Hi all,
Any advice would be welcome. Having just passed my IVA (Retest - 13.5.11), brakes must have worked reasonably well for the original test where these
passed (Original - 1.4.11), I am now experienceing two different problems.
Warped disc!
If the car has been sitting unused it might just be a rust patch on the disc but normally with floating Sierra style callipers a disc has to be quite
badly warped before you can feel it through the pedal.
If you can feel a wobble or vibration through the steering wheel it is a front disc.
Normally to warp a disc the disk has to be stonking hot then car parked up immediately without any normal running to cool the brakes;
With very hot brakes holding the car stationary with the foot brake brakes is a sure way to increase the likely hood of warped brakes.
Washing the car without driving it afterwards to dry the brakes can lead to a rust patch on the discs which has the same effect as a warped disc.
Without a dial test gauge the first stage in putting things right is to try rotating each disc by hand to try and feel for run-out and visually
examine the surface of the disc. Find which of discs it is warped and replace the disc, If the disc just has a rust patch try cleaning the
surface with 80 grade production paper.
If the disc is warped it might be worth investigating why the brakes are getting over hot ie are they binding when warm due to fluid expansion?
[Edited on 25/5/11 by britishtrident]
[Edited on 25/5/11 by britishtrident]
somebody posted a link on here when i had a similar problem, saying warped discs is somewhat of a myth, but more a transfer of pad meterial which when
very hot, after heavy breaking for example, and brakes are left on at a standstill, the pad material sticks to the disc. when you drive, the
'lump' on the disc keeps catching the pad, making it very hot and it hardens.
think it said something like, if using semi metallic pads a few heavy high speed stops, ensuring the brakes are released before coming to a complete
stop should help to clear it.
of course, he says warped discs is a myth, others say its not, who's right? i don't know. but if you've only done 24 miles, might be
worth a try before replacing the discs. if its old discs, i'd replace anyway, and of course check you calipers aren't sticking and dragging
on the disc
edit: here it is
http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#
[Edited on 25/5/11 by blakep82]
I can assure you warped discs are not a myth, neither are warped (oval) brake drums.
Warping of disc rotating disc shaped rotating components that are subject that are subject to heat is also common in all sorts of engineering plant.
why would keeping the brake applied after they get really hot cause the disc to warp?
and why would releasing the brake stop it warping? thats what i don't get.
Whether its warped discs or hardened pad material stck to the disc.... the only thing to do is get new discs. You can't 'drive' it off, they're ruined.
quote:
Originally posted by blakep82
why would keeping the brake applied after they get really hot cause the disc to warp?
and why would releasing the brake stop it warping? thats what i don't get.
quote:
Originally posted by Doctor Derek Doctors
Whether its warped discs or hardened pad material stck to the disc.... the only thing to do is get new discs. You can't 'drive' it off, they're ruined.
Thanks for the input guys, Considering the post above, I have cortina hubs and brakes could this wobble be from run out?
if the discs aren't correctly seated on the hubs then it could do it i guess. are the faces of the disc and hubs all clean and smooth?
It might be worth checking the wheel bearing adjustment.
quote:
Originally posted by britishtrident
Due to the front suspension design the Capri had a particular problem in that even a tiny amount of brake run out could induce a steering wheel wobble.....[Edited on 25/5/11 by britishtrident]