Oh yeah, you're in the middle of nowhere. I use the brakes all the time in the city, I'd probably get burned if I touch the rotor. Went for a drive once with snow still on the rims and was actually causing some vibration. Afterwards it had all melted.
2 Year Brake Fluid Changes--Overkill?
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???? Not in my experience!
Put another way, I routinely get 5 years out of brake pads. That's over 100k, often 125k. That goes for my wife's car too.
I moved recently. My prior town didn't have any stop lights. This new town does have a blinking yellow/red, so I guess it's a bit more populous. The only stop lights I know of in a 20 mile radius is a couple miles from me, and unfortunately I usually have to stop for one of them. Now if I drive 25 miles or so, to the cities, then yeah, I'll find some lights.
Do a stop from 40 mph to zero at a normal type of braking for a red light and then get out and touch the rotor. You will straight up burn your finger.
I'm sure I can get them hot if I wanted to. Why would I? Just going to cost me more in brakes. Save a bit of gas if I drive conservatively, and no, that's not hypermiling & annoying the people behind me.
I upgraded from 16 year old dot 3 to dot 4 in my truck and couldn't feel a difference in the pedal in my case. If I was towing down some steel hills I imagine there'd be a noticeable difference but I only used dot 4 because it was the same price. My brakes don't get used very heavily.
Well if you live in the type of conditions you do then yes you can keep them cooler for sure. But most people have to deal with stop lights, stop signs, traffic and what not, which of course is just considered normal driving for those types of areas. 3-400 degrees is pretty normal with about 800 being top end for street pads.
Normal people could probably get out and grab the caliper, I would believe that. But not the rotor.
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I haven't been rude, haven't called anyone names, used profanity nor have I gone against anything prohibited on BITOG. I also haven't used multi-syllable scientific explanatory terms or past experience of why I don't need to bleed brakes. What I have done is proposed a simple experiment that an 18 year old high school boy with his first vehicle and a few tools is capable of conducting. Be it known that I work at a testing laboratory (we don't do oil), and there is a brass plaque on a monstrous old hydraulic machine that proclaims "One test is worth a thousand expert opinions."
To the best of my knowledge, Phoenix test strips are the only known (and patented) means of testing brake fluid: https://www.amazon.com/Phoenix-Syst...rds=phoenix+test+strips&qid=1609362973&sr=8-2
There is also a video on the Phoenix website with a female narrator claiming that brake fluid is the most important fluid in your car. To parents with small children, or even grandparents, I agree this perspective may be reasonable:
To the best of my knowledge, Phoenix test strips are the only known (and patented) means of testing brake fluid: https://www.amazon.com/Phoenix-Syst...rds=phoenix+test+strips&qid=1609362973&sr=8-2
There is also a video on the Phoenix website with a female narrator claiming that brake fluid is the most important fluid in your car. To parents with small children, or even grandparents, I agree this perspective may be reasonable:
Those techs, sadly, know very little about brake fluid!
I've ridden sport bikes with 3-4 old fluid and then ridden them again after a brake bleed that I did with fresh DOT 4. The difference is night and day, truly an incredible difference.
I've used many brands of brake fluid over the yrs in cars and bikes - the fresh fluid always gives a slightly firmer pedal/lever.
Temperature has nothing to do with it. We are not talking about natural convection. We are talking about diffusion driven by concentration gradients. Brake fluid is the solvent and water is the dissolved solute. The brake fluid does not have to move anywhere. The dissolved water moves within the brake fluid until there is a uniform concentration. This is not an “expert opinion”, it is simple, well understood science.
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50C is enough to burn a finger, that might just be 10C over ambient....
So in Death Valley in July you get insta-burnt if you go outside?
I said it before, do a normal braking routine from 40 mph and get out and touch the front rotor. Let me know how it goes
As for changing brake fluid every two yrs - yep seem likes overkill for the average daily driver. I wonder if some mfrs spec that interval knowing full well that many mechanics will not fully flush the system. I prefer every three yrs except for motorcycles and cars that get tracked.
You don't know that I'm a dealer technician. We regularly do brakes on cars that just pull up. Those done more than a few stops. They can be hot in summer, but in this weather they're no more than luke warm.
I'll bring my thermometer when I go shopping in a few hours, I'll be able to gve exact data.
Went to the shops. The car body measured 2C as did the 4 disc brakes on the car. Started the car, the dash thermometer confirmed 2 degrees aswell, drove to the end of the street, didn't have to yield to anyone so proceeded on the main road and got up to 50 mph. A few hundred yards up the roads is a collection point for glass where I can pull over so I braked and got on there. No traffic so could do it in one smooth motion.
All 4 brakes registered between 10 and 11C after the stop from 50 mph. Proceeded on my way but took a very scenic route, over 20 miles of rural roads, lots of turns and intersection, and a few miles of dual carriage. I braked 4 times from 50 to 20 on a longer straight section, for no other reason than to heat up the brakes. Everywhere I could I braked a bit more than I normally would and I approached a bit faster as I normally would.
When I got to the shop, the front brakes were 51C, the rears 32C. The front wheels measured 18C and the rears 15C. Touched the rear discs and they were warm, but not hot to the touch. Shopping took about 15 minutes and when I got back out, the brakes and wheels were fairly even in temperature, around 20C. Took the short way home (less than 3 miles) and drove as I normally would. More traffic now so had no choice in the matter.
When I got home the brakes were 28 degrees front and 35 degrees rear. Warm, but not hot. Could definitely hold on as long as I wanted. This included 4 sets of traffic lights where I had to stop. But the majority of travel was uphill so the brakes have light duty and the rears actually can work to their full potential.
The car weighs 1500 kg +- 5 kg with a full tank of gas (like today) and I weigh 90 kg. It's a medium weight vehicle and has been weighed 2 weeks ago at the recycling centre (when entering, and when leaving)
Front brakes are 330 x 28mm , rears are 278 x 12mm. Good size, but not the biggest either.
I understand the idea of diffusion. I'm just dubious of this method (changing only the master cylinder) is going to keep fresh fluid throughout the system. Short distances, absolutely. Longer periods of time, perhaps. But 15' out to the farthest caliper?
Would be an interesting experiment. Take one car and change the master cylinder fluid once a year (or whatever schedule), and take another car, in the same climate, driving schedule, etc, and not change the fluid at all. Somehow sample the fluid in the calipers and see if there is a difference between the two cars. I may well be wrong--if anything, I'd like to be wrong. Changing fluid only in the m/c is much easier than changing in the m/c and then going to each wheel. I'd change the m/c fluid twice a year if I thought it worked well.
This sounds like quite the experiment.
You expect me to believe a moderate stop from 50 mph resulted in brake rotor temps of 10 and 11C? I don't see where you live but that is below ambient in half the country.
No data, just an educated guess. I didn't say three yrs is necessary, just my preference, as well as the average recommendation of most auto mfrs.
I’ve heard mixed feelings about this - DOT4 seems to be more immune to being hygroscopic, the better fluids are formulated with borate esters on top of their glycol esters/glycol ether base chemistry. ATE/Conti, Bosch don’t make their fluid - they buy it from the two German chemical companies, BASF and Clariant. DowDuPont and CCI supply a majority of American and Asian service fill and retail brake fluid.
Japanese DOT 3 fluid tends to share the high dry boiling point as DOT4 fluid and the corrosion resistance of such. A long time ago, Toyota had a brochure at their parts counters - it states “original” Toyota fluid is based on borate ester chemistry. And there was a recall/TSB recommending only Toyota-bottle fluid in some models due to a squeal from the MC.
it was 2c ambient
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