Brake Fluid - DOT 3 TO DOT 5 ???

bluebikerblan · Posted: July 5, 2007, 8:23 pm Post subject: Brake Fluid - DOT 3 TO DOT 5 ???

I'm a definite proponent of DOT 5 silicone brake fluid and about to do some overhaul of the brake systems on my still new to me 78' SE. I'd really like to switch from DOT 3 to DOT 5 if possible while I'm at it. Has anyone made this change? Are their any known compatibility issues? Now would seem to be the time with new lines and seals since I'm sure a complete clean out is necessary. I've seen nothing in the archives on the subject. Thx

Retiredgentleman · Posted: July 5, 2007, 9:51 pm Post subject: Re: Brake Fluid - DOT 3 TO DOT 5 ???

Probably not a good idea. There can be complications using Dot 5 on old bikes.
go to..................www.xs11.com/tips/maintenance/maint1.shtml

bluebikerblan · Posted: July 6, 2007, 5:07 pm Post subject: Re: Brake Fluid - DOT 3 TO DOT 5 ???

Thanks for the info Sir.......I'm a member of AIRHEADS, know well of the
Beemer guru "Oak" referenced in the technical article above you site BUT;
had not seen that piece. Since the benefits are marginal and the compatibility risks undefined I think I'll leave it alone and stay with DOT 3 after getting the aged junk cleaned out and replaced with new. Thx for the time and attention and very good info. in the article. Best, Blue

mo650chopper · Posted: July 6, 2007, 7:00 pm Post subject: Re: Brake Fluid - DOT 3 TO DOT 5 ???

I'm running DOT5 brake fluid in mine without caliper problems. I'm running aftermarket HD master cylinders that required it + it doesn't F up paint. I had my calpers and piston completely clean & new lines when I did mine a couple years back. I don't know how XS master cylinders would react to it.

bluebikerblan · Posted: July 6, 2007, 9:55 pm Post subject: Re: Brake Fluid - DOT 3 TO DOT 5 ???

Yeah MoChopper....I used DOT 5 in my Harleys too but; was warned against doing so in the my Airhead Beemers hydraulics. So that's why the question exists re stock XS system. Silicone brake fluids are absorbed and will swell and soften some types of rubber. Probably not a great item to do road testing experiments on to find out?

Not long ago, I learned (after all these years) that DOT 3 & DOT 4 fluids are supposed to be changed out regularly. Bet there aren't 2 in 10 users that do it or perhaps even know that they should???

mo650chopper

I would definetly stick with DOT 3 if I was running all stock XS componets. I went to 1" bars and forward controls using the aftermarket DOT 5 master cylinders. I've done a lot of riding and been around drag bikes as well and have never seen nor heard of any problems with moisture and brake lock up. I consider brake to be the most important system on the bike, crashing sucks!

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