jgimar
XS650 Addict
would someone be able to tell me the differences between the '77 disc and other discs? i understand there are some diminsional differences. i need some sizes so i don't mix them up.
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The 72 disc was a one year thing. The 73 to 76 was a two piece disc, The disc it self bolted to the center that bolted to the hub. From 77 up they where a one piece disc.
All years were the same diameter and thickness.
If you lay them flat on a table so the hub mount is up and measure them from the table up to where they bolt to the hub. This is offset. The early rotors had .2 inch more offset.
The offset differs to match the caliper used. The early two piston caliper needs more offset so it wouldn't hit the spokes.
The later single piston calipers have the wheel side much thinner. They need less offset to not hit the spokes.
You can't use early calipers with late rotors or late calipers with early rotors.
If you have a 77 and want to replace it or add one besure it is a one piece rotor. They also used the same brakes on other Yamahas of the same years. The XS400, SR500, some of the XS750, XS850 and XS1100. The specials on some used a different front end and brake calipers and the rotors were smaller. If buying off ebay ask them to measure the rotor diameter. it should be 11.7 inches or 298 mm. If 10.5 or 267 they are will not works.
Some of the other models had centers that look different, they had slots, some 5 mm thick instead of 7 mm thick. These things won't keep them from working for you. Just be sure they are the same where they bolt to the hub.
I have a set of two that are slotted and 5 m thick and work great. I have another set of two that are slotted and are 7 mm thick. They work too. The sellers told me they both came off XS1100's. The thick ones I think so, not sure on the thinner.
I like the thinner they way about 25% less.
Leo
All years were the same diameter and thickness.
If you lay them flat on a table so the hub mount is up and measure them from the table up to where they bolt to the hub. This is offset. The early rotors had .2 inch more offset.
The offset differs to match the caliper used. The early two piston caliper needs more offset so it wouldn't hit the spokes.
The later single piston calipers have the wheel side much thinner. They need less offset to not hit the spokes.
You can't use early calipers with late rotors or late calipers with early rotors.
If you have a 77 and want to replace it or add one besure it is a one piece rotor. They also used the same brakes on other Yamahas of the same years. The XS400, SR500, some of the XS750, XS850 and XS1100. The specials on some used a different front end and brake calipers and the rotors were smaller. If buying off ebay ask them to measure the rotor diameter. it should be 11.7 inches or 298 mm. If 10.5 or 267 they are will not works.
Some of the other models had centers that look different, they had slots, some 5 mm thick instead of 7 mm thick. These things won't keep them from working for you. Just be sure they are the same where they bolt to the hub.
I have a set of two that are slotted and 5 m thick and work great. I have another set of two that are slotted and are 7 mm thick. They work too. The sellers told me they both came off XS1100's. The thick ones I think so, not sure on the thinner.
I like the thinner they way about 25% less.
Leo
jgimar
XS650 Addict
thanks but that doesn't help me. what i have is a '77 650D and some years back, i mounted dual discs on it. at the time i didn't know any better, or at least the "mods" i read didn't mention anything about the '77 discs being different from all the rest. so, i went to the local salvage yard and loctated me another disc and caliper and wala!, i have dual discs, except, i'm don't know from adam if they are both '77 discs. i am preparing for a big redo of my bike and will be dropping the dual look. i am curious if anyone knows the diminsional differences between the '77 discs and other years 650 discs. when i sell them off, i would like to be someone accurate of my description and not mislead someone. thanks for the help though
jgimar
XS650 Addict
leo,
thank you. that's what i was looking for. i think i'm okay but i needed to be sure. you've been very helpful.
jgimar
XS650 Addict
i'm just learning how to do the forum thing so if i repeat myself numerous times, forgive me. you guys got me the answer i needed. special thanks to leo. appreciate the time.
No problem, we were all newbies once upon a time. If you keep at it and learn more about these wonderful machines, you to can help others.
Leo
Leo
