View Full Version : brakes
hello friendly folk of png, i rarely come on here, dont know why as theres alot of canny people. thought id ask some advice on brakes. sorry if its the wrong section, could admin move it if it is please
problem ive got. bought the corsa and the lad who sold it to me didnt know much about the mods that had been done to it before he got it (was a run around to him). said its got gsi callipers, i said "gsi what, corsa astra...?" he said "oh i dina, just gsi ones" :roll:
cut a long story short it seems to be warping the discs quite quick, it was fine when i got it then started to warp them (not for of needing replaced anyway) so i replaced them with mintex 256x20 (normal for corsa gsi's/1.6sports) and these new ones have only lasted about 3 month of not really driving it loads.
i know that the 2.0l's use 4mm thicker discs, does it sound like ive got 2.0l callipers and have fitted 1.6 discs and pads or is it true that this cant be done??
whats the part numbers/significant differences in the 1.6 and 2.0 callipers please?
thanks you :thumb:
Opening a can of worms talking about discs warping, apparently they don't warp its deposits from the brake pad being left on the disc surface.
With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification, in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc. I have seen lots of cracked discs, (FIGURE 1 (http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#)) discs that had turned into shallow cones at operating temperature because they were mounted rigidly to their attachment bells or top hats, (FIGURE 2 (http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#)) a few where the friction surface had collapsed in the area between straight radial interior vanes, (FIGURE 3 (http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#)) and an untold number of discs with pad material unevenly deposited on the friction surfaces - sometimes visible and more often not. (FIGURE 4 (http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#))http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
Its also unlikely you have Corsa GSi calipers and 256X24 discs as a mate accidentally tried to fit some 256X24 discs in his Corsa GSi calipers, the discs got jammed by the brake pads and couldn't really turn.
Edit: Sorry you've put 2.0 calipers and 1.6 discs, I doubt it too as the disc wouldn't be wide enough
hmmm, whats the warping cause then, i cleaned them up about 2 weeks ago and it didnt make a difference to it. its not really bad just when im doing 60ish and brake hard the steering wheel wobbles. cant be other issues because when they were new it was spot on. confused
When you say cleaned, what does that mean......
Are you sure the runout is as low as possible with the hub face etc.
When you say cleaned, what does that mean......
Are you sure the runout is as low as possible with the hub face etc.
will check that :tard: doh
i emery clothed the discs and used the very small amount of copper-slip i had left on the callipers
that screw that hold the disc in place before you put the wheel on is missing on one side but cant see that being an issue when the wheels are tight
Emery cloth wont remove the uneven deposits.
I'd go and bed the pads in again and see if that makes the transfer layer even again
AndrewJenkins
14-10-11, 07:21 AM
have you checked all the sliders are free too?
have you checked all the sliders are free too?
they seem fine tbh mate
Probs the rear brakes.
dont think so bud as the wobble disappeared when i first changed the fronts.
check your u2us on CS mate
no can of worms on the discs bathfart.... if a disc was warped, you would get an almighty wobble & steering kickback when just driving normally.
discs just hotspot. its drums that go oval, and that hasn't really been an issue since decent front discs were put on production cars...
wire brushed them thoroughly, inside outside, in the centres and the hub centre part...
seems to of died down a touch but it was still doing it so i done it again untill my feeble muscles couldn't scrub any more and took it for another spin, still wobbles a bit under HARD braking... :sad:
http://img638.imageshack.us/img638/3526/1abcd0003.jpg
http://img189.imageshack.us/img189/8875/1abcd0004.jpg
and just to confirm that these are 1.6 callipers, think they are..
http://img804.imageshack.us/img804/791/1abcd0007.jpg
http://img249.imageshack.us/img249/7951/1abcd0008.jpg
jedro, what you aren't grasping is that when discs get really hot (as in too hot), they end up with hard spots in the metal, and these different bits have different friction characteristics. so as you brake hard, they will grip or slip as the disc rotates. this causes the judder, and most of the time, only remachining the discs to remove a layer of metal or disc replacement will fix it.. also, if you replace the discs, you must replace the pads.
They look like valver calipers to me
jedro, what you aren't grasping is that when discs get really hot (as in too hot), they end up with hard spots in the metal, and these different bits have different friction characteristics. so as you brake hard, they will grip or slip as the disc rotates. this causes the judder, and most of the time, only remachining the discs to remove a layer of metal or disc replacement will fix it.. also, if you replace the discs, you must replace the pads.
Skimming discs is a very false economy indeed.
on average model road cars, i'd agree, but on commercials or big car discs, its worth it. i used to work at a proper brake reline workshop, and it cost me nowt to get them done..
Jon_nova1
15-10-11, 10:01 AM
you've worked everywhere, and if they are valver brakes he's got 256MM on them anyway
General Baxter
15-10-11, 10:05 AM
i know how much, hgv disks and pads cost lmao
you've worked everywhere, and if they are valver brakes he's got 256MM on them anyway not everywhere, just some interesting places along the way... i've worked for my brother for 16 years now, and have had about 12 different positions in that time.....
baxter, re the discs on a wagon...before we bought the haulage company off our stepdad, our merc 4 wheeler had the rear brakes done by the dealer in 2008.... it cost £3k and was off the road for 4 days...
in 2010 i did it again, and found the dealer had put the sliders in backwards, and it had seized up, taking the discs with them... we spent 6 hrs on it & 300 in bits... merc had taken the axle off cos they couldn't be ar$ed to undo the caliper bolts with a ring spanner & a soft hammer.......
so are they valver callipers?
im running the discs that are 256x20 (for 1.6) and valver ones are 256x24.
put a split pin through your hub nut ffs!
took them out when i was rubbing them down with the wire brush as they were looking a bit dated so i put new ones in
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