Topic: 77 750 SS, rear wheel lock up...

[Lumbee]

...sup all...picked up a basket base 77 750 last weekend.  Got it running today and took it for a maiden voyage around the block.  Notice it seemed sluggish, then stoped and noticed the rear brake was smok'n like Tyra Banks in a mini skirt!  Thought I was gonna have to walk home and get tools to get it unstuck, but I pumped it a few times and it freed up.

...I've read about this b4 so it must be a common problem.  Is there any maintanance I can do to clean the caliper up, or is a rebuilt a must?

I know everyone likes pics, so here ya go...

[Lumbee]

...oh, also a question about the comstars.  Is the entire wheel aluminum?  I thought it was, including the "spokes" that attached the rim to the hub.  Now I'm questioning this becuase this bike had a fair amount of rust on the spokes, and I thought aluminum didn't rust?  I hit them with a wire brush on my drill, and they look pretty good, but I'm wondering if they'll just rust again?   

[Jughead]

Sounds like the Caliper is getting Crudded Up on the Inside.The Caliper on my 78 F2 was Frozen up when I got it.You can Probably get by with popping the Piston out and cleaning it out.If the Bore of the Caliper is  Corroded you can Hone it out a bit.If the Seal isn't Leaking you can Probably reuse the seal.If the Piston is Pitted you can Probably get by with smoothing it down with a Little Crocus Cloth.

[Lumbee]

...yea, the rear brake was pretty cruddy around the MC, I cleaned that up today, so I image the bottom end probably has some junk in it too...

[Sam Green Racing]

Mark, your rims are aloy but the spokes are for want of a better word, pressed tin.

Clean rust down to bare metal, prime and paint.

Nice Christmas present

Sam.

[Lumbee]

... thought they were a little to heavy to be aluminum...

[Sam Green Racing]

Wouldn't have thought they were that heavy, the ones I have seen have been quite thin.

[Chris in Ramsey]

The rear brake on my '78F would lock up on once-in-a-while at the MOST in-oppertune moments and finally seized up when I stopped at a border crossing from British Columbia into Washington state. Had to get the tool kit out and loosen the caliper to release the death grip on the disk.(minor traffic hold-up) When I tore it apart to clean it up I discovered that the circlip holding the master cylinder together was corroded so badly that it cracked and part of it twisted and jammed the piston enough to prevent it from releasing. Good luck

[Terry in Australia]

Wouldn't have thought they were that heavy, the ones I have seen have been quite thin.

Merry christmas Sammy! The comstars on an F2/F3 were alloy hub and rim, with steel spokes. About the same weight as a conventional steel spoked wheel with steel rim, but enormously stronger, and not as susceptible to torsional flexing as a conventional wire spoked wheel.

Of course you can run modern tubeless tires on a Comstar rim, so they're safer as a tubeless tire won't "blow out" like a tubed tire. If you've ever had a "Blow out" on a bike, you'll never forget it!

The later Comstars were all alloy, and extremely light. i've got one sitting in my garage (off either a CBX or CB900F) and compared to a cast alloy rim of the same era (Suzuki GS1000S) the all-alloy comstar probably weigh less than half! Cheers, Terry.