Lost brakes

Lost brakes

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Discussion

Andrea7

Original Poster:

196 posts

15 months

Sunday 6th April
quotequote all
Hi all.
Today, after a ride of an hour or so and many brakes on a tortuous downhill mountain road, I had totally lost the brakes.
So I slowed down and drove without brakes trying to come back home with lower gears and some handbrake....
After 15minutes I tried to brake again and.....it works.
Perfectly.
Is it possible that the only problem is the brakes oil grade?
I changed the brakes pump as soon as I took the car and the oil brakes too....
The servo always worked.
What I don't understand it's how is it possible to lost COMPLETELY the brake and then have it COMPLETELY functional after a little bit of cool down...

Gary C

13,525 posts

192 months

Sunday 6th April
quotequote all
I have boiled brakes in the past, the fluid gets so hot it voids (either water vapour or fluid vapour) then when it cools, the bubbles condense back. The pad material can also overheat and combust/gas off such that your braking on a layer of gas.

Got a picture somewhere of my Mk1 Astra with Mintex M141 pads with little flames at the edge, gripping cherry red disks. Lost brake function completely (Austrian mountain pass , eeek !), but after a good cool, it came mostly back.

Good job I always took a full toolkit on holidays. Brake fluid change on a campsite.

Edited by Gary C on Sunday 6th April 13:05

MarkwG

5,458 posts

202 months

Sunday 6th April
quotequote all
Moisture in the brake fluid would be my suggestion: boils as the brakes heat up, lose pressure, as it cools down, regain the pressure. I'd do a complete fluid change with known quality fluid.

Andrea7

Original Poster:

196 posts

15 months

Sunday 6th April
quotequote all
Quite agree with both of you.
Last time Motul 600 or 660 was used...don't remember now.
Could the mechanic maybe changed only last parts of fluid near brake calipers so the circuit maybe resented of the older ones in the circuit?
I'm speculating....
I generally do it by myself but not on the Cerbera cause I was very busy at the time.....
And consider that I don't know anything about the previous fluid and how old it is

Edited by Andrea7 on Sunday 6th April 19:02

Andrea7

Original Poster:

196 posts

15 months

Sunday 6th April
quotequote all
What is the total capacity of brakes fluid on the Cerbera?

Gary C

13,525 posts

192 months

Monday 7th April
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from this thread https://www.pistonheads.com/gassing/topic.asp?h=0&...

"System capacity is considerably less than 1L, but if you're bleeding it yourself, then don't be too wasteful or you'll run out! (i.e. close the bleed nipple as soon as the fluid turns clear)."

Byker28i

72,308 posts

230 months

Monday 7th April
quotequote all
I had this with the clutch shortly after buying it, when we did the London Thunder protest in 2006?
600 plus TVR's driving through London to Downing Street and I still had the cats in then. Clutch/gearbox got hot in London traffic and the pedal got long. Letting it cool brought it all back