changing dot 3/4 to dot 5 brake fluid

[amamet]

during the rebuild, I rebuilt both master cylinders and ultrasonic cleaned them, I was wondering if I should do the same to the calipers and clean the lines out to go to dot 5 brake fluid.  is it worth it?  this is what happens when you have too much time on your hands
thx
allen

[Rich A]

I think Brembo says not to do this unless you replace the MC & caliper seals, but you should verify this. Dot 5 evidently can cause the seals to swell.

(Some have said they've done this with no problems)

Rich

[skippy]

I would not recommend using DOT 5 unless it is DOT 5.1. Even then I would recommend DOT 4 be used and changed on a regular basis. But here is some information for you.

https://www.powerstop.com/different-types-brake-fluid/

Skippy

[Old Jock]

As per skippy, although personally I don't care much if it's 4 or 5.1, depending on the manufacturer and the type (racing etc:) I've seen DOT 4 with better Specs than 5.1

I always flush mine through ideally ever other year but sometimes go out to 3, if other tasks are a higher priority

I'd stay well clear of 5, never used it, but seen literature that it can attack seals unless the whole system is designed specifically for it.

[amamet]

yes, sorry, meant 5.1, forgot about that.  the master cylinders pistons and seals have been replaced and cleaned, but the calipers and brake lines have been run previously with dot 3.  in order to run 5.1 or 4 would I need to rebuild the calipers and clean out the lines or are they compatible?

[amamet]

google says 3,4 and 5.1 are all compatible, guess I answered my own question, guess ill go with dot 4

[PeteS]

When DOT 5 first came out I tried it in my Dunstall brakes. Bad idea. The motion became very notchy, like adding sand to the mix. Went back to Dot 4 and all was good again. I believe the higher number of the glycol base fluids have a higher boiling point. Use 5.1 in a race bike otherwise Dot 4 should be sufficient.

Pete

[moto-uno]

  ^The other (real) advantage to DOT 5 , was when you spilled it on the paint and never noticed it , the paint wouldn't come off later
when you wiped it  ,  Peter

[pat80flh]

Can be done but all rubber in brake system must be replaced, including hoses and caliper seals, metal lines must be thoroughly cleaned. Iy is the mixyure of dot 4 and 5 which causes rubber to swell.

[Murray]

I have found 5.1 solved a brake fade problem on my track bike so there is something to it, admittedly the local track is pretty brutal on brakes (3 very hard stops in just over a minute). For a road bike it won't do any harm and if it helps you sleep at night all good but I don't see it as absoutely required.

[s1120]

5 avoid....  It lasts a long time, and doesnt eat paint...  but frankly I dont think its really good for much past that. I havent used 5.1 but it is compatible with 3 and 4, so if you want go ahead. Personally Ive never needed any more then dot 4.. 

[sdcr]

Is 5 and 5.1 compatible?

Or. would your braking system need to be flushed completely, if you have one of these fluids, in order to use the other?

[s1120]

Is 5 and 5.1 compatible?

Or. would your braking system need to be flushed completely, if you have one of these fluids, in order to use the other?

5 and 5.1 are not compatible..  5.1 is more like 3 and 4..  I think its kinda stupid that they named the spec 5.1 being 5 is so different.. and the general public does not read...   

[sdcr]

Paul,
  Thanks for clarifying. Yeah, I agree about the names.

[roadventure]

Why?  Use what the OEM recommends. Unless you are into racing there is no reason to do otherwise.