Brake Systems Flush or Complete Rebuild?

Hello:

I have a 1981 GPZ with around 16,500 miles on it that I purchased recently and have begun to get it in good running condition.

The brakes (both ends) on my bike look good, brake pad thicknesses are within spec, the hoses look fine, the brakes' action seem to function fine, there are no leaks evident, and with the wheels off of the ground, they spin freely.

Since I am going over a lot of things: electrical, engine, and chassis, I'll be going into the brake systems at one point. Based upon your experiences and knowledge, should I do a complete rebuild of the brake systems, or just flush out all of the old brake fluid and replenish with new DOT3 fluid?

If flushing out the brakes systems is in order, is it okay to use isopropyl alcohol instead of new brake fluid? According to the factory service manual, this type of alcohol (and ethyl alcohol) can be used to clean the brake system components. I read on another site, that one guy does this. However, is it a problem to have any residual amount of alcohol within the system when backfilling with new DOT3 brake fluid?

It's a thirty year old bike, but based upon what I'm seeing on it, I don't see the need for complete rebuilds of the master cylinders and calipers, and hose
replacement. However, I can be swayed upon your comments and advice. I know how important brakes are. Who doesn't?

Thanks in advance for your feedback and advice.

Marty

What I usually do is take he calipers apart and clean out the grooves that the piston seal sits in. You can do it with a wire wheel on a dremmel tool. You can clean out the lines with a can of brake part cleaner and then blow them out with air. While everything is apart you can check for bad rubber parts. I have found that most of the time when the brakes stick it's because gunk and corrosion build up in the piston seal groove and that makes it hard for the piston to release back into the caliper.

My '77 KZ650-C1 (triple disks) has never had the calipers apart or the brake lines replaced and the brakes still work great. However, since it was new, I've flushed the brake fluid every 2 years, so it hasn't developed any nasty sludge, and the bike is kept covered or in a garage when not in use, so the rubber brake lines haven't deteriorated from being over exposed to the elements. The bike has just about 50,000 miles. I would not use alchohol or anything else other than brake fluid to flush the brakes, and if they "seem" to be in good shape, I wouldn't disassemble them. What I would do actually is try to gain access to a pressure bleeder, make an adapter, set the pressure at 12 - 15 psi, and pump about a quart of brake fluid through the brake system. You should be able to see very quickly if the old fluid if terribly funky or if it's just normal dirty. If it doesn't look too bad this simple flushing should be adequate. I use a KD-2222 pressure bleeder to do mine with an adapter made from an old master cylinder reservoir cap. It's fast, clean, and easy and it allows me to pump fluid though both front calipers at the same time; plus, I don't need to pump the lever. If you can track a bleeder down (you may find a garage that has one if you don't want to invest in one) and if you need advice on making the adapter, let me know. Ed

The factory Service Manual would have had the recommendation to replace the brake system rubber components several times by this age. They are also pretty cheap for the rubbers seals, the pistons are a bit more. But really this would be a big safety issue, and with the other work you have in mind, a "piece of mind when you clamp down hard."

Flush out the system with the newer DOT4 fluid. It is quite a bit better than the old DOT3

Motor Head wrote:

The factory Service Manual would have had the recommendation to replace the brake system rubber components several times by this age. They are also pretty cheap for the rubbers seals, the pistons are a bit more. But really this would be a big safety issue, and with the other work you have in mind, a "piece of mind when you clamp down hard."

OK, you gotta help me out here. I have 3 Kawasaki factory service manuals. They describe intervals for checking and changing brake fluid, checking brake pad wear, and adjusting brakes. They also tell how to rebuild each component of the brake system. However, I cannot find any recommendation to replace any of the rubber components or to rebuild anything unless damage is found or the system is not working properly. Please tell me what chapter you found this in as I have never seen this "recommendation.". Thanks, Ed

Sorry, I've got the newer Bike, 82 KZ1000. It says in the Lube and Maintenance chapter.
Every 2 years for the brake rubbers and 4 for the hoses. That's the FSM interval.
If you got a way to take it from the PDF and put it in the post tell me and I'll edit.

I managed to get a PDF to post by doing the following:

Open the PDF file
On the toolbar - click on "Edit"
On dropdown that appears - click on "Copy file to clipboard"
Open microsoft Word
On a new blank document click on "Edit"
On dropdown click on "Paste" (this should paste PDF in Word document)
Save the Word document

On KZR reply or new thread (at bottom) next to"Select file to attach" browse until you find the Word document then select it. That will put a link to the document in the reply.

I hope this made sense. Thanks, Ed

Try This?

Well thats not what I was hoping for, that's the table, copied to clipboard, moved to Word and attached.
I also down loaded a "Screen Capture Tool" but it doesn't seem to be saving the area.
Patton the man, but I don't see him online at the moment.

FSM's for Z1~'79KZ1000 say change brake fluid annually or every 6000 miles, whichever sooner, or if gets contaminated with water or dirt, but don't mention replacing any rubber brake parts as periodic maintenance.

The chart below is from Motor Head's post.

Good Fortune!

[Click on image to enlarge view.]

Patton, thanks for the post.
When you get a moment PM me with the way to do that right, Thanks.