Brake Systems Flush or Complete Rebuild? - 1981

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 thickness 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 master cylinders and calipers, and hoses replacements. 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

id just flush it with new fluid

All:

Oops! Forgot to put this post in the Chassis section. Will do.

Sorry.

Marty

I have had good luck using a good quality brake cleaner spray like CRC or Advance Auto store brand.I would take everything appart and spray out the lines,front splitter,and wash out the calipers spraying into the inlet,and letting it run out the bleeder hole.It's a good way to pre-clean the components if the old fluid is all gunky.Then flush it thru with new fluid.Personally,I use a full synthetic DOT 4 type.It doesn't absorb as much moisture as regular fluid.If the master cap rubbers are "iffy",replace them too.

How lucky are you?

When I swapped out my 79 front master cylinder for one off a 96 GPz1100, I wasn't very lucky. Since I flushed it out with new brake fluid and everything worked good prior to install I went ahead and used it. Week later, when going into a 90 degree corner a little hot, front master cylinder decided it was time to retire.

At least I didn't brake any bones when I low sided that time, so I had at least a little luck.

I flat refuse to install a used master cylinder without rebuilding it first now.