| Author | Message | |||||
     Jonas TRACHSEL New User Username: jonas_trachsel Post Number: 7 Registered: 2-2005 |
I refer to the latest Tee-one Topics Number 54, title article, on disc brake rotors having their wear limit stamped on the outer edge as shown in the picture by Bill Coburn. The stampings on the outer edges of these rotors are often hard to decipher, as there is a lot of rust and scale. Why are there no wear limit indicators ground directly onto the wearing faces? By having a groove of the correct depth machined into the rotors you could easily see at a glance if a rotor is still within limits. When the groove has disappeared you know instantly without a micrometer that the rotor is undersize and has to be replaced. We have such a system with the wear index on tyre treads, why not on brake rotors? Jonas Jonas | |||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 680 Registered: 4-2003 |
Gosh Jonas - someone actually reads my dribblings!! Your idea sounds great but my concern would be weakening the rotor. You of course would also leave a ridge on the brake pad and that would probably set up some stresses. Overall the rotten things will warp so easily any such grooves could well exacerbate that problem. Rotors also, will, if abused literally shatter which is apparently quite terrifying so I suspect the manufacture and the maintenance of uniform structure would be the main objections to your idea. A micrometer is not expensive. You can get under the car and measure the rotor thickness without even taking the wheel off. Another quick check of course is to feel the ridge on the outer edge of the rotor when that gets quite noticeable - get them measured or buy yourself a micrometer. | |||||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1051 Registered: 4-2003 |
Jonas, I often thought that a short groove at the tip not extending into the friction area may be sensible, but as Bill points out a metallurgist may shoot us down in flames. These things go from -20C to +500C in less than a minute on a winter's full stop, so maybe that explains it. At my bi-annual roadworthiness test, the guy looks up a table then snaps on a digital measuring calliper to test instantly for excessive rotor wear. As Bill points out, you can do the same yourself even with a cheap calliper. Fortunately mine are unworn, but I know of cars which chew through rotors to the legal limit after 20,000km in the mountains. Also, never leave a pad change, if needed, to within 2,000km of a roadworthiness test where brakes are tested dynamically or it may fail as the pads need time to bed in fully, especially with such large brakes as these. Testers pay special attention to the rotors if the pads are almost exhausted as it is a sign of potential neglect. Having endured the Canberra vehicle testing stations for decades at Dickson and Phillip, and now the similar testing station here in Zurich, I have learned many ways to appease an overzealous vehicle tester. Low brake pads and worn rotors are their number 1 hate, but anything is fair game for some testers. They either love Crewe cars, or attack them like a Rottweiler. For example, this year in Winter I forgot to turn off the climate control on the way to the test. The ensuing puddle of water condensate in the test bay pit infuriated Mr Tester. He rejecting any notion of the compressor possibly operating an a snowy day, and failed me on the spot for a cooling leak. By turning it to Economy (compressor off), driving around the block, and paying $100 for a retest, it passed of course. | |||||
| Jonas TRACHSEL New User Username: jonas_trachsel Post Number: 8 Registered: 2-2005 |
Dear Bill and Richard Thanks a lot for your education on this crazy idea of mine. I have seen brake rotors for sports and racing cars with spiral grooves and even with rows of holes right through, so I thought it should be no problem to implement my idea... Bill, I eagerly await every new issue of Tee-One, even though I do not (yet) own a car of those models Tee-One is thought for. I print them out and file them away and have learnt a lot from them that is applicable to any car. I always have thought that SY and SZ cars are far too complicated and far too expensive to maintain, but through your education with Tee-One my anxiety is slowly diminishing and I dare consider to own one of these fine models one day. Therefore I take the chance to thank you for your great work! Jonas | |||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 683 Registered: 4-2003 |
Jonas/ Thank you | |||||
| Hameed Noor Mohamed Experienced User Username: hameednoor Post Number: 18 Registered: 12-2006 |
Are there any alternatives for brake rotors for SZ cars other than from Crewe. Also is it possible to fix performance discs / pads on SZ cars | |||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 916 Registered: 4-2003 |
There is at leastone after-market manufacturer of front brake Disks for vented SY and SZ cars - Robert Chapman in Bayswater Victoria Australia. A slightly different design, the actual 'disc' is bolted to the hub rather than peened over as in the genuine item. This means that replacement is simpler and much less expensive. The whole assembly is also considerably cheaper than the genuine. | |||||
| Jonas TRACHSEL Experienced User Username: jonas_trachsel Post Number: 18 Registered: 2-2005 |
Grrrr! Someone stole my idea!  Almost two years ago I suggested to bore holes into the face of brake discs as an easily controllable wear limit indicator instead of embossing a wear limit thickness on the outer circumference, where it most often cannot be read for all the rust and scale. Now I have got recently a set of brake rotors for my wife's Opel with exactly this feature (see pics below). I think that this is a most useful feature that should be incorporated in all brake rotors. Jonas
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| Paul Yorke Prolific User Username: paul_yorke Post Number: 117 Registered: 6-2006 |
Jonas - unlucky there! Should have gone for a patent! Simple but effective - The best ideas usually are! The trouble with just measuring a discs thickness can give problems where cars have had a sticky brake pad or calliper piston. One side of the disc can wear twice as much as the other - This leaves you with an overall thickness that is within limits but one side dangerously thin and one side fine. Another thing to watch on cars which get used very little is the discs rusting from the inside out. Once again the overall thickness will be fine, but the metal left inside will be to thin. |
Brake Rotor Wear Indicator
Brake rotor with bores