Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Rimjam]

My 2000 SERG had a hydraulic clutch unit installed when I bought it used.  Seller said it had DOT 5 in it so I've continued to use same in both brake & clutch master cylinders.  My understanding is that DOT 5 does not absorb water - true or false?  Any drawbacks to DOT 5 ?  If not why did HD change to DOT 4 ?

[SIKBIRD]

DOT 5 does not absorb water as bad as DOT 4 but I would still change it out every few years because it does get nasty.  It’s really easy if you have a mighty vac.  It is my understanding that H-D went to DOT 4 when they started putting ABS on bikes.  I don’t think DOT 5 plays well with an ABS system.

[gunny627]

DOT 5 does not absorb water as bad as DOT 4 but I would still change it out every few years because it does get nasty.  It’s really easy if you have a mighty vac.  It is my understanding that H-D went to DOT 4 when they started putting ABS on bikes.  I don’t think DOT 5 plays well with an ABS system.

I change my break fluid every year. Dot5 is a silicone based fluid. That was developed for use where moisture or water was almost certain. Dot5 has a higher boiling point than Dot3 or Dot4. Dot5 exhibits more compressibility than glycol ether brake fluids. There are Dot4 fluids with boiling points that exceed Dot5 so there's realty no need to consider using Dot5 for on road use. And Dot3 and Dot4 cannot be mixed with dot5 fluid.