Replaced callipers - long brake pedal and reduced braking

Replaced callipers - long brake pedal and reduced braking

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Hereward

Original Poster:

4,494 posts

240 months

Sunday 17th November 2024
quotequote all
2005 Mark 5 Golf 1.6 FSi

I replaced one front and one rear calliper, bled and went for a drive. Brakes now don't start to bite until way past the normal point and also require more shove.

I bled the callipers again - no air at all.

Is it possible to damage seals in the brake master cylinder during manual bleeding? With the engine Off I firmly pressed down the brake pedal multiple times with my hand to seat the pistons and bleed air into a bottle 1/3 full of brake fluid. Could this have flipped internal seals?

Per my below pic I also note that the front pads are only contacting the outer half of the front disc. Is that a factor?



Cheers for any advice.

Hereward

Original Poster:

4,494 posts

240 months

Sunday 17th November 2024
quotequote all
Thanks a lot for all the replies.

I have a replacement car already and this car was destined to be sold for £500 or scrapped. I put it through its MOT hoping for an easy pass but it failed on two binding brakes. Hence I was hoping for a quick and easy fix by simply replacing the two offending callipers.

I will bleed the callipers again (good point about taking them off and manipulating their orientation to dislodge air), and also bleed the untouched callipers. If it's the master cylinder I will throw in the towel since access is a nightmare.

I was hoping to give the car a more dignified send off since it's been in the family for 15 years but it is what it is.

Cheers.

Hereward

Original Poster:

4,494 posts

240 months

Sunday 17th November 2024
quotequote all
Daryl357 said:
Check if the master cylinder has bleed nipples, if it does, then bleed them. Common problem on TT's of a similar age.
Ooohh, thank you. Access is appalling (engine is mounted to the offside of the engine bay) but I will go and have a look now. Actually I will look online for a picture first.

I bled everything again an hour ago and still have the late/low point of brake engagement.

Hereward

Original Poster:

4,494 posts

240 months

Sunday 17th November 2024
quotequote all
Hereward said:
Daryl357 said:
Check if the master cylinder has bleed nipples, if it does, then bleed them. Common problem on TT's of a similar age.
Ooohh, thank you. Access is appalling (engine is mounted to the offside of the engine bay) but I will go and have a look now. Actually I will look online for a picture first.

I bled everything again an hour ago and still have the late/low point of brake engagement.
Daryl, thank you so much for this.

No bleed nipples (apparently on Mk4, not Mk5 Golf) but I pressurised the reservoir and cracked open the two master cylinder brake lines until they dripped then nipped them back up. That seems to have done the job.

MOT re-test at 0900hrs tomorrow!...

Hereward

Original Poster:

4,494 posts

240 months

Sunday 17th November 2024
quotequote all
Daryl357 said:
Christ I can't believe I missed that the first time round, your pads are the wrong way too, the pad with the 3 pronged clip is to go inside the caliper piston, not the side facing outwards.
OMG, then they have been like that for years, as fitted by the garage! The other pad, in the piston, is nice shiny metal prongs, having been protected from the elements in there.

It's pissing down now so I will leave as-is (until this plays on my mind to the point where I have to go out and sort it).

Cheers.

Hereward

Original Poster:

4,494 posts

240 months

Monday 18th November 2024
quotequote all
MOT re-test passed and car sold for £500.

Cheers all.