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[grifter]

Not that long ago I put new front discs and pads and had rebuilt the rears with new discs and pads and pin set. I changed the fluid as well and bled with one of those one way valves. Brakes were brilliant, now they are starting to feel quite spongy again, like they way they were before when I hadn't bled them correctly. Pedal travel is getting further down and the bite they had is gone.

Any idea why they might be getting spongy again, the fluid is up to level - hasn't dropped - and all the serviceable items are only recently replaced.

Cheers

Andrew

[Doctor Gollum]

Crap pads/discs.
Crap fluid.
Not bled properly.
External leak.
Mastercylinder leak.
Not braking properly.
Degraded hoses.
Rusty pipes.

As a start.

[Nick W]

Bleed it again, and see if that helps.


If it doesn't, I'd start with dodgy hydraulics.


If it isn't losing fluid, it's unlikely to be an external leak - rusty pipe, bad hose, poor joint.


Which would point me at the master cylinder as that's much easier to inspect than the ABS valve block.

[BlackieNo1]

Tired or “worn out” brake flexi’s could give the impression of spongy brakes. As in they could be expanding under the braking pressure if you follow me?

[grifter]

Ok I'll have a look at the flexis/pipes as a start and then onto the master cyclinder.

Cheers all

[cam.in.head]

also .extra suggestions.
if you clamp the front hoses and the pedal feels much better then its an issue with the fronts.usually the slider pins but can be air or hoses as suggested.
if you clamp the rear and the pedal feels much better then its a rear issue.again could be air or hoses but also could be seized pads in the caliper or a stuck piston causing the disc to push to one side.
if you bleed it all and it goes perfect ,then starts to go softer again a few weeks/ months down the line suspect a caliper slightly leaking seal drawing air back in .
just afew ideas

[grifter]

also .extra suggestions.
if you clamp the front hoses and the pedal feels much better then its an issue with the fronts.usually the slider pins but can be air or hoses as suggested.
if you clamp the rear and the pedal feels much better then its a rear issue.again could be air or hoses but also could be seized pads in the caliper or a stuck piston causing the disc to push to one side.
if you bleed it all and it goes perfect ,then starts to go softer again a few weeks/ months down the line suspect a caliper slightly leaking seal drawing air back in .
just afew ideas

Cheers mate will check all that in due course. Had freed off the F/O/S caliper about a year and a half ago, and it went sticky again so it might be I need new slider seals or something.

[cam.in.head]

thesliders do tend to seize due to rust or the grease drying out.
if you clean them its best make sure the bore is clean by using a exact size drill bit to clear them and then a thorough wipe out / spray with cleaner.
then wire wheel the pins so as they are totally rust free.
using the correct silicone grease and making sure the rubbers are good should ensure they stay good for a long time.

back calipers are prone to the pads getting tight/ stuck .

[Doctor Gollum]

I've seen rear calipers where half the metal below the pads  has rotted away completely and most of the support was from the pins

It's just a shame that you have to get creative to replace the vented calipers

[Nick W]

Cheers mate will check all that in due course. Had freed off the F/O/S caliper about a year and a half ago, and it went sticky again so it might be I need new slider seals or something.

I would suggest that new pins and seals would be sensible at this point, just to save messing about in the future. That's <£10 per side, and means you can concentrate your effort on cleaning out the bores they slide in - soak them in solvent and scotchbrite.


Seized calipers tend to make the pedal harder, not spongy.

[grifter]

Cheers mate will check all that in due course. Had freed off the F/O/S caliper about a year and a half ago, and it went sticky again so it might be I need new slider seals or something.

I would suggest that new pins and seals would be sensible at this point, just to save messing about in the future. That's <£10 per side, and means you can concentrate your effort on cleaning out the bores they slide in - soak them in solvent and scotchbrite.


Seized calipers tend to make the pedal harder, not spongy.

I realised this, but i don't think it'll do any harm as I've noticed the lower section of the disc on the N/S isn't as shiny as the upper part of the disc, leading me to think  the caliper sliders might be sticky again.

[cam.in.head]

seized caliper pistons will make the pedal harder yes but a single stiff slider can make the whole caliper try to twist and cause a springy pedal.the omega ones can and do seize but if properly sorted they are ok. a far cry from the 80's floating caliper design used on many vauxhalls thatused to seize for fun !