1980 Kz750E Front Master Cylinder

You must be way more picky than I am Matt.  That M/C looks very nice to me.

Rick H.

wrote:

You must be way more picky than I am Matt.  That M/C looks very nice to me.

Rick H.

Thanks Rick. 

I'd say it looks 99.9% better. hee. That m/c is kind of a poor design & has a tendency to leak at the cap, maybe consider using a sealant of some sort on the diaphragm.  I refurbished mine a few years back, cleaned the grooves thoroughly & installed a new diaphragm. used an awl to scrape off the hardened crud & hit the groove w brass wire wheels. but it still leaked within a year.   At the time I thought about using a sealant. probably should've done.  Here's a pic from an old clymer manual.


Baking a Fr Br m/c in the oven. www.kzrider.com/forum/6-paint-a-bodywork...c-in-the-oven#774813

Martin_csr. Thanks for posting the link to your M/C restoration. I was thinking of baking the M/C but was worried about the site glass. I was thinking the glass and seal should handle a temp at least if not higher than the boiling point of the fluid. Just a guess. I’m going to bake it similar. I fit the diaphragm yesterday and it seamed shrunk up. I like the idea of getting a NOS. 

That diaphragm is NLA & probably pricy on EB.  Honestly, I would consider reusing the old one & install w a very light bead of sealant.  It's kind of the pits to go thru all the trouble, get it all nice n pretty, install a new diaphragm, then still have it ruin the paint.

Thanks to martin_csr for the confidence to oven cure the M/C. First cure was about 145 of 30 minutes. Second was 200 for 45. All turned out great. Assembly tomorrow and then on to the front calipers. 

Thoughts on using DOT 5?

 

DOT5 is okay if everything is fresh and clean (new lines, rebuilt calipers) if I remember correctly. I like the idea of it not eating paint; however, I'm uncertain if I like that it doesn't absorb water. I just use cheapy DOT3 and it's fine. 

Wow reading up online about DOT5 is rough it’s either “I’ve used it for 25 years and love it” or “I had nothing but problems. It trashes the pressure switches, and the brakes fail diving up in the mountains. I flushed it out and went back to DOT4 and not a problem sense”. 

 

DOT 4 for sure.  5 has drawbacks and only minimal upside.  

I haven't used DOT5, but I read a bit about it when I was just rebuilding the brakes on my Z1R.  The thing that scared me off was that DOT5 and water do not mix at all, and this can allow any water that does manage to get in to accumulate at the lowest point in the system in a puddle.  That didn't really seem appealing to me.  Bleeding DOT3/4 out of the system is pretty fast, and it carries any accumulated water away with it.  That seems fine.

DOHC, I read similar things. I was looking at the paint safe aspect. It seems as Nessism mentioned it has drawbacks and minimal upside. I’ll stick with the DOT5.

Assembly went smooth. Just need to get a replacement cover screw. Need to pull the calipers and get a look at them. 

Thanks.

Here the finished product. Minus the cover screws.