Looking for some feedback here. I run my MINI at the track and have Carbotech pads on the front brakes ... the wear sensor is disconnected and zip-tied out of the way. I just upgraded the fluid to ATE Super Blue, and everything worked out fine. Until today, when I was on my second run session at Lime Rock Park when I got the sinking brake pedal action and the red BRAKE lamp came on. I was able to pump the brakes back up to almost normal but they were still spongy. Brought her into the pits, turned her off, and restarted her ... the "MINI on a lift" light came on as well. I opened the access port and there was fluid spilled on the outside of the reservoir, and the level was pretty much at the rim inside. I did not fill her past the MAX level during the conversion to the Super Blue.

Brought her home and bled the brakes again ... not a bubble seen at any of the bleed points. I called my non-MINI mechanic for advice and he thinks that it is the master cylinder.

What is weirding me out is this:

1. I just changed the fluid to ATE SB on Friday.
2. The MINI was fine on a Fri night drive.
3. The MINI was fine during some pretty intense driving for the first run today.
4. The pedal went almost to the floor at the start of the second run (after an hour cooldown).
5. The fluid on the outside of the reservoir
6. Brakes are about 75% normal, lamps still on.

I would not expect a lot of volume expansion from heating, but maybe I should have filled to below MAX? Could the overpressure from expansion have blown a seal in the master cylinder? Why have the brakes partially recovered?

I really hate going to the dealer even for warranty work, but it's looking like that's my MINI's fate.

Comments? Thanks!

 

I had the same feeling at Laguna Seca, a track that has 3 highspeed, critical hard braking points. I also have a Viper that I track and the difference between the Brembos and MINI brakes are night and day.

I have decided to go with stainless braided lines all around and the StopTechs in the front.

What are your thoughts?

 

what CT Pad are you running?

 

Hawk HPS

 

Hi Dustin. I'm running XP10s in the front. Stock pads in the rear. I have not yet installed the latest set of XP10s that I bought from you...or the XP8s that I bought from you near the end of last season ... i.e., the current pads are unchanged from late last season. The only thing done to the system this year was a fluid flush.

I've been searching NAM etc. for similar situations ... might be a master cylinder, might be an ABS control module, might be ?

 

Please change out the rear pads. I bet that helps if not resolves the issue.

 

Hi Dustin. Why would this help? There's like 50% left on the stock rear pads, and they've been working fine with the XP10 front pads since last September. Please share your thinking on this. Thanks!

PS - I do plan on changing the pads all the way around soon. Do you think that I should try the warning lamp reset procedure and see what's up? It's the pedal went soft - and then recovered after pumping the brakes thing that has me confused here.

 

Having the stronger pads on the front and OEM pads on the rear means you've probably got to much front brake bias (fronts are doing all the work) and your overheating the pads and or fluid. I go with Dustin...balance your pads out with CT's on the rear too... My 2 cents.

 

Ditto, and since your OEM's are wore down they are really heating up faster then ever and making the fronts work harder and hotter too. All of which leads to fluid issues and so on and so on.

 

OK, I get the picture. Would it make sense that the pedal sank way down, yet she's physically about normal now (off the track)?

I have the red BRAKE lamp lit and the "MINI on a lift" lamp still lit on the tach display ... which, according to the manual, means "vehicle electronics failed".

Can you comment on this? Thanks again, gents.

 

When the brake system cools down it's going to be "normal" but over heating the system many times will lead to failure, that's one of the main reasons why many track guys change fluid at every event.

As for the lights, I'm at a loss on that one. The R56's got too many sensors for me and I'm sure there's someone on NAM that can address that issue.

 

Once things cooled down the pedal came back some and didn't you say you flushed the system with new fluid afterward? If not, you need to. Not sure about the electronic failure light, could be two different things......

 

Yes, the lights situation is frustrating. I have searched the known (online) universe and have really gotten nowhere, other than to find posts saying 'park it'.

Dustin, I appreciate your great followups on your sales. You treat your customers right.

 

I think what happened was you boiled your fluid, and that's why you had fluid outside the MC, it expands a lot when it boils like that........

Anywho, replace your pads with the same kind all around, bleed and change the fluid and you should be good to go.........

 

She went to the dealer today, and the SA called asking about the ATE Super Blue ... telling me that his mechanics told him that ATE Super Blue has caused master cylinder failures in the past.

I told him that MINI spec's DOT4, and ATE SB is DOT4.

Let's see where this goes....

 

I had ATE SB in my car when the Front Rotors & Pads were replaced. It's not a problem.... or at least it shouldn't be.

 

Wow, that's a new one on me........

 

I changed the pads all the way around, re-bled the brakes, still had the lamps....pedal was good to go. The dealer replaced the rear brake sensor and bled the brakes with MINI (TM) fluid. Everything is fine now ... but they charged me for the bleed and the new rear brake wear sensor ... they said no warranty because I mucked around in there (Keeler MINI in Latham, NY). However, I got free flatbed service 100 miles each way.

I want my ATE SB tho....

Thanks everyone for the help!

 

Don't go to Keeler if you have ATE SB. They told me that I have voided my brake warranty with it because you cannot put additives into brake fluid. So I now use Type 200 only so they don't know the difference.

 

See my post about your cracked rotors and work on changing your braking style. When you brake coming to a stop sign, you start by gently pushing on the brake pedal. As you get closer to the stop sign, you brake harder and harder until you stop, but generally, not hard enough at any time to make the nose dive (or even make the car squat). This is NOT the way to brake at a track. This "don't spill the water in the glass on the dashboard" braking style is not the way to brake at the track, and will really heat up the brake system components, including fluid.

Consider the 10, 10, 10, 9, 8, 7, 6, ... style of braking. With the push to 6 making the whole car squat, increasing the contact patch of the now very weighted tires, you can REALLY bring the car down quickly. The shorter time spent on the brakes combined with the very hard braking really only superheats the surface area of the rotors and pads, which cools more quickly than the deep heat caused by prolonged "water glass on the dashboard" braking.

Google threshold braking.

Also - personal opinion here, and I'm not trying to start a "which is the better spark plug or better oil" type of argument - try Motul and move away from the Ate SuperBlue. I tried Ate after several years of Motul. I did one track day and flushed it for some new Motul. I had a LOT of brake fade and until I flushed it out - spongy pedal. On a really hot day on one of the "big brake" tracks, I might have to bleed off some cooked Motul after the event. On one of my usual tracks, by the time I get home (half hour drive to the closest track), the brakes are back to normal.

I've been driving tracks on the west coast for almost 30 years and teaching HPDE for 20+ years, and used Ate only the one time, so maybe things have changed, but Motul works really well for me, and I usually have someone else in the car when on the track (our clubs encourage instructors to take students with us).

BTW, I am not a proponent of big brake kits. If you can lock up your tires with the stock brakes, you have big enough calipers. The only reason you might need big brakes is if your local tracks are the kind where you have lots of short, high speed sections followed by tight turns. Still, even with big brakes, you need to use threshold braking techniques and stay off the brake pedal - get on it only for the minimum amount of time needed to slow the car. If you go to big brakes, REALLY pay attention to keeping the car's balance as close to stock as possible.

Hope this helps.

Pat

 

I had a similar problem at the track but not as extensive as what you described earlier. I definetely experienced the sinking pedal but with still lots of braking power. I didn't experience the boil over of fluid not the warning lights coming on though.

I use ATE SB also as was recommended by my friends who go to the track on a regular basis. They have never complained that it ever caused them a problem. I think my issue was more related to improper bleeding of the system where old fluid remained and became a contaminant that effectively lowered the boiling point. Also, instead of using fresh fluid from unoppended container, I used some fluid from container opened months before. I'll never do that one again.

Now here's the good part. I went to the dealer yesterday for a brake flush before starting the track season. Local club wants it to be done by a shop at least once before starting. Anyway, when I picked up the car, they told me that they found this blue fluid that was used to top up the system and that this would damage the system and to only use the BMW OEM fluid. They even were asking if I used the correct DOT level of fluid

I wasn't impressed. I have the OEM fluid in the car now and will see if it makes a difference. But I don't believe for one second that ATE SB could cause damage to the system.

Good advice by Pat by the way. This is exactly the method that was instructed by the club instructors to minimize heat soaking your brakes.