Paul Bryant
Living Legend
O.K. so for some time I've been thinking about how to gear up the Rocket.
Often we've heard people saying we need another gear.
Well I thought easy, lets modify the diff ratio.
Well having "Nazareth" (thank you Phil) in my workshop now . . .
I decided to dissect the diff.
As you may know, this bike was in a horrendous fire, everything is stuffed !
So I start un-bolting the diff, all the bolts were just finger tight and came undone easily.
Here's what the inside of the diff looks like. . . .
Crown wheel, 37 teeth.
Pinion, 13 teeth.
Diff inner cover, sagged tremendously from the heat, as is the housing itself.
Note that the drain plug is quite a bit off the bottom of the housing, so when you drain the oil to change the oil, there will still be quite a bit of the old oil still left in there.
Probably best to lean the bike over to the left to get the last of the old oil out !
The ring retaining the Pinion and shaft into the diff housing is retained by a R/H thread, the diff and this "ring" are both alloy, the heat had distorted both badly so un-screwing them was impossible.
So I cut the bugger open.
This photo below shows the assembly.
We have a pinion (13 teeth) with a shaft that extends through two bearings to the Female adaptor for the drive shaft.
So I am thinking, lets price having a Professional Helical Gear cutting Firm make a new set of gears.
I did a Gooooogle search and came up with a Company who does this sort of work in Auckland (NZ) gave them a call and explained what I was after.
Turns out that just today they had pulled apart a V Max Yamaha to look at doing exactly this.
The Guy tells me it is exorbitantly expensive to do !
I ask so how much, as a one off he tells me between 3-4 K NZ$ Chit ! I was thinking maybe a couple of grand (NZ$) so then I talk about doing 10 sets, thinking maybe 10 people world wide might want a higher ratio diff. He agrees NZ$2K maybe possible. Chit !
So I continue to think about this.
I now look at the available space to fit said improved ratio gears.
Well Folks, I'm sad to say, that it's just not going to happen, a smaller diameter (less teeth) crown wheel is no problem, but a larger diameter pinion (more teeth) well there's just no room to accommodate this.
So sadly, that is the end of that story !
Oh well, now we know what the inside of the diff looks like.
Often we've heard people saying we need another gear.
Well I thought easy, lets modify the diff ratio.
Well having "Nazareth" (thank you Phil) in my workshop now . . .
I decided to dissect the diff.
As you may know, this bike was in a horrendous fire, everything is stuffed !
So I start un-bolting the diff, all the bolts were just finger tight and came undone easily.
Here's what the inside of the diff looks like. . . .
Crown wheel, 37 teeth.
Pinion, 13 teeth.
Diff inner cover, sagged tremendously from the heat, as is the housing itself.
Note that the drain plug is quite a bit off the bottom of the housing, so when you drain the oil to change the oil, there will still be quite a bit of the old oil still left in there.
Probably best to lean the bike over to the left to get the last of the old oil out !
The ring retaining the Pinion and shaft into the diff housing is retained by a R/H thread, the diff and this "ring" are both alloy, the heat had distorted both badly so un-screwing them was impossible.
So I cut the bugger open.
This photo below shows the assembly.
We have a pinion (13 teeth) with a shaft that extends through two bearings to the Female adaptor for the drive shaft.
So I am thinking, lets price having a Professional Helical Gear cutting Firm make a new set of gears.
I did a Gooooogle search and came up with a Company who does this sort of work in Auckland (NZ) gave them a call and explained what I was after.
Turns out that just today they had pulled apart a V Max Yamaha to look at doing exactly this.
The Guy tells me it is exorbitantly expensive to do !
I ask so how much, as a one off he tells me between 3-4 K NZ$ Chit ! I was thinking maybe a couple of grand (NZ$) so then I talk about doing 10 sets, thinking maybe 10 people world wide might want a higher ratio diff. He agrees NZ$2K maybe possible. Chit !
So I continue to think about this.
I now look at the available space to fit said improved ratio gears.
Well Folks, I'm sad to say, that it's just not going to happen, a smaller diameter (less teeth) crown wheel is no problem, but a larger diameter pinion (more teeth) well there's just no room to accommodate this.
So sadly, that is the end of that story !
Oh well, now we know what the inside of the diff looks like.
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