Brake fluid.

toglhot

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The caliper pistons on the TX were horribly pitted from the rust, so, I bought new stainless pistons, cleaned the callipers up and painted them. Six months later I finally got around to bleeding them but must have spilt fluid on the caliper as some of the paint was affected.
This time around, I ran a belt grinder over the calipers to remove all the casting roughness and repainted them. This time I' want to use Dot 5 as it is hydrophobic and supposedly doesn't affect paint.
But first I'd like to know if anyone runs Dot 5 in their brake system?
 

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Dot 5 is not hygroscopic and will not affect paint like dot 3/ 4, but the system has to be flushed of all dot 3-4 fluids. Some guys have used isopropyl alcohol to clean the original hoses. Dot 5 does entrain very small air bubbles and is sometimes hard to bleed. I have tried it but went back to dot 4 because of the difficulty in bleeding. If you do try it make sure all the other parts (master cylinder) are rebuilt and or cleaned first. Also do not shake the bottle of that dot 5 because you will never get all the fine bubbles back out.
 
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Rather than the potential hassle of filling with Dot 5 perhaps the answer is to be careful when filling and bleeding the brakes?
Areas that may be susceptible to spillage can be protected with clingfilm and provided any spills are wiped off immediately no damage will be done.
I would have used a paint that is oil and fuel resistant as this will give a little more protection e.g one of the VHT products.

I also use Dot 5.1 which is still Glycol based but has a higher dry and wet boiling point than Dot 4
 
2K is fuel and oil resistant, but that doesn't help with brake fluid. Spills happen no matter how careful you are. I don't even remember spilling any on the caliper, no idea how it got there. But if you can use something that doesn effect paint, and better still, is hydrophobic, is more compressible, provides better brake feel and is fade free, why wouldn't you use it.
 
is more compressible, provides better brake feel
?????
Recently looked around at brake fluids and IMHO if you just HAVE to change from 3 or 4, 5.1 for the win.
Madness has calipers that were powder coated clear DECADES ago, they are still in VERY good condition. no lifting, discoloration, or peeling.
Rotors have been changed for thinner late model units, new pads but I'm not sure I've ever touched the front brake fluid, prolly due for a rebuild.
Recently did front brake on a CB750, it was stuffed from sitting in a shed for decades, had to drag the front wheel, it wouldn't turn. caliper and MC cleaned and painted with high build fleet satin black, re assembled, and bled via the patented gggGary method, not a drop of fluid spilled, brake is "perfect" (for 70's tech).
 
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I tried DOT 5 years ago in one of my bikes because it was all the rage back then. The only benefit I found was it didn't hurt paint. I got no braking improvement. It was a real hassle to install because of the need to thoroughly clean out the system of all DOT 3. It's also quite expensive. I'd never use it again.
 
I Try to not deviate to much from what was available when the machine was designed.
Whatever machine it is.

There can be problems slipping clutches for some oils

And Seal formulations does not necessarily like the additives in the Chemicals available now.
We are talking 50 years developments XS 650
look at the Radio 50 years ago and today May even have problem find one for sale

I do run 20 W - 50 but Mineral so far
Furthermore Brakes is a Safety component .I perhaps don't change fluid as often as I should.
But I look in the service manual and a little never is OK I do that .But when it comes to the new " Snake Oils " I start shaking my head
Saying --- " You Can keep that overpriced **** "
 
Whilst Dot 5 doesn't attract water any that does accumulate due to condensation will pool at the lowest point.
If that happens to be at the calliper then the first you are likely to know about this is as it vaporises after giving the brakes some welly and/ or the corrosion starts to gum things up.

Also:
  • DOT-5 traps air bubbles easier which can lead to a spongy brake lever if precautions are not taken during filling and bleeding.
  • DOT-5 can be "squishy" compared to glycol based fluids. Again, a spongy lever. Using braided brake hoses helps restore some (but not all) firmness.
  • DOT-5 has less lubricity than glycol fluids. This can result in seals that weep a bit compared to glycol fluid.
  • DOT-5 can be abused. The fact that it does not absorb moisture can make people NOT change it periodically. Like all fluids, it does need periodic replacement.
  • DOT-5 is silicone based. While it won't damage paint, if spilled on paint, touch-up or repair of the paint can be complicated.
 
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I've used DOT 5 in a few XS250's in the past and I can say I've never had any problems with replacement seal material complaining. In all cases the entire system was re-built and the rubber hoses replaced with Teflon/Braid replacements. I would not use DOT 5 without a total rebuild. A very light coat of silicon grease on the seals, internal and external, and the pistons during re-assembly. Seems far more resistant to corrosion.
Please re-read the points raised above by Max, they are all valid and need to be taken into consideration if you do want to use DOT 5. I try just as hard to avoid spills with DOT 5 as DOT 3 etc.
Note: DOT 3 is somewhere around 20% less hydroscopic than DOT 4.
Side note: I'm intrigued, has anyone boiled fresh DOT 3 in these bikes systems?
 
The caliper pistons on the TX were horribly pitted from the rust, so, I bought new stainless pistons, cleaned the callipers up and painted them. Six months later I finally got around to bleeding them but must have spilt fluid on the caliper as some of the paint was affected.
This time around, I ran a belt grinder over the calipers to remove all the casting roughness and repainted them. This time I' want to use Dot 5 as it is hydrophobic and supposedly doesn't affect paint.
But first I'd like to know if anyone runs Dot 5 in their brake system?
If you change your brake fluid annually, you won't have to worry about it.
 
2K is fuel and oil resistant, but that doesn't help with brake fluid. Spills happen no matter how careful you are. I don't even remember spilling any on the caliper, no idea how it got there. But if you can use something that doesn effect paint, and better still, is hydrophobic, is more compressible, provides better brake feel and is fade free, why wouldn't you use it.
Your using the wrong word. Hygroscopic not hydrophobic
 
Nope, Dot 5 is hydrophobic, hydrophobic means lacking an affinity to water, Dot 3,4,5.1 is hydrophobic, ie. Dot 5 is also silicon based so doesn't affect paint.
Dot 3,4.5.1 is hydroscopic. Hydroscopic means readily taking up water and moisture.
 
I have DOT 5 in my early model V-Rod which was original and love it, but as others have mentioned you will need to clean/flush the entire system to change as the two types are not compatible. What I like most about it is it doesn't affect paint or powder coat like DOT 3 or DOT 4 will. I've had no trouble flushing and bleeding.
In 2006 when HD switched from Kelsey Hayes to Brembo as their brake provider they went back to DOT 4
 
I have DOT 5 in my early model V-Rod which was original and love it, but as others have mentioned you will need to clean/flush the entire system to change as the two types are not compatible. What I like most about it is it doesn't affect paint or powder coat like DOT 3 or DOT 4 will. I've had no trouble flushing and bleeding.
In 2006 when HD switched from Kelsey Hayes to Brembo as their brake provider they went back to DOT 4
Looks like the brake fluid debate is almost as intense as "which oil should I run" LOL
 
Looks like the brake fluid debate is almost as intense as "which oil should I run" LOL

The solution is simple just dont Change it .. Eventually the piston will rust and seize up after ca 15 - 20 years.
The you take it apart and refurbish.
The JIS screws on the front reservoir top are impossible to open anyways
( Just joking of Course )
 
A spray bottle of water will save any paint or plastic that you spill on. Hose off the whole thing when you're done to save everything from spills that you didn't notice. It works !!!!!!! So, when adding fluid or bleeding brakes, be ready to spray and hose instantly.
 
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