• Can't post after logging to the forum for the first time... Try Again - If you can't post in the forum, sign out of both the membership site and the forum and log in again. Make sure your COG membership is active and your browser allow cookies. If you still can't post, contact the COG IT guy at IT@Concours.org.
  • IF YOU GET 404 ERROR: This may be due to using a link in a post from prior to the web migration. Content was brought over from the old forum as is, but the links may be in error. If the link contains "cog-online.org" it is an old link and will not work.

Brake fluid service life

C

CC Rider

CC Rider
Member
Just as winter hit, my front brake suddenly got squishy, finally to the point where the bike was unrideable. Hmm, old brake fluid or time for a rebuild?

Two years ago I replaced the (2-year old) original, cheap brake fluid with Motul RBF 600. The difference was huge. Bled the brakes today with fresh RBF 600. The first thing to come out of both calipers was a small slug of brownish white crap. The rest looked OK. Brake performance is much better but not as good as when the switch to RBF 600 was first made.

Neither clutch or rear brake have fresh fluid (duh, shoulda done that, it's next on my list). But they are both fine, with 4-year old (cheap) fluid. Then again maybe the rear is contributing squishiness.

Motul RBF 600 has an 18-24 month service life, RBF 660 (wow, expensive!) has a 12-month service life. My takeaway is that premium brake fluid has a much shorter service life and MUST be changed every 12-months.

I'm thinking cheap brake fluid might actually be better for the clutch and rear brake. They don't see super-high temps, and much as I like bleeding stuff, changing every other year in future would be OK.

My 1988 ZX10 went 30 years before it had a brake rebuild. Hopefully RBF 600 has been kind to the brake seals and master cylinder.
 
i just did my brake pads and clutch / brake fluid. easy job. used some good dot 4 not that expensive except i need to start buying smaller bottles. getting into the habit of doing this every 2 years. one mechanic said i should always replace the diaphragm, and right he was. after that everything worked so much better. i was a bit surprised as the brake pads were still good but after replacing them the brakes are biting hard especially the rear brake surprised me. not sure if i had different kind (organic?) brake pads on before.
 
redline said:
i just did my brake pads and clutch / brake fluid. easy job. used some good dot 4 not that expensive except i need to start buying smaller bottles. getting into the habit of doing this every 2 years. one mechanic said i should always replace the diaphragm, and right he was. after that everything worked so much better. i was a bit surprised as the brake pads were still good but after replacing them the brakes are biting hard especially the rear brake surprised me. not sure if i had different kind (organic?) brake pads on before.
Click to expand...
"Always replace the diaphragm". Thanks will do. What difference did it make?
 
Always replace the diaphragm eh? The ones in the reservoir lids, presumably? That may help to keep some moisture out but testing the fluid for moisture eliminates guesswork.
 
I've been thinking about this recently, after flushing and replacing all fluids on the C14.

I just replaced the brake fluid on my wife's car because it seemed like a good idea.

But my 20 yo car is running fine with the original stuff.

So do we really need to?
 
I replace all 3 reservoirs when I get my C14 out of storage every season. The old fluid is always darker than new (moisture in it) and I get the chance to make sure all air is out of the system. A couple bottles of BelRay brake fluid is cheap insurance to know I always have optimum brake performance.
 
Freddy said:
Always replace the diaphragm eh? The ones in the reservoir lids, presumably? That may help to keep some moisture out but testing the fluid for moisture eliminates guesswork.
Click to expand...
yes the black rubber cover inside the reservoir. doing that every 2 years is really not that expensive. the front brake and clutch use the same, the rear is different (round)
 
redline said:
yes the black rubber cover inside the reservoir. doing that every 2 years is really not that expensive. the front brake and clutch use the same, the rear is different (round)
Click to expand...
Great tip. I plan to replace mine this spring. They likely are the originals and 15 years old!
 
You must log in or register to reply here.
Top