Promai Joe
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| posted on 25/5/11 at 06:31 PM |
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Brake problems
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.
- Brakes feel like ABS is working (no abs installed) slight pulse felt through the pedal
- Steering wobbles side to side on reasonably heavy breaking
Do both these problems point to warped discs? They were ok and I have not done much braking since as only got my plates yesterday (23.5.11). So the
only two runs I have done were about 12 miles in total being cautious as it is a new toy? Can the IVA test have done this (not that I would dare go
back) or does this point to something coming loose? All of the marks made on the nuts when they were tighted seem to be in the same place.
Any other suggestions?
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rusty nuts
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| posted on 25/5/11 at 06:50 PM |
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Warped disc!
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britishtrident
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| posted on 25/5/11 at 06:58 PM |
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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]
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blakep82
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| posted on 25/5/11 at 07:07 PM |
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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]
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IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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britishtrident
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| posted on 25/5/11 at 07:24 PM |
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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.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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blakep82
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| posted on 25/5/11 at 07:29 PM |
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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.
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Doctor Derek Doctors
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| posted on 25/5/11 at 07:50 PM |
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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.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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britishtrident
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| posted on 25/5/11 at 07:57 PM |
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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.
Asymmetric cooling causes warping the area of the disc outside the calliper cools much quicker than the area under the calliper, Holding pressure
on the brake pedal clamping a hot pad on to the disc makes the situation worse.
When returning to the paddock after hot laps the car should not be left stationary for the first couple of minutes after stopping every twenty
seconds or so push the car a foot or so forward to even out the cooling of the disc.
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britishtrident
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| posted on 25/5/11 at 08:10 PM |
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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.
Strangely brake pads with an abrasive top layer are made to do precisely that, Supplied by Girling I first encountered them around 1980 when they
were widely used to counter brake induced steering vibration problems on Ford Capris. 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 even without the brake applied. Often fitting new discs,
pads and suspension bushes would not cure the problem but abrasive pads would result in an almost instant cure.
[Edited on 25/5/11 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Promai Joe
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| posted on 26/5/11 at 10:56 AM |
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Thanks for the input guys, Considering the post above, I have cortina hubs and brakes could this wobble be from run out?
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blakep82
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| posted on 26/5/11 at 11:47 AM |
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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?
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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britishtrident
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| posted on 26/5/11 at 12:59 PM |
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It might be worth checking the wheel bearing adjustment.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Dick Axtell
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| posted on 26/5/11 at 01:50 PM |
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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]
Ah-ha! The Capri problem(s) have raised their heads! This wasn't the only Capri issue encountered by Girling. Even now, the slightest mention of
"brake hose", causes some former Girling blokes to twitch very nervously. I recall several guys working furiously to distance themselves
from this major safety issue.
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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