gearbox whine

[greasemonkey62]

I have a problem with slight gearbox whine in second gear and a more distinct whine in third gear, no problems in first and fourth, I have stripped an engine on the G5/model 8 down to the crank out and all back together again without problems, (except once when it would not start until I put in the pushrods I had left out) but apart from renewing the broken pawl spring and renewing the kickstart and gear change shafts "0" rings I have never touched a gearbox internals, I assume its a bearing/bush that is worn are they easy to do? or is it a press in job for a professional workshop?

Cheers Ray.

[Ozmadman]

I have stripped down two of these boxes, replaced all the bearings and bushes( all easy to do at home, no workshop needed, just a kitchen oven to warm up the casings) and still I have a slight 3rd gear whine despite there being no apparent wear on any of the gears!! Put in down to a standard thing on some of these, not sure about the 2nd gear whine you have though. The boxes are easy to strip and rebuild and if you decide to do it come back to me if you need any help/tips, especially if you have to replace the layshaft bush that sits in the end casing next to the output beating as there is an issue with the spec on these. BTW...MAKE SURE YOU KEEP THE BOX TOPPED RIGHT UP TO THE BOTTOM OF THAT INSPECTION/FILLER PLATE

[Rob Harknett]

My old 1936 A Jay does that. When I get to a hill and drop down to third, the exhaust choughs and spits out a bit more smoke, its twin port pipe's slow to a heavy thumping PUTT PUTT deep sound, the gear box whines. That's the sweet sound of an 80 year old having go at pulling me up hill.

[greasemonkey62]

great stuff I will have a crack at it i think, if all bushes are available in the spares shop, what is the issue with the layshaft bush you mentioned ?

Cheers Ray.

1959 G5
1962 model 31
2013 Yamaha TDM 900

[greasemonkey62]

Plenty of bushes in the spares shop but i cannot find any kickstart or gear change "o" ring seals, do the "o" ring seals from the twins AMC gearbox fit the shafts on the lightweight, there is a slight oil leak from the kickstart shaft, I cannot see the "o" rings on the parts list or photos for the lightweight gearbox.

Cheers Ray.

[Rangy65]

Hello Ray, i have now done over 250 miles on my G5 since finishing it.My box also has a slight whine in 3rd but is more noticeable when changing down 4-3-2-1. See the threads for gearbox info. Paul's method of building up the gear box is far far better than in the manual. My box leaked from Kick start shaft so the mod is to fit the 'standard' O ring first P/n 040006 then fit pushed up to it an X type seal P/n 040006X both available from the club. The other O rings are 040079 and are also available from AMOC spares. I find that these can get damaged/ trapped when putting on the outer cover. As these are cheap order a few more than you need ( just in case).

Have fun
Steve

[Ozmadman]

Not all the bushes will be worn but most are available either from the club, Russell Motors or Andrew Engineering or AMC Classic Spares.The layshaft bush I mentioned will probably be worn and this is the issue. As said a few times previously, the ones from club spares, unless they have resolved it are incorrect see the picture, the flange is too thin which will mean, if used, the layshaft will rub on the gearbox casing and wear it away. You need to get the thicker one from any of the above suppliers but unfortunately, not club spares. As for the kickstart shaft leak, I used two 040006X seals ( no leaks)and as long as you give the kickstart ratchet enough tension when you rebuild the box all should be ok. Also, be nice to the big output shaft bearing, they are £70 to replace!

Paul

[RAY BOWMAN]

My G2 suffers a whine in third also a leak from the kick start shaft. Seems a weakness in
these boxes. I have decided to live with them.

[greasemonkey62]

great stuff many thanks for the info, just the job, well worth the membership fee just for peace of mind.

Thanks all, Ray.

[Ozmadman]

great stuff many thanks for the info, just the job, well worth the membership fee just for peace of mind.

Thanks all, Ray.

no worries, BTW.. the layshaft bush number is 041289 and if you get difficulty finding one they are also used in the Norton lightweights(Jubilee and Navigator) as are many other parts under the same part number..