I'd like to generate a collection of data on swingarm length across several monster models to get an idea about subtle geometry differences.
The gearingcommander has a neat little database of front-rear sprocket distances. I could use that data, but only if the distance between the front sprocket and the swingarm pivot is the same for all monsters.
Anyone know?
(For reference, the swingarm length on my M695 is 515mm measured from the center of the swingarm pivot to the center of the rear axle, with a 14t front sprocket, original chain and +15mm rear ride height. Anyone have a number for an S2R or S4R?)
BK
Quote from: BK_856er on January 27, 2009, 09:35:29 PM
(For reference, the swingarm length on my M695 is 515mm measured from the center of the swingarm pivot to the center of the rear axle, with a 14t front sprocket, original chain and +15mm rear ride height. Anyone have a number for an S2R or S4R?)
How accurate would that measurement be when bikes have their axle adjusted differently due to chain length?
Also, to make it more complicated, the SSSA's eccentric hub screws with the bikes geometry depending on where it is positioned?!?!
Quote from: DarkStaR on January 27, 2009, 10:02:31 PM
How accurate would that measurement be when bikes have their axle adjusted differently due to chain length?
Also, to make it more complicated, the SSSA's eccentric hub screws with the bikes geometry depending on where it is positioned?!?!
Good questions. I assume that gearingcommander uses the same basic math, so differences are relative, which would be fine as long as the sprocket-pivot distance is fixed for the various models. Number of chain links and sprocket teeth are defined. I'm just trying to get some basic baseline numbers. I came up empty after poking around for an hour or so....
BK
Here are some numbers I grabbed from the gearingcommander:
year/model, stock sprockets, stock chain links, distance between the sprockets
’03 M800: 15/42 102 579mm
’06 M620: 15/48 106 585mm
’07 M695: 15/42 106 611mm
'07 M695: 15/42 102 579mm
’06 S2R800: 15/42 103 587mm
’06 S2R1000: 15/41 103 591mm
’06 S4RS: 15/43 106 607mm
’03 S4R: 15/42 104 595mm
Changing the other bikes to match my gearing/chain produced 611mm, implying that the front sprocket-swingarm pivot distance is the same for all the bikes, and therefore the differences in sprocket distances reflect effective swingarm length differences (if the swingarm angles are identical). In other words in stock trim an M800 has 30mm less swingarm length than my M695. Those deltas look pretty large to me, so maybe something is goofy here.
BK
* edit: Apparently simple logic fails me late at night - the numbers came out the same because I imposed it with gear/chain choice - doh! *
* edit#2: Gearingcommander is wrong for the M695. I counted the links on my original chain and there are only 102. The other info above is therefore also suspect. *
All of them have an adjustability, so should be expressed as a range, but, that said, the old SBK style SSS is about 1/2" shorter than the usual DSS, and the racing (Corse) SSS are almost 1" longer. The biggest variable in performance is swingarm angle and lower shock mount position. If you really want to collect some great data, do "pole of the moment" drawings for all of the variables.
Not sure if all Monster motors have the same sprocket to swingarm pivot dimensions.
IMO, it would only be different between small-case and large-case motors, so all 800cc and under would be one dimension, and all 900cc and over would be another dimension.
Thanks, guys.
There is an adjustment range, but the adjustment range is quite large, so I wanted to try and understand the factory starting points on the assumption that it would be in a tested happy place. One hypothesis I had was that Ducati might use this parameter to fine-tune the riding characteristics of the various models, and that could influence how I might alter things in the future as I replace parts....looks kinda sketchy from the numbers.
Pole of the moment....I'm going to put down my pencil and try to get more riding in :o
Or maybe it's time to get that suspension theory book. [drink]
BK