77 GS750B Front Caliber - What make/model will swap?

[93Bandit]

The mounting holes are 72.43mm or 2-27/32" center to center, give or take a hair.

Since the calipers are already off of the forks I struggled to get the bolts (axles?) out to separate it and check the piston. It got late and it's cold in the garage too. I may try a bit of compressed air to move the piston tomorrow. The climate here and in Colorado where this bike lived is pretty dry, plus all of the fluids I drained from this 650 were the appropriate colors so the PO took care of maintenance it seems.

What if you took both calipers, the fork legs, rotors and scrounged up a spoke wheel that you could put another rotor on. That'd be a sweet upgrade. Sounds too easy though. The upper fork tubes are 35mm. Would they even fit a 750? These are 31-3/16 long from the top to center of the axle.

I set my dial caliper to 72.4 and held it up to the mount holes on the fork leg. Looks like that dimension is the same so the caliber should mount. Whether or not it's the correct offset or not, I don't know.

I measured my fork tubes and they are 35mm and ~31" long as well, so they would likely fit a 750. However, that's a bit more involved than I wanted to get right now, not to mention I wouldn't be able to afford the shipping costs on all that.

As for piston movement, don't worry about it. Wouldn't hurt to rebuild it anyways probably. I'll PM you.

[Grimly]

Only thing I found as a gotcha was the L model forks have a different caliper mounting bracket, because of the axle position and the placement of the caliper on the disc as a direct result of that. However, the caliper is the same, so acquiring another pair of standard caliper mounts sorted that out.
I'm not even sure the 750 35mm fork legs even had an L model to muddy the waters, anyway.

[93Bandit]

Only thing I found as a gotcha was the L model forks have a different caliper mounting bracket, because of the axle position and the placement of the caliper on the disc as a direct result of that. However, the caliper is the same, so acquiring another pair of standard caliper mounts sorted that out.
I'm not even sure the 750 35mm fork legs even had an L model to muddy the waters, anyway.

That would make sense, the differences between G and L due to L axle placement.


Roger is sending me all 3 calipers from the 650G. I will be sure to update the thread once they arrive and are installed.

Thank you again to all those who helped out!

[93Bandit]

The calipers Roger sent me arrived today. I'm under the weather so won't be able to check fitment for at least a few days, but I'll update as soon as I get the chance.

[93Bandit]

Finally had a chance to get back on the 750 yesterday. thought I'd update this thread in case anyone in the future needs the info. I test fitted the 82 GS650G front L brake caliper on my 77 GS750 and it fits perfectly.

[Grimly]

Just to clarify - the caliper is mounted on your old bracket and not the L bracket?

[93Bandit]

L bracket??? My 750 is a 77, L version wasn't available at that time as far as I'm aware.

I'm using the 82 650G Left caliper on my bike, bracket and all. Bolted right up, no issues at all.