Cooked brakes

Author
Discussion

Drive Blind

Original Poster:

5,412 posts

192 months

Friday 3rd June 2022
quotequote all
2016 mk7 Golf GTD

I was out the other evening for a random drive and managed to overheat the brakes. There was some brake fade and the pedal went very long.
Since this the pedal doesn't feel the same and the brakes don't have the same initial bite.

Will a brake fluid change resolve this or have I wrecked the pads and/or discs ?
To my eye the discs and pads still look ok.

Front discs and pads were replaced approx 30K miles ago. Fluid was changed 2.5 years ago.

E-bmw

11,051 posts

167 months

Friday 3rd June 2022
quotequote all
Unless you are familiar with working on & fault finding on brakes, they are one thing best left to the professionals.

There are just so many things that are critical & if you aren't sure, best to find a trusted garage to send it to.

Peanut Gallery

2,587 posts

125 months

Monday 6th June 2022
quotequote all
I did this recently, had a real hoon, brakes started to feel a bit long, not the same initial bite, but still had full efficiency etc, so it was not a safety issue, just a different feel / more difficult to brake as gently.

It took a fair amount of miles, but the brakes did come back to their old self, just need to wear out the slight glazing on the pads and disks is what I put it down to!

Did the same when the other half was learning to drive, she managed to ride the clutch enough that it started to glaze over, it would slip when even depressed a tiny amount and you could feel it wanted to engage, but hardly provided any drive until the very end of travel. I drove it gently for a couple of drives, and the bite point started to return to normal, then she would have a go at driving again, repeat. Eventually her driving improved, and the clutch lasted another 80k miles, and was starting to get a little high when the bearings decided not to bearing.

(Note to self, change brake fluid)

GreenV8S

30,859 posts

299 months

Monday 6th June 2022
quotequote all
Drive Blind said:
Since this the pedal doesn't feel the same and the brakes don't have the same initial bite.
Those are the symptoms of cooked brake fluid. Replacing the fluid will make a big difference. Depending how you were driving you may have also cooked the pads or distorted them due to wear under heavy braking. If so, you'll need new pads. Check the condition of the rotors too - if they've been overheated you may eventually get fatigue cracks due to differential thermal expansion, but IME these usually develop quite gradually and are unlikely to be a problem after just a single overheating episode.

The big danger from overheated brakes is that you push the fluid past its boiling point. If this happens, the brakes will feel the same as usual in the corner where you boil them but will boil as soon as you come off the brakes and you'll have nothing at the next corner. If you're hooning, make sure you've got some feel on the pedal before you commit to heavy braking.

Tony1963

5,682 posts

177 months

Tuesday 7th June 2022
quotequote all
I’d test the brake fluid by going for a drive and on a straight, safe, quiet stretch of road at 60mph ish hit the brakes hard… don’t stop, just come off the brakes at 10mph ish, repeat twice. If the brakes manage that ok, the fluid is ok. But: when was the fluid last changed? It may well be due a change soon anyway, and it’ll put your mind at rest.

GreenV8S

30,859 posts

299 months

Tuesday 7th June 2022
quotequote all
Tony1963 said:
If the brakes manage that ok, the fluid is ok.
I don't see that giving any useful information about the state of the brake fluid except that it's present.

Drive Blind

Original Poster:

5,412 posts

192 months

Tuesday 7th June 2022
quotequote all
thanks for the feedback.

I have done a few tests since the event and I still do have adequate brakes, so no panic there.

I'll look into getting the brake fluid changed ASAP.

E-bmw

11,051 posts

167 months

Tuesday 7th June 2022
quotequote all
GreenV8S said:
Tony1963 said:
If the brakes manage that ok, the fluid is ok.
I don't see that giving any useful information about the state of the brake fluid except that it's present.
^^^^Wot 'e said, a couple of near stops will not boil brake fluid even when badly contaminated, the heat would need to get through the pads & the caliper to quite some level before fluid boil would become evident.

Probably 3 hot laps of Cadwell park might stand a chance unless there is a stuck caliper.

Tony1963

5,682 posts

177 months

Tuesday 7th June 2022
quotequote all
Well the point is, and taking into consideration the OP’s posts, if the fluid is past its best it won’t do its job for three hard stops (obviously this depends on exactly how past its best it is). Ok, if the OP wants to go for extended spirited drives, then for the sake of what, £60-90, have a garage replace the brake fluid. I don’t care at all, and on public roads I don’t often brake very late from high speeds into corner after corner after corner…