Primary Drives.

Drive chains have improved significantly in the past 4 decades, no need for 630 final drive monsters, & even 530s are being replaced by 520s, sans issues.
Has anyone done a similar primary drive mass reduction kit, like a hi-capacity simplex chain swap for that heavy, thrashing, mainshaft stressing, triplex?

Not that I'm aware of. And it would seem pretty pointless going back to the Atlas type of single chain and steel clutch wheel when belt drives on ally hubs have pretty much done away with primary chains of any type in terms of lower weight and durability plus maintenance free.

Belt drives are not totally issue free..as for weight, efficiency, cost,durabilty factors... belt vs premium simplex, I`d like to see the numbers..

The chain is sure cheaper if you don't replace it with a belt.

Dave
69S

I finally replaced my primary belt after 12 years and 29,000 miles.

I suppose I could have kept going on with it but it seemed like something I should do.

What surprises me is how totally trouble free they are, I set the tension when I bought it and have not touched it since then, I guess they don't stretch much, if at all.

I did install a left side threaded gearbox adjuster to insure it tracks true.

Boils down to how well kept the transmission is. If clutch don't wobble then belts beat the snot out of oil bath chains, but if clutch support wears to wobble then chains will carry on and on and on but a belt won't stay on. Best thing would be electromagnetic coupling all the way to the rear patch like my scout craft project in the shed.

WWWHAAAA.. Hobot, you dont really got boy scouts enslaved in your shed? Dang, you are way down in Dixie aint ya...Or are you Santa, & they are elves assembling new [S.G.] Commandos for Xmas...?

One advantage to having an oil bath primary is it keeps down oxidation. Down here in South Florida, we run 80-95% humidity 80-95% of the time. Anything left outside is junk in a short order.

I just saw a Combat at Wes' shop Friday that spent two years in a storage warehouse. Looked like it spent a decade leaned up against a barn.

JAW I have miles of dicey loose stuff to get to pavement so I tend to spend extra time in lower gears which drys out the sleeve bushes which lets clutch wobble. I have stopped riding Trixie d/t discovering significant clutch wobble again to prevent expensive parts damage till whole drivetrain gone through - again. On Peel most her hi speed chicane flings was in 2nd to 85 mph so also learned me about belts and clutch wobble bad juju. If factory Trixie had belt primary I'd of been shut down 5000 miles ago and missed out on many adventures and likely gotten caught out from home with belt piled up around crank pulley and inside alternator.

99% of us are safe with the belt then. 85 in second? Gee I rarely see that in
high! You trying to kill yourself or the bike first?

Ugh, I said most to the time but when solo would run Ms Peel to 90 mph close to 8000 rpm, but felt WTF faster than that as was only done where possible in the short 'straights' - in wagon trail ice broken pavement on plateau face narrow hwy with tightest close together switch backs marked 10 or 15 mph. So Peel was not leaning much when topping out in 2nd. Peel entered the 10 mph at 55 and came out showing 65 before more upright to keep on it. Her surprising power was just icing on the cake of the robust rear link and two wimpy helper links. Anything less than above was just ho hum-non athletic-low skill testing - so to get tremble level adrenalin i had to leave pavement. The belt drive is way to go for better acceleration if clutch wobble wear kept ahead of. I got stranded with Peel's belt destroyed 100 mile from home, but a stranger took me home then came back with PU to take me to home base, after dark. W/o a Commando my social life is way more limited. What happens as clutch wobbles the belt tends to work off the clutch and so rubs on the front pulley plates till it unravels then packs up in front of primary. Alterntor nut came loose on a fling after this and put holes in belt one big enough to run a pencil through but as tranny bushes backed up with a 3rd then plus ATF and no rubbing of side edges I ran it for 1000's of miles and still would but for going to 40 mm next time out. Except for the clutch wobble wear a belt is definitely a maintenance hassle lowering upgrade.