silver-7 Posted March 8, 2005 Share Posted March 8, 2005 Yet again i have warped front disks, car is an R300 with AP big front brakes. last year had two new disks fitted under warranty now 6,000 miles later i have the same problem !! Whats causing it ? is it my hard braking (came to light after a Cadwell track day) or is there something wrong with my set up ? car has standard caterham fit pads. help please as my previous car had an identical Ap brake set up and never (18,000 miles) missed a beat ! cheers Alex Link to comment Share on other sites More sharing options...
James Tricker Posted March 8, 2005 Share Posted March 8, 2005 there was a thread some time ago that might be worth checking out. here it had a link to another article somewhere about cementite formation... James (1.8 SV) Edited by - James Tricker on 8 Mar 2005 17:16:10 Link to comment Share on other sites More sharing options...
david nelson Posted March 8, 2005 Share Posted March 8, 2005 I thought I had warped disks same set up as you, I rubbed them down and put rs15 in and problem resolved. David Link to comment Share on other sites More sharing options...
Myles Posted March 8, 2005 Share Posted March 8, 2005 Brake discs do not warp in the simple sense - too much heat = bendy disc. Poor bedding in of the pads causes localised formation of cementite (form of cast iron). This provides an uneven surface wear and results in an uneven braking surface. If you don't bed you pads in right this will happen on any brake disc. - -Peter C. Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
V7 SLR Posted March 8, 2005 Share Posted March 8, 2005 Alex, check they are actually warped by passing a micrometer around their surface. I have had to replace disks on the Scooby because they feel warped but it is always this localised exchange of pad material into the iron surface causing friction hotspots. In my case this was caused by braking hard with an underbraked car on poorly balanced wheels. It happens often with the Scoob *because* the wheels go out of balance regularly. I don't know why this happens. I have them rebalanced regularly and they always find the wheels seriously out of balance. Sometimes cheap tyres does this but mine are NOT cheap. In the case of the Scooby the surfaces of the disks were too badly gone but with a light car such as the Caterham, you ought to be able to rub the surface with some light emery to remove the hotspots. Do it now before it gets too bad and possibly irreversable. I think this explains it fairly well here although there is a better report somewhere that someone here or on the Se7ens list posted previously. I just can't find it. Edited: URL is not spelt ULR 😳 Edited by - V7 SLR on 8 Mar 2005 18:59:53 Link to comment Share on other sites More sharing options...
Myles Posted March 8, 2005 Share Posted March 8, 2005 You mean this? here Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
silver-7 Posted March 8, 2005 Author Share Posted March 8, 2005 thanks Guys will check them out tomorrow Caterham sent the last ones back to AP and found a problem with the disk !, going to try some different pads to see if that helps to.. cheers Alex. Link to comment Share on other sites More sharing options...
silver-7 Posted March 8, 2005 Author Share Posted March 8, 2005 As a thought the problem only shows its self during & after winter, car is kept in a cold un heated garage separate from house.... wander if the pad material hardens on the disks over the winter due to lack of use ? Link to comment Share on other sites More sharing options...
tom7 Posted March 8, 2005 Share Posted March 8, 2005 Alex, you got my flywheel and clutch off yet 🤔 😬 Tom Link to comment Share on other sites More sharing options...
Myles Posted March 8, 2005 Share Posted March 8, 2005 Alex - yes, it's extremely hard to stop the pads from attaching themselves to the discs during storage - I thought I'd cracked it on my tintop (stored for most of its life) by leaving the handbrake off - but even though the brakes aren't hot when I roll it into the garage, there's always a bit of a lurch when I move the car after a month or two. Having said all that - there are a huge number of 7s that hibernate - and the problem rarely gets a mention in spring. Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
JAG Posted March 9, 2005 Share Posted March 9, 2005 The problem with stored cars is due to moisture. This is absorbed into the friction material during storage and can increase the initial friction levels - at least until the pads have had some use and dryed out. If you leave the handbrake on the pads/shoes can attach themselves to the disk/drum. This will cause the brakes to be locked on (obviously ) Most modern friction materials (used in mass produced vehicles) don't do this anymore. Some materials used by aftermarket suppliers still do - cheaper pads/shoes are worse than more expensive ones - GENERALLY SPEAKING. This same phenomenon can cause friction material to transfer onto the disk surface during first use after storage. This will feel like warped disks - carefully cleaning with emery paper may clear it up. If you carry on driving the car it may well clear up on its own. Justin A closed mouth gathers no foot. Link to comment Share on other sites More sharing options...
JAG Posted March 9, 2005 Share Posted March 9, 2005 Ar5e - first ever double post (I think 😳) Edited by - JAG on 9 Mar 2005 11:28:50 Link to comment Share on other sites More sharing options...
wonkey eyed barmaid Posted March 9, 2005 Share Posted March 9, 2005 alex, not sure where you are, but just saw in EVO last night that ABP Motorsport in Crewe cheshire have the equipment to skim the face of discs, while still attached to the hub, to ensure they are perfectly true [or flush or whatever the word is] Link to comment Share on other sites More sharing options...
silver-7 Posted March 9, 2005 Author Share Posted March 9, 2005 Think we might have found the cause.. cleaned the disk surface with wet & dry today seems much better ! will change pads and put some miles on now. thanks for everyones help cheers Alex Link to comment Share on other sites More sharing options...
wonkey eyed barmaid Posted March 9, 2005 Share Posted March 9, 2005 have you tried deglazing your existing pads alex? when i have my wheels off for cleaning or for swapping round i often pop the pads out and give them a quick scrub with some sandpaper wrapped round a block of wood. enough to scrub off the surface smoothness and reveal fresh pad material.. Link to comment Share on other sites More sharing options...
silver-7 Posted March 9, 2005 Author Share Posted March 9, 2005 Granteuk, I'll give that a try at the weekenfd thanks now done 30 miles and the brake feel is 100% improved ! cheers Alex Link to comment Share on other sites More sharing options...
Peter Carmichael Posted March 10, 2005 Share Posted March 10, 2005 Also worth noting on the "warped brakes myth" link is this: Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted March 10, 2005 Support Team Share Posted March 10, 2005 I believe that Garnet Paper is the right thing to use. Yellow SL #32 Link to comment Share on other sites More sharing options...
silver-7 Posted March 10, 2005 Author Share Posted March 10, 2005 Another great excuss for Dave Jacksons sprint excusses 😬 "would have gone faster but didn't have enough Garnet paper " 😬 😬 😬 Shaun, Peter thanks will have a go with Garnt paper if I can find some ? Alex Link to comment Share on other sites More sharing options...
wonkey eyed barmaid Posted March 10, 2005 Share Posted March 10, 2005 is that Garnett Paper for cleaning the surface of the discs..? cos I mentioned sandpaper, for scrubbing the surface of the pads.. Link to comment Share on other sites More sharing options...
Mad7ner Posted March 10, 2005 Share Posted March 10, 2005 Had the same problem as well warped disks, I just had them reground on a lath £30 solved the problem 😳 Link to comment Share on other sites More sharing options...
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