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Post by jeronimo on Feb 28, 2008 3:32:25 GMT -5
Good Morning, everyone! Please indulge me on this one. I've been going through my '78 SR, and was discussing it with a co-worker. He claimed that I can run Dot 5 brake fluid as long as I have completely removed all of the old type, which I have done with a complete rebuild of all the brake components with new SS lines. I want to believe the man, but alas, he's a car guy and not a motorcycle guy. Any advice would be greatly appreciated. Thank You. Jeronimo
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Post by bigshingle on Feb 28, 2008 9:46:52 GMT -5
Jeronimo, no, no, indulge me on this one — I insist.
Why do you want to use Dot 5? Is there some problem with Dot 3 I haven't heard about?
Thanks, José
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RD
Full Member
Posts: 176
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Post by RD on Feb 28, 2008 14:15:37 GMT -5
Hi guys
from deep in the bowels of my memory (it's filthy down there) DOT5 is silicone based so has a higher boiling point and won't remove paint.
cheers
Rich
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Post by jeronimo on Feb 28, 2008 14:17:17 GMT -5
In response to bigshingle's query: Considering the crap I cleaned out of the system after it not being changed in 30 years, and considering the supposed reduced maintenance requirements of Dot 5, that's why. Does that answer your question, Jose?
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Post by G Man on Feb 28, 2008 16:08:30 GMT -5
Dot 5 is a silicone based brake fluid. Yes, it does have a higher boiling point than 3 or 4. Dot 3 and 4 brake fluids are hydroscopic and will absorb water right out of the atmosphere if left exposed. They also blend very well with any moisture or water in your brake system. Water in the brake system can of course cause the internals of your brake components to rust over time. However, as the dot 3 and 4 fluids do fully absorb it well, any moisture would be spread out fairly evenly and may not gather and concentrate at the lowest points. You also have a fighting chance of removing it from your system easily with fluid replacement on a bit of a regular schedule. (read, more than once in 30 years) By absorbing the water fully, it is not left to gather in the lowest point such as the calipers where it could boil and cause a mushy lever or worse a loss of brakes. Silicone based fluids such as dot 5 do not absorb water at all. Any moisture than gets into, or forms in your brake system will naturally be forced to the lowest point in the system such as the calipers, whereby lowering the boiling point there and negating any perceived advantages of the silicone fluid. If you could guarantee no moisture, then the higher boiling point can be perceived as an advantage of the dot 5. However, another nasty point of silicone fluid is that it will firmly attach itself to any sludge or dirt in the system and could create issues. Silicone fluid is almost impossible to remove from a system once installed. The only real way to ensure none would be left if one wanted to switch back to dot 3 or 4 would be to strip the brake system in its entirety and replace ALL components.
Ummm, I kind of rambled on there for a bit...
Good luck,
G Man
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Post by bigshingle on Feb 28, 2008 17:51:26 GMT -5
Does that answer your question, José?
Yes, lots of good answers. Thanks all around.
I'm redoing the front master cylinder and last week I bought a bottle of Dot 3 I haven't opened. So I thought if there's something wrong with it I won't use it. I'm pretty good about maintenance, so now I know there's probably no reason to take the bottle back and get Dot 5.
Looks like Dot 3 will do fine, if not for 30 years, well, maybe for 5. That's good enough.
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Post by chew652 on Feb 28, 2008 19:19:27 GMT -5
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Post by bigshingle on Feb 28, 2008 21:13:44 GMT -5
Chew comes through too. Thanks. As you say, that pretty well sums it up.
We're in an election year here, so if you want to write a message on a car that has bumper stickers you don't approve of, Dot 3 or Dot 4 is the ticket. Don't waste your time with Dot 5.
Jeronimo — I realize now my post may have offended you. No offense meant. As you're starting to see, this is heavily an Aussie site, and people say things back and forth that in American biker bar would cause gun-play.
As for Dot 3/Dot 5, as another Oklahoman (Will Rogers) said: "It's not what I don't know that bothers me, it's that I know so much that's wrong."
That's why I was asking why you wanted to switch fluids — I should have put a smiley face at the end.
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Post by jeronimo on Feb 29, 2008 3:42:46 GMT -5
Yes, that sums it up very well for me as well. Thank you gentlemen. And thank you bigshingle for that quote from the great statesman and fellow "Okie", Will Rogers. Now I can lay down my arms and get on to restoring this bike! Please understand that I do all the maintenance on my KLR and intend to do so on my SR once completed. This bike was entirely stock down to the original tires, brake fluid, etc., not too sure on the engine oil/filter. 7,000 miles on the clock. Anyway, considering the cost of rebuilding my brake systems, I thought that perhaps the Dot 5 would keep my brakes in great shape for a long time to come. I'll just have to do a better job of maintaining than the previous 2 owners. Thanks again to all of you! Jeronimo
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Post by miker on Feb 29, 2008 10:30:52 GMT -5
Jeronimo, pick up a set of speed bleeders and put them in before you fill the system - makes flushing dead easy, you'll do it every spring just for the fun of it.  miker |
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Post by jeronimo on Feb 29, 2008 13:46:38 GMT -5
Already got 'em, miker! I have them on my KLR as well and they do work well. I bought a banjo bolt brake switch for the rear to get rid of the ugly contraption Yamaha slapped on there. Hope it works alright.
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