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Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

dragging brakes	Sun, 12 September 2004 10:37

hey before i get flammed for not searching, i did and i couldnt find any info ive upgraded my front brakes to ae92 SX series 2 / GTZ calipers n rotors. im still using the standard CS-X master cylinder and booster and the front brakes seem to be dragging. I've bedded in the pads as best as i think they can get. the pedal feel is also bad, i have to push the pedal almost to the floor before the thing stops, its almost as bad as the 12mm solid disks! although they dont fade anywhere near as much. just wondering if the dragging is because the pads are still new and the rotors havent been machined i just got out the drill and a circular wire brush thing and cleaned all the surface rust off. Or is it because the master cylinder isnt pushing enough fluid into the piston on these new calipers, is this also the reason for the bad pedal feel?? i've got a ae92 sx master cylinder but i wasnt gonna put it in untill i put the ae82 rear disks in. i got the standard drums at the moment. and im prolly gonna need a free weekend to do all that. Cheers for any help edit [typos] [Updated on: Sun, 12 September 2004 10:42] [Report message to a moderator]

oldcorollas
Forums Junkie

Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003

Re: dragging brakes	Sun, 12 September 2004 10:42

sounds remarkably like you need to completely rebleed the brakes... lots of pedal? need to compress the air bubbles. pads dragging? when brakes heat, the air expands, pushing pads onto discs... and so it continues. Cya, Stewart [Report message to a moderator]

Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

Re: dragging brakes	Sun, 12 September 2004 11:52

i have blead the brakes had a mate help me out and make sure that no air was coming out or going back in. the pads drag when the car is cold to. oldcorollas: you dont think its a master cylinder/ not enuff fluid thing? i mean i originally had 12mm solid disks and tiny calipers and now ive got much bigger calipers n 22m disks cheers [Report message to a moderator]

oldcorollas
Forums Junkie

Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003

Re: dragging brakes	Sun, 12 September 2004 12:47

thickness of the discs is, for the most part, not important. what is the difference in surface area of the pistons between the two calipers? [Report message to a moderator]

Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

Re: dragging brakes	Sun, 12 September 2004 13:37

umm the pistons on the new calipers vs the old ones. the new ones are a fair bit bigger still the same pads tho DB308s but the piston is yeh bigger thats why i was think it needs more fluid to push it out hence the long pedal travel but im still not sure why its draggin on the disc cheers [Report message to a moderator]

Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

Re: dragging brakes	Mon, 13 September 2004 11:05

anyone got any ideas? Cheers [Report message to a moderator]

Scorpion
Forums Junkie

Location:
Menai area of Sydney
Registered:
June 2003

Re: dragging brakes	Mon, 13 September 2004 11:09

Are the pads rubbing on the unmachined part of the rotor surface next to the hub ? i.e. the pads might be too close to the hub and you need to get more of the rotor machined. [Report message to a moderator]

allencr
Regular

Location:
tallahassee FL usOFa
Registered:
May 2002

Re: dragging brakes	Mon, 13 September 2004 13:53

so, you've got 2 problems. 1 - the "dragging" from a stuck/sticky piston, and/or caliper slides, and/or improperly adjusted MC pushrod & linkage holding pressure. 2 - the soft pedal from air, bad MC, and/or caliper twist from mis-alignment or using pads that have a taper from wear. or have you only got one problem that is mis-named & mis-described????? [Updated on: Mon, 13 September 2004 13:55] [Report message to a moderator]

Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

Re: dragging brakes	Mon, 13 September 2004 23:20

Scorpion:- When i put them on and noticed they were dragging it didnt look like the pads were touching that part of the rotor i'll pull them off again and have a look when i get a chance, thanks. allencr:- yep 2 probs. its not so much a soft pedal feel. its a long pedal push, ok yeh soft, before anything happens but once u get to about 2/3 down the last bit really makes the brakes bite hard, but you have to push hard, this is not city driving, im talking about stops from like 120-130km/hr to 0. i mean the brakes work well, once they're warm but you really have to mash the pedal to the floor. and its just that the pedal has to go down a lon way before anything happens. thats why im thinkin that its because of the larger pistons in the calipers require more fluid and the fact im still using a smaller M/C but no one seems to comfim this? I might pull the calipers off and try and work the caliper slides a bit they could be the culprit of the dragging as these brakes may be have lying around for a while. I got some pads with the brakes that are in there at the moment they look like a harder compound and the leading edges have been filed down a bit so looks like this /----\ dont think that would be causing it but thought i'd let you know. if the above stuff doesnt fix it ill try some new pads in there as well. Thanks guys [Updated on: Mon, 13 September 2004 23:21] [Report message to a moderator]

BradW
Regular

Location:
Bottom of the hill, Sydney
Registered:
April 2004

Re: dragging brakes	Tue, 14 September 2004 12:13

Measure the piston size of the new callipers and compare it to the piston size of your original calipers. If there is a difference you may need to change your master cylinder. I was once told that if your master cylinder was too small your pedal will be soft and the brakes would "grab" when the pedal is near the floor, and if it is too big the pedal will be rock hard but the brakes wont work too well. (I think I got that around the right way). Brad [Report message to a moderator]

Hunty
Forums Junkie

Location:
Adelaide
Registered:
July 2002

Re: dragging brakes	Wed, 15 September 2004 00:13

Ok im a clown i adjusted the pushrod on the brake pedal and now the pedal doesnt go down nearly as far as i had to before BUT the brakes still drag, ill play around with them on the weekend a bit more, the slides could be a little stiff. BradW. Interesting u should say that becuase my pedal is now rock hard after adjusting it but the brakes dont seem to working fantastically i mean they're as good as the ones they replaced but u really have to push the brake pedal hard, its like there is no vacuum assistance, like i said i've got a ae92 booster and master cylinder i've also got ae82 rear discs to go in so im not too worried about the feel at the moment but the dragging brakes is a pain in the ass. Thanks again for the ideas guys [Report message to a moderator]

oldcorollas
Forums Junkie

Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003

Re: dragging brakes	Wed, 15 September 2004 00:17

are you actually getting vacuum in the servo? is the one way valve in correctly (so air is only sucked out of it)? [Report message to a moderator]

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