ConcoursMustang Forums
Restoring - General discussions that span across many different groups of years and models => Misc Items => Topic started by: Morsel on March 28, 2018, 07:13:02 PM
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So I sent out my master cylinder to be rebuilt and re-sleeved by White Post, despite all the comments about them, they did a fine job, it looks really good. The only thing that surprised me is they said they will not guarantee their work if you use Dot 5 brake fluid because of the breakdown of the rubber seals. But then I had Jim Cowles do my calipers and he said to ONLY use Dot 5 (which I know is because of these classic and basically Dot 3 and 4 are like paint remover), and he used it while rebuilding my calipers, so they are filled with Dot 5.
I was planning originally on using Dot 5, but the little note freaked me out. My car is sweet and I drive it, and sometimes drive it hard, don't want any brake problems.
So what would you all do, ignore White Post or Jim Cowles, it seems like a pretty obvious question based on both their reputations and the fact that Jim Cowels is doing HiPo cars, but I'm curious what others are doing and using.
Thanks,
Jason
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I’ve used dot 5 since 1981 are have had zero issues.
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Used since 2003 and going strong without issue. Also there is no need to flush or replace the fluid every 3 years as should be done for a car that sees limited use with dot 3 or 4 fluid.
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So I sent out my master cylinder to be rebuilt and re-sleeved by White Post, despite all the comments about them, they did a fine job, it looks really good. The only thing that surprised me is they said they will not guarantee their work if you use Dot 5 brake fluid because of the breakdown of the rubber seals. But then I had Jim Cowles do my calipers and he said to ONLY use Dot 5 (which I know is because of these classic and basically Dot 3 and 4 are like paint remover), and he used it while rebuilding my calipers, so they are filled with Dot 5.
I was planning originally on using Dot 5, but the little note freaked me out. My car is sweet and I drive it, and sometimes drive it hard, don't want any brake problems.
So what would you all do, ignore White Post or Jim Cowles, it seems like a pretty obvious question based on both their reputations and the fact that Jim Cowels is doing HiPo cars, but I'm curious what others are doing and using.
Thanks,
Jason
A important question to be considered before answering is how you intend to drive the car. Do you plan to do open track or street/pleasure driving?
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A important question to be considered before answering is how you intend to drive the car. Do you plan to do open track or street/pleasure driving?
Plan on mostly cruising, going to car shows and an occasional “what can this K-Code do” ;) Put probably 200 to 300 miles a year on it.
Jason
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I have used DOT 3 in my older and classic cars. I use the brake strip testers each year to see if there's any deterioration. Never seen any deterioration, but I still change the fluid every 5-6 years. The cars only get 300-700 miles or so a year and are in a heated garage. No track time. For my daily drivers I change the fluid every two years.
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Plan on mostly cruising, going to car shows and an occasional “what can this K-Code do” ;) Put probably 200 to 300 miles a year on it.
Jason
I and others have used the Dot 5 for years in the vehicles that do not get used as much as a daily driver because the fluid is more maintenance friendly. The fact that the silicone does not absorb water into the system keeps the brake calipers and wheel cylinders ,proportioning valve etc. from freezing up internally from rust . Regular brake fluid absorbs water faster and must be changed frequently to keep rust from forming on the internal metal surfaces. Another plus is if or when it break fluid leaks somewhere it will not eat the paint . The Dot 5 is not good if you are doing open track with the car. I don't use Dot 5 in any car that I would vintage race. Those type use vehicles should have brake fluid flushed every 6 months or so. Dot 5 has a lower boiling point and gives a softer pedal feel. Given your driving habits and expectations and it sounds like the dot 5 would be what I would suggest using.
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+1 Dot 5, had it in my cars for decades, no track use, no issues.
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Well, it's sounding like everyone is happy using the Dot 5 and with it being overall a safer alternative I'm probably going that way. I'm doing all new lines anyway to the back of the car, new restored rear end, the front lines and proportion valves have already been cleaned out, and have new front calipers with Dot 5 used to assemble, sounds like I'm good to go.
Thanks everyone for giving your insight on this, very helpful.
Jason
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DOT 5 seems to be harder to bleed for some reason (Harder to get rid of the air bubbles)..
:o)
Tony K.
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DOT 5 seems to be harder to bleed for some reason (Harder to get rid of the air bubbles)..
:o )
Tony K.
Yes, whatever you do, do not shake the can of DOT 5!
I wonder why White Post refused to warranty their work with DOT 5? Never had a problem with seals...
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Yes, whatever you do, do not shake the can of DOT 5!
I wonder why White Post refused to warranty their work with DOT 5? Never had a problem with seals...
Yeah, it kind of shocked me when I opened the box and found the disclaimer in there considering I was planning on using it. I will be very careful and let it sit for a few days in the bottle before bleeding. I'm vacuum bleeding the brakes so it should go through ok I would think...
Thanks,
Jason
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I heard if you are currently running DOT 3 and want to go to DOT 5, everything has to be changed so there is no trace of DOT 3 in the lines before adding DOT 5. Is that true?
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I heard if you are currently running DOT 3 and want to go to DOT 5, everything has to be changed so there is no trace of DOT 3 in the lines before adding DOT 5. Is that true?
That's my understanding; either that or flush the system completely.
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I heard if you are currently running DOT 3 and want to go to DOT 5, everything has to be changed so there is no trace of DOT 3 in the lines before adding DOT 5. Is that true?
Yes it is true, do not mix.
Also as noted previously, do not shake can prior to pouring into master cylinder as dissolved air is a known risk with silicone fluid which contributes to a soft pedal.
More on boiling points and high altitudes as well http://www.dtic.mil/dtic/tr/fulltext/u2/a251835.pdf
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Here's a good explanation.... that's why I'm sticking with DOT 3 fluid...
https://techtalk.mpbrakes.com/brake-fluid/can-i-use-dot-5?hs_amp=true
:o)
Tony K.
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Here's a good explanation.... that's why I'm sticking with DOT 3 fluid...
https://techtalk.mpbrakes.com/brake-fluid/can-i-use-dot-5?hs_amp=true
:o)
Tony K.
I'm installing a totally new brake system. No water, no old brake fluid. Dot 5 should be good for me then? Driving will include some fun sport activities. I am expecting higher temps.
Per the mentioned article, where does this water come from that can turn into vapor?
Boiling point ranges
Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F)
DOT 5.1 260 °C (500 °F) 180 °C (356 °F)
DOT 5 - Wikipedia https://en.wikipedia.org/wiki/DOT_5
Per Wikipedia and http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm, DOT 5 fluid has a higher dry/wet boiling point than both DOT 3 and 4. DOT 5 does a better job at keeping water intrusion out of the rubber hose than 3 or 4.
The only issue I can see is that the DOT 5 silicone fluid is that it is more compressible than glycol fluid, especially at elevated temperature. In a test (http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm), at 400 °F wheel cylinder/caliper temperature, pedal travel increased by 13.5 mm to 18 mm (0.5 to 0.7 inches) in two sample systems. The brakes with silicone fluid continued to operate at this temperature in spite of the compressibility. Nothing was said about the DOT 3 fluid when it reaches 400 °F wheel cylinder/caliper temperature, as 1 more degree would be boiling point and that would make that cylinder/caliper fail.
Is there any fault in what I am reading, that DOT 5 IS a better choice then DOT 3/4 based on the documentation I have provided?
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I'm installing a totally new brake system. No water, no old brake fluid. Dot 5 should be good for me then? Driving will include some fun sport activities. I am expecting higher temps.
Per the mentioned article, where does this water come from that can turn into vapor?
Boiling point ranges
Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F)
DOT 5.1 260 °C (500 °F) 180 °C (356 °F)
DOT 5 - Wikipedia https://en.wikipedia.org/wiki/DOT_5
Per Wikipedia and http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm, DOT 5 fluid has a higher dry/wet boiling point than both DOT 3 and 4. DOT 5 does a better job at keeping water intrusion out of the rubber hose than 3 or 4.
The only issue I can see is that the DOT 5 silicone fluid is that it is more compressible than glycol fluid, especially at elevated temperature. In a test (http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm), at 400 °F wheel cylinder/caliper temperature, pedal travel increased by 13.5 mm to 18 mm (0.5 to 0.7 inches) in two sample systems. The brakes with silicone fluid continued to operate at this temperature in spite of the compressibility. Nothing was said about the DOT 3 fluid when it reaches 400 °F wheel cylinder/caliper temperature, as 1 more degree would be boiling point and that would make that cylinder/caliper fail.
Is there any fault in what I am reading, that DOT 5 IS a better choice then DOT 3/4 based on the documentation I have provided?
Regardless of what fluid you use air along with moisture is introduced through the master cylinder vent system made into the cap. Read reply #6 for general conscience and best usage per driving style.
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Regardless of what fluid you use air along with moisture is introduced through the master cylinder vent system made into the cap. Read reply #6 for general conscience and best usage per driving style.
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Re: Brake Fluid - What are you guys using...
« Reply #6 on: March 29, 2018, 12:29:21 PM »
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I have used DOT 3 in my older and classic cars. I use the brake strip testers each year to see if there's any deterioration. Never seen any deterioration, but I still change the fluid every 5-6 years. The cars only get 300-700 miles or so a year and are in a heated garage. No track time. For my daily drivers I change the fluid every two years.
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1966 289 C code auto convertible December 1965 scheduled build at Dearborn.
1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.
Reply #6 does not tell me much. Now Reply #7
I and others have used the Dot 5 for years in the vehicles that do not get used as much as a daily driver because the fluid is more maintenance friendly. The fact that the silicone does not absorb water into the system keeps the brake calipers and wheel cylinders ,proportioning valve etc. from freezing up internally from rust . Regular brake fluid absorbs water faster and must be changed frequently to keep rust from forming on the internal metal surfaces. Another plus is if or when it break fluid leaks somewhere it will not eat the paint . The Dot 5 is not good if you are doing open track with the car. I don't use Dot 5 in any car that I would vintage race. Those type use vehicles should have brake fluid flushed every 6 months or so. Dot 5 has a lower boiling point and gives a softer pedal feel. Given your driving habits and expectations and it sounds like the dot 5 would be what I would suggest using.
Dot 5 does NOT have a lower boiling point. It is higher. And at 401 deg when the Dot 3 is boiling, Dot 5 is still working, though with a slightly lower pedal. Why not change it out every 6 months?
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Re: Brake Fluid - What are you guys using...
« Reply #6 on: March 29, 2018, 12:29:21 PM »
Quote
I have used DOT 3 in my older and classic cars. I use the brake strip testers each year to see if there's any deterioration. Never seen any deterioration, but I still change the fluid every 5-6 years. The cars only get 300-700 miles or so a year and are in a heated garage. No track time. For my daily drivers I change the fluid every two years.
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1966 289 C code auto convertible December 1965 scheduled build at Dearborn.
1966 289 C code auto convertible
October 1965 scheduled build at Metuchen.
Reply #6 does not tell me much. Now Reply #7
Dot 5 does NOT have a lower boiling point. It is higher. And at 401 deg when the Dot 3 is boiling, Dot 5 is still working, though with a slightly lower pedal. Why not change it out every 6 months?
I misspoke on the lower boiling temp but regardless when you are operating at those temps you would be typically track racing where it is not typically desirable. For context I am re posting my previous post for context. I and others have used the Dot 5 for years in the vehicles that do not get used as much as a daily driver because the fluid is more maintenance friendly. The fact that the silicone does not absorb water into the system keeps the brake calipers and wheel cylinders ,proportioning valve etc. from freezing up internally from rust . Regular brake fluid absorbs water faster and must be changed frequently to keep rust from forming on the internal metal surfaces. Another plus is if or when it break fluid leaks somewhere it will not eat the paint . The Dot 5 is not good if you are doing open track with the car. I don't use Dot 5 in any car that I would vintage race. Those type use vehicles should have brake fluid flushed every 6 months or so. Dot 5 has a lower boiling point and gives a softer pedal feel. Given your driving habits and expectations and it sounds like the dot 5 would be what I would suggest using.
The silicone is typically shunned by the vintage race crowd because of the soft pedal . You are expected to change the conventional brake fluids every 6 months on a track car because of contaminants (moisture etc) in the fluid that could compromise the performance since this a safety issue for the driver and others around the drivers car. Most likely the silicone brake fluid would be expected to be done the same way ,that is if it was even used in that situation . There is nothing that is written that says that you are prohibited from using the Dot 5 silicone fluid in spirited driving it but it will not perform as good as the Dot 3/4 in those spirited driving situations. It is your choice what you use.
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You are expected to change the conventional brake fluids every 6 months on a track car because of contaminants (moisture etc) in the fluid that could compromise the performance
Is it common practice to remove the calipers to drain the fluid or is there some other trick? The bleeder valves up top on 65/66 only let out air and excess fluid pumped in but do nothing to drain any cr@p or old fluid at the bottom of each caliper
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Is it common practice to remove the calipers to drain the fluid or is there some other trick? The bleeder valves up top on 65/66 only let out air and excess fluid pumped in but do nothing to drain any cr@p or old fluid at the bottom of each caliper
For the purposes of this discussion on the track cars the fluid is typically flushed without removing the calipers . When it is changed that often you don't typically get the build up of debris associated with corrosion breaking off from surfaces inside the system .Or it is just faster and gets most everything out anyway. ;)
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I use the brake strip testers each year to see if there's any deterioration.
I don't know what's in my brake system , ie, DOT 3/4 or 5. It doesn't remove paint, but neither did my Valvoline Synthetic DOT 3/4. I need
to determine, absolutely, what my system has. What kind of indication will these testers give if the system is DOT 5?
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I think you can try taking a teaspoon of fluid from the master cylinder and mix it with a clean glass of water. If the fluid mixes in with water it is conventional 3 or 4. If it is dot 5, it will not mix with water and will probably float to the top...that’s my understanding anyway.
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Regardless of what fluid you use air along with moisture is introduced through the master cylinder vent system made into the cap. Read reply #6 for general conscience and best usage per driving style.
This introduction of "air along with moisture" issue can be addressed on non-driven cars should a person wish to do an undetectable modification to the cap.
I mention "non-driven" because of a very slight issue of safety and any related liabilities associated with the nature of any potential of an "accident" caused because of brake failure and how lawyers look for loopholes to assign blame. This "modification" could actually be done to "driven" examples too but for reasons stated already, perhaps not such a great idea.
So, how does the moisture get past the cap? Through the vents designed in the cap, right? Why are the vents needed then? Because of FLUID DISPLACEMENT, right? Where does the fluid go? Leaks? Not likely on a show car, right? Displacement into the wheel cylinders or calipers when braking is temporary and as soon as the brakes are released, returns to the Master cylinder, right? So why the REQUIREMENT of the vents? Easy answer is so that a vacuum does not develope within the master cylinder and by nature, air will seap in by ANY means possible and that is obviously worse than any introduction of moisture. Hence, the vents were designed to remove ANY CHANCE of this air entering in (air entering in past the wheel cylinder seals or the master cylinder piston-end seals are a few examples of "where" air can enter in that come to mind). A "Trailer Queen" would not likely ever see such a condition while a driven car has a POSSIBILTY only so this "idea", by default has flaws in it. Then you add the very fact that none of us will live forever and the car will one day be sold so even a "trailer queen" could one day be driven. Basically, the master cylinder cap has a diaphams that allows for the NORMAL displacement but if a leak were to occur anywhere in the system at all, if the diaphams was fully extended, it COULD cause a brake failure that MIGHT not have happened if the cap was designed to vent air into the reservoir....hence the vents.
Clear as mud? If you are worried about moisture getting in, you could consider this idea to modify your cap regardless WHAT fluid you choose. Most of us are not likely to do this but it can be done. Just an idea.
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For the purposes of this discussion on the track cars the fluid is typically flushed without removing the calipers . When it is changed that often you don't typically get the build up of debris associated with corrosion breaking off from surfaces inside the system .Or it is just faster and gets most everything out anyway. ;)
The point I was trying to make is how do you "flush" the fluid out of the lower 80+% of a K/H caliper? The inlet hose, transfer tubes and bleeder are all up top so there is no way to push the old fluid out that I know of without removing the caliper, turning it upside down and letting gravity do its job. K/H should have put the transfer tube at the bottom like Brembo
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Sorry to beat a dead horse with this older post, but I'm getting close to doing my brake fluid now and I just want to confirm one last time. As I mentioned the calipers came from Jim Cowles who only uses Dot 5 bake fluid in his rebuilds. So I was originally just going to go with his recommendation on using it until I started hearing people voicing their opinions about it being "a softer pedal". So what exactly does this mean, is it spongy and not as snapping coming back into position after a hard brake or is it just a slightly different feel? I do only drive the car about maybe 200 miles a year at most, but when I do drive it, I do drive it rather aggressively at times, I mean it is a K-Code, so you got to drive it hard sometimes ;) I'm fine with a different feel of pedal, but I just don't want it to be "less performance and a liability" of any kind.
If people think I should be using Dot 3 and bail the Dot 5 entirely, as mentioned by the pervious post, how would I go about flushing the calipers to remove the Dot 5 that's in it? They are not on the car currently, and I don't really want to break them apart again, but I guess if that's the only way to flush and get the old dot 5 out, I guess so be it. The rest of the lines and master cylinder are completely clean...
Thanks,
Jason
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Moisture entering the system through the MC cap vents probably isn't a big issue since the vents are actually above the gasket. The diaphragms in the gasket make up for pad wear and minor leakage - so the top side is necessarily open to the atmosphere but bottom side is sealed.
I think the only way to make sure no old fluid or moisture is in the calipers is to pull them apart - you cant get everything out of there otherwise.
I would also be wary of relying on a flush to remove everything in the system.
With DOT 5 any water entering the system will seek the lowest spots since the fluid floats on top of water. The lower part of the caliper would be one collection spot. I am still on the side of using DOT 5 because I think it is the best option for seldom driven non racetrack vehicles.
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Moisture entering the system through the MC cap vents probably isn't a big issue since the vents are actually above the gasket. The diaphragms in the gasket make up for pad wear and minor leakage - so the top side is necessarily open to the atmosphere but bottom side is sealed.
I think the only way to make sure no old fluid or moisture is in the calipers is to pull them apart - you cant get everything out of there otherwise.
I would also be wary of relying on a flush to remove everything in the system.
With DOT 5 any water entering the system will seek the lowest spots since the fluid floats on top of water. The lower part of the caliper would be one collection spot. I am still on the side of using DOT 5 because I think it is the best option for seldom driven non racetrack vehicles.
Well not worried about my lines and flushing them to remove the old Dot 3 because they are all new including the freshly rebuilt master cylinder, and the except the front lines and proportioning valve which I did clean, I removed the fittings and ran alcohol through the lines using a vacuum brake bleeder several times and also ran it through the proportioning valves and then they've been dry now for about a month, so hopefully I'm good and the system is completely clean.
I guess I'm going to stick with the Dot 5 and give it a try, sounds like most are happy with it and I don't really want to take apart my calipers that Jim did.
Thanks,
Jason
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Well not worried about my lines and flushing them to remove the old Dot 3 because they are all new including the freshly rebuilt master cylinder, and the except the front lines and proportioning valve which I did clean, I removed the fittings and ran alcohol through the lines using a vacuum brake bleeder several times and also ran it through the proportioning valves and then they've been dry now for about a month, so hopefully I'm good and the system is completely clean.
I guess I'm going to stick with the Dot 5 and give it a try, sounds like most are happy with it and I don't really want to take apart my calipers that Jim did.
Thanks,
Jason
Don't worry .The soft pedal statement is more in reference to extreme braking in comparison to the Dot 3. I doubt you will notice any difference in pleasure driving.
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Don't worry .The soft pedal statement is more in reference to extreme braking in comparison to the Dot 3. I doubt you will notice any difference in pleasure driving.
Thanks Bob, don't know why I'm stressing over this since so many seem to use it, there's so much more to stress about on the car, haha. But I appreciate the feedback on my question, just didn't want something like "wow, where'd my braking go".
Jason
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The softer feel of the pedal using DOT 5 is something like having your rear drum brakes not quite adjusted as tight as they could be, more like after a fair amount of driving without backing up to adjust your rear drums. It is quite subtle and hand-adjusting the rears will more than compensate for that difference in feel.
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The softer feel of the pedal using DOT 5 is something like having your rear drum brakes not quite adjusted as tight as they could be, more like after a fair amount of driving without backing up to adjust your rear drums. It is quite subtle and hand-adjusting the rears will more than compensate for that difference in feel.
Ahh, good one... as for the feel, if it's not that much different, it's been so long since I've driven the car I probably won't remember what it felt like before ;)
Jason
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Next question. Who's DOT 5 fluid are you using and where do you get it? I have shopped all the auto and major stores in my area that carry auto parts and none carry DOT 5 fluid. Counter guy at AutoZone even tried to tell me I was mistaken, that I needed DOT 5.1 as there is no DOT 5.
Looks like its eBay purchases or the smaller motorcycle shops that carry the 11oz or less bottles.
And a quick search again and I see Summit Racing IS selling the 11oz Maxima DOT 5 fluid for $11.99 ea (https://www.summitracing.com/parts/mxo-80-81911).
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I bought some yesterday at Advance Auto.
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I use the Wilwood fluid. 600 degree boiling point. Dot 5 feels mushy. If you have a big block car and drive it hard, you need something better than DOT 5.
-Keith
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I use the Wilwood fluid. 600 degree boiling point. Dot 5 feels mushy. If you have a big block car and drive it hard, you need something better than DOT 5.
-Keith
If you read the entire thread you will see that which fluid is better for spirited driving is not in debate.
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Well, Bob... I skimmed on my phone between departure from DFW and the check list for arrival at ORD. You'll have to forgive me this time.. I see DOT 5 pushed constantly here and other forums. I'm not a fan.
-Keith
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Well, Bob... I skimmed on my phone between departure from DFW and the check list for arrival at ORD. You'll have to forgive me this time.. I see DOT 5 pushed constantly here and other forums. I'm not a fan.
-Keith
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Keith, Dot 5 is not pushed or even suggested for track cars or ones where there is frequent spirited driving . Given the main thrust on this forum is restoration and maintenance of cars that are restored back to factory the dot 5 is the choice of many enthusiasts and restoration shops alike because it is maintenance friendly for those mostly pleasure driven cars.
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Bob, I didn't say you pushed it. I also understand the concern with damage to paint, which DOT 5 is paint-friendly. I didn't even care for it as a driver fluid. It gives a very strange feel to an already anemic brake system. No need to take personal offence. I know many live on a trailer here. However, I would venture to guess the majority drive their vehicle and disc brakes transfer more heat to the fluid than drum. As you also know it's catastrophic to mix it with any other fluid. Just my experience.
-Keith
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Bob, I didn't say you pushed it. I also understand the concern with damage to paint, which DOT 5 is paint-friendly. I didn't even care for it as a driver fluid. It gives a very strange feel to an already anemic brake system. No need to take personal offence. I know many live on a trailer here. However, I would venture to guess the majority drive their vehicle and disc brakes transfer more heat to the fluid than drum. As you also know it's catastrophic to mix it with any other fluid. Just my experience.
-Keith
Keith,I didn't take personal offence but was just trying to explain to you in case you mis understood the context of the position many have on the DOT 5 . The message was meant in informative but friendly spirit. You are certainly welcome to your opinion.