[BRAKES] Soft Pedal - Help

[Andrew Chapman]

Hi all.

I'm looking for a bit of advice on a non VW.

I bought a Renault Vel Satis as a week ago as i've always fancied their unusual looks. The car was owned by an elderly couple and had been off the road for a year or so due to covid. MOT running out late last year.

I had the car trailered back to my home, and the only driving i did was off the trailer onto my drive. I didn't notice the brakes were particularly poor or weird but the discs were excessively corroded so for safety's sake decided to change all discs and pads front and rear.

Have now completed this, but with the engine running the pedal slowly sinks to the floor , motor off pedal remains firm.

When doing the work i saw no evidence of leaks and the pistons went smoothly back into the calipers.

I had to remove some fluid from the reservoir as the new discs and pads were more meaty than than the warn ones coming off, but nothing out of the ordinary. When i test pumped the brakes the level in the reservoir is not decreasing indicating an external leak.

I have not bled the brakes as yet - I'm after some ideas of what i should do next and what the possible issue is.

Thanks in advance

[farmer rob]

It sounds like you are leaking brake fluid past the seals in the master cylinder if you have no leaks. As it has been stood and with this 'cold ' weather, the seals may be a bit hard, as it warms up next week, you might find they will bed-in again and be no problem

[Bada Ben]

If the car has been stood for that long, and previous service history is unknown, I'd replace all the brake fluid anyway, (should be replaced every 2 years as standard service/maintenance) .
As you mentioned: " with the engine running the pedal slowly sinks to the floor , motor off pedal remains firm " also check the servo for vacuum leaks and/or brake fluid leaking past the Master cylinder end seal into the servo itself.

[Andrew Chapman]

Hi . Thanks for the suggestions.

I checked again in the daylight for leaks - absolutely nothing i could see. I then did a 20psi pressure bleed and full fluid change.

What came out was old and dark, but no bubbles.

Tested the car again and exactly the same.... I think its pointing to the Master cylinder ?

For those in the know, how much should i expect to pay to have this work done. The cylinder itself is approx £80-90???

Thank you

[2much]

Hi Andrew, you are probably looking at 1.5 hrs labour at a garage and between $60 and $100 per hour ex. VAT per hour depending on garage plus Cylinder and other sundries 's my estimate.

Always fancied a Vel Satis or Avantine (spelling ?)...

[Andrew Chapman]

Yes, we would have like an Avantime but after viewing four £3-5k cars we decided that they were really poorly made. The cabin material don't seem to stand up to even gentle use. Particularly the door cards, they get really scratched and because they are cream coloured it really stands out. Also very hard to get any trim spares etc.
The VS seems much higher quality in terms of materials rather than the Matra built Avi

[Hoosier]

It could be that the brakes need bedding in.
If i were to do front n rears.
Id replace the fronts, take it for a run for a few miles.
Then do the rears.

Has it got electric handbrake or a normal lever type?

The servo sounds ok to me. If the pedal stays hard and you feel no difference when you start the engine then id say servo. But as the pedal sinks, id say its doing its job.
Only thing i would suggest is start it up and leave it running for 10 seconds or so then switch it off again.
If you can hear a hissing noise for a few seconds after switch off then it may have a leak but ive got my doubts its that.
Maybe worth checking the vac pipe from the servo.

If you get someone to slowly press the pedal up and down (with the engine running) whilst you look in the top of the reservoir you should see swirling/rippling as brake fluid comes back up from the master cylinder into the reservoir. Id say master.

My money is in either handbrake adjustment or they need bedding in.

Rich