noticed that if my pedaling form isn't very good, or in other words if I'm a bit clumsy with the transition from one foot moving forward to the other, I'll get a bit of a thunking sound from the pedal-mast-adjuster pins like someone else described earlier in this thread, but that's definitely different than the feeling and sound of fin slap since it happens after you've reached the end of your pedal stroke and have started moving the other way.

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PostPosted: Thu Nov 19, 2009 9:42 pm 
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Here are a couple of points to keep in mind.

The Drive is capable of pushing the fins well beyond horizontal as shown here.
Image


Most hulls stop the fins way short of their potential limits. Depending on the boat, the masts will either slap the hull with the fin or the Drive will make contact on the side of the sprocket as highlighted in this next view:
Image
In most cases you will find this to be your limit and will adjust your pedal settings to stop short of this point. This is the most common noise. It usually happens on one side or the other due to normal fin alignment, Drive alignment or leg length variations.

The current sprocket cogs are designed to eliminate chain skip that could occur in the older Stainless Drives. The fat center cog as can be seen here, is purposely a tight (press in) fit. This is to secure the chain during assembly and again keep it from skipping during operations.
Image
If the fins are allowed to rise much past the horizontal position (depending on Drive wear. chain tension and hull limits), the chain can pop in and out of this master cog. This is very noticeable, but is not a defect nor does it cause any damage. Normally, either hull slap or your pedal adjustment should stop you short of this point.

So, as you're troubleshooting your various thunks, thwaps and thuds, keep these in mind.

All the aforementioned happens at the end of the stroke. In Eecher's case, it sounds a lot like Synovis' chain alignment problem, as it's happening near mid stroke under certain chain loads. A close inspection of the cog edges for chaffing may confirm if and where this is occurring. Just be conservative in where and how much you file. 8)


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PostPosted: Fri Nov 20, 2009 6:01 am 
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Eecher wrote:
Hey Folks
After examining my troublesome drive unit, it seems like I have the same problem as Synovis-- the rear chain isn't seating onto its sprocket quite right, causing a kind of ratcheting effect as it moves through its range of motion. There's one spot on the chain that's particularly "sticky" that matches up with exactly the spot in the pedaling range where I feel and hear the "thunk" most of the time. I'm 99% sure that it's the chain snapping fully down onto the sprocket that I'm feeling. So I'm going to disassemble the whole business, do some light sanding/grinding and apply some BreakFree and see what happens. Thanks for everyone's help with this! My next question will be about how to keep your feet warm out on the water in the wintertime...
-Eecher


The other option is to just keep using it and it will wear down to the point that the knocking will stop anyway.
If you're fishing though, this could be a problem. :wink:

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PostPosted: Fri Nov 20, 2009 3:45 pm 
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Thanks all...when I have the time, I'll take a closer look at what I have.

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PostPosted: Thu Nov 26, 2009 9:13 pm 
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Check the mirage drive for sideways play when installed. It should not have any. Adjust the screw down knobs and if necessary adjust with allen wrench. My dealer had to adjust mine and that stopped the thump/slap problem.

I have an '07 Revo bought new in '09.. Dealer told me that is a common problem on the older mount with the Revo and Outback.

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