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Jun 11, 2011 10:18 am
Jun 11, 2011 10:18 am
Subject: Re: G9 gearbox
Morning Bill,
Good questions, but ones I can answer if I understand your questions correctly.
1st and 3rd Q. The gears on the Lay shaft are all Fixed permanently in place, Other than the "Drop gear" which you call 4th. You need to space and adjust these correctly on each individual box you build or trouble may arise! The mating Herring bone gear should engage tightly with it's corresponding gear on the Main shaft and this Main shaft gear should float and then be located by the Lay shaft gear. The Drop gear on the input shaft will do the same to the corresponding "floating" gear on the input of the Lay shaft. NO movement is allowed here other than small gear clearance. Your bearings for those gears on the Main shaft should also be absolutely perfect and not sloppy or gear damage will occur! Obviously the position of the gears on the Lay shaft relates to the gears on the Main shaft and a little trial and error will be needed here to get all perfect. We "bench build" a couple of times just to make absolutely perfect. The synchro hub needs to be centred fairly well with Third and Fourth and the selectors checked for positioning.
2nd Q. An even gap is required between 1st and 2nd and preferably between 3rd and 4th, whatever this is depends on the individual box being built. ALL are a little different! However 1mm seems very tight ! Side load is what breaks the Herringbone teeth more than anything else! Try to avoid forcing 3rd and 4th like the plague! as you can imagine, because the gears are only located by their "mesh" with the Lay shaft gear, any side load is taken directly on the teeth! Being weak anyway, this is not good!
4th Q. The sleeve bearing between the input and output shafts is Double floating for the following reason.
Sometimes bearings / shaft assemblies like this have a tendency at certain speeds to "Gyrate" while turning and thus cause damage. By making the bearing float both internally and externally this motion is dampened and therefore nullified! (Look at modern Turbocharger bearings for example)
Hope I understood your questions Bill, but please don't hesitate to post again or phone if you need any other info etc. Pleased to help if we can.
Best regards,
Julian
Morning Bill,
Good questions, but ones I can answer if I understand your questions correctly.
1st and 3rd Q. The gears on the Lay shaft are all Fixed permanently in place, Other than the "Drop gear" which you call 4th. You need to space and adjust these correctly on each individual box you build or trouble may arise! The mating Herring bone gear should engage tightly with it's corresponding gear on the Main shaft and this Main shaft gear should float and then be located by the Lay shaft gear. The Drop gear on the input shaft will do the same to the corresponding "floating" gear on the input of the Lay shaft. NO movement is allowed here other than small gear clearance. Your bearings for those gears on the Main shaft should also be absolutely perfect and not sloppy or gear damage will occur! Obviously the position of the gears on the Lay shaft relates to the gears on the Main shaft and a little trial and error will be needed here to get all perfect. We "bench build" a couple of times just to make absolutely perfect. The synchro hub needs to be centred fairly well with Third and Fourth and the selectors checked for positioning.
2nd Q. An even gap is required between 1st and 2nd and preferably between 3rd and 4th, whatever this is depends on the individual box being built. ALL are a little different! However 1mm seems very tight ! Side load is what breaks the Herringbone teeth more than anything else! Try to avoid forcing 3rd and 4th like the plague! as you can imagine, because the gears are only located by their "mesh" with the Lay shaft gear, any side load is taken directly on the teeth! Being weak anyway, this is not good!
4th Q. The sleeve bearing between the input and output shafts is Double floating for the following reason.
Sometimes bearings / shaft assemblies like this have a tendency at certain speeds to "Gyrate" while turning and thus cause damage. By making the bearing float both internally and externally this motion is dampened and therefore nullified! (Look at modern Turbocharger bearings for example)
Hope I understood your questions Bill, but please don't hesitate to post again or phone if you need any other info etc. Pleased to help if we can.
Best regards,
Julian