sprint st 955 09' gearbox rattle driving me mad - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 1 (permalink) Old 11-11-2012, 11:09 AM Thread Starter
Main Motorcycle: sprint ST 955i 1999 16k
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Join Date: Jun 2012
Location: christchurch, dorset UK
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Other Motorcycle: kawasaki gpx 750r F1 1986
sprint st 955 09' gearbox rattle driving me mad

my ST trasmission ALWAYS rattles, especially low power cruising.

if you put the bike on the centre stand, put it in any gear at idle, as soon as you drop the clutch and the final drive is working, you hear this jumping rattling souns and vibration coming from inside the gearbox, you even see the rear wheel judder and obviously its spoils the ride, on otherwise perfect bike.

Ive searched the forum, and the internet, its not the normal things, my feeling as an experienced mechanic myself, is that one of the rotating parts mybe balancer shafts or gear shafts is tapping into another bit of metal inside.

you can feel it very clearly if you push the rear brake lever a bit during low acceleration, and it definitely is worse on rough roads which leads me to think something is loose inside.

obviously ive inspected the final drive chain and sprocklets, all perfect now, and ive tried on the minimum and maximum limit tension - no change.

sounds like the chain jumping, but ive eliminated that, it's definitely inside the final drive area, and you cant feel it at idle or full power, only when riding with little or no acceleration (nearly all the time)

i am from UK, Ive bought this 6 months agio, a 09 sprint ST 955i with only 18k from careful previous owners, FSH, showroom condition.

ive investigated this problem with my mechanic, adjusted everything, the main dealer reccomended the alternator pulled, which i did, and renewed the noisy bearings but no difference. no prob with alt. drive plate bolt etc we suspected, it was perfect. unfortunately main dealer and my mechanic could not be persuaded to road test it at low acceleeration, where its most obvioulsy something disturbing.

ive heard there a thrust bearing in the clutch, or a balancer shaft issue that could be out. but i dont want to break clean gaskets and open it up chasing re-herrings

I have balanced the throttles, but am only getting 36mpg 170 miles/tank, and the engine sounds rough at idle, but incredibly powerful any other time, its a joy to ride fast RPM.
a mate of mine whos had bikes all his life and a 09 daytona rode it 10 mins could feel a thing, i am sure thats because he thrashed it, so waste of time.

another irritating thing id like to fix, -i notice when going down into 1st gear the ECU speeds up the idle after a second, which nearly causes you to crash in a slow tight corner, but now i am expecting it, not. ive bought the usb dongle and tuneecu but dont know if i can adjust the anti-stall settings. id like to lower the idle speed but afraid it will sound too rough.

i thought i could fix gearbox myself, as i am a skilled mechanic, so ive bought and studied both haynes and triumph manuals, but what i would like, is to identify the fault before i have to take it off the road to strip, and know where to look for wear etc.

does anyone have the same gearbox problem/found the cause/solution?

is there a step-by-step guide to removing the gearbox bottom cover and checking for things like lazy fork return springs?

any pointers appreciated, but please dont suggest anything to check unless it fits MY symptoms (rattling in ALL gears, particularly NOT under load)

it sounds and feels through your feet, someone is tapping the metal footrests with a small hammer, erraticaly but roughly in time with the sprocket RPM


anybody SURE what this is?
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