1976 KZ400 D3 Front Brake Caliper Issues

Hi all.

I recently removed my front wheel, which required me to remove the front brake caliper. Curious that I am, I squeezed the brake lever several times while the caliper was off of the disc. Both pads have fallen out and my piston is now stuck all the way out.

I made matters worse by attempting to remove the caliper from the brake hose, and rounded the bolt in the process. No amount of WD40 & plying has made it budge.

I also ended up draining the brake fluid entirely.

I'm pretty stuck - what is the plan of action here?

Here are 2 links to the schematics of the caliper n front hub. Some of the parts are still available from www.cmsnl.com and shipping is quick, 3-4 days.

Caliper: www.cmsnl.com/kawasaki-kz400d3-1976-cana...model_q=1976+kz400d3

Front Hub: www.cmsnl.com/kawasaki-kz400d3-1976-cana...t/52451.html#results

On my 75, the piston was also frozen inside the caliper. We soaked it in the parts cleaner for a few days and had to heat it up afterwards to get it out. Lots of corrosion, but we got it all cleaned up. I hope you get yours fixed up.

Hopefully you didn't mess up the piston seals. Those have been unavailable for years. I would heat the caliper up with a heat gun or hair dryer and try to work the piston back in. Be careful, you do not want to damage those seals (there are two).
Heat is also your friend for the stuck bolt. That and penetrating oil. Soak the threads for a couple of days and use heat to work that bolt out.
Good luck

GPzGuy, Im wondering what the difference is between the 74-75 caliper and the 76-77 caliper...from the schematics everything looks the same...

I think the piston size is different. Are the part numbers the same? Too bad the KZ400.com site went away. This was much discussed on there.
I am in contact with a guy who is having them made. Not cheap but you shouldn't need to replace very often. I should have one in my hand soon for comparison. Fingers crossed.

If you like, I could measure the distances between the mounting holes and what not on the 75...seems the 74-75 caliper parts are plenty vs the 76-77. My 77 cadaver has the entire kit still in tact...wonder if you could put the 74-75 caliper on in its place...

ThatGPzGuy wrote: .......... Too bad the KZ400.com site went away. This was much discussed on there.
.....................

That site didn't go away. The link below goes to it. Ed

www.kz400.com/index.html

Right you are Ed. I meant the KZ400 Forum.

Hi all.

Here's the update. Bolt is still stuck but I managed to get the piston unstuck and put back into proper position!

New issue:
Should the smaller brake pad be loose, or should it be attached to the caliper in some way?

Jack_Mills wrote: If you like, I could measure the distances between the mounting holes and what not on the 75...seems the 74-75 caliper parts are plenty vs the 76-77. My 77 cadaver has the entire kit still in tact...wonder if you could put the 74-75 caliper on in its place...

The caliper seal part number is the same for the caliper on the 74-79 kZ400. You were able to find a new seal? I did a whole fork/ caliper swap because there were no seals available.

I got the dust seal and the piston seal at www.cmsnl.com arrived in 3 business days from Netherlands for my 75kz400. Best thing to do is search their site fully and grab any parts you need all at once (saves on shipping)...

If you search under 1976 KZ400D3 the seals are unavailable. Partzilla shows the same thing.
What is the diameter of your caliper piston? Mine is 41.3mm.
Anyhoo, I rec'd my "new" seal from the guy on eBay so I am going to be trying that one today. Unfortunately I need to re-use the wiper seal. I'll report back the results.