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Whistling noise?

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R

RobH

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This post is about my buggy but I'm posting this here because the Savage and other .21 class R/C's have the same engines, pipes and clutch bells.

I installed a 12 tooth clutch bell in my buggy (stock is 13). I ran it maybe 10 minutes and it seemed fine. I then installed my THS Off-Road Racing pipe a day or two later. It works great but, now I hear this weird whistling noise as I take off. It starts at a low pitch that increases sharply as the buggy gets up to speed. It seems to go away as it hits the top-end but it's hard to say with the racket of the engine drowning it out.

It doesn't sound normal at any rate. I figure it could be three things:

1.) the new bell and the old slightly worn spur gear are making the noise as the teeth mesh together. (maybe i didn't place it right too)

2.) the noise i hear is exhaust leaking out someplace it shouldn't (gasket maybe?)

3.) the engine is spinning the three shoe clutch against it's will inside the clutch bell (like it's not grabbing the bell like it should)

Last night I repositioned the clutch bell and the spur gear to double check nothing was too tight or too loose. I ran it again and the noise is still there.

While at idle, I pushed the buggy as hard and as fast as I could. This made the spur gear turn the clutch bell as if I were taking off. If the gear on the clutch and the spur gear were the cause of the noise, I'd surely hear it. I didn't. No Whistling.

I also did I test where I lifted the the buggy off the ground and gunned it. When I do that, the noise is gone. That means it can't be an exhaust leak as the engine is still doing it's think just off the ground. It also points to the clutch. When the wheels are off the ground there is less resistance in the drive trains and hence the bell is basically easier to turn and not putting nearly as much stress on the clutch shoes.

My theory is that the three shoe clutch isn't doing a very good job. I think the whistle I hear is the clutch shoes rubbing on the inside of the bell. I think as the engine revs up and the clutch shoes fly out, they don't have enough grab to hold on. I think my engine is kicking the **** of the stock clutch shoes.

I've never had a problem with a clutch before. I don't know what happens as they wear out. If my clutch is the problem, what's a pair of bad *** clutch shoes that can cope with the power?

Do you guys have any ideas why my buggy may be making this noise?
 
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are your clutch shoes aluminum or composite?

plus - when u "pushed the vehicle" are u sure the pinion and spur gears are moving? mine dont when i push it forward - only backwards
 
yep it moves regaurdless of which way I push it

they are composite I guess. I'd call them rubber or something. They are surely not aluminium.
 
hmmm - i dunno then - i have aluminium shoes on my GS - and when they get glazed - they sometimes squeal a lil.

I'm still voting on a clutch issue...maybe. does it do it at idle too? or only when u accelerate? how about 30% throttle cruising? testing these ideas could help eliminate other possibilities.
 
If it is indeed your clutch shoes spinning within the bell, and you did enough of it, wouldn't it generate some abnormal amount of heat due to the added friction or lack there of. At full clutch engage there would be minimal slippage. Maybe repeat the process and check the bell for temps.
 
no,i doesn't whistle at an idle. i'll try the temp on the clutch thing.
 
I was just going to post on this thread this morning, but i figured i'd wait until I took my clutch apart. the engine pro at the track is convinced that it's a clutch bell bearing.

I don't know how that is possible. The output shaft spins in the CB (using the bearings) only when you're sitting at an idle. After the clutch engauges, the bell and the shaft spin as one. Why would I hear the noise durring acceleration when the CB and output shaft are spinning as one and the bearing is still?

He also thought it could be an exhaust leak. I picked up the buggy and gunned it. No whistle. Exhaust leak and poor gear mesh would produce the noise on the ground or off the groud.

I'm am convinced the noise is the clutch slipping. I'll find out tonight when I take it apart.

-Rob
 
i figured out my whistling noise. i checked out my clutch bell and the outside of it has a groove worn in it. the 12 tooth clutch bell sits closer to the spur gear because it is smaller (fewer teeth). the brake pads, however, are also closer. so close infact that one has been rubbing on the clutch bell. I'm gonna dremel a very small round shape out of the metal break assembly. it shouldn't effect the brake much or even make it look that much different.

thanks for the help guys. watch your clearance when you install a clutch bell with different number of teeth than stock. ;)
 
Rob.. on a slightly different note.. Are you still not happy with the low-end your hyper-8 is producing? or did the new pipe improve things????
 
I had my Inferno out last night (first run after putting it back together after cleaning it) cause I wanted to check the gear mesh between the pinion and spur gear. Immediatly I thought of this thread.....theres this little whistling noise...hmmm....only difference is it was getting worse and worse the more I stomped on it.

Went back in the house took everything apart and found two nasty grooves cut out of the inside of the CB housing. Also, although the shoes "look" aluminum i think they are just coated or painted to look aluminum. There are only 2 clutch shoes and both have very apparent wear marks on the edges. Everyother part of the shoe is shiny aluminum, the tips or edges look like flat colored opaque plastic. Grrrrr

So, now I'm off to find a 3 shoe "real aluminum" setup with a 12 or 13 tooth bell. I guess those sticks that got caught up in the spoke of the wheels last week did more damage than i thought. I say sticks cause it happened more than once.
 
RobH DOES THE WORK SO WE DON"T HAVE TO !!!!!!

Good catch. I'll file this one under "I have a flat spot on my forehead from banging it against the wall".
 

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