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Jun 08, 2011 8:17 pm
Jun 08, 2011 8:17 pm
Subject: G9 gearbox
I wonder if anyone has any information on rebuilding the G9 gearbox please ? I am a little mystified as to how the double helical gears find their correct position in relation to each other between the layshaft and the mainshaft. 2nd and third on the layshaft have a fixed position and cannot move sideways. But 2nd and 3rd on the mainshaft have a certain amount of sideways movement. Are 2nd and 3rd intended to have a certain amount of sideways movement so that they effectively line up correctly when "driving" ? On my gearbox (already dismantled and I am now rebuilding) there appears to be approx 1mm gap between 1st and 2nd and also between 2nd and 3rd on the mainshaft. Is this ok ? However what happens when a certain amount of side load is applied when changing into 2nd and also (in the opposite direction) when changing into 3rd. The bush inside 3rd gear has a large "shoulder" on the side between 2nd and 3rd. Presumably this is to take a certain amount of side load ? What sort of gap should be left between 2nd gear and the shoulder of the bush in 3rd Gear ?
4th gear is different as it is fixed on the mainshaft (input shaft) but not on the layshaft. There is considerable "float" on the layshaft (about 5mm on the layshaft itself !). There appears to be no provision to space out this gap. Is this really correct and that therefore 4th gear on the input shaft finds its own (correct) position when driven ?
One further point please. Is it correct that the bush between the input shaft and the output shaft is designed to move in relation to both shafts ? i.e. it is NOT fixed inside the 4th gear shaft. I realise how vital this bush is. If it is worn it can allow the output shaft (supported only by one bearing at the back) to "droop" and this often causes broken teeth. If it must be able to revolve in relation to both inoput and output shafts why is this ?
Sorry to post such a long question but any technical information gratefully received.
Many thanks in anticipation if anyone out there is kind enough to take the trouble to reply.
I wonder if anyone has any information on rebuilding the G9 gearbox please ? I am a little mystified as to how the double helical gears find their correct position in relation to each other between the layshaft and the mainshaft. 2nd and third on the layshaft have a fixed position and cannot move sideways. But 2nd and 3rd on the mainshaft have a certain amount of sideways movement. Are 2nd and 3rd intended to have a certain amount of sideways movement so that they effectively line up correctly when "driving" ? On my gearbox (already dismantled and I am now rebuilding) there appears to be approx 1mm gap between 1st and 2nd and also between 2nd and 3rd on the mainshaft. Is this ok ? However what happens when a certain amount of side load is applied when changing into 2nd and also (in the opposite direction) when changing into 3rd. The bush inside 3rd gear has a large "shoulder" on the side between 2nd and 3rd. Presumably this is to take a certain amount of side load ? What sort of gap should be left between 2nd gear and the shoulder of the bush in 3rd Gear ?
4th gear is different as it is fixed on the mainshaft (input shaft) but not on the layshaft. There is considerable "float" on the layshaft (about 5mm on the layshaft itself !). There appears to be no provision to space out this gap. Is this really correct and that therefore 4th gear on the input shaft finds its own (correct) position when driven ?
One further point please. Is it correct that the bush between the input shaft and the output shaft is designed to move in relation to both shafts ? i.e. it is NOT fixed inside the 4th gear shaft. I realise how vital this bush is. If it is worn it can allow the output shaft (supported only by one bearing at the back) to "droop" and this often causes broken teeth. If it must be able to revolve in relation to both inoput and output shafts why is this ?
Sorry to post such a long question but any technical information gratefully received.
Many thanks in anticipation if anyone out there is kind enough to take the trouble to reply.