Rear brake pads fitted...BEDDING IN PROCESS?

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ALFAHOLIC

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Hi ouens,

So this morning I went and got the rear pads fitted. The ones that came out were 99.9% finished!:erm: I asked the guy after he put the brakes on to try and wiggle the wheel to see if there's any play that will give away the signs of wheel bearing damage. NOTHING! I was so happy! I drove off with my new Ferodo pads on...and guess what, no shoo shooo shoo shoo shoo sound...for about 1km!

The brakes started to catch on the disc and almost slow the car down! It took extra revs just to ge the car up to speed...so they were definately catching more than they should. I think the piston was at the set position for the old pads...its self adjusting, so with the newer pads the guy just moved the piston back to accomodate the new pad...but it seems the piston did not adjust at all or is probably still adjusting???

http://www.zeckhausen.com/bedding_in_brakes.htm

Going by this guide, I think I F'd the brake discs up...as previously I did some spirited driving and then immediately washed the car while the brakes were still hot...stupid mistake I know...I think that messed the discs up...I'll follow this bedding in process lunch time...I think it'll work.

I took a quick blast(so wrong) and then off to work, wasn't even 7km from my work, I parked the car...at 12 I'll be heading out for lunch so hopefully then the brakes would have settled into normal position. We know now its not the wheel bearings but the brake pads rubbing against the disc...will the brakes self adjust with some more driving, and Ms. Daisy driving?

Your thoughts.
 
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I don't know about your car, but what I do know is to always push the piston as far back as possible when changing pads. It's a little extra work but a great safety measure since the new brake pads are (obviously) wider than the old ones and you don't want unnecessary pressure on them when you're not pressing the pedal. Open it up and push the piston to the maximum 'open' position. Speaking of which, time for me to buy new discs for my car. Anyone know of where the best place to buy them is? (I don't want anything big, fancy and cross-drilled, just a normal disc or 4 :'( $$$).

P.S. In CT.
 
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Yep...I just drove again and it feels better...a bit, still doing the bedding in process, I think the piston will set itself.
 
That isn't normal. I don't own a Alfa so I can't say for sure but I've changed pads on many, many Opels and never had the brakes catch. You are supposed to gently push back the piston(s) as far as it can go. After you pump the brakes until pedal is back to the usual stiff setting.

Either the pistons are worn or the guy didn't do it properly, so far as I know sticking is a early sign of piston wear (according to wikipedia it's a sign of leaking, never had it before so I'm not sure, just pointing it out). Refurbishing Calipers is a mission :(

Oh yeah forgot to say, if your discs are warped (IE. damaged because you drove too "enthusiastically" ;) or because of rapid cooling) you'll feel a shuddering as you brake, it'd be less pronounced if it's at the back because the bias valve on the brake line or master cylinder causes less brake pressure at the back (so that the rear wheels don't lock up when you brake as the car is heavier in the front).

@UnUnOctium: Cross drilled discs are stupid anyway, it's only for looks. You don't get better brake performance. That said I usually call Midas, Toolman, AutoZone and Goldwagen. Ask the prices on the items at each then buy at the cheapest ;) I only buy Ferodo, I would recommend it.
 
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Gnome said:
That isn't normal. I don't own a Alfa so I can't say for sure but I've changed pads on many, many Opels and never had the brakes catch. You are supposed to gently push back the piston(s) as far as it can go. After you pump the brakes until pedal is back to the usual stiff setting.

Either the pistons are worn or the guy didn't do it properly, so far as I know sticking is a early sign of piston wear (according to wikipedia it's a sign of leaking, never had it before so I'm not sure, just pointing it out). Refurbishing Calipers is a mission :(

Oh yeah forgot to say, if your discs are warped (IE. damaged because you drove too "enthusiastically" ;) or because of rapid cooling) you'll feel a shuddering as you brake, it'd be less pronounced if it's at the back because the bias valve on the brake line or master cylinder causes less brake pressure at the back (so that the rear wheels don't lock up when you brake as the car is heavier in the front).

@UnUnOctium: Cross drilled discs are stupid anyway, it's only for looks. You don't get better brake performance. That said I usually call Midas, Toolman, AutoZone and Goldwagen. Ask the prices on the items at each then buy at the cheapest ;) I only buy Ferodo, I would recommend it.
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Gnome...I stood there as he did the job...those pistons did NOT go back easy! He had a tool that he used to push them back in...it doesn't stick per se, the car can still drive, but there's a noticable catch - Im taking it back there at 4pm, I'm 100% sure the pistons needs to be pushed back to the furthest position to accomodate the wider pads...he probably just pushed them back enough for the pads to squeeze in...
 
ALFAHOLIC said:
Gnome...I stood there as he did the job...those pistons did NOT go back easy!
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Yeah, it's normal, remember he is pressing against the hydraulic pressure of the entire system, even with the brake pedal (with the power brake disabled/car switched off) it takes quite a bit of effort once vacuum is lost to fully depress the brakes, this is similar but in reverse on a small little piston. They don't go back easy, they do however have to go back fully. When I said gently I meant, gentle, as in don't damage it ;) The piston can be damaged if done incorrectly. Good luck!
 
ALFAHOLIC said:
Gnome...I stood there as he did the job...those pistons did NOT go back easy! He had a tool that he used to push them back in...it doesn't stick per se, the car can still drive, but there's a noticable catch - Im taking it back there at 4pm, I'm 100% sure the pistons needs to be pushed back to the furthest position to accomodate the wider pads...he probably just pushed them back enough for the pads to squeeze in...
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The pistons on most rear brake callipers need to be screwed back with a special tool, but they only need to go back enough to accommodate the pads (after all, first press on the brakes sends the pistons to the position where they hold the pads against the discs).
 
Claymore said:
The pistons on most rear brake callipers need to be screwed back with a special tool, but they only need to go back enough to accommodate the pads (after all, first press on the brakes sends the pistons to the position where they hold the pads against the discs).
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My thoughts exactly. There is no way that the piston can be in the wrong position, the minute you have braked for the first time.

You might have to dig a little deeper....
 
Fazda said:
My thoughts exactly. There is no way that the piston can be in the wrong position, the minute you have braked for the first time.

You might have to dig a little deeper....
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My "little deeper" was that the piston must not be back properly, but seeing as this is a self adjusting unit...it should have self adjusted a long time ago! Sure thing is, the pads ARE rubbing to the point where you smell brakes when I get to work...so there's no doubt they need to be taken off AGAIN and refitted with surity that its not going to rub, that's my only guess now...there goes another R300 I could have spent eating out or something!
 
ALFAHOLIC said:
there goes another R300 I could have spent eating out or something!
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Eish, that is nonsense man, you should take it back and have them fix it on THEIR cost, I mean WTF, they are professionals right?
 
I thought long and hard about doing it myself hey! I even downloaded the flippen step by step guide with pictures on how to do it. I paid them R345 to fit it...I might as well have just bought me that special tool to turn back the piston and done the job myself...I'll rethink that...

Anyway the car is fine now...rolls back etc it still makes that shoo shoo shoo noise...I took it back there and i drove with the one guy and he said its the tyres...they're flippen new tyres! And I rotated them 3 weeks ago ...

I'm thinking of just buying new discs and taking it somewhere else to fit as i don't have the tools to take off a disc.

because the pads ARE rubbing against the discs...not so much more now...
 
You dont really need any special tool, the wooden handle of a hammer works excellent or a piece of wood with a C-clamp (you dont want to bork it up). He's talking crap if he says it's the tyres. Go and refuse to leave until they fix it, simple. Tyres don't smell of burning brakes. I'm going to be changing my car's discs soon (230k KM originals :D ) and will be doing myself, I'll just need to buy the discs, a wrench set and pads while i'm at it.
 
ALFAHOLIC said:
I thought long and hard about doing it myself hey! I even downloaded the flippen step by step guide with pictures on how to do it. I paid them R345 to fit it...I might as well have just bought me that special tool to turn back the piston and done the job myself...I'll rethink that...

Anyway the car is fine now...rolls back etc it still makes that shoo shoo shoo noise...I took it back there and i drove with the one guy and he said its the tyres...they're flippen new tyres! And I rotated them 3 weeks ago ...

I'm thinking of just buying new discs and taking it somewhere else to fit as i don't have the tools to take off a disc.

because the pads ARE rubbing against the discs...not so much more now...
Click to expand...

Discs are usually easy to replace (if you can get the brake calipers off, that is). You may find that your pistons are sticky, and not being pulled back properly.
 
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