Anyone use DOT 5 brake fluid in there elise.
Discussion
I am about to change the brake fluid in my car and fit braided hoses at the same time. The user guide says to use DOT 4. Now as far as I know DOT 5 is a higher grade with a higher boiling point. I have never encounted brake fade yet in the elise but I am sure a track would sort that out. Can DOT 5 be used instead?
Do NOT use DOT5
You can use DOT5.1 (the .1 is the important distinction)
DOT5 is silicone based brake fluid and it needs a brake system that's specifically desgined for it.
DOT5.1 is compatible with DOT3 and DOT4 and can be used. 5.1 is often used for ABS cars as it's a little less viscous than DOT4.
Temperature-wise there's not much in it. Plenty of DOT4 types have much higher boiling points than DOT5.1 types.
Bye, Arno
You can use DOT5.1 (the .1 is the important distinction)
DOT5 is silicone based brake fluid and it needs a brake system that's specifically desgined for it.
DOT5.1 is compatible with DOT3 and DOT4 and can be used. 5.1 is often used for ABS cars as it's a little less viscous than DOT4.
Temperature-wise there's not much in it. Plenty of DOT4 types have much higher boiling points than DOT5.1 types.
Bye, Arno
What he says! This is good stuff to use without being overly pricy - though not from this source (US) - it just has the necessary details:
www.znoelli.co.nz/productcart/pc/viewPrd.asp?idcategory=2&idproduct=4
Most specialists use this stuff.
UK: www.plansmotorsport.com/showroom/components/#brakes
>> Edited by shangani on Tuesday 17th January 11:26
It has a lower boiling point - gives you earlier brakefade on the track when the brakes get hot. Fine for road use. Piooly will be giving his car a serious workout. Most of the cost however is the labour, so you might as well use good fluid. There is other stuff that is over 50 quid for 500ml!
shangani said:
It has a lower boiling point - gives you earlier brakefade on the track when the brakes get hot. Fine for road use. Piooly will be giving his car a serious workout. Most of the cost however is the labour, so you might as well use good fluid. There is other stuff that is over 50 quid for 500ml!
Brake fade is not caused by fluid boiling! It is caused by the frictional coefficient of the brake pads reducing due to pad temperature rising above its working range...that's why fast road/race pads resist fade better but are cr*p when cold - their range of working temperatures has been moved upwards by use of different compound for the pad meaterials. If your fluid boils, you will know about it - at best the pedal will become very spongy, and at worst it will go straight to the floor with no braking effort at all, because you are trying to compress a gas instead of an incompressible fluid.
If you ever boil the fluid, you will need to bleed new fluid through the brakes anyway, since they remain spongy even when they have cooled down again!
Cheers guys,
I'm doing the fluid change myself, no point paying the garage to do an easy job. My theory has always been if you cant fix the car, you dont deserve to drive it. I know a lot of people will diagree with this but lets face it, the elise is not rocket science...... If something does brake, it gives you a better understanding of what might be the problem. It is always a bit worrying when you fix something for the first time but you soon get over that fear and I'd tackle just about anything except stripping the engine down. (I'd give it a try if I had the workshop and a freind who knew what he was doing....
I'm doing the fluid change myself, no point paying the garage to do an easy job. My theory has always been if you cant fix the car, you dont deserve to drive it. I know a lot of people will diagree with this but lets face it, the elise is not rocket science...... If something does brake, it gives you a better understanding of what might be the problem. It is always a bit worrying when you fix something for the first time but you soon get over that fear and I'd tackle just about anything except stripping the engine down. (I'd give it a try if I had the workshop and a freind who knew what he was doing....
Sam_68 said:
It has a lower boiling point - gives you earlier brakefade on the track when the brakes get hot. Fine for road use. Piooly will be giving his car a serious workout. Most of the cost however is the labour, so you might as well use good fluid. There is other stuff that is over 50 quid for 500ml!
If your fluid boils, you will know about it - at best the pedal will become very spongy, and at worst it will go straight to the floor with no braking effort at all, because you are trying to compress a gas instead of an incompressible fluid.
If you ever boil the fluid, you will need to bleed new fluid through the brakes anyway, since they remain spongy even when they have cooled down again!
There is more than one cause of brakefade - pad fade is only one of them!
There are three kinds of fade commonly encountered in fast driving; pad fade, green fade and fluid fade. Below are listed an explanation of each.
Pad Fade
Pad fade occurs for several reasons. All friction material (brake pad stuff) has a coefficient of friction curve over temperature. Friction materials have an optimal working temperature where the coefficient of friction is the highest. Sometimes you can use the brakes so hard that you get the temperature over the point of maximum friction to where the coefficient of friction curve starts to decline.
The mechanics of this decline in the coefficient of friction are varied. At a certain temperature, certain elements of the pad can melt or smear causing a lubrication effect, this is the classic glazed pad. Usually the organic binder resin starts to go first, then even the metallic elements of the friction material can start to melt. At really high temperatures the friction material starts to vaporize and the pad can sort of hydroplane on a boundary layer of vaporized metal and friction material which acts like a lubricant. Pad fade is felt as a car that still has a decent, non mushy feeling brake pedal that won’t stop even if you are pushing as hard as you can. Usually it builds somewhat slowly giving you time to compensate for it ,but some friction materials have a sudden drop off of friction when the heat is put on them resulting in sudden dangerous fade.
Green Fade
This is perhaps the most dangerous type of fade that has injured more race car drivers than any other type of brake incident.
Green fade is a type of fade that manifests itself on brand new brake pads. Brake pads are usually made of different types of heat resistant materials bound together with a phenolic resin binder. These are thermosetting plastic resins with a high heat resistance. On a new brake pad, these resins will out-gas or cure when used hard on their first few heat cycles. The new pad can hydroplane on this layer of excreted gas. Green fade is dangerous because many people assume that new brakes are perfect and can be used hard right off the bat. Green fade typically will occur much earlier than normal fade so it can catch a driver that is used to a certain car’s characteristics unaware. Typically the onset of green fade is rather sudden, further increasing the danger factor. I was a victim of green fade once. The crew forgot to tell me that new brake pads were installed on the car and when I went out on the track, I was flying down the escape road at about the third corner! Some teams have a new pads warning sign that they place on the steering wheel to inform the drive to be careful on his first few laps.
Green fade can occur if you change the pads and drive on the street for a few hundred or even thousand miles, never braking hard, then suddenly start using the brakes hard. I think that this is the fade that many list member complain about on their own cars.
Green fade can be prevented by bedding the pads. This is a simple procedure to boil off the resins and break in the pads under controlled conditions which I will explain later.
Fluid fade
Fluid fade is caused by the boiling of the brake fluid in the calipers. This produces bubbles in the brake system. Since bubbles are compressible, this makes for a soft spongy pedal. In worse cases, the pedal can plunge to the floor with very little slowing! Fluid fade can be avoided by running a high grade racing type brake fluid and/or frequent changes of brake fluid. Also if you change the pads before they get super thin, the remaining friction material will help insulate the calipers from the heat. Some people have had some success with having swaintech spray thermal barrier coating on the backing plate of the pads to help isolate the heat but I have never tried this.
Fluid fade usually has a gradual onset.
If you are having an exceptionally bad day your brakes can fade from all three of the above reasons at the same time! The reason why I am explaining them to you is so that you can identify what kind of fade that you are suffering from and do the proper thing to fix the type of fade that you have with the correct countermeasure. If you are experiencing pad fade, switching brands of brake fluid won’t help. If you are getting fluid fade, the trickiest carbon pads won’t stop you a bit sooner. If you have the finest brake parts available, you could still fall prey to green fade.
www.se-r.net/car_info/brake_performance.html
http://en.wikipedia.org/wiki/Brake_fade
www.h-e-l.co.uk/HEL_Performance_Motorcycle_Brake_Lines_Brake_Doctor_Brake_Fade.htm
Don't be quite so fast to correct people!
I do not believe my statement was incorrect. The discussion was about brake fluid - Piooloy wants to do more tracking, so I suggested a reasonable brake fluid type that has a higher boiling point to at least reduce that aspect of fade of the track. The pad and disc issue is another debate altogether. >> Edited by shangani on Tuesday 17th January 13:46
I had started out trying to advise Piooly on an issue that I researched a while ago before opting for mintex fluids, RS42's and braided lines. I have not had the same issues of brake fade since. Piooly wants to put fluid in - I am sure he has covered the pad side of the debate.
Why does every specialist recommend uprated brake fluid for trackdays - even if you buy it elsewhere? Why do they stress boiling point?
>> Edited by shangani on Tuesday 17th January 14:00
Why does every specialist recommend uprated brake fluid for trackdays - even if you buy it elsewhere? Why do they stress boiling point?
>> Edited by shangani on Tuesday 17th January 14:00
The advice I have is that a high spec DOT4 like "Castrol Super DOT4" is fine, you dont need stuff like Castrol SRF. Good fluid changed often (e.g. 10 hours on track or annually) is better than racing stuff changed never ... unless you suffer from affluenza or enjoy pissing money away in which case please disregard and do whatever makes you happy.
piooly - if you are going to change it yourself then Id advise having an 'e-z-bleed' tool or such like - theres often quite some infuriating stories on SELOC with people who try to do it themselves to save a few quid and end up spending a whole Sunday messing around trying to bleed the brakes and still end up with a spongey pedal they cant get rid of !
to me £40 for an hours labour is not worth a whole day gone at the weekend whilst swearing under the car !
to me £40 for an hours labour is not worth a whole day gone at the weekend whilst swearing under the car !
hbaumhardt said:
The advice I have is that a high spec DOT4 like "Castrol Super DOT4" is fine, you dont need stuff like Castrol SRF. Good fluid changed often (e.g. 10 hours on track or annually) is better than racing stuff changed never ... unless you suffer from affluenza or enjoy pissing money away in which case please disregard and do whatever makes you happy.
you (temporarily) American Heretic. 
Having a good time?bogie said:
Id advise having an 'e-z-bleed' tool
An excellepnt suggestion, but cautionary tale; I tried to do my brakes with an ezbleed once, but still managed to a) spend a full day swearing under my TVR b) spill fluid all over the garage floor and then c) drive around with spongey brakes until I took it to a professional to sort. Another task that I will never ever do again.
Keep me posted - They are spraying the front splitters and I will probably have them fitted at Specialised Paintwork - the labour will be offset against the 150 mile round trip (times 2 as they want the car overnight to fit them). If so I might want you to collect them.
Do you want me to tell them to get your car ready for Saturday?
Do you want me to tell them to get your car ready for Saturday?
shangani said:
There is more than one cause of brakefade - pad fade is only one of them!
Sorry, but whilst I agree with you about pad fade and green fade (gassing on new pads), I wouldn't classify boiling fluid as fade...the symptoms are quite differennt.
With pad fade the pedal stays hard, you just need enormous pedal pressure to get any braking effort.
With fluid boil the pedal travel increases dramatically and in my experience onset can be quite sudden and extreme. The pads skim the discs (and therefore generate a small amount of heat) even when you aren't braking, so once there has been enough heat soak to start boiling the fluid in the calipers, you are usually past the point of no return and the first you know about it is when the pedal goes straight to the floor when you brake for a corner. I've had it happen a few times, and it's not nice. Unless you have faulty (binding) brakes or moisture in your brake fluid (which lowers the boiling point), or unless you are capable of driving very hard, though, it is unlikely to happen on a modern car, regardles of whether you are running DOT 4 or DOT 5.1 fluid.
>> Edited by Sam_68 on Tuesday 17th January 18:05
Sorry to disagree with you, but it happens frequently on the track - people end up with no brakes whatsoever and overshoot the end of the straights. (I did this in a BMW M3) Ask anyone who runs trackdays - they even include it in the briefing at Bedford! Using a higher boiling point brake fluid does offset this to a degree. I was not suggesting this is the only cause, but as the discussion was about brake fluid, not pads, this is why I mentioned that aspect of the fluid.
In road use it should never be an issue - while pad fade of course might be. Piooly is a member of the BoLOCS who has told me he is planning to do a few trackdays - indeed we are all doing an airfield day next week. He is pretty quick and will certainly heat up the brakes on a track. If he is goint to track the car and is putting in new brake fluid, a competition type fluid with a higher boiling point would be the way to go. I can't see why that is incorrect advice.
>> Edited by shangani on Tuesday 17th January 18:29
In road use it should never be an issue - while pad fade of course might be. Piooly is a member of the BoLOCS who has told me he is planning to do a few trackdays - indeed we are all doing an airfield day next week. He is pretty quick and will certainly heat up the brakes on a track. If he is goint to track the car and is putting in new brake fluid, a competition type fluid with a higher boiling point would be the way to go. I can't see why that is incorrect advice.
>> Edited by shangani on Tuesday 17th January 18:29
I don't disagree that you might as well use the highest spec brake fluid you can - the cost difference is trivial - but if you do encounter braking problems it's important to be able to diagnose them correctly.
My personal experience, both on track and on road, in a large variety of cars, is that noticeable pad fade tends to occur well before fluid boil on most braking systems [i}in good condition{/i}, unless you are using fairly 'hard' competition pads of a type which most people wouldn't tolerate for road use.
Since fluid boil is much more dangerous than normal pad fade (though I accept your comments about gassing on new pads being equally scary), if you are suffering fluid boil because you have competition pads fitted, then your pads are too hard and you need to change them for something less extreme. Better to suffer a little brake fade which just requires higher pedal effort, than risk fluid boil which might mean no brakes at all as your pedal hits the the bulkhead?
The last mile of my trip home every day is on a twisty bit of road (appropriately named 'Corkscrew Lane'!) and my benchmark for whether I've had a good run is whether I still have discernable brake fade as I pull onto the drive after cooling off a bit through the village...I've yet to suffer fluid boil on any road driving except where there was a brake fault.
We'll have to agree to differ on whether the term 'brake fade' is appropriate to apply to fluid boil, but I'd argue that if you can identify pad fade, it will act as an early warning that ought to ensure you avoid fluid boil.
I'd also maintain that, particularly on a light car like an Elise, fluid boil is much more likely of be a result of poorly maintained brakes (most often old fluid that has absorbed moisture) than incorrect grade of fluid.
By all means use DOT 5.1...but above all remember to change it regularly for track use. I'd rather be in a car with fresh DOT 3 than one with 5 year old DOT 5.1!
My personal experience, both on track and on road, in a large variety of cars, is that noticeable pad fade tends to occur well before fluid boil on most braking systems [i}in good condition{/i}, unless you are using fairly 'hard' competition pads of a type which most people wouldn't tolerate for road use.
Since fluid boil is much more dangerous than normal pad fade (though I accept your comments about gassing on new pads being equally scary), if you are suffering fluid boil because you have competition pads fitted, then your pads are too hard and you need to change them for something less extreme. Better to suffer a little brake fade which just requires higher pedal effort, than risk fluid boil which might mean no brakes at all as your pedal hits the the bulkhead?
The last mile of my trip home every day is on a twisty bit of road (appropriately named 'Corkscrew Lane'!) and my benchmark for whether I've had a good run is whether I still have discernable brake fade as I pull onto the drive after cooling off a bit through the village...I've yet to suffer fluid boil on any road driving except where there was a brake fault.
We'll have to agree to differ on whether the term 'brake fade' is appropriate to apply to fluid boil, but I'd argue that if you can identify pad fade, it will act as an early warning that ought to ensure you avoid fluid boil.
I'd also maintain that, particularly on a light car like an Elise, fluid boil is much more likely of be a result of poorly maintained brakes (most often old fluid that has absorbed moisture) than incorrect grade of fluid.
By all means use DOT 5.1...but above all remember to change it regularly for track use. I'd rather be in a car with fresh DOT 3 than one with 5 year old DOT 5.1!
Gassing Station | Elise/Exige/Europa/340R | Top of Page | What's New | My Stuff