Do I need to run new brake pads in?
What's the best way to do it?
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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I normally just drive along for about 300 yards with the brake pedal partially depressed.
Make sure that
(a) you do those on a quiet road...
(b) you have a suficient run-off afterwards to allow the discs to cool off.
I have a favourite hill which works well for this.
(also garvity takes a lot of the engine load off!)
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Don't use the brakes lightly as this will glaze them. Other than that, just drive as normal
My brother once fitted new pads to my Scirocco, but fitted some really cheap ones without telling me. They took a few miles to work properly - I was leaving brown streaks everywhere till I got the hang of braking a lot sooner than I used to...
Once they were worn in a bit, they were fine, tho.
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Glad you raised this Toad.
After much research and prompting from other LR men I changed the front pads of my Disco. No probs, but. Many years ago I put new brake shoes on a Mini-van and noted that a return spring kept them from rubbing on the drum. With the brake pads on the Disco there is nothing to push the pads off the disc after the piston has pushed them forward on braking. As a result there must be friction so there must be heat. So why isn't my front brakes on fire?
DVD
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DVD:
I've never thought of this before, but aren't the hydraulics double acting, so that when you depress the brake pedal, the pads move towards the disc, and when you release the pedal, the opposite?
Andy
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The rubber seals on the caliper pistons spring back a bit, thus puling the pad off the disc.
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Yes that sounds feasible.
However I had to apply considerable pressure to get the pistons back into the caliper so I could slot the pads in.
Come on DW put us all at ease.
DVD
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DVD,
I'm a mechanic..I fit new pads...30K later I fit another set...that's my need to know stuff. ;-)
I always thought that the minute runout on a disk was the main thing that moved the pads back from the disk enough to stop binding. Some folks say the piston rubbers are supposed to pull the pistons back in as well. To be honest I see them as dust rubbers and they seem to have very little effect in that direction. Also there are Citroen rear brakes with no outer rubbers and those pads come back in OK.
I always advise running/bedding in pads. It is supposed to extend their life and give best performance. With an old disc and new pads in particular the area that touches for the first few miles can be quite small until the pads have bedded in. If you use the brakes very hard this will tend to localise the area of the disc that heats up possibly causing a change in the disk properties at that point. Over many miles this can then cause uneven wear of the disc surface.
David W
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Yes that sounds feasible. However I had to apply considerable pressure to get the pistons back into the caliper so I could slot the pads in.
I have an old carpentry G-Clamp which I use for this very purpose.
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With the brake pads on the Disco there is nothing to push the pads off the disc after the piston has pushed them forward on braking. As a result there must be friction so there must be heat. So why isn't my front brakes on fire?
In general, pads are knocked away from the disc by small amounts of movement of the disc surface relative to the pad surface. This occurs either because of (a) distortion of the disc (b) axial free-play in the wheel bearing or (c) variation in thickness of the disc from one point to another. It only requires for the pad to be moved a few thousands of an inch (or hundredths of a millimetre, for the "metric-only" fraternity !!) for there to be no contact of the pad with the disc. Most vehicles will suffer from (a), (b) and (c) to some degree or other.
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Firstly having just overhauled my rear caliper I can confirm that the pads spring back a fair bit when the brake pedal is released. Must be some property of the hydrolics because there is no spring. Pumping the pedal with no pads they come out about 5mm and get \'sucked\' back about 3mm.
I didn\'t wear the pads in very carefully but they seem ok.
A little message to everyone on the A44 tonight. a) Yes, I am considerably quicker than you. b) On the contrary, the road *is* my personal race track. c) No, double whites don\'t apply to me; they are a tool of oppression for cage drivers. d) No need to thank me for spectacle of my rocket like descent of Fish Hill which was a joy to behold.
Best ride I\'ve had for yonks.
Also heard today that biker deaths in Worcestershire have halved which if my maths serves me right, means I can be twice as reckless in perfect safety.
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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Epitaph on the A44
The world has held great Heroes,
As history books have shown
But never a name to go to fame
Compared with that of Toad.
Slow down and live.....
DW: Thanks for puuting my mind at rest. No need to go out and buy a Green Godess.
DVD
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Epitaph on the A44
Just re-read this and comprehended the point you were making.
Thanks for your concern. You can take my word for it that I have a very strong self preservation instinct. I think Toad just had a bit of post blast bravado on Friday night!
Top poem!
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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Toad,
If you get passed* on the way back up The Fish by a blue TD Xantia that'll be SWMBO... visiting the old stamping grounds also this weekend.
Take care on the top corner, still catches them out.
*I think she's found the boost limit override switch.
David W
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If you get passed* on the way back up The Fish by a blue TD Xantia that'll be SWMBO... visiting the old stamping grounds also this weekend.
;-) Classic gaff. Walking across a field of stubble on Bredon Hill pretending to be the wise old countryman.
I opined that the stubble would need burning off soon.
Apparently Europe stopped them doing that 20 odd years ago... ;-(
Take care on the top corner, still catches them out.
Have no fear. Am pretty careful.
The old cheese crashed there in the 80's. Someone stopped in the carriageway just round the corner at about 6:45am for a *breakfast* picnic. ;-) The old mans fault of course but a silly place to stop.
'Course they've ruined the bottom half now. In my pre-bike days I dreamed of the day I'd ride a big bike down fish hill on a frosty morning into the village. They moved the road when I got the bike. Now there's the soulless wide NSL SC and you approach the village from the north and turn left into the high street. Not the same.
But then even nostalgia isn?t what it used to be!
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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"Pumping the pedal with no pads they come
out about 5mm and get 'sucked' back about 3mm."
If your pads retract 3mm during normal service, then you are in dead trouble ~ and dead is probably the operative word !! This would mean that the cumulative swept volume in the brake caliper cylinders would exceed the swept volume of the master cylinder. In other words, even pressing the brake pedal completely to the floor would not be sufficient to make the pads contact the discs again. In practice, the pads should only retract a minute amount. More than this and you have (at the very least) a "very spongy brake pedal". At most you would have complete brake failure.
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L'Escargot: They certainly don't retract 3mm with the pads in and the caliper on the bike. But then to do get pushed out 5mm 'cos there's a disc there! The point holds true though - there is a small amount of retraction off the disc when the pedal is released. Of course most discs and pads can be heard rubbing dragging to some small extent!
DVD: LOL! Now all I have to do is to get some others to accept my own opinion of my motoring talent.
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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Aplogies, everyone - well *nearly* everyone! - the following post should of course have appeared here, and not in Discussion under the heading \"Take it easy\".
Ignoring the general tenor of Toad\'s post (which Mid Life Crisis might not ...), he certainly gets my award for \"Poor Taste\" post of the week, smiley implied or otherwise. No surprise then to recall that \"Common toads (Bufo bufo) inhabit holes and gaps under stones for much of the year\".
Nothing personal, but since, on reflection, MLC is may be too polite to mention it, suggest you also reread the long Discussion thread on \"Take it easy\", especially the contributions from MLC, Growler, and DVD.
And I seem to remember someone who responded to MLC\'s post:
\"I\'ve just attended my fifth fatal road accident in 7 weeks last night. Yet another 1am knock on the door. No lectures forthcoming, I\'d just like to ask you all to take it easy and beware of the imbecile coming the other way.
Safe driving.
by posting umpteen times? - starting with:
\"Are there common factors in accidents MLC?
By this I mean is there a single thing you can do to avoid the majority of RTAs?
Paticularly on a bike here.\"
Oh yes! I remember who it was now and, as someone (probably Growler) might say, paraphrasing the old saw about pilots:
There are lots of old bikers, lots of bold bikers, but not too many old and bold bikers
Mind how you go, Sir!
Jack
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he certainly gets my award for \"Poor Taste\" post of the week
Point taken. This is the tech board. Not really somewhere for a chat.
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Parp, Parp!
Note: All Toad posts come with an implied smiley.
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Has anyone ever melted a set of pads?
Mother wasn't pleased. I think they lasted a few k beforehand.
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Dave,
A long while ago, I recall standing near the end of the straight at Kyalami, late at night, watching the sports cars braking down from mega speeds...
the glow coming off the discs was very impressive (Like those neon kits - but better!)
At a recent race meeting here, one of the drivers stripped his pads, and was running metal-to-metal, camr in to pit, left foot on brake too long, and effectively welded the pad to the disc!
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One of the managers at a firm I was working at had new pads on his company car.
On the way home from the garage the throttle jammed open, so he controlled speed with the brakes. (It was an automatic).
He got home safely but with glowing discs.
Next day the garage picked it up, fixed the throttle and replaced the worn-out pads.
Must be something of a record on a road-going car!
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