Gear Compatibility

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johnny650
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Thu Jul 26, 2018 10:06 am

Doom Patrol wrote:
Wed Jul 25, 2018 9:42 pm
I once heard about someone who fitted the 3rd gear from a Spanish LI in an Italian gearbox. It apparently jammed owing to the fact that the Spanish gear was thicker.
thats a surprise .... . I thought that that was pretty standard practice to replace the thin pacemaker 3rd gear with one from a standard Li150 gear set. Perhaps it has to be an Innocenti 3rd gear not Indian or Spanish .?

YAMLAM
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Thu Jul 26, 2018 11:29 am

always check the diameter across 3 teeth of the loose gear , they all might be 37T or what ever but can vary. Fit and check that they mesh ok.
win or lose have a booze

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GTFOMWSC
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Thu Jul 26, 2018 11:44 am

johnny650 wrote:
Thu Jul 26, 2018 10:06 am
Doom Patrol wrote:
Wed Jul 25, 2018 9:42 pm
I once heard about someone who fitted the 3rd gear from a Spanish LI in an Italian gearbox. It apparently jammed owing to the fact that the Spanish gear was thicker.
thats a surprise .... . I thought that that was pretty standard practice to replace the thin pacemaker 3rd gear with one from a standard Li150 gear set. Perhaps it has to be an Innocenti 3rd gear not Indian or Spanish .?
No there is a difference it may only be small but it makes a big difference when you use it. eg the italian li150 2nd gear has the same teeth as a spanish but it is 105 compared to 106 across the teeth this means that it isn't quite meshing fully and can rip the teeth.It's why it takes the more knowlegdable people to come up with the correct gears for certain ratios and why you can't just swap out any old gear gog because it has the same number of teeth
the man don't give a f@@k

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Doom Patrol
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Thu Jul 26, 2018 2:32 pm

GTFOMWSC wrote:
Thu Jul 26, 2018 11:44 am
johnny650 wrote:
Thu Jul 26, 2018 10:06 am
Doom Patrol wrote:
Wed Jul 25, 2018 9:42 pm
I once heard about someone who fitted the 3rd gear from a Spanish LI in an Italian gearbox. It apparently jammed owing to the fact that the Spanish gear was thicker.
thats a surprise .... . I thought that that was pretty standard practice to replace the thin pacemaker 3rd gear with one from a standard Li150 gear set. Perhaps it has to be an Innocenti 3rd gear not Indian or Spanish .?
No there is a difference it may only be small but it makes a big difference when you use it. eg the italian li150 2nd gear has the same teeth as a spanish but it is 105 compared to 106 across the teeth this means that it isn't quite meshing fully and can rip the teeth.It's why it takes the more knowlegdable people to come up with the correct gears for certain ratios and why you can't just swap out any old gear gog because it has the same number of teeth
Exactly. Although, you put it better than me. :-)

johnny650
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Sat Jul 28, 2018 11:26 pm

GTFOMWSC wrote:
Thu Jul 26, 2018 11:44 am

No there is a difference it may only be small but it makes a big difference when you use it. eg the italian li150 2nd gear has the same teeth as a spanish but it is 105 compared to 106 across the teeth this means that it isn't quite meshing fully and can rip the teeth.It's why it takes the more knowlegdable people to come up with the correct gears for certain ratios and why you can't just swap out any old gear gog because it has the same number of teeth
this is all very well buts its more anecdotal opinion which is not based on any demonstrable facts. ;) What do you mean about 'rip teeth' for instance ? I would assume that 50+ year old gear sprockets are going to be pretty worn most probably out of tolerance but they still work fine in thousands of scooters around the world because the working tolerance on gear mesh for these gears is huge . They are in no way a precision gearbox by any stretch of the imagination.

On the one hand you have lots of folk on forums and in various books saying swop the early pacemaker 3rd gear for a later thicker stronger 3rd gear
Then there are other experienced enthusiasts like yourself that say the exact opposite is true....... :?

The problem is there doesn't appear to be any facts anywhere so these 'opinions' just carry on influencing other Lambretta owners decision making .
I'm sure there must be some Engineering drawings and specifications somewhere on the Net

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GTFOMWSC
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Sun Jul 29, 2018 12:56 am

johnny650 wrote:
Sat Jul 28, 2018 11:26 pm
GTFOMWSC wrote:
Thu Jul 26, 2018 11:44 am

No there is a difference it may only be small but it makes a big difference when you use it. eg the italian li150 2nd gear has the same teeth as a spanish but it is 105 compared to 106 across the teeth this means that it isn't quite meshing fully and can rip the teeth.It's why it takes the more knowlegdable people to come up with the correct gears for certain ratios and why you can't just swap out any old gear gog because it has the same number of teeth
this is all very well buts its more anecdotal opinion which is not based on any demonstrable facts. ;) What do you mean about 'rip teeth' for instance ? I would assume that 50+ year old gear sprockets are going to be pretty worn most probably out of tolerance but they still work fine in thousands of scooters around the world because the working tolerance on gear mesh for these gears is huge . They are in no way a precision gearbox by any stretch of the imagination.

On the one hand you have lots of folk on forums and in various books saying swop the early pacemaker 3rd gear for a later thicker stronger 3rd gear
Then there are other experienced enthusiasts like yourself that say the exact opposite is true....... :?

The problem is there doesn't appear to be any facts anywhere so these 'opinions' just carry on influencing other Lambretta owners decision making .
I'm sure there must be some Engineering drawings and specifications somewhere on the Net
for example if you put the italian gear that has the same teeth as the spanish gear in an af close ratio 4 speed box as its not the correct size the meshing of the gear is not complete so its short and if you then accelerate quickly as its not fully meshed it can rip the teeth off the cluster or the cog.If the correct size albeit a fraction larger is used it fully meshes and you'll not supposedly rip the teeth.If it was that simple every shed mechanic would be producing close ratio boxes and they don't because its not that simple,AF,Broady,Casa they know what they're doing so they produce them.I use the AF ones myself although a late pacemaker box is nearly as good but i wouldn't swap out the dodgy third cog in an early one and use it i'm sure the cluster is different as well not just the cog but might be wrong there.
the man don't give a f@@k

dirtyhandslopez
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Mon Jul 30, 2018 2:29 am

Some gears gears just won't fit together correctly, that's all there is to it. If you would like to count gears and make up gearboxes, come have at it.
That's not going anywhere...

dirtyhandslopez
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Mon Jul 30, 2018 2:39 am

Some gears gears just won't fit together correctly, that's all there is to it.
That's not going anywhere...

johnny650
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Mon Jul 30, 2018 5:59 pm

dirtyhandslopez wrote:
Mon Jul 30, 2018 2:39 am
Some gears gears just won't fit together correctly, that's all there is to it.

that answer isn't exactly informative is it ! :roll: thats a complete generalization like saying 'if you eat too much you'll get fat '

which gears precisely ?...........in your personal experience ;)

I thought that this was intended to be a serious discussion and all I'm hearing so far is old wives tales :lol:

Grumpy225
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Mon Jul 30, 2018 7:06 pm

johnny650 wrote:
Sat Jul 28, 2018 11:26 pm
GTFOMWSC wrote:
Thu Jul 26, 2018 11:44 am

No there is a difference it may only be small but it makes a big difference when you use it. eg the italian li150 2nd gear has the same teeth as a spanish but it is 105 compared to 106 across the teeth this means that it isn't quite meshing fully and can rip the teeth.It's why it takes the more knowlegdable people to come up with the correct gears for certain ratios and why you can't just swap out any old gear gog because it has the same number of teeth
this is all very well buts its more anecdotal opinion which is not based on any demonstrable facts. ;) What do you mean about 'rip teeth' for instance ? I would assume that 50+ year old gear sprockets are going to be pretty worn most probably out of tolerance but they still work fine in thousands of scooters around the world because the working tolerance on gear mesh for these gears is huge . They are in no way a precision gearbox by any stretch of the imagination.

On the one hand you have lots of folk on forums and in various books saying swop the early pacemaker 3rd gear for a later thicker stronger 3rd gear
Then there are other experienced enthusiasts like yourself that say the exact opposite is true....... :?

The problem is there doesn't appear to be any facts anywhere so these 'opinions' just carry on influencing other Lambretta owners decision making .
I'm sure there must be some Engineering drawings and specifications somewhere on the Net
MBD use to publish a book on all the Lambretta gearing combos. I couldn't find it but on the site but I'm sue they would still have the information. Might be worth an email to Mark?

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