Show whole topic Jun 13, 2011 10:00 pm
bill Offline
Member
Registered since: Jun 08, 2011
Location: -


Subject: Re: G9 gearbox
Dear Julian,
Sorry I have only just picked up your reply to my queries.
Firstly, very, very many thanks for taking the time and trouble to reply as I am sure you are very busy.
Thanks to your information I think that I understand the principles a little better !
Could I please ask you to clarify things a little more for me. I am sorry if I do not have the correct terminology. I will number my queries hopefully to make replying easier.
1. I am still a little unsure about the gaps between 1st and 2nd and 2nd and 3rd gears on the mainshaft itself. Should I try to adjust these at all ? If so should this be done by pressing the bushes slightly in or out of the centres of the gears ? Or is there a better way of doing it ? Alternatively should they be shimmed in some way ?
2. I am of course renewing all the ball and roller bearings and also the 3 brass/bronze bushes as I realise the condition of these is vital. Having fixed the layshaft and its gears in their final position inside the gearbox casing my intention then is to put 2nd and 3rd gear in on the mainshaft individually so that I can measure where each gear wants to be located when meshed firmly with its pair on the layshaft. I could then tell (I hope) whether the 1 mm clearance I have previously referred to is actually too much or too little and also in the correct place (i.e. not too far one side or the other). Does this make sense ?
3. The bush inside 3rd gear has a large shoulder on the side between 3rd and 2nd gear - presumably this is to absorb a certain amount of side load ? How should I decide what is its correct position ? If it is pushed too far sideways out of 3rd gear (towards 2nd gear) it could presumably harm the meshing of either gear with the individual drop gears on the layshaft. If it is pushed too far inside 3rd gear (giving a larger gap between 2nd and 3rd on the mainshaft) then the same consequence could happen. Is it intended to take side load or not and should I adjust it in this way ?
4. 4th gear (or rather its drop gear on the layshaft) does not seem to be as critical as 2nd and 3rd because there is 5mm "float" on the layshaft. Presumably with this gear the side load on the gear on the mainshaft/input shaft is less critical as the gear is fixed and it cannot really be pushed sideways. Am I correct on this ?
5. There was some evidence on my gearbox of overheating on the 3rd gear bush and I have therefore taken some trouble to push the gear itself off its keyways and clean out all the oilways. These seemed quite clogged. Were these gearboxes originally set up on Castrol R ? I have also done the same with 4th gear which seemed to have the same problem. Not an easy job !

Many, many thanks again for all your help. I hope I have explained everything clearly so that you can understand the problems I am referring to.