Loud clunk going through gears

[Ratchet Richard]

Hi Guys
My A7 has developed a loud clunk (couldn’t think of any other way of describing it) since rebuilding the primary side after an engine rebuild.  The gearbox wasn’t removed or interfered with.  The clutch was stripped down to get the inner chain case off. 
On rebuilding the clutch a tried to replace it the same as it was before dismantling as the clutch action was very light with no slipping or drag. 
The clutch still has a light action with no drag or slip but I did alter the angle of the clutch arm on the gearbox to try and get it at a right angle when pulled in. 
I now find that after about 20 mile done that the gearbox has developed a loud clunk when going through the gears.  I have searched the forum to see if I can work out why this is happening. 
I am thinking (hoping) that the clunk is related to the clutch not being set up quite right, is this likely and if so how do I set the clutch to fix it?  I am thinking that perhaps I have over done it on righting the springs on the pressure plate. The clutch is a four spring one.  I hope it is the clutch as don’t fancy stripping the gearbox as I would be way out of my comfort zone. 

[berger]

you might have answered your question. do half turn back offs on the springs , make sure it is running pretty true when kicking it over and clutch disengaged, then do a few trial runs with the outer case off.

[RogerSB]

Here are photos of the SRM 4-spring adjustment on my A10, engaged and disengaged - may be a useful reference for you. Photos were taken in 2018 and not been adjusted since and it's been pulling a sidecar since Jan 2020 without a problem - and here in the west country it's very, very hilly.

Also check that your primary chain isn't too tight. If it is you can get a mystery clunking noise from the clutch when you pull the lever in to disengage it. If you discover your primary chain has tightened up, secondary chain snatch can tighten it if you haven't taken up the slack in the adjuster on gearbox side correctly after adjusting it.

Rog.

[Ratchet Richard]

Thanks for replies Rog and Berger. Very helpful.  I am going to go for the SRM clutch plate being as I have the clutch stripped out now.  I will then set it all up as per Berger recommendations.  I do hope it solves the problem. 

[chaterlea25]

Hi Richard,
Is the crank cush drive nut fully tightened? 65ft/lbs

John

[Ratchet Richard]

I will check that John.
When I had the primary side dismantled I replaced the old c spanner cush drive nut with one from SRM.  I did tighten that to 65 ft/lbs but I will check it again.
I tried fitting the new SRM allow clutch plate this morning. It was difficult getting the springs and cone nuts on.  When I tried to get the plate square on the clutch using the nuts with a pointer I couldn’t get it to seat square at all.  One side was way out and no  matter how hard I tried to alter it with the nuts it wouldn’t line up.  I am going to take the clutch off and re check it all.  Why isn’t anything simple!
Thanks again Richard

[Swarfcut]

Richard. I've just revisited this bike from your initial post and I can see that a lot of work has been done.

 With your recent engine rebuild there should be no increase in crank endfloat just yet. This float can give strange noises. Worth checking the three front primary chaincase bolts, if too long these may be touching the crank from time to time as the primary chain and cush system work their magic and if the crank has some sideways movement. Cush assembly is also a possible for a "clunk" as is clutch drag or badly adjusted primary chain, making the cush drive snatch.

 The new alloy pressure plate should be a straight swap but may require a fettle to get a perfect sliding fit. As ever we assume the rest of the parts are correct, but seeing the history of the bike again I have a feeling that stripping off the clutch entirely and checking every part for correctness and fit will be worthwhile. According to SRM, the clutch pushrod needs to be shortened and you may also need to back off the clutch adjusters on the cable and  clutch arm in the gearbox (as well as the centre one in Roger's picture) to aid assembly.

 Swarfy.

[berger]

i would check you have the correct springs i bought a 4 spring for mine and it it had various lengths of springs which took a bit of sorting out

[Ratchet Richard]

Quick update and thanks for all the comments.  I should have said from the first post that the clunk was pretty much definitely from the gearbox (should never say definitely, about anything to do with this bike I know) as it goes into gear.  I have checked the cush drive nut and it is at 65lbs per square inch.  I think I have found the trouble I was having with the SRM new clutch plate,  I had followed the instructions given for fitting it but made a mistake or misread the bit about offering up the pusher and roller bearing.  I put the pusher in the pushrod hole, having removed the pushrod from the gear-lever side, then put the clutch plate on and wound in the 4mm allen adjust thinking it would abutt with the pusher, it didn’t, it wouldn’t go in far enough.  I checked with SRM who told me this was alright and just go ahead and cut the push rod to length and set it all up. 
The trouble I had when I did this was that the hole in the Allen key adjuster did not line up with the pusher.  This resulted in cutting the pushrod to slightly the wrong length and I assume the problem with getting the springs and cone nuts on. 
Anyway it’s all good now, just need it to stop raining so as I can take the bike for a spin to get the clutch pressure right before the out cover goes back on.  Fingers crossed the the clunk will have reduced. 

[Ratchet Richard]

Clutch fitted, nice light action, selects all gears and easy to find neutral.  I took the bike for a run the other day and the gear change clunk was still there.  Having ridden the bike again yesterday I noticed the clunk was still there and if anything worse.  Also noticed a rattle coming from gearbox when engine reved, the rattle stopped when the clutch lever was pulled in.  I now think I might have a problem with the gear box, as the clutch is working well.  I do not feel confident enough to strip the gearbox as I have never done one before.  I have started another thread asking for recommendations for gearbox rebuilder in UK.