1000 triple 180 gears module

Enrico

Enrico

New member
Location
Italy
I am curious why manuals and workshop books reports different gear ratios.
I am assuming that the modules of the gears did not changed between the gearboxes of 1000 180°.
I made my calculations and results are:

  • Motor axis / triple chain: 51, 25 (i=2.04)
  • Primary shaft: 17, 22, 26, 28, 30
  • Layshaft: 34, 29, 25, 23, 21
  • For the chain transmission (primary shaft / wheel): 19, 40 (i=2.105)

Does anyone have information about the modules of the gears that are actually in the motor?
 
I have a mate who is an engineer and has done a lot of motorcycle engine design work for himself various companies. He tells me that gearboxes very often do not use standard 'module' sizes. In order to get the desired mix of ratios all at exactly the same shaft centre distance, it is necessary to use a mix of standard module sizes, imperial diametral pitch sizes, and it's also common to have completely custom gearforms.

I don't recall exactly, but yes most of the 1000-180 shared the same ratios. The 1982 120-Jota used a unique close-ratio set of gears and the RGS was completely different again. In the 750's (which are very similar) there were a number of ratio sets used throughout the years and across the different models. When I was racing a 750 I used a mixture of shafts and gears from different models to try to get the best ratios for the track we were racing.

The one thing that is always true on any 750 or 1000 is that 5th gear is always 1:1, since it is a 'sleeve gear' arrangement which locks the input and output parts of the mainshaft together when in top gear.

Also (and thinking now, this might be what you are really asking) because of the sleeve gear arrangement, for gears 1-4 the "gear ratio" (input rpm vs output rpm) is a compound between two pairs of gears. So in your numbers above, for first gear the power first goes to the layshaft via the 17/34 gear pair, and then back to the output shaft (sleeve gear) via the 30/21 gear pair. So the ratio would be (17/34) x (30/21). For second gear it would be (22/29) x (30/21) and so on. In top gear the dog ring locks the sleeve gear direct to the input main shaft, turning it into one shaft so the ratio is always 1:1.
 
OK, then my first paragraph quite possibly/probably applies. Maybe they're all standard metric module, but based on my friend's experience don't be surprised if they don't align with any standard.
@redax5 may be able to comment at least on the 4th and 5th gears, since he's had custom ones made up.
I know when I made my 750 gear primary drive with floating idlers I ended up with a spec like 'module 2.5, overcut 0.15mm' or something like that to make it all line up.
 
Today I’ve received the proper explanation and I am glad to shared this with the group.
The change between the various models of the triple 1000 180 is only on the 1st gear.
The one machined on the main shaft has 18 theeth, while the idler wheel on the layshaft has 33 teeth. This means a gear ratio on 1st gear equal to 33/18 x 30/21 = 2.619
Starting from ‘77/‘78 the machined shaft and the first idle gear on the layshaft changed to 17 and 34 to increase the torque to start.
This means a gear ratio on 1st gear became equal to 34/17 x 30/21 = 2.857
Those are the numbers I’ve found on various manuals, data sheets, workshop procedures.
On 1000 120, RGS the gearboxes changed, but it’s another story.
Thank you all for your help.
 
breganzane said:
I have a mate who is an engineer and has done a lot of motorcycle engine design work for himself various companies. He tells me that gearboxes very often do not use standard 'module' sizes. In order to get the desired mix of ratios all at exactly the same shaft centre distance, it is necessary to use a mix of standard module sizes, imperial diametral pitch sizes, and it's also common to have completely custom gearforms.

I don't recall exactly, but yes most of the 1000-180 shared the same ratios. The 1982 120-Jota used a unique close-ratio set of gears and the RGS was completely different again. In the 750's (which are very similar) there were a number of ratio sets used throughout the years and across the different models. When I was racing a 750 I used a mixture of shafts and gears from different models to try to get the best ratios for the track we were racing.

The one thing that is always true on any 750 or 1000 is that 5th gear is always 1:1, since it is a 'sleeve gear' arrangement which locks the input and output parts of the mainshaft together when in top gear.

Also (and thinking now, this might be what you are really asking) because of the sleeve gear arrangement, for gears 1-4 the "gear ratio" (input rpm vs output rpm) is a compound between two pairs of gears. So in your numbers above, for first gear the power first goes to the layshaft via the 17/34 gear pair, and then back to the output shaft (sleeve gear) via the 30/21 gear pair. So the ratio would be (17/34) x (30/21). For second gear it would be (22/29) x (30/21) and so on. In top gear the dog ring locks the sleeve gear direct to the input main shaft, turning it into one shaft so the ratio is always 1:1.
Click to expand...
Your answer was right but not the question 😬
 
Vince said:
Thats listed in the green book.
Click to expand...
Correct. The green book has the improvement. The manual of 1973 that I have of my 1000 3C shows the other gear ratio.
Today I have been in Breganze and chance to discuss this topic and had the reply that I reported above.
 
Enrico said:
Today I’ve received the proper explanation and I am glad to shared this with the group.
The change between the various models of the triple 1000 180 is only on the 1st gear.
Click to expand...

The gear ratio change was not the only one. Somewhere along the way, the layshaft gear was changed from running on a bronze bush to a needle roller bearing.

There was also a close-ratio gear set available for the 180s, this had various other gears running on needles as well.

piet
 
sfcpiet said:
The gear ratio change was not the only one. Somewhere along the way, the layshaft gear was changed from running on a bronze bush to a needle roller bearing.

There was also a close-ratio gear set available for the 180s, this had various other gears running on needles as well.

piet
Click to expand...
A bit like the SFC. (a bit)
Paul
 
Paul Marx said:
A bit like the SFC. (a bit)
Paul
Click to expand...

The triple CR 'box was actually a carbon copy of the SFC gearbox, just with different mainshaft and ratios. I think there was only one type offered, but 2nd-4th could be adjusted a little if required, using SFC gears. 1st was of course determined by the integral mainshaft gear, 5th was direct, just like all others.

piet
 
The only problem I have with the std gb at least on SF is the bloody big gap between 2nd and 3rd gears, I hated it when racing. A taller 1st would be even tougher on race starts for sprint races, or uphill starts heavily loaded.
 
Even after donkeys years of riding my 3c, it takes me a while in twisty country to find the best most effective gear for linked tight 35k bends especially if there is some climbing involved and I don't know why. Not even sure what gears I am using but sometimes I find I am constantly too low or too high a gear and sometimes I crack the sweet spot where braking isn't needed and it just pulls nicely into and out of bends. Just for giggles, I might try counting gears to see what actual gear I am using. I just go down till I run out of clicks and go up doing the same.
 
Vince said:
Even after donkeys years of riding my 3c, it takes me a while in twisty country to find the best most effective gear for linked tight 35k bends especially if there is some climbing involved and I don't know why. Not even sure what gears I am using but sometimes I find I am constantly too low or too high a gear and sometimes I crack the sweet spot where braking isn't needed and it just pulls nicely into and out of bends. Just for giggles, I might try counting gears to see what actual gear I am using. I just go down till I run out of clicks and go up doing the same.
Click to expand...
What ignition are you using?
Paul
 
Vince said:
Even after donkeys years of riding my 3c, it takes me a while in twisty country to find the best most effective gear for linked tight 35k bends especially if there is some climbing involved and I don't know why. Not even sure what gears I am using but sometimes I find I am constantly too low or too high a gear and sometimes I crack the sweet spot where braking isn't needed and it just pulls nicely into and out of bends. Just for giggles, I might try counting gears to see what actual gear I am using. I just go down till I run out of clicks and go up doing the same.
Click to expand...
I dont have the issue very often when riding the RGS or SFC. I normally just use it between 2500 and 5000 rpm, maybe when accelerating heavy also up 8000. But I think also on narrow windy roads usually it is in the right gear- but I think we have more of those roads in Europe and we have a good practice. I also never know which gear I am using. If the bike does not pull I switch down and if it revs too much I go up. Almost never use the first, just for starting.
Last year I bought my first Zane Formula and it is so different. My longer Trip was in the Harz moutains on my way to Oschersleben race track. Even when I just closed the throttle to lower the speed slightly in front of a curve, I was in the wrong gear later and often I had to go 2 gears down. It is so different, and I am not sure whether I like it or will lear it any day. :)
 
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