At the end of my recent track day the brake pedal on my 2 started going all the way to the floor. However, it does still apply the brakes, you just have to push it in to the floor.
I noticed there are small bubbles in the brake master cylinder. All brake lines/calipers etc. look fine. Is this indicative of the master cylinder being broken? Will a kit like the one below be worth a shot? I've read that buying a new master cylinder can be fraught with issues e.g. they're refurbished used units so no better than refurbing yourself or that they're for left-hand not right-hand drive cars (see Autodoc).
https://www.ebay.co.uk/itm/333551431579 (https://www.ebay.co.uk/itm/333551431579)
It sounds like you have boiled the brake fluid.
Do you know when it was last flushed?
I would bleed out all the calipers with fresh fluid before looking into master cylinder fault.
Jon
Quote from: mr2garageswindon on September 29, 2022, 12:43It sounds like you have boiled the brake fluid.
Do you know when it was last flushed?
I would bleed out all the calipers with fresh fluid before looking into master cylinder fault.
Jon
I bled all brakes with fresh RBF600 fluid a couple of weeks before the track day. I did wonder about boiling it but seemed unlikely to me? Maybe my bleed wasn't very good, will definitely try a re-bleed first though thank you.
Must also say we were utterly hammering the brakes to the point of locking up wheels at points...
Quote from: MrChris on September 29, 2022, 13:34I bled all brakes with fresh RBF600 fluid a couple of weeks before the track day. I did wonder about boiling it but seemed unlikely to me? Maybe my bleed wasn't very good, will definitely try a re-bleed first though thank you.
Must also say we were utterly hammering the brakes to the point of locking up wheels at points...
As a reference I replaced / renovated all four calipers and used one litre of brake fluid to refill/ bleed.
When you use high performance fluid and if it takes in very little water or contaminants the boiling point drops dramatically. This is why high performance fluid has to be flushed out frequently especially before a race.
Dot 3 on the other hand can tolerate water and contaminants for a very long time without much fall off.
I had problems with RBF600 especially in the cold because it was more viscus. When I added it to the clutch master it would work for a month or so and then it would fail. I believe it is due to seal compatibility.
Quote from: Dev on September 29, 2022, 15:09When you use high performance fluid and if it takes in very little water or contaminants the boiling point drops dramatically. This is why high performance fluid has to be flushed out frequently especially before a race.
Dot 3 on the other hand can tolerate water and contaminants for a very long time without much fall off.
I had problems with RBF600 especially in the cold because it was more viscus. When I added it to the clutch master it would work for a month or so and then it would fail. I believe it is due to seal compatibility.
Did I include the two bottles or RBF600 and are those the ones you used?
If so, it could be because they're old. I don't know how they age or what the use-by date is.
But, the reason I never used them is because of what Dev said. You're much better off with a good Dot3 or 4.
Quote from: Dev on September 29, 2022, 15:09When you use high performance fluid and if it takes in very little water or contaminants the boiling point drops dramatically. This is why high performance fluid has to be flushed out frequently especially before a race.
Dot 3 on the other hand can tolerate water and contaminants for a very long time without much fall off.
I had problems with RBF600 especially in the cold because it was more viscus. When I added it to the clutch master it would work for a month or so and then it would fail. I believe it is due to seal compatibility.
Quote from: shnazzle on September 29, 2022, 15:35Did I include the two bottles or RBF600 and are those the ones you used?
If so, it could be because they're old. I don't know how they age or what the use-by date is.
But, the reason I never used them is because of what Dev said. You're much better off with a good Dot3 or 4.
No you didn't, I used new RBF600.
Slightly confused as RBF600 is Dot4 which I thought was also a good quality brake fluid. RBF600 was my goto on my BMW 130i and never let me down. Any recommendations for the 2?
Quote from: shnazzle on September 29, 2022, 15:35Did I include the two bottles or RBF600 and are those the ones you used?
If so, it could be because they're old. I don't know how they age or what the use-by date is.
But, the reason I never used them is because of what Dev said. You're much better off with a good Dot3 or 4.
The story goes that a friend and I split a case of RBF600. When I flushed out all my fluid it worked fine but as the temps dropped in the winter the pedal became wooden. I flushed out the fluid and added fresh RBF and it was fine again until it started having the same issues and that is because DOT 4 is more viscus than DOT 3. As for the clutch the following spring it would not fully disengage causing grinding until it wouldn't disengage at all but once I let it cool it came back to normal. I have a very strong pressure plate so the demands are high and after another flush the same thing happened.
I suspected the fluid so I changed back to Toyota DOT 3 and never had a problem after that.
I come to find out from a leading authority on brakes the nuanced reason. On the internet they say DOT 4 is compatible and it might be for some other cars but not all cars especially where it says DOT 3 fluid only.
https://centricparts.com/getmedia/aaff9ed4-541c-45a4-abc2-a3b667385808/Centric_and_APC_Technical_Whitepaper_D1-Brake-Fluid-1A_8-2018.pdf
Also Toyota brake fluid has a special polymer lubricant in the formulation that is specific for the seals and it was a known cause of a brake master failure for a particular car that went bad because alternative fluid was used as sited by Toyota.
Although our cars was not part of the bulletin I believe the Toyota formulation has merit for the longevity and health of the seals.
What a great response, thank you
@Dev Seems like this is a case of 'RTFM' (it does indeed state DOT 3 only) and 'don't believe everything on the internet' :))
I'm going to get some quality DOT 3 and see how I get on. I just hope I haven't buggered the seals.
Quote from: MrChris on September 29, 2022, 15:56No you didn't, I used new RBF600.
Slightly confused as RBF600 is Dot4 which I thought was also a good quality brake fluid. RBF600 was my goto on my BMW 130i and never let me down. Any recommendations for the 2?
BMW is compatible with DOT 4 because it is DOT 4 fluid only. The 2007 BMW that I owned was like that and I assume yours is also.
Toyota DOT 3 is specified as a heavy duty brake fluid and is not your typical DOT 3. It is suspected to have a very high boiling point considering it is used in their heavy vehicles including those that are used for towing. I would switch to the Toyota brake fluid and give your car another track day and see if you observe any fade issues.
Just spoke with local Toyota garage. They said based on my reg, DOT 4 is recommended... completely at odds with the manual. They did quote me on DOT 3... over £230 for 1 litre :o Turns out that this is for the Lexus LFA and is the only DOT 3 they can get at the moment. I've found some Comma DOT 3 so will be getting that instead!
I also used ATE200 (blue) as it was then.
Utter shite. It lasted about 6 months before it was next to useless. It was phenomenal for a few good hard uses.
To be fair, the RBF600 site (and bottle?) even says to swap it out every track session.
When you got it, it just had bogtstandard DOT3 in it. That lasted best and brakes always flew through MOT with a higher efficiency ratio than they would normally see
Quote from: shnazzle on September 29, 2022, 16:52I also used ATE200 (blue) as it was then.
Utter shite. It lasted about 6 months before it was next to useless. It was phenomenal for a few good hard uses.
To be fair, the RBF600 site (and bottle?) even says to swap it out every track session.
When you got it, it just had bogtstandard DOT3 in it. That lasted best and brakes always flew through MOT with a higher efficiency ratio than they would normally see
I almost went for ATE but it was way more than Comma. Also I've had good experience with Comma in the past. Interesting about replacing every session, thought it would stand up to more abuse. Bedford is known for hard braking zones, but even so... I shall report back after the weekend hopefully as the DOT 3 should be with me on Saturday.
Quote from: MrChris on September 29, 2022, 16:48Just spoke with local Toyota garage. They said based on my reg, DOT 4 is recommended... completely at odds with the manual. They did quote me on DOT 3... over £230 for 1 litre :o Turns out that this is for the Lexus LFA and is the only DOT 3 they can get at the moment. I've found some Comma DOT 3 so will be getting that instead!
The fluid you need is the factory fill fluid for all Toyota cars and trucks. It is inexpensive and should be available. I would not trust the garage as they are not officially Toyota representatives. It was the Toyota dealers that was servicing the Toyota cars under warrenty that was the cause of the master cylinder failure by substitution of generic fluid and after investigation they were given an official notice by Toyota to only use their fluid because it contains the special lubricant that does not dry out seals.
I just did a search and it seems that Toyota now carries DOT 4 fluid but it is probably specified for new Toyota cars that require it based on new seal materials and components. I would not use it in older Toyotas that specify DOT 3 only.
I had a long lengthy debate on another forum where some said that "DOT 3 only" means it can use DOT 4 even though I presented my resources. As I researched further I stumbled on a Toyota car of the same generation where the master cap said DOT 3 or DOT 4 which was specific for that car. DOT 3 only in my opinion means DOT 3 only.
Quote from: MrChris on September 29, 2022, 16:59I almost went for ATE but it was way more than Comma. Also I've had good experience with Comma in the past. Interesting about replacing every session, thought it would stand up to more abuse. Bedford is known for hard braking zones, but even so... I shall report back after the weekend hopefully as the DOT 3 should be with me on Saturday.
For other than track days there was, what turned into a thread about brake fluid:
https://www.mr2roc.org/forum/index.php?msg=873276
In my ownership there has been Dot 3, followed by Dot 5.1 as recommended by my Main Dealer, and now Dot 4, following the discussion as link above.
Track day fluid is another kettle of aquatic creatures.
I'd imagine the much more sophisticated BM brake system is dissipating the heat better as well, if not generating less with the piston to weight ratio.
There is a lot of variation between two different DOT 4 fluids. Some are high viscosity and some are low viscosity and they can have different formulations that can create issues. Even if you use a DOT 4 fluid with success it doesn't mean its ok to use as you might be damaging the rubber seals and after a prolonged amount of time your brake components might not last as long.
I suspect why the RBF fluid did not last long in my car was due to seal incompatibility which allowed water and contaminants to breach and lower the boiling point quickly compared to a car that is specified for DOT 4 that uses different seal materials. When I drained out my clutch fluid it was abnormally dirty and full of contaminants. This was not the case when I used DOT 3 even for an extended time.
One of the most misunderstood aspects of brake fluid is DOT 3 is more hygroscopic which means it absorbs more water from the air compared to DOT 4 which makes it sound like DOT 4 and DOT 5.1 is better for longevity.
What they don't tell you is that DOT 3 has a much higher tolerance for water and therefore the drop in dry and wet boiling points is minimal. DOT 4 on the other hand absorbs less but it is far more sensitive and therefore its drop is dramatic.
Have long had a nagging question in my head.
Could it be the brake fluid chemistry that causes rear brake caliper adjusters to seize.
Not all.dot 3 r 4 are created equal.
They will meet the stansard but not ness oem recipe.
The brake master cylinder cap on my 2 and on my 7 years younger ct200 both say DOT3.
Replaced the dot 4 in the 2 with comma dot 3.
So far no issues.
Caveat. I don't do track days.
Quote from: Ardent on September 29, 2022, 22:09Have long had a nagging question in my head.
Could it be the brake fluid chemistry that causes rear brake caliper adjusters to seize.
Not all.dot 3 r 4 are created equal.
They will meet the stansard but not ness oem recipe.
The brake master cylinder cap on my 2 and on my 7 years younger ct200 both say DOT3.
Replaced the dot 4 in the 2 with comma dot 3.
So far no issues.
Caveat. I don't do track days.
Hard to say.
There are a lot of unknowns in any of these fluids when you deviate from the manual or what is written on the cap. The smallest details in a formulation can be overlooked. I do not want to find out (but I did) or worse will never know if using an unspecified fluid created damage over time to where you cant pin the blame on any one thing and after that you replace the components and use it again out of ignorance.
Even if DOT 4 is acceptable why would anyone consider it over DOT 3 for a street application. Did anyone experience brake fade using DOT 3 on the road. At least with DOT 3 it is more forgiving to change intervals and keeping its dry and wet point stable.
I used RBF600 for 2 seasons with absolutely no problems, before moving to RBF660 with no problems. Although, importantly, I'm not using OEM brakes. It is a top quality brake fluid very popular with the track day crowd.
I wouldn't use anything but a high performance brake fluid at a track day. Not to say some of the OEM stuff isn't quality, but I've bled RBF600 between sessions with no air bubbles - and I like that.
I've had the discs glowing red without the pedal getting soft. However, I will doing a complete flush before every event, and maybe every 3 track days.
Seems to me that the OEM brakes require DOT 3 as per the manual and using DOT 4 may have helped to compromise the system. I agree with you
@AJRFulton that RBF600 is great and has been for me in the past, but as above, the MR2 as standard needs DOT 3.
I am going to flush through some DOT 3 and at least try and get the brakes back to where they should be for the road and take it from there.
While this thread is about brake fluid and the pros and cons of grades that differ from that mentioned in the handbook and on the filler cap I wonder what consideration is given to those other fluids that may or may not be of some importance, such as:
Engine oil, how many Members use non synthetic (Toyota) SAE 5W-30 oil?
Gear oil, how many use (Toyota) SAE 75W-90 oil?
SMT oil- how many use Toyota Genuine Sequential M/T Fluid?
Coolant- how many use Toyota Genuine Long Life Coolant.
Also of note- Tyres- how many use 185/55R 15 81V front, 205/50R 15 85V rear or whatever the FL model is recommended?
Unrelated to brake fluid you might think, but these items were, around 20 years ago, what was recommended.
Bit of an update as I had to pop out in the 2 earlier briefly: The pedal goes solid when the car is off - it does not go to the floor at all. As soon as engine is on, the pedal goes to the floor (but still stops the car). Does this point to another issue other than the fluid?
Quote from: MrChris on September 30, 2022, 15:09Bit of an update as I had to pop out in the 2 earlier briefly: The pedal goes solid when the car is off - it does not go to the floor at all. As soon as engine is on, the pedal goes to the floor (but still stops the car). Does this point to another issue other than the fluid?
I'd be confident that isn't fluid. Whilst these fluids are not as long life, they aren't this short of a life.
However try and bleed them, if your not getting excessive bubbles then I'd think it's unlikely to be fluid and it points to something else.
@MrChris Seldom, if ever mentioned on here is the tandem brake circuit and the vacuum assist.
My understanding and the implication of their malfunction is insufficient to say whether either of these could be your problem. But the vacuum assist only operates when the engine is on. The tandem system is designed to be fail safe but does alter the feel of the pedal.
Quote from: MrChris on September 30, 2022, 15:09Bit of an update as I had to pop out in the 2 earlier briefly: The pedal goes solid when the car is off - it does not go to the floor at all. As soon as engine is on, the pedal goes to the floor (but still stops the car). Does this point to another issue other than the fluid?
I would replace the fluid and see what it does before taking the next step in diagnosis if there are any internal leaks taking on air from bad seals.
When the engine is off the vacuums assist boost of the diaphragm is no longer functioning and the pedal will be stiff due to over coming the spring in the master and the fluid. If there is a little air in the system it can be greatly appreciated once the car is on.
Quote from: Joesson on September 30, 2022, 16:13@MrChris
Seldom, if ever mentioned on here is the tandem brake circuit and the vacuum assist.
My understanding and the implication of their malfunction is insufficient to say whether either of these could be your problem. But the vacuum assist only operates when the engine is on. The tandem system is designed to be fail safe but does alter the feel of the pedal.
Yeah a quick google lead me to articles/YouTube videos showing that something to do with the ABS could be at fault, or as I initially suggested: the master cylinder. It is very specific behaviour though which makes me think maybe ABS system. Engine off: Rock hard pedal, Engine On: all the way to the floor and brakes at the end of the travel.
Quote from: Dev on September 30, 2022, 16:30I would replace the fluid and see what it does before taking the next step in diagnosis if there are any internal leaks taking on air from bad seals.
When the engine is off the vacuums assist boost of the diaphragm is no longer functioning and the pedal will be stiff due to over coming the spring in the master and the fluid. If there is a little air in the system it can be greatly appreciated once the car is on.
Will bleed the system tomorrow and see what is what.
Quote from: Joesson on September 30, 2022, 10:34While this thread is about brake fluid and the pros and cons of grades that differ from that mentioned in the handbook and on the filler cap I wonder what consideration is given to those other fluids that may or may not be of some importance, such as:
Engine oil, how many Members use non synthetic (Toyota) SAE 5W-30 oil?
Gear oil, how many use (Toyota) SAE 75W-90 oil?
SMT oil- how many use Toyota Genuine Sequential M/T Fluid?
Coolant- how many use Toyota Genuine Long Life Coolant.
Also of note- Tyres- how many use 185/55R 15 81V front, 205/50R 15 85V rear or whatever the FL model is recommended?
Unrelated to brake fluid you might think, but these items were, around 20 years ago, what was recommended.
There is nothing set in stone when it comes to fluids recommendations and sometimes Toyota gets things wrong. There can be non Toyota parts that can exceed the manufactures but its hard to know so it depends.
Toyota fluids have been formulated specifically for Toyotas including engine oil and they have a very good track record of giving excellent service. There have been alternative fluids that have been in used in place of Toyota and they have also given great service however there are also fluids that had issues with their formulations even though they claim they have exceeded the manufactures fluid. Then we have those that take chances on using fluids that are not specified for the vehicle and it may return some initial benefit but there might also be a major trade off in longevity which take years to find out or you will never know because you cant say what caused the failure.
There have been many failures even beyond fluids with non OEM parts. One of the great things about Toyota is their stringent quality control that some third party manufactures cant match.
Sometimes trying to get a benefit might actually be causing damage. One thing we can be assured of is if you go with OEM in a sea of unknowns you are at least guaranteed some peace of mind especially when there is not a substantial difference in price.
When you look further into it as I have you find out that there is specific reasoning to stick with some of the OEM fluids especially if it is a street car.
Quote from: MrChris on September 30, 2022, 16:42Yeah a quick google lead me to articles/YouTube videos showing that something to do with the ABS could be at fault, or as I initially suggested: the master cylinder. It is very specific behaviour though which makes me think maybe ABS system. Engine off: Rock hard pedal, Engine On: all the way to the floor and brakes at the end of the travel.
Will bleed the system tomorrow and see what is what.
Curious to know what happens and good luck. Hopefully it isn't the master or ABS unit as they rarely go bad.
Not much to add, but as always on here. Lets start at the cheapest, easiest thing to try.
A good methodical bleed of the system seems the best place to start.
Have used the one man type bleed systems but still prefer having a second pair of hands or foot.
With 2 ops, you can do it as Mr T, describes.
Apply pressure to pedal. Open bleed valve. Pedal goes down. Fluid comes out. Close bleed valve. Release pedal. And repeat.
A small difference, but I do believe that to be the optimal method. Vs. Open press release close.
I first used one of these in the '60's, after many years of company cars, when I didn't use it and 4 house moves I lost/ couldn't find it. I invested £2.80 in 2020 and got another, from Amazon.
Current price is £4.04 , such is inflation, but available elsewhere for slightly less.
It can be used single handedly , but easier with a partner and it is not necessary to close the bleed valve between pumps of the pedal.
Copy and Search the following line and you will see various offers. Recommended.
Brake or Clutch Bleed Tube [PWN189] 25cm Long Rubber Bleeding tube.
After trying many methods of bleeding I now switched to gravity bleeding which is the easiest method with the best results.
Just need a clear tube over the bleeder nipple and cup to catch the fluid. Suck up the existing fluid in the reservoir and fill it with fresh fluid, open the bleeder and drain. Close the bleeder screw once fresh fluid comes out. If there are any bubbles they find their way out since the force of gravity pushes it out the line.
Small update: the dot 3 hasn't arrived. Ran through some fresh rbf600. Braking has improved but the pedal is still super spongy and goes down way too far. There did appear to be a fair bit of air in the lines. The ABS did engage when I took it for a drive when I pressed really hard. I guess next thing is to wait for the dot 3 and run that through.
Regardless of what DOT rated fluid you have just put in, its fresh fluid so that wont be the issue. If you're still not getting a firm pedal there has to be another issue somewhere.
Any signs of leaks around the master cylinder or calipers?
I ran the rbf600 for a bit on track but it just didnt last long before it needed changing, i have sinced swapped to using Gulf rf1000 which seems to be holding up better.
Braided or stock brake lines?
My money is on a leak. You clearly have a problem, as this is not normal.
Quote from: Alex Knight on October 2, 2022, 12:33Braided or stock brake lines?
My money is on a leak. You clearly have a problem, as this is not normal.
Braided lines. Just did another bleed, was slightly better after. Pumping the brakes helps while driving. Can't see a leak as the fluid has not gone down and I can't see an issue with the lines or at the master cylinder.
You probably still have air in the system if you gained a sight improvement especially if it doesn't get worse. Sometimes air can get trapped under the master piston which is hard to get out. It can also get trapped in the ABS unit on a lot of cars where the dealer uses Techstreem to initiate the ABS while bleeding. Our cars generally do not have this issue with trapped air in the ABS module but its possible especially if you boiled the fluid. If there is trapped air it has to make its way back to the master or it ends up at the caliper after multiple presses which is then relived once you crack open the bleeder.
I had a very hard time bleeding on a different car where the pedal just wouldn't get as tight as I remember. Eventually after multiple bleeds between drives had one of the calipers expel air and then everything was ok after that.
Another tip is to tap on the master housing using a tool and also the caliper before you bleed again to shake any trapped bubbles so they can find their way out.
What are you using to bleed the system?
Quote from: AJRFulton on October 3, 2022, 10:46What are you using to bleed the system?
Wife in car, tube on the nipples (ahem). Push brake pedal, open bleed screw, close bleed screw, release, repeat until no air bubbles. Next step is to try gravity bleeding, possible get a vacuum bleeder but have read this is not necessary.
The air pump pressure bleeders make life easier as it makes it a 1 man job is. Mine was like 25 quid off eBay about 5yrs ago. however, you know how to bleed
RBF600 might not be the best fluid for your need, but it won't be going off that quickly. It's not long life and the type of thing if you don't need don't use, but I'd expect at least 12mths if everything was working correctly.
Worth giving JSpec a call, and asking for a master cylinder and ABS pump, explain the situation and I'd imagine they'll be ok with a return if you don't need the part. I'd change the master cylinder first. Relatively straight forward, and IMO the most likely culprit.
Unfortunately without an obvious cause and leak, it might be a bit of trial and error.
Quote from: MrChris on October 3, 2022, 11:38Wife in car, tube on the nipples (ahem). Push brake pedal, open bleed screw, close bleed screw, release, repeat until no air bubbles. Next step is to try gravity bleeding, possible get a vacuum bleeder but have read this is not necessary.
The automatic bleed tube I suggested in post #30 costs very little but really does simplify things. There is no need to close the bleed valve between pumps, the tube has a longitudinal razor slit that effectively works as a one way valve. Keep pumping with the tube end and slit immersed in a clear container of brake fluid until no bubbles issue from the slit.
I have not previously heard of gravity bleeding so cannot comment other than it apparently takes a while to do it and, as with any method, the master cylinder must be kept topped up during the process.