Brake fluid types within 3-4

[whatscooking]

Was wanting to change the brake fluid in a bike I have. Need to use DOT 4 my shop manual says, do NOT use a silicone based fluid only glycol. I know the DOT 5 is a silicone base but on the bottle of 4 I have on my shelf is states it is a silicone base. This has me worried the flushes I have done on some of the other equipment I have flushed, Kubota RTV, Honda four wheeler, and other motorcycles i might of messed up.

[steve murdoch icoa #5322]

Never heard of a silicone based Dot 4.
If you have indeed mixed the glycol and silicone based fluids together i would flush and rebuild the m/c, lines and calipers.
From what i have read the seals can swell and the fluid can gel.
I use Belray Dot 4 in all the bikes.
https://www.motorcyclistonline.com/mc-g ... -explained

[whatscooking]

I just returned the little bottles to Wally World for a refund, they were in a Prestone bottle, look them up on E-bay and you will see both DOT 3 and 4 are marked synthetic. I too thought this about Dot 3 and 4 brake fluid.

[whatscooking]

My bad, I was crossing the synthetic, silicone for some reason, glad as I was facing a bunch of brake problems.

[cross]

I use ATE TYP200 DOT4 in all my bikes. It has higher temp rating. Little pricey though

[Larry Zimmer]

DOT 4 good stuff. One bottle should do a brake job.

[RFA]

I'm rebuilding the brakes on my 79' CBX. What's the problem with Dot 5 brake fluid? Please school me before I make a mistake. Years ago I used Dot 5 on a bike and never had a problem.
Thanks

[bobcat]

The problem with DOT5 fluid is that it shrinks under repeated hard braking like you would do
in Road Racing where it overheats.
We used DOT5 in our race bike once and kept trying to figure out why the
brakes (front) kept fading after several laps and would need to be pumped up a couple of
times before each corner. Bleeding the sys. repeatedly only helped until the brakes got hot
again and started to fade. A former SCCA racer that hauled our bikes to the track asked what
our problem was, then asked what fluid we were using. He then said DOT5 was our problem
and handed us some DOT3-4 and after flushing the sys. it cured the problem.

However I would recommend using DOT5 in the rear brake sys. since it is water/moisture
resistant and the rear mast. cyl is most exposed and not the primary bake sys. and heat fade
isn't an issue.

[mrcbx]

what about 5.1 ?

[pmcburney]

The problem with DOT5 fluid is that it shrinks under repeated hard braking like you would do
in Road Racing where it overheats.
We used DOT5 in our race bike once and kept trying to figure out why the
brakes (front) kept fading after several laps and would need to be pumped up a couple of
times before each corner. Bleeding the sys. repeatedly only helped until the brakes got hot
again and started to fade. A former SCCA racer that hauled our bikes to the track asked what
our problem was, then asked what fluid we were using. He then said DOT5 was our problem
and handed us some DOT3-4 and after flushing the sys. it cured the problem.

However I would recommend using DOT5 in the rear brake sys. since it is water/moisture
resistant and the rear mast. cyl is most exposed and not the primary bake sys. and heat fade
isn't an issue.

So, unless you're racing your CBX, DoT5 is fine?

I use DoT5 in all of my classic bikes and I've never had a fade issue, I'd say mostly because I don't race them.
I also never have any corrosion, leaking or paint damage issues either.

My two cents... use DoT5 in your classic bikes, especially those that don't get ridden all that often as it was specifically developed for vehicles prone to long-term storage.

It's a no-brainer to do the changeover at the same time as an overhaul (DoT5 does NOT mix with any other fluid) and will be far easier to manage and use than moisture-loving, corrosive, glycol-based fluids into the future.

For info, DoT5.1 is glycol-based and is incompatible with DoT5.

[pmcburney]

.

[daves79x]

I've written many times about my experiences with DOT 5 brake fluid and CBXs. I don't even try it any longer.

Dave

[CBX-tras]

One thing that I will not mess/guess/screw around with is brakes. DOT 5 fluid will off-gas with heat and altitude causing spongy pressure, no pressure at all or apply the brakes for you (when least expected). I have witnessed other people with problems that could have had fatal results.

Nissin (the brake component manufacturer for CBX brakes) does NOT endorse the use of DOT 5 fluid of any type or brand.

I use a DOT 4, semi-synthetic, with great results.

FAFO.

[Larry Zimmer]

Keep in mind that while Dot 5 does not absorb and suspend water into the fluid as the other fluids do, as any moisture does get into the system (AND IT DOES) the water settles out to sit there in a puddle, of sorts, in the bottom of your cylinders. Not so easy to flush since the bleeder is at the top of the cylinder. If it works for anyone, good. I would not touch it. Dot 5.1 is OK. Just flush your system occasionally with 'standard' fluids. (Flushing won't help with silicon.)

[bobcat]

To each his own. I was just reporting my experiences with DOT5.
I wouldn't use it in a race or track bike.

I've tried it on my arthritic joints before : didn't work