Not an oil thread

[SBKBee]

That is way cool info, I will use that in all my future brake fluid dissertations! Tell your son he is being quoted!

[FJ1100mjk]

It was cheapo Walmart DOT 3,  Being exposed to the atmosphere for a few months the fluid had absorbed about 8% water which was significant in affecting the boiling point.

Another good reason to go with silicone oil, besides what standard brake fluid will do to paint and some plastics.

[Earl Svorks]

    So, do we assume that glycol based fluid is hygroscopic by accident? I still am not sure how the DOT 5 stuff deals with the presence of water. I always thought the implication was that water suspended was somehow less a threat than water collected in a pocket. I guess it's hard to know if there's enough water present in your DOT5 system at any given time to be a problem.How much water can you expect over how much time? In any case in 50 years of driving, I have never had a problem caused by boiling brake fluid. I hope it stays that way.
   Cheers
Simon

[Urban_Legend]

I have seen brake fluid boiling only once, and that was in a rally car that I was navigating in, after a particularly difficult stage. And I must say we had the discs glowing pretty well too.

Mark

[FJ_Hooligan]

Simon,
I have several DOT 5 data points for you.  

When I changed my FJ over to DOT 5 in the late 80s the fluid in the front brake system wasn't drained or flushed for about 14 years.  The only reason it was eventually changed was when I converted the front end and installed monobloc calipers around about 2002.  Disassembly and inspection of the stock calipers revealed no corrosion or deterioration.  

The DOT 5 fluid lived untouched in the monobloc calipers until last year when I decided to flush it to clean a sticking piston (unrelated to the fluid).  The DOT 5 looked just slightly discolored from fresh fluid.

Also back in the '80s when I originally swapped the brakes, I also converted the clutch slave to DOT 5.  To this day, I have not touched the slave cylinder.  The DOT 5 fluid in there is almost 30 years old!  Perhaps its time to go ahead and change it?

I think the key is since DOT 5 doesn't absorb water it is "dry" when it is installed.  If you take care and don't accidently spill your beer into the master cylinder, the fluid remains uncontaminated since there's no magic force that's trying to driving water into the system.  Brake systems are sealed, water doesn't typically penetrate the system unless there is some kind of seal fail.  For the clutch slave that happens when the slave seal fails and allows water to start contaminating the fluid and rusting the piston.  Another interface is the master cylinder cap gasket.  I've seen fluid on the outside of this gasket many times.  If fluid can get out of the system, then air can get in.  It you have a fluid that attracts water this is a likely interface.  If you have a fluid that doesn't attract water, then even if there is interaction at this interface it doesn't necessarily cause water to condense into the fluid and contaminate it.  

Or, I've just been lucky multiple times with DOT 5?  Maybe I should buy lottery tickets.  :-)

[ribbert]

Pat, I think you and I will just have to respectfully agree to disagree on this one.

Noel

Pat, it appears my diplomatic attempt not to pursue this topic failed.


The average distance travelled annually by cars in the US is 15,000 miles,  motorbikes – 1500 miles (Harley's apparently only average 1150 miles per year, or so they claim!)

So, cars on average travel 10 times further than motorbikes.

Say a manufacturer recommends changing the hoses after 6 years, a common and conservative number, then convert that to distance based on average vehicle use and you get 90,000 miles!
To travel 90,000 miles at the rate of 1500 per year (motorbike average) would take 60 years. That places them at about half life at 30 years!


Brake hoses become unserviceable for two reasons (excluding damage), rupture and rust. Rust does not cause failure but slowly reduces efficiency of a long time, it clogs the metal end fittings. 
Excluding damage, eventual rupturing is attributed to normal wear and tear while in use. Heat, bending, twisting, pressure cycling and whatever the road throws up at them, in other words, use. That's why they fail near where the hose joins the metal fitting at the wheel end, where they flex the most, not from sitting in the garage.


No doubt hardening and cracking in the outer protective sheath is going to compromise the hose strength. To what extent the Sun contributes to this is pure speculation but you see a lot more of it on cars than you do on bikes, and they are never exposed to UV's.
I am still of the opinion that car brake hoses have a much harder life per mile than motorbike hoses, for many reasons.

And while we're at it  my long standing objection is not suggesting the hoses don't need changing, it's putting the fear of God into people about the danger of not doing so based purely on age.
Rubber hoses don't "burst" (excluding damage). They swell, they weep, they leak, all over time, and if entirely visible brake hoses and a sight glass on the M/C don't alert you to that, maybe you should get someone else to service it.
For the greater motoring public, brake hoses have always been something that is replaced when signs of deterioration are observed (this generally does not happen quickly)
The mileage and time over which this happens is so varied it's difficult to establish a trend. I don't recall ever being asked to replace a set purely because of age and without failure symptoms.

This is entirely my opinion from observation (and I doubt there are any figures available to verify/dispute it) but I believe a majority of vehicles will, after many decades of use and many hundreds of thousands of miles, end up at the wrecking yard or metal recyclers still wearing the brake hoses they left the factory with.
The oldest hoses that I know for a fact (family car) were never changed did 1,000,000 kms over 39 years on a Volvo.

While there will always be an exception to everything, a few years back the question was posed here on the forum for anyone who had ever suffered a brake hose failure on an FJ, no one responded. It was then extended to any vehicle they'd owned, still no answer (specific damage aside).

Complete brake failure is an extremely rare occurrence in modern times. Cars for many years have been required to have a split system, effectively two brake systems, motor bikes have this by default with separate front and rear brakes.
My point was, if you are going to advocate changing them on one sort of vehicle, you have to do it to the other, you can't differentiate between one and the other, they are subjected to the same conditions. It is the manufacturer who determines the life span of their product, it's up to the user to decide if and in what form they pass that on to their customers. Yamaha appear to be the only ones who do this. As you pointed out, no car manufacturer does and as far as I'm aware, no other motorcycle manufacturer does, doesn't that tell you something?

I stand by that statement and I'm not standing alone. I have a lot of company saying the same thing.

Well, you got me there Pat, I don't have a posse, just me and the dogs at this end.


Congratulations on the new bike, any attempt to conceal your lust for one of these "Best of Breed" models ever since one passed through your hands a while back was a miserable failure – well done and about time!
To quote yourself on the subject "You'll love it" 

Noel

I think I'll keep my opinion on brake fluid to myself.

[Pat Conlon]

Hey Noel, yes, this '92 I'm currently working on is one of the cleanest bikes I've ever seen... well cared for and at 31k miles, just broken in.
My last '92 went to Paul Lawson and it was a great bike, made better with my mods. IMHO the '91/92's (non abs) are the best of the breed.

My last comment on oem brake hose replacement is this:

There is a difference between anecdotal evidence and empirical evidence.

Brake hose manufacturers use empirical evidence in the testing and certification (DOT,TUV,etc) of their product, and based on this empirical evidence, they come up with a service life.
Your experience with long lasting oem brake lines (e.g.39 year old Volvo brake lines) would be considered anecdotal (or subjective) and thus your opinion is based on anecdotal evidence.

I'll base my conclusions on empirical evidence over anecdotal evidence any day.

I do value your insight and 0pinion, but yea, we will have to disagree on this issue. There is a reason for the manufacturers service life recommendations.

..... It is the manufacturer who determines the life span of their product, it's up to the user to decide if and in what form they pass that on to their customers. Yamaha appear to be the only ones who do this. As you pointed out, no car manufacturer does and as far as I'm aware, no other motorcycle manufacturer does, doesn't that tell you something?

No, you're wrong ^^ Yamaha is not the only motorcycle manufacturer that specifies a service life for the oem hoses.
Check it out. Don't assume.

I have read about an oem hose failure on a motorcycle. It was around ~2004 and a '84 owner on the old Yahoo list had a split on the AD hose next to the crimp collar. He reported he was riding when he squeezed the front brake lever and the lever came back to the handlebar. Along with the surprise, he mentioned that, when he pumped the lever, the spray of DOT 3 fluid went everywhere and ruined his paint and windscreen.

Yes, cars have a great safety record. Vehicles made after 1957 (in the USA) are required to have a redundant brake system with 2 master cylinders each pressurizing alternate front and back wheels. Loose line pressure in one system and at least you have a separate system controlling 2 wheels you can rely on.

My point: Loss of brake line pressure on motorcycles can be worse than on cars. On motorcycles, loose line pressure on your front brakes, a system that handles 80% of the braking load, you had better hope you have the room to use your back brake.

Finally, on my signature line I state: "Replace your oem rubber brake lines (because) They are long over due. Do it now."
I don't say because you will die if you don't. I let the reader's imagination conjure that up.

Perhaps I should say: Replace your oem rubber brake lines because your brakes will work better.  On that, you and I agree.

[ribbert]

I'll base my conclusions on empirical evidence over anecdotal evidence any day.

So do I. Empirical evidence is exactly what the mechanic in the field sees. To suggest their observations are anecdotal is being dismissive of the experience and skills of an entire industry.

em·pir·i·cal  əmˈpirik(ə)l 
adjective
adjective empirical
based on, concerned with, or verifiable by observation or experience rather than theory or pure logic.
experiential practical heuristic firsthand hands-on observed evidence-based seen demonstrable

I would be very surprised if hose manufacturers conducted any tests beyond mechanically simulated use (I have seen such a jig in operation first hand at Ford Product Engineering) and the known properties of the materials they use. Gathering empirical evidence would require putting it into service in large numbers and observing it's performance until such time as it fails.

I have no interest in keeping this thread alive nor addressing any other point you made but I do take exception to the above. Other than the average mileage of vehicles in the US I have not researched or read anything on the subject for the purpose of this discussion. If you have information or a link on how they are tested I would be interested to read it.

Re the old Volvo hose, maybe I should have balanced that out with the fact that I have also seen them fail while still under new car warranty!

I don't know whether they are your words or someone else's, but in my opinion, one is wrong and the other offensive. You know we have a member who is an authority on the word "empirical," perhaps he could settle it.    Hmmm....maybe not.


You are a lucky man to have found a pristine '92. I don't know about over there but here, when I turn up to look at a "pristine" "as new" "showroom condition" etc bike and I'm confronted by some rough old shitbox (the camera does lie), the answer when nailed about the gaping discrepancy between the ad and the bike is always the same, ....."for it's age"

I had never seen another one since I bought mine, until recently. I offered to buy it instantly at his asking price, which was very reasonable, and he withdrew it from sale. Not sure what was going on but I suspect the moment he realised it was actually about to go, he couldn't do it. If I ever find another one I will buy it in a heartbeat.

How about some photos.

Noel

[Pat Conlon]

I'll post some pictures as soon as I get those new Spiegler lines on......