EW350 gearbox/transmission noise under load

[oily bloke]

Hi all,
The EW is finished at last and entered into the Banbury. I have been doing some shakedown runs to iron out any issues and have a perplexing problem which I am struggling to identify the cause. Under load, particularly in second but also in third the transmittion is juddering and sounds like it is missing a tooth. It is what I would expect the cush drive, outboard of the gearbox, to sound like if it was overrunning the face cam but there is no evidence of this on the cam. If you back off the power is stops and if you gently accelerate it is fine. Steep hills can be climbed gently in first but too much power causes it. I am aware of the layshaft and 2nd gear mod the club does but I am not sure of what the issue is that precipitated this mod and therefore what the symptoms are. Can anyone shed some light?
The gearbox was fully rebuilt with all new bearings and bushes and appeared in good nick with little if any wear to the gear teeth. It seems to select OK too.
The clutch, albeit a bit temperemental, is not slipping and the motor is sweet and surprisingly powerful for what it is.
Thanks for any advise.
Andy

[Clive]

Hi Andy ,
Sounds like the shockabsorber , screw the  adjusting nut up anyway if only to eliminate it do the easy jobs first.
Regards
Clive

[eddie]

Andy,
         Excessive noise in the intermediate gears usually points to problems with the mesh of the sleeve gear and it's partner on the layshaft. I would suggest you check out these gears to make sure you have a true pair - in the prewar period, Mr Douglas used 2 forms of gear - some were stub tooth whereas others were the full involute form. Whilst these gears will run in mixed pairs, the mesh is not good, so mixing should be avoided.
  Regards,
                Eddie.

[Doug]

Andy.

Also if the bearings are worn or loose in the housing the sleeve gear can 'tip' excessively, creating sub-optimal mesh with its mate. Grab the sprockets (particularly the output if possible) and see if they can be wiggled out of plane.

Also possibly a broken tooth, which while not skipping, can be felt as a harshness and make additional noise. 

However the fact that the problem persists in top gear argues against this being a mesh problem as the main shaft and sleeve gear are locked together. The gears are still of course spinning, but not transmitting any appreciable load. Then it suggest a very bad bearing on the main shaft. I took apart an Aero gearbox where the cage and balls were removed from the ball bearing units and the inner race was allowed to wallow around inside the out race. Aggressive tooth wear showed it had been run a significant amount in that state!

But as Clive suggests the first suspect should be assurance it is not the cush drive. It could over run and not show wear. Jam a twig between the cam rams and see if it gets knocked out by the cam overriding. It there is a  thick, undisturbed layer of grime, then that would be a good indicator the cush drive is not the fault.

Doug

[oily bloke]

Hi all,
Thanks for the help and advise. As usual it was forthcoming and accurate. After some dismantling and head scratching it turns out to be the cush drive/face cam assembly on the gearbox was riding the face cam. Springs not strong enough it seems. This posed another problem as it is a complete pain to reassemble with the club supplied springs. So much so I found it impossible. I will have to make a compressor to get it together. In the mean time, as it is entered into the Banbury run this Sunday, I decided to make some pins to sit inside the cups to lock the assembly up to get me through the run. After that I will decide how to approach the issue.
Good luck to all the other riders and particularly those on Dougli'.
Cheers
Andy