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Brake fluid

  • Thread starter Thread starter Jackbob
  • Start date Start date
J

Jackbob

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GS1000 - Wondering what the difference between DOT4 and 5 brake fluid is - and is it OK to use if filling a rebuilt system?? (cleaned and dry with new OEM seals)
Cheers
 
Do a search on brake fluid and you will find many posts.

Dot 4 is what you want - higher boiling point than DOT 3 and none of the silicone incompatability issues of DOT 5. There is a new DOT 5.1, or something to this effect, which is an extension of DOT 4 thus no silicone. That one may be okay but honestly, just go with the 4 and you are good to go.
 
DOT 3 is fine for our GS bikes. Have been using DOT 3 on all my GS bikes since 1986. House brand is best. Save your money, use DOT 3, and be happy.

It does not make a bit of difference if you use 3 or 4 on our GS bikes. Boiling point is not an issue, because the fluid temp never reaches anywhere near the boiling point.

More important is that you change it regularly, use braided steel lines, and keep everything down in the calipers neat and clean.

Save your money. Use DOT 3, the cheap stuff.
 
Grandpa said:
DOT 3 is fine for our GS bikes. Have been using DOT 3 on all my GS bikes since 1986. House brand is best. Save your money, use DOT 3, and be happy.
Yes, DOT 3 is fine, and probably specified for our GS bikes. May have been specified only because DOT 4 was not yet available.

It does not make a bit of difference if you use 3 or 4 on our GS bikes. Boiling point is not an issue, because the fluid temp never reaches anywhere near the boiling point.
MOST OF THE TIME it won't matter if you use DOT 3 or DOT 4. If you live in higher (mountain) elevations or do a LOT of high-speed corner carving, boiling point CAN be an issue. You will not notice a temperature increase at the reservoir, but the fluid in the caliper will be HOT. :shock:

More important is that you change it regularly, use braided steel lines, and keep everything down in the calipers neat and clean.
Yes, very important to change fluid regularly. Some do it every year, I tend to do it every two years. Stainless lines are nice, but rubber lines in good shape work well, too.

Save your money. Use DOT 3, the cheap stuff.
Save your money? I have not priced the difference (I only get DOT 4 for myself), but I don't think DOT 4 is going to cost that much more than DOT 3.
Click to expand...

DOT 5 is a whole, 'nother matter. It is a silicone-based fluid, not glycol-based. As Nessism mentioned, there are sometimes compatibility issues with DOT 5. If you are planning on converting, it is best to replace all the hoses and seals to make sure there are no traces of earlier fluid that will contaminate the new fluid. It is also much more important to change the fluid regularly. Because DOT 5 does not absorb water, any moisture that finds its way into the system will tend to collect at low points, instead of being evenly-distributed in the fluid. Collected moisture at the low points can accelerate corrosion at those points. DOT 5 has a higher boiling point and is great for high performance vehicles like race cars, but they tend to get a lot more service than our day-to-day vehicles. 8-[

Here is some additional reading on the subject:
Battle of the DOTs
How to convert
"Everything You Should Know About Brake Fluid"
Other useful information.



.
 
Excellent points, Steve. You're right about small savings from DOT 4 to 3, but I'm just a cheap SOB! :-D
 
Well, Grandpa, we are just gonna have to meet some time. :shock:

I don't like being called 'cheap'. I prefer 'frugal'. 8-[


.
 
I bought DOT4 when I flushed my brakes this summer; it was ~25 cents per pint more than DOT3. I flushed both front and rear systems completely, and used less than 2 pints. For 50 cents, I decided to not buy a coke and buy the better fluid instead.
DOT5.1 is also fine, but I would only spend the extra money on my sport bike, not the other ones, which are not ridden nearly as hard.
AFA braided versus rubber, my KZ has firmer brakes than the GPz, which does have the SS lines. But others have reported good results with the SS lines, which are quite expensive, for those who are "frugal". But I do check all the lines regularly, for any irregularities and/or leaks.
 
Speaking of flushing brake systems...I did just that on both my 550's after they sat for a bunch of years and the fluid turn dirty brown. Brake system seemed to work fine but the fluid started to turn dark fairly soon thereafter. Decided to build a teflon/stainless brake line and was surprised by the amount of brown crud inside the old rubber brake line. Tore down both the caliper and master and was further surprised by how much grunge still remained in the nooks and cranies. After doing the first bike I went to the second and it was the same story. Learned that flushing the system is not good enough if there is grunge inside - a teardown is in order. My opinion of course, yours may vary.
 
Last edited:
Steve said:
Well, Grandpa, we are just gonna have to meet some time. :shock:

I don't like being called 'cheap'. I prefer 'frugal'. 8-[


.
Click to expand...

Cheap should meet frugal some time, I agree.

My daughter is a student at UD, and my wife and I are Flyer Faithful. We go there often.
 
Nessism, you are correct. Flushing the brake system is preventive maintenance, and should be proactive. Once the crud is in the system, only a rebuild will remove it all.
 
Ok thanks to everyone for the info- i will err on the side of caution and continue to use DOT4. :-D
 
Dot?

Dot?

I kinda like Grandpa's approach. Flush often, at least every year, use new clear fluid each time.
Year old fluid will have water in it.
If it's not clear use it to flush, then flush it out with new clear fluid. I have old bikes and keeping a well maintained braking system clean is most important.
Lee :-D :-D :-D
 
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