aka Keith
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| posted on 7/11/11 at 12:36 PM |
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clunking in 4th on the overrun
This happened to me yesterday, and I am hoping that the collective can help pin it down.
Was in 4th, and off the throttle at about 8k revs and I got this clunking noise/vibration from the transmission/dirveshaft - as this was happening as
I was merging with the A3 and it dissapeared as soon as I was back on the throttle, and thought no more about it - assuming it was rumble strips or
holes in the road that I had hit.
However later on, it was praying on my mind, so I thought try it again, so again at about 8k revs, off the throttle and as the car starts to slow ,
clunk, clunk, clunk..feck.
But here is the bugger, I cannot get it to hapen in any other gear or at any other revs.
So to re-iterate, on throttle gear changes are fine and no noise/vibration from the transmission, off throttle I get clunking , but only in fourth and
only at 8k revs whilst slowing down (engine braking), ie I do not get any issues at 4k and slowing down.
Any ideas as to what is wrong, anyone had this before?
Engine is zx9r.
Cheers
Craig
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r1_pete
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| posted on 7/11/11 at 12:51 PM |
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1st easy check are propshaft joints, and the gearbox / prop adapter flange - if this is loose it could just clunk at the frequency and negative load
on slowing up.
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Moorron
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| posted on 7/11/11 at 01:45 PM |
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Also check the driveshafts for play and also the diff, most of my clonking was the main bottom boly onto the diff to rear chassis connection was only
nipped up.
Check wheels too. basically go around all moving parts of the car and check. Will only take 30 minutes and might save you from something nasty.
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bowood14
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| posted on 7/11/11 at 02:16 PM |
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I have just replaced my ZX9 C engine and gearbox for this exact problem. Only on overrun in 4th. It was the easiest option as I have a trackday at
Snetterton next sunday. I will look at rebuilding the box over winter but to be honest if it costs to much I wont bother cheaper to by complete
unit!!
[Edited on 7/11/11 by bowood14]
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aka Keith
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| posted on 7/11/11 at 04:27 PM |
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Bowood, do you know what was causing the issue? I have a box/engine in the garage, but I would like to know what causes it before replacing the
box.
cheers
Craig
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mrwibble
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| posted on 7/11/11 at 04:38 PM |
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might be worth a phone call to AB performance?
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aka Keith
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| posted on 7/11/11 at 09:55 PM |
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so i have been out to the garage tongith, and the sprocket adaptor appears to have some play in it - not the drivehaft to the sprocket adaptor, but
movement in the shaft coming out of the engine itself.
I assume that this shaft is not meant to have any movement?
Having not to the car together in the first instance, how easy or difficult is it to take of the sproket adaptor?
I have no idea as to how they are attached.
Cheers
Craig
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-matt
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| posted on 7/11/11 at 10:13 PM |
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The sproked adaptor will be held on with one large nut.
But you will need to disconnect the prop shaft first to get to it, so i would disconnect the prop and check that bolt is done up nice and tight,
although it should have notch hammered into the spline to stop it coming undone. but i think there is usually a little bit of play in the shaft
anyway.
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danny keenan
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| posted on 7/11/11 at 10:21 PM |
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hi kieth
it sounds to me like 4th gears on its way out.old fireblade are well know for this.
if you need any help give me a call thanks danny
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aka Keith
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| posted on 3/12/11 at 12:38 PM |
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Well, took the engine out, checked all I could without cracking the case, tightened up some loose bolts and put the engine back in last night. Took
the BEC out today for a shakedown, and problem still exists. Off throttle in 4th and only in fourth and only around 8k revs and you get a a
thump/braking feeling in the seat of your pants.
Bugger - looks like I will have to take the engne out again....
if anyone has any ideas as to what cause this probelm, please let me know.
Cheers
Craig
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bowood14
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| posted on 3/12/11 at 06:14 PM |
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Google zx9 gearbox loads on there I have now gone through two engine/gearboxes one same as yours forth noisy on overrun and one won't downshift
to third !! So I am now going to modify. As Suggested in some of the bike forums is yours a c type engine?
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bowood14
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| posted on 3/12/11 at 06:15 PM |
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[Edited on 3/12/11 by bowood14]
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Jon Ison
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| posted on 4/12/11 at 06:35 AM |
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I know you have tried to get it to do it other ways but have you tried at exactly the same speed in other gears rather than looking for same engine
speed?
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aka Keith
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| posted on 4/12/11 at 10:17 AM |
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Jon, just took the car out for a test following your note.
up to 70 ish in fourth then off throttle - clunking
up to 70 is in 5th or 6th then off thrttle - no clunking
up to 8/9k revs in 4th then off throttle - clunking
up to 8/9/10k revs in any other then off throttle - no clunking
up to 70 ish in 4th then off throttle - clunking - dip clutch then no cluncking
off throttle in 4th at any lower speed than 50 and no clunking at all
so part of me says it has to be fourth gear, but then why does it not happen at all revs and road speeds?
cheers
Craig
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Steve Hignett
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| posted on 4/12/11 at 10:58 AM |
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Because at other speeds other gears/synchros/forks etc are meshing with it or supporting it etc?
I think you are trying to find other faults because the obvious one is a pain in the arse...
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aka Keith
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 posted on 4/12/11 at 12:25 PM |
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I expect that, there lies the truth
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