Front sprocket installation error... did I ruin my gears?

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Front sprocket installation error... did I ruin my gears?

#1 Unread post by pilot_greg » Wed Apr 28, 2010 12:08 pm

While in the process of doing a major maintenance on my bike in preparation for the coming season (and because some of the major maintenance items were due anyway), I recently changed the sprockets and chain of my '02 GSX-R750. Following the maintenance manual, I removed both sprockets, cut the chain, and then remounted all three. During the installation of the front sprocket though, I ran into trouble trying to torque the mounting bolt on to the specified 83.2 ft/lbs of torque because there wasn't any resistance from the engine. The maintenance manual makes no reference to putting the engine in gear or any other method of mounting the bolt, just that it needs to be at the specified torque. Remembering that 1st gear has a lot of resistance, I popped the bike into that gear and again tried to install the bolt. I still couldn't get enough resistance from the engine to install it, except this time when I got close, the wrench seemed to slip and at the same time make a sort of clicking noise. Eventually, decided I needed to install the chain and then use a pipe through the wheel to lock the sprocket in place, which ultimately worked fine.

I would have thought nothing more of this situation, as I thought that the clicking noise was just some slipping in the clutch or something like that, but when I told one of my friends who has experience doing these jobs, he told me that I might have sheared off some of the teeth on my first gear. He said there was no way to tell without starting it and running it up to a few miles per hour in each gear, while on the rear stand, to see if there was actually any damage, so I did and it seemed to run normally, though there were some sounds coming from the area around the sprocket that I wasn't familiar with. First, when in 1st and 2nd gears, when I released the gas after running it around 10-12 mph, there was a repetitive clunking noise that died out after 3-5 repetitions. Then, when I ran it a little faster, I got a similar sound from the same area, only much faster. There were also some other, random clunking sounds that would come, but without a predictable pattern. The problem is I can't tell if the sounds are related to damaged gears, additional chain lash due to being run on a rear stand rather than on the ground with my weight compressing the rear shock, an improperly adjusted chain tension, or even the fact that I didn't add more chain lube over the prepackaged grease already on the chain yet (I know this is a must, but I didn't ride it yet, and I only ran it for about 5 mins, 2 of which was warmup with no wheel movement to make sure the oil was moving in the engine).

I'm hoping that someone here has experience enough with this situation to be able to tell me 1) if there really is a chance that I've sheared teeth off my gears and how likely that is to have happened, 2) if I did, what symptoms should I really be looking for, 3) whether the noises I described are, or could be, from damaged gears, 4) what other alternative causes are there for the noises I'm hearing, and 5) is there any way to be sure that did or did not damage the gears without actually breaking open the gearbox to visually inspect them?

Thanks,
Greg

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Re: Front sprocket installation error... did I ruin my gears

#2 Unread post by Wrider » Wed Apr 28, 2010 2:40 pm

Uh oh, it sounds like you might have done that bad thing you were talking about.
1. Yes there is a chance, yes it is very unlikely.
2. Put on the rear brake and try to move in first gear. Does it engage clunkily or weird?
3. It could be from them, new chains don't make clunking sounds, they make whizzing sounds usually.
4. Not sure of any random clunkings that should come from the engine.
5. Just the way I said in number 2. You can also drain your oil and look for any metal parts/shavings in there.
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Re: Front sprocket installation error... did I ruin my gears

#3 Unread post by pilot_greg » Wed Apr 28, 2010 8:51 pm

Ok, first off, did you mean to say very likely? or is it really unlikely that I did any real damage? Second, do you think I'll be able to do this test with front brakes and my weight? My rear master cylinder has been dead since last fall and its not really high on my list of repairs since I rarely get to the track anymore. As for number three, is it possible to have a slightly loose chain (no weight on the bike) pull away from the sprocket and bump up against the sprocket cover screw covers? Or is it possible that the unlubricated chain might be extra noisy as each tooth strikes the chain? The reason I'm asking is because as I look at the way the chain moved and the noises that accompanied it, it really seems like the repetitive clunking happens at the same speed that the chain links pass through the sprocket cover, both at low speed and high speed, and all of the random clunks seem to happen at the same time that the chain lashes. I'm not sure which is causing which, but I'm just observing the situation.

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Re: Front sprocket installation error... did I ruin my gears

#4 Unread post by pilot_greg » Wed Apr 28, 2010 11:51 pm

Ok, new development... I'm not sure if it shows anything, but I just went and tried the front brakes thing in both 1st and 2nd gears. In first gear, I held the front brakes and slipped in the clutch under power and was able to hold the wheel in place until the rear developed enough force to push the front along the cement floor, I then rode it outside to the asphalt parking lot and tried again where there is more grip. Both 1st and 2nd gears held until the engine died without the rear spinning. In all three attempts, there were no strange noises or odd happenings coming from the engine, though I'm not 100% sure just how much force was being applied, partly because I'm still updating maintenance, so it really badly needs new oil, and it really badly needs new spark plugs, and the fuel is 6 months old. That all being said, I'm wondering if I can take this as an early sign that I managed not to kill my bike? Or maybe I'm just getting overly optimistic?

Thanks,
Greg

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Re: Front sprocket installation error... did I ruin my gears

#5 Unread post by BuzZz » Thu Apr 29, 2010 12:42 am

At this point I would say...

Do the maintenance it needs. Check your valves, change plugs, change/clean the air filter, change the oil, adjust the chain, and hey what the hell, fix the brakes, lol.

Then ride it in first gear and see it it feels clunky, notchy or vibrates. And how it shifts. And if it jumps out of second gear under load, or when the engine unloads on decell.

Or you could drop the motor, split the cases and inspect the gears, but that's a ton more work.
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Re: Front sprocket installation error... did I ruin my gears

#6 Unread post by pilot_greg » Thu Apr 29, 2010 2:36 am

Unfortunately I've got no jack to lower the engine out of the bike and that is the one tool that none of my friends have either. I also don't have a private garage which I can take over for a week or two to actually do the work, at least not now, so, if I really did kill some gears, then it will mean I'm spending the summer saving for the engine work rather than riding the bike. That all being said, the way the thing behaved during this test seems to indicate that, if I did any damage, it probably not serious, but then again, I could get out onto the road and immediately have an engine seizure, so I guess only time will tell.

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Re: Front sprocket installation error... did I ruin my gears

#7 Unread post by pilot_greg » Thu Apr 29, 2010 3:49 pm

I still want to verify, Wrider, whether you meant to say it was likely or unlikely, because, again considering the situation, if its unlikely, I'd be a lot more inclined to believe that maybe everything is ok. But if you mean to say likely instead, I'll be a little wary, with the possibility of unobserved damage still in the gearbox...

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Re: Front sprocket installation error... did I ruin my gears

#8 Unread post by Wrider » Thu Apr 29, 2010 7:49 pm

I meant to say it's highly unlikely you messed anything up. Think about it, the tranny gears have to maintain a minimum of about 63 ft lbs of torque just when you're on the gas, and more when you are shifting it in and out of gear. I seriously doubt you managed to screw something up. But like Buzzz said, do your maintenance, you can use a car scissor jack to put under the engine if you need to in a pinch, and get it on the road! :)
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Re: Front sprocket installation error... did I ruin my gears

#9 Unread post by storysunfolding » Fri Apr 30, 2010 5:35 am

pilot_greg wrote:except this time when I got close, the wrench seemed to slip and at the same time make a sort of clicking noise.
Maybe I'm missing something, but you were you using a dialed in torque wrench... because that's what I would have expected to happen.
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Re: Front sprocket installation error... did I ruin my gears

#10 Unread post by HYPERR » Fri Apr 30, 2010 6:36 am

storysunfolding wrote:
pilot_greg wrote:except this time when I got close, the wrench seemed to slip and at the same time make a sort of clicking noise.
Maybe I'm missing something, but you were you using a dialed in torque wrench... because that's what I would have expected to happen.
+1

I assume this is one of those front sprockets that use only one big nut to hold the sprocket? Those are usually a pain to loosen, not tighten. To loosen, you usually need a impact wrench. To tighten, it usually is not a problem.

Like Story said, the torque wrench slips and clicks when the preset torque is reached.

I have no idea why you had to put a pipe through the wheel to tighten it....I can't imagine what knd of torque you must of generated there. I would loosen it and check for damage then retorque it to the proper torque.
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Re: Front sprocket installation error... did I ruin my gears

#11 Unread post by mgdavis » Fri Apr 30, 2010 7:52 am

storysunfolding wrote:
pilot_greg wrote:except this time when I got close, the wrench seemed to slip and at the same time make a sort of clicking noise.
Maybe I'm missing something, but you were you using a dialed in torque wrench... because that's what I would have expected to happen.
What I was going to say as well. If you know how to set a torque wrench you presumably know how to tell when it reaches the setting, but who knows. Was it the wrench that slipped and clicked, or the transmission?
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Re: Front sprocket installation error... did I ruin my gears

#12 Unread post by pilot_greg » Fri Apr 30, 2010 12:56 pm

The best way I can think of to describe my torque wrench is an angle-pop... when it hits the right torque, it pops once in the direction of the rotation. As the torque rises the pop gets bigger, so at 83.2 ft/lbs which is what my front sprocket bolt calls for, its a massive POP, but there is not slipping or clicking. I could pull it and try to torque it on again, but still, I'm pretty sure its already on correctly.

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