Post by ssxnitro on Oct 7, 2011 21:16:03 GMT -6
A bit of my background before I get into this...
My father used to own a Honda motorcycle dealership, which he supplemented with selling sno-pony's for a short while & then sold Chaparral sleds. My dad sold the Honda dealership franchise to Rick Hacker in '74 (Chaparral was done by then)- the Hacker family owned a Yamaha dealership, and so became "Hacker's Honda & Yamaha" dealership that is fairly well known here in Michigan. Hacker's is also known for campaigning a grass drag race team closely associated with Bender Racing.
I was the parts dept. manager & the service dept. assistant manager there for a few years as well...
Anyway... One of our part-time technicians & race team drivers (Dan Dantuma) also used to oval race his own Yamaha sleds, and found and bought a fairly complete Bombardier Twin Tracker race chassis with plans to rebuild it for racing using modified Yamaha body, an SRX700 motor, and Yamaha blue paint with decal set. These chassis were hand fabricated & featured more suspension set-up adjustments and geometry settings than the common mechanic could figure out... it was unbelivable at how much adjustment there was in the sled. Luckily, the sled came with documentation & a log book detailing various set-ups for different tracks and conditions so at least he would have something to go off of.
This chassis would have been a great way to play with cause & effect of nearly any suspension geometry question you wanted an answer to: roll centers, arcs of movement, scrub angles, caster, camber, mounting points, A-arm lengths, offsets, weight jacking, cross weighting, weight transfer, rear suspension arm interaction... it was all here & all adjustable... It was literally it's own laboratory to understanding anything you wanted to know about suspension setup.
But to answer the question if a differential was used... no, not exactly. Going straight, both tracks were engaged off of the chaincase, but when you turned the handlebars a set amount the inside track would begin to de-clutch (the inside track was equipped with a dry multi-disk clutch pack off the output shaft of the chaincase, as I recall)- how much clutch slippage & how much steering input to activate the clutch could all be adjusted as well. I think that inside/outside braking bias could also be adjusted independently from the two tracks. This is how the Bombardier Twin Tracker worked... which I'm sure is different than how the Mantas were.
Interestingly, this was around the same time when Bob Bracey introduced the Trail Roamer. Bob himself introduced the Trail Roamer personally to Hacker's & a few of them were bought from him to sell... one of them sold right away while the other languished in the showroom for a couple years. I think the Trail Roamers used a differential between the tracks in the gearcase- which had forward & reverse as well.
My father used to own a Honda motorcycle dealership, which he supplemented with selling sno-pony's for a short while & then sold Chaparral sleds. My dad sold the Honda dealership franchise to Rick Hacker in '74 (Chaparral was done by then)- the Hacker family owned a Yamaha dealership, and so became "Hacker's Honda & Yamaha" dealership that is fairly well known here in Michigan. Hacker's is also known for campaigning a grass drag race team closely associated with Bender Racing.
I was the parts dept. manager & the service dept. assistant manager there for a few years as well...
Anyway... One of our part-time technicians & race team drivers (Dan Dantuma) also used to oval race his own Yamaha sleds, and found and bought a fairly complete Bombardier Twin Tracker race chassis with plans to rebuild it for racing using modified Yamaha body, an SRX700 motor, and Yamaha blue paint with decal set. These chassis were hand fabricated & featured more suspension set-up adjustments and geometry settings than the common mechanic could figure out... it was unbelivable at how much adjustment there was in the sled. Luckily, the sled came with documentation & a log book detailing various set-ups for different tracks and conditions so at least he would have something to go off of.
This chassis would have been a great way to play with cause & effect of nearly any suspension geometry question you wanted an answer to: roll centers, arcs of movement, scrub angles, caster, camber, mounting points, A-arm lengths, offsets, weight jacking, cross weighting, weight transfer, rear suspension arm interaction... it was all here & all adjustable... It was literally it's own laboratory to understanding anything you wanted to know about suspension setup.
But to answer the question if a differential was used... no, not exactly. Going straight, both tracks were engaged off of the chaincase, but when you turned the handlebars a set amount the inside track would begin to de-clutch (the inside track was equipped with a dry multi-disk clutch pack off the output shaft of the chaincase, as I recall)- how much clutch slippage & how much steering input to activate the clutch could all be adjusted as well. I think that inside/outside braking bias could also be adjusted independently from the two tracks. This is how the Bombardier Twin Tracker worked... which I'm sure is different than how the Mantas were.
Interestingly, this was around the same time when Bob Bracey introduced the Trail Roamer. Bob himself introduced the Trail Roamer personally to Hacker's & a few of them were bought from him to sell... one of them sold right away while the other languished in the showroom for a couple years. I think the Trail Roamers used a differential between the tracks in the gearcase- which had forward & reverse as well.