Gearbox Broken? (Motorbike)

Fireskull

Fireskull

Fireskull

Soldato
Joined
31 Oct 2006
Posts
9,802
Location
Wiltshire / Winchester
Background GSXR 750 k4 thats done just under 18k

Coming home tuesday night, 6th gear had to decelerate then as soon as I put the power back on goes over 6k Revs and it thats where it all goes wrong, awfull sound that scares the crap out of me when your doing 80 in the outside lane, basically sounds like gearbox cogs grinding teeth, and obviously no power.
Grabbed the clutch almost instantly, down to 5th and slowly let the clutch out :p all fine there and in the other gears, got home safely but damn was I paranoid about it locking up :/

Been told it sounds like a Selector fork has bent or snapped, sound about right?

Also last few weeks I had noticed getting into 6th was tricky sometimes, I thought it was just me not clicking up properly as I just short-shift into 6th normally just cruising along even 40mph.

Anyone with experience of this on bikes?
According to haynes manual to get to the transmission its a engine out of frame job, now im always willing to have a go at anything but it seems a big job, but I can imagine giving it to a garage ill be looking at £500+ ?

Any Help/Advice/Comments is appreciated :)

I miss my baby already knowing that I wont be riding for a while :(
 
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I have no idea man but hope it's not serious... last time that happened to me the TL1000 siezed up a few miles later never to run again (though admitedly the noise was in all gears)

the fact that it's only in sixth can only be a good sign though..I think a suzuki dealer is gonna be at least £500 in labor alone getting to it :(

seems strange for such a low milage bike


guess plus side is you can still pull over 160 in 5th ;)
 
Yeah, sounds like a fork as you said.
Don't ride it at all. If the fork is bent it will be stressed and could break, jamming the box and detonating your engine.
Get it out and stripped ASAP. Replacing the fork is a lot cheaper and easier than replacing the entire engine/gearbox combo.
 
Short shifting is bad, you are not on a racetrack.
If a selector fork is broken, you wouldnt be able to change gear.

I think you have stripped some teeth off of 6th gear.
 
Yea not going to start it up, been told it could have stripped teeth and they will be sitting in my sump waiting to get sucked into the engine! EEEK!

To get to the fork is that still an engine out of frame job? Will read my haynes manual again tonight but at a quick glance didnt see anything about the forks so not sure where to look :/

Sorry by shortshifting I mean clutch in from like 2nd and just clicking up to 6th, I dont mean I change up without using the clutch, I dont even do that on track lol, save .1 of a second for the sake of my bike no thanks lol, just emphasizing that on an average day to day ride Im just cruising along in a higher gear than needed (for a sportsbike, could sit in 1st everywhere and be in legal speeds :p ) so not putting strain on the engine.
 
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If you can drop the motor out of the frame your self, would save a hell of a lot on labour charge if you have to take it to a dealers to be fixed.

Depends which way the crank cases split on the engine as to how big a job it is.
 
Shoei said:
If you can drop the motor out of the frame your self, would save a hell of a lot on labour charge if you have to take it to a dealers to be fixed.

Depends which way the crank cases split on the engine as to how big a job it is.
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Cool yea someone else just suggested that to me on msn, think thats probably the best way to go if my old man dosent want to have a go with me :p

Cheers guys :)
 
Plus clutchless up changes are not bad at all in my experience. In all the racing that goes on at our club one of the least likely things to go wrong is the gearbox. Heck we have more crankshafts snap than gearboxes go (our class of 30-40 SV650's is up to 5 this year alone!).

I would suspect that changing up more than 1 gear at a time is more likely to have hurt it. The gearbox is sequential and does not like being changed multiple gears at once, don't ride it like you'd drive a car.
 
Dogbreath said:
I think you may be confusing short shifting with clutchless changes?
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What he is talking about is "block shifting".

I've always thought of clutchless changes as short shifting cause you just bang it up the box without the clutch.

That apparently is just changing up early.

Eitherway, looking at the cons of what he is doing by block shifting into 6th, it appears that is the cause of the problem due to miss matched speeds when he finally releases the clutch.
 
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atpbx said:
What he is talking about is "block shifting".

I've always thought of clutchless changes as short shifting cause you just bang it up the box without the clutch.

That apparently is just changing up early.

Eitherway, looking at the cons of what he is doing by block shifting into 6th, it appears that is the cause of the problem due to miss matched speeds when he finally releases the clutch.
Click to expand...

Short shifting isn't block changing. It's just changing up well before peak power, keeping the revs relatively low.
 
Oh unlucky Fire, I think my instructor said only block shift coming down 3rd-1st? Or some other lot I forget. Not that that's much help right now :/
 
Dureth said:
Plus clutchless up changes are not bad at all in my experience. In all the racing that goes on at our club one of the least likely things to go wrong is the gearbox. Heck we have more crankshafts snap than gearboxes go (our class of 30-40 SV650's is up to 5 this year alone!).

I would suspect that changing up more than 1 gear at a time is more likely to have hurt it. The gearbox is sequential and does not like being changed multiple gears at once, don't ride it like you'd drive a car.
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same, never use clutch moving up through gearbox, on modern machines you just don't need it

i think I use clutch 1st to 2nd thats about it....

don't think there is any need to ever change more than 1 gear at a time on bike... :confused:, coming down through box I use every gear to assist braking and keep engine speed at a level where I can accelerate instantly without delay. How high I keep revs up while decending gearbox is dependant on road / corner I'm on, how fast I'm going and how fast I want to accelerate out of it...

never heard of block shifting thing and cant think of why you'd do it.... changing any more than one gear at a time up or down is going to damage gears I'd imagine as revs drop because of time envolved and that causes gears to not engage smoothly. (just a guess)

i rode a gixxer 750 with a quickshifter and the speed you could accelerate was crazy... just a endless wave of power. everytime you nudged the gear pedal the quckshifter cut ignition just for enough time for next gear to engage, you just held the throttle to stop and tapped with foot.
 
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Mohinder said:
Short shifting isn't block changing. It's just changing up well before peak power, keeping the revs relatively low.
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Sorry for confusion, but im doing what mohinder says here, my reply at the top was just me thinking atpbx meant I changed up without using clutch. I do: first big revs change into second big revs then in 3rd little bit of throttle, clutch in 4th etc and repeat to 6th gear, cant remember any time when ive clicked up to 6th straight from 2nd on one go, do block shift down a lot though, specially on track, but still I would imagine that wouldnt have caused 6th gear to go? I would think straight away it would be me doing something wrong if it was the lower gears but not 6th :confused:
 
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After a lot of thinking pondering and :o at prices etc, it now looks like the much easier hassle free option and one of cost would be to source a second hand engine, straight swap job done lol, so anyone got one handy? haha :D

At least then the one with knackered gearbox I can tinker with and eventually start a little project with :p
 
Some pics of the progress :p

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