1100 rotor sizes

[Sflex]

I am in the process of swapping the front end on my 83' 750t to a front end from an 83 1100 of some sort. The problem is that I cannot mount my calipers (from the 1100 front end) with the rotors that I have (from a spare 1980 750 wheel I had) the rotors seem to be about a mm or two too wide. I thought that the rotors were the same for the 750 and 1100 from 80' through 84' but apparently not. My question is, what rotors do I need? Are all the 1100 rotors the same (E, ES)? are other 750 rotors compatible? I would appreciate any help.

Thanks

[salty_monk]

I have rotors from a 1980 GS1000G & a 78 1000E if they are any use to you.....

I also have calipers off the G too. Rotor size is about 294 from memory, maybe 296mm. The wear limit on both is set at 4.5mm. The G's are slotted. The 78's are solid.

Dan

[bwringer]

IIRC, the rotors themselves should be the same, but is the wheel different?

In other words, are the rotors spaced farther apart?

[psyguy]

as brian said, i also think all the '80 and up rotors (and the calipers too i think) are the same so your prob is likely to do with the forks/wheel spacing

[Sflex]

I see how one wheel could be wider than the other, and the outer tire diameter can be different, but how could the distance from the center of the axle to the rotors be any different from wheel to wheel if the rotors bolt up? Am I missing some kind of spacer between the axle fork? I have one in there and it looks normal.

[bwringer]

The width of the wheel where the rotors bolt on may be different. With the wheel mounted to the motorcycle, straddle the front wheel and look straight down. How wide is the hub between your knees?

If you can, it would be best to use the entire front end from the donor bike so things will line up. Even though the brake calipers and rotors are the same between these models, the caliper mounting holes on the fork legs and the width of the wheel hub may be different. I believe there's more space between the fork legs on the 1100 front end.

I hope I'm not misunderstanding your problem here.

[psyguy]

some 750s have smaller diameter forks compared to larger models
that would be one way how the things would not line up unless you're swapping the entire front end

[Sflex]

I have swapped the whole front end, the only difference is the tire and rotors. Its not the width, the spacers seem to work fine. Its that the calipers wont fit over the rotors and attach to the mounts on the forks. If the calipers were about 2 mm less in diameter they would be fine. any suggestions guys?

[Suzuki_Don]

Mock it up and give us a photo if you can. Have you mounted the caliper in the original position. Is the caliper on the correct side of the lugs on the forks. Compare both sets of forks and see what the differences are. Swap the old forks back in with calipers attached, it might let you see what you are doing wrong with the other set. Just grasping at straws here, but when the obvious doesn't work then you have to go for the unobvious (is that a word).

[psyguy]

take the calipers off the brackets and take the pads out as well
try mounting first the brackets then the calipers
that might help figure out whats going on

[Sflex]

I have tried mounting just the brackets and they bottom out on the rotors, its like the rotors are a couple mm too long. You guys are sure that all the rotors are the same size? Im stuck here.

[psyguy]

take a few pics

i havent yet heard of a prob guys here couldnt solve

[Suzuki_Don]

I have tried mounting just the brackets and they bottom out on the rotors, its like the rotors are a couple mm too long. You guys are sure that all the rotors are the same size? Im stuck here.

All rotors are not the same size. Are your rotors the slotted ones. I have three different sizes of slotted rotors from memory. Whether they are just on bikes for OZ I don't know. Give us a picture. Measure your rotors for us. Are the mounting lugs on both front ends the same distance apart from each other and the same distance from the axle location. Give us some pics of both front ends, the front wheel and rotor, dummy up the front end for us. We need more info here. So we can help.

[Suzuki_Don]

I think I might have latched on to something here. The 750T only had a single disc if I am correct. And Suzuki's habit was to mount a large disc on the single disc models. All the 1983 1100's had twin discs so going by this theory their discs would be smaller. Therefore the larger disc that is still on your original 750T front wheel is too wide to let the 1100 caliper sit all the way down to mount on the fork leg properly.

All the '83 1100s had twin discs and they all have the same part number. So there are no variations on disc size on the 1100s of that year. The disc off your 750T has a different part number, and this disc was never fitted to any 1100s. So I would suggest that your single disc (I am assuming that is what you have as we don't have that information) is larger in diameter than the 1100 discs which the front forks and calipers came off.

[Suzuki_Don]

If you get the rotors off an 1100 they should bolt straight up to your 750T front wheel. No problems. BTW I have a CBR900RR front disc on my GS so all type of mods are possible.