Topic: brake fluid

[ev0lution7]

I know this has been asked time and time again.. but i did a search and couldnt find a CLEAR answer..

i'm rebuilding my front brakes (77 CB750) i've put a factory (Honda) master cycl rebuild kit in stainless steal braided lines.. rebuild caliper (new piston brakes and piston Seal) and have flushed and cleaned all other assoated lines.

so my question is will there be any advanteges to running DOT 5 over Dot 3?   i realize they are NOT compatable so that is why i'm asking NOW because i'm replacing EVERYTHING and didnt want to ask this AFTER my brake seals touched DOT3.

[TwoTired]

There isn't a CLEAR answer on this forum.  Only personal opinions.

But, the decision to convert IS one way.  Silicone is very tenacious stuff that you can't totally remove from the system.  That's why the US military doesn't convert away from silicone fluid in their fleet.  No way to throughly flush it.

Water doesn't mix with it.  But, it still gets in the system and the innards corrode over time.  So, you have to change it just as frequently as Dot 3.  The military learned the hard way there is no savings in routine maintenance.
IMO the ONLY thing going for it is that is doesn't damage paint.  If that is your priority, make the conversion.  Otherwise, stick with DOT 3 or convert to Dot 5.1.

You have to replace ALL the seals and rubber bits for the conversion, as they are permeable and absorb some fluid.  This then mixes with whatever you converted to, negating any purist fluid idealistic qualities.

Silicone is slightly more compressible than DOT3 or 5.1.  Some report noticing the system as slightly more spongy.

Many that have converted, swear by it anyway.  But, I'm steering clear of it.

Cheers,

[eldar]

fluid is fluid. It all does the same thing, works the same way. Just cant be mixed.
Water will get into a system no matter what but the process has been slower in my brakes. I change fluid every 2 years on the synthetic fluid I use. With dot 3, it was every year because it needed it.
before I switched, every new season began with cleaning out the caliper as there was ALWAYS corrosion. Dot 3 attracts water very well.

Facts are that both work fine and there really is no HARD evidence other than dot3 attracts water and can ruin paint if left on. You cannot mix them.

[ev0lution7]

like i said everything on the system is being replaced and cleaned. so it seams that i should just stick with Dot3?

[Gordon]

like i said everything on the system is being replaced and cleaned. so it seams that i should just stick with Dot3?

No one's going to give you a direct answer to that (well okay, somebody probably will ), but you'll get lots of opinions.  Do a search for Dot 5 on the tech forum (not from the top of this thread), read through all the topics, and make a decision for yourself.

[eldar]

Either one. both work just as well. AS stated above, everything else is personal experience.
For me and others, dot 5 is great. Others have not tried it. Most that go against it have not tried it themselves but heard about it from others.

Military exp might account for something but given how wasteful the military is, and having an uncle who was an f16 mechanic, their experience is not the end all.

Your brakes will work either way, you just have to flush dot3 more and make sure it does not sit on paint.

[crazypj]

 We've been here before haven't we
I have used DOT 5, had problems with it and wont use it again.
 Flushing the system doesn't work, you have to physically remove the pistons to clean them.
 So, even if you only do it every two years, you end up doing more not less work. ( silicon floats on any water that gets in the system through condensation and doesn't move high enough in caliper to get flushed out)
 I think maybe TwoTired  posted this link originally
http://www.motorcycleproject.com/motorcycle/text/cows-brakefluid.html
 read it and make a relatively informed decision
PJ

[eldar]

What issue did you have?
I always had good luck with dot5 but then everyones experience is different.

What happened to you?

[crazypj]

Flushed system every year, after 4 yrs the pistons and master cyl bores were so corroded they needed changing.
 Luckily, the CB550 has same calipers as the CB/CJ range so parts were not a problem. Early CB750 calipers are different so that could be a problem if you get excess corrosion.

PJ

[eldar]

Hmmm. I had corrosion with dot 3 but nothing further after I switched. I do ride in the rain once in a while. Not on purpose but have been caught in it.

Very interesting.

[crazypj]

I fitted braided stainless lines when I changed to silicon fluid, you don't have to ride in the rain, water vapor actually permeates through the rubber seals/bellows
 I lived in Britain at the time but I think Florida would actually be worse as humidity here is higher most of the year.
In Britain its either raining and 100% or it isn't, in Florida its 80~95% humidity a lot of the time.
 It probably makes a difference where you live, high desert with low humidity, probably not a problem, coastal area's, maybe
PJ

[eldar]

Well up in ND, it gets quite humid but does not always stay that way. Maybe that is the difference.

[bwaller]

Can I give one more opinion without starting anything?

I've tried DOT5 and switched away from it also. I can only attribute it to the fluid not being as good a lubricant, I really don't know, but I found the pistons wouldn't retract as well.

That being said I'm also guilty of leaving the DOT3/4 too long between changes and this spring needed to replace the pistons.....again. (it's been six years and the bike is stored in a heated shop...#$%*) I do believe this fluid should be replaced at least every two years however you choose to do it.

However this time I replaced the originals with phenolic pistons. We'll see how they last!

[eldar]

I dont have piston issues either. I wonder if the 78 masters may have been slightly stronger on the retraction. The internals are different. Only a thought. A person would need to hook both up to a test machine to find out.

I will say I did have retraction issues until I took a brass brush to the inside to get all the old corrosion from the dot 3 fluid out. I swore it looked good but the dust flew when I did that!

I do still hold with the 2 year fluid switch though.

So one person had corrosion issues in humid areas and another piston retraction issues.

Lets see if we can get some other stuff together on this. Might be something for the FAQ section.