2nd Gen Brake Fluid

[Boomer]

Doing a top off of the rear brake fluid but before I pour....The Owners manual suggests DOT 4 for both the brakes and clutch. I have never changed to anything else so is this legit? DOT4 ?

 

Thanks in advance!

[LilBeaver]

Yes.

 

Either DOT 4 or DOT 5.1 will work fine. (NOTE that DOT 5 and 5.1 are different and NOT interchangeable).

 

I stick with the OEM recommendation of DOT 4.

[kevin-vic-b.c.]

Yup seam the new bikes .... and cars are asking for DOT 4. Do not know the diff... but that is what they want.

[Boomer]

Thanks!....BTW I did find the answer - It really helps to read the top of the cap....DUHHH!

[skydoc_17]

I'm not trying to be a "smarty pants" here, but being one of those guys that likes to know what I am using in my scoot, and why, here is some information about brake fluid that you may find interesting.

DOT 3 brake fluid is Glycol Alcohol based. (very much like the antifreeze we use in the radiator) It's "boiling point" is at about 360F.

DOT 4 is the same except it boils at about 450F.

Now the DOT 5 is silicon based and boils at a much higher temperature, and doesn't "draw" moisture to it like the DOT 3 or 4 does, but will destroy the seals in a brake or clutch Master Cylinder unless the seal material is designed for silicon based brake fluid.

This is the reason you can't use the DOT 5 in older bikes (like First Gens) and also why you can't mix the two in the newer bikes (oil and water principal)

Just thought you might like to know,

Earl

[1BigDog]

And the DOT 5.1 has an even higher boiling point. I just flushed out my clutch and brake system with 5.1 from Motul.

[Squeeze]

.... I just flushed out my clutch and brake system with 5.1 from Motul.

 

That's great Stuff !!

[Condor]

That's great Stuff !!

 

When going from DOT4 to 5.1 does the system have to be completely flushed? Or... can the 4 just be drained out and the 5.1 added???

[Squeeze]

When going from DOT4 to 5.1 does the system have to be completely flushed? Or... can the 4 just be drained out and the 5.1 added???

 

Well, if you don't run the old Fluid out of the Lines, you won't benefit much of the better Fluid you're adding, because the better Stuff mostly just stays in the Reservoirs.

 

This Motul 5.1 is great Stuff and if your at it, it's worth just flushing the old Fluid out of the Line. You, know it's a 5 to 10 Minutes Job if you stay concentrated and don't run the Reservoir down.

 

I'd empty the Reservoir with a Sringe and refill with fresh Fluid, then just bleed the Lines like you're used to.

[1BigDog]

Well, if you don't run the old Fluid out of the Lines, you won't benefit much of the better Fluid you're adding, because the better Stuff mostly just stays in the Reservoirs.

 

This Motul 5.1 is great Stuff and if your at it, it's worth just flushing the old Fluid out of the Line. You, know it's a 5 to 10 Minutes Job if you stay concentrated and don't run the Reservoir down.

 

I'd empty the Reservoir with a Sringe and refill with fresh Fluid, then just bleed the Lines like you're used to.

 

 

What he said^.....I also used a mityvac on mine.

[Condor]

Well, if you don't run the old Fluid out of the Lines, you won't benefit much of the better Fluid you're adding, because the better Stuff mostly just stays in the Reservoirs.

 

This Motul 5.1 is great Stuff and if your at it, it's worth just flushing the old Fluid out of the Line. You, know it's a 5 to 10 Minutes Job if you stay concentrated and don't run the Reservoir down.

 

I'd empty the Reservoir with a Sringe and refill with fresh Fluid, then just bleed the Lines like you're used to.

 

Thanks Squeeze. Sounds like they are somewhat compatable....

[Tartan Terror]

I'm not trying to be a "smarty pants" here, but being one of those guys that likes to know what I am using in my scoot, and why, here is some information about brake fluid that you may find interesting.

DOT 3 brake fluid is Glycol Alcohol based. (very much like the antifreeze we use in the radiator) It's "boiling point" is at about 360F.

DOT 4 is the same except it boils at about 450F.

Now the DOT 5 is silicon based and boils at a much higher temperature, and doesn't "draw" moisture to it like the DOT 3 or 4 does, but will destroy the seals in a brake or clutch Master Cylinder unless the seal material is designed for silicon based brake fluid.

This is the reason you can't use the DOT 5 in older bikes (like First Gens) and also why you can't mix the two in the newer bikes (oil and water principal)

Just thought you might like to know,

Earl

Not really sure why everyone is still convinced that Dot 5 is so destructive. I have had Dot 5 in my bike for 4 years and never had a seal issue. Had it in my Honda before it for 5 years that I owned it and the new owner still has it in and no issues. Most classic car builders use it too as its not as carrosive and wont hurt paint. Only thing you have to keep in mind is that you must totally purge the system before using Dot 5 as it will clot up. Now Dot 5 wont absorb moisture like the others will so you must bleed a little every year as any moisture will find its way to the lowest point.