Spongy brakes after new pads & discs..

[Jim 2]

Hi folks..

 

Last weekend I fitted new pads and discs to the Rado. We were careful when doing the work not to put any strain on the flexi hoses, etc (they're Goodridges anyway) and used genuine VW discs and ATE (OE supplier) pads, and put it all back together with new bolts. Problem is on the way home I thought that the brake pedal has to travel a hell of a lot more down before i'm getting any bite.

 

Put the car away as i've been away for a few days and coming back and driving the car again it still feels dreadfully spongy. Obviously i'm not doing any heavy braking yet as I need to bed the pads in but even in mild braking it still feels a bit hairy.

 

I'm guessing I could do with getting the brake fluid changed / bled as par for the course - but how could the brakes have gotten worse?!

[boost monkey 0]

Just a couple of things off the top of my head, Captain Sideburns:

 

Did you brake clean or sand the discs down before you put them on? they may well have an anti-corrosion coating on which can be similar to teflon/non-stick stuff! Not handy for brake discs when in use.

 

ditto for the brake pads? Wouldn't have thought they'd need it, but could have a layer of something like grease on the top of the friction material.

 

A fluid change isn't a bad idea, but you should be able to swap discs and pads without bleeding the system :-S

[Jim 2]

Hm.. well you got me there. I admit that I didn't sand the discs or pads at all before putting them on though they were neatly wrapped in about 300 metres of plastic from VW to keep them free from contaminants. I did give a disc on one side a blast with brake cleaner but forgot on the other side (duh) - hoping that whatever coating is on there removes itself as it feels a bit dangerous at this point!

[davidwort 0]

did you remove fluid from the reservoir when you pushed the pistons back to accomodate the new pad and disc thickness?, I guess it's possible you got some air in the system somehow, a partial fluid change/bleed should sort it, they'll also take a few hundred miles to bed in properly.

I've always manually bled with a 'helper' pressing the pedal, but I used a pressure bleeder connected to a spare tyre valve and those things are great, much less chance of running out of fluid when bleeding and so easy on your own to do the job, only about 15 quid IIRC.

 

It's also possible the backing coating on the new pads means the pad friction surface isn't perfectly flat on the disc surface, again this should sort itself out with some heavy braking and a few miles on them.

[boost monkey 0]

I never found that the easy bleed systems had a top and gasket/seal which fit the brake reservoir properly. it used to just all squirt out of the lid and run down the side! Would be interested to hear which one you have used David.

[Jim 2]

Hi David. Yeah - Eric was on the ball with the fluid reservoir so we did siphon off the excess when we pushed the pistons back in. Thanks for the advice on the brake bleeding, etc. Won't have a chance to tackle this now till after Germany - luckily I won't be using the car much till then and will only be pottering around on local roads till then anyway. Quite tempted to just wheel it in to Stealth to get it done being as they're so local - and i'd assume its only an hours labour plus fluid to do..?

[Toad 0]

You girl, try braking a bit harder, the disks and pads probably just need bedding in properly...

[davidwort 0]

providing none of your brake bleed nipples are siezed its only going to take 15-20 minutes at most, particularly with a pressure bleeder, it's literally: fill the bleeder reservoir with fresh fluid, screw it's connector to the top of your reservoir, connect up the air line to a tyre valve and crack off each of the bleed points in turn for a few seconds, job done.

 

It's a good idea to bleed a small amount of fluid out every year, not a full change but just a small amount from each wheel as any water aborbed into the fluid tends to collect at the low points in the system, i.e. your calipers!

[Supercharged 2]

Yeah, always a good idea to change the fluid after a pad change, also may need to bleed the master as this will affect the travel is there is any air in there - bed them in first then nip into Stealth / VW for the fluid change.

[pete_griff 0]

the 300m of plastic over the discs would have been holding in the protective oily type stuff that is put on discs to protect them and stop them going rusty when they are new.

 

you shouldn't need to sand the discs before they go on, although a good clean with brake cleaner/white spirit is definitely a must to remove all the protective gunk.

 

you always don't have to, but it's not a bad idea to lightly sand the surface of the pads before you put them on - just helps them bed in better and ensures any contaminants are removed.

 

it might be worth just whipping the pads out, giving them a quick sand, cleaning the discs with brake cleaner/white spirit and whacking it all back together.

 

most brakes take a while to bed in anyway, not matter how thorough you are when installing them. it normally takes a good few journeys for them to bed in properly and have good bite/feel. (manufacturers quote something like 100-200 miles, but that's a bit excessive IMO). until they are bedded in you will not stop as quickly as you normally would, especially when you intially brake for the first couple of times.

 

like toad says, just give them a few more hard stops without frying them and they should start to feel much better.

 

let us know how you get on :D

[Toad 0]

Try driving a short distance with one pedal on the brake and one on the throttle (maybe in a car park), just to speed the bedding in process up.then press the pedal nice and hard a few times, then see what they are like...

 

Pads and disks take a little while to settle down, I'd not be running off to throw money away just yet...

[Jim 2]

They do seem to be improving actually mate! Done a few more miles now. I think its psychological as much as anything - trying not to jump on them and do more progressive braking coming up to junctions, etc just for a few hundred miles to bed them in!

[skinnyman9000 0]

My brakes suffer from the same problem. The first inch, maybe more, of pedal seems to do naff all, when i drove my mates mk4 gti the other day i nearly went through the windscreen, instant bite on his.

 

Ive bled the system twice with no change, so im still struggling to solve this mystery too

[Supercharged 2]

Rear calipers can take a while to self adjust after a pad change so can affect feel, as can the Bias valve...

 

One of the best things about the Corrado is the progressive brake feel, I love it compared to new cars that are way to 'sharp' imo.

[The_Dude 0]

I just had my zorst changed and it now feels distinctly woolly, but we bled the rear brakes and no air came out...any ideas?

[pete_griff 0]

I just had my zorst changed and it now feels distinctly woolly, but we bled the rear brakes and no air came out...any ideas?

 

it wouldn't be a bad idea to do the whole system - you most likely got some air trapped somewhere when it all came off - the only way to be really sure is to give the whole system a thorough bleed - doesn't take too long and at least you will have effectively done a fluid change afterwards (if you take the trouble to remove all the old stuff...)

 

don't forget to bleed the two nipples on top of the abs pump as well as these are often overlooked, not a bad idea to do the one on the master cylinder as well really, just to be sure.

 

also, like mr supercharged says - it seems some rado's are funny old things when bleeding the brakes and they might not feel "quite right" for a while after bleeding until everything has settled down - probably due to the convoluted brake line setup they run.

 

hope you manage to get it all sorted anyway buddy :)