Topic: 1978 front caliper interchangeability?

[vlocci]

I’m rebuilding a ’78 CB750K8, and have a stuck piston in the front brake caliper.  After a weekend of soaking, it refuses to move.  I’m looking to simply replace the front caliper.  Does the 77-78 front caliper differ from a pre 77 part.  Can I just swap on a pre 77 part without any changes?

[Bob Wessner]

Before you go to the expanse and trouble of replacing the entire caliper, give the piston another try. Either do a search here for various methods or, my favorite which worked like a champ was lightly screw a small grease gun into the brake line end of the caliper and make sure the bleed screw is tight. Give it a few pumps and the grease forced the piston right out. Some use compressed air (which I didn't have access to) but this avoids the possible explosive discharge of the piston that can happen with the compressed air method. Clean out the grease, replace the piston seal and the piston if it is pitted and corroded. Also clean out the recess in which the piston seal sits really well, I used a dental pick.

[jgary]

I just went through this stuck piston stuff this weekend.  I used a combination of WD-40 and a hammer to get the piston to move at all.  After that, I used a portable compressor that plugs into a cigarette lighter as my source of compressed air.  It took a few tries, but I finally got it apart.  Kept the whole thing in the bed of the truck, which turned out to be a really good idea.  Once that piston came loose it came out like a shot. 

John.

[vlocci]

I'm afraid to admit the thing is stuck...  Tried 150 psi compressed air to no avail., even after spending the night soaking in penetrating fluid.

Even tried the greasgun trick, and went to 800 psi of pressure before giving up.  At this pressure it is easy to do some serious damage.  Honestly this thing wont move, and I'm afraid of going much higher on the pressure side.  Even if I do manage to get the piston out, I'm guessing the piston bore will be all scuffed up.

So back to the original question, will a pre 77 part swap on?

[vlocci]

Did manage to get the piston out of the caliper after some serious pressure.  Bore of teh caliper is pitted beyon duse.

So back to the original question, will a pre 77 caliper bolt onto a 78 front fork?

[cben750f0]

mate check ebay, they have heaps of parts, and from what i can remeber about 2-3 78 fronts.... there should be calipers on there somewere... goodluck...peace

[rob]

One thing I have found useful was the website, www.bikebandit.com, and their OEM parts list. 

You can select various years and styles and then check the schematic to see if the parts are the same.  I recently did this, and found that quite a few models made in the early 80's use the same brake fluid reservoir system.

Rob