Discussion
Checking my car prior to a track day on Saturday, a Sr3 2006, i noticed hair line cracks on the rear discs, i have the upgraded brakes on my car, having purchased the car last month from the factory i rang to complain as the car was supposed to be checked over prior to purchase, to my surprise they told me this is quite common and not to worry!! having spoken to other owners it does not seem to be a safety issue, although on a road car they would be condemned, any thoughts, and if i need to replace where can i buy them apart from Radical (ON PRINCIPAL)
Edited by JS on Wednesday 7th April 17:57
Edited by JS on Wednesday 7th April 17:59
They all do that Sir...
Been racing for six years now and every set of disks I have had have been like that, its nothing to worry about. If the cracks are anything other than radial they you should change the disks.
Simon
BTW I've had a few road cars with the same feature and had no issue wth MOTs either
Been racing for six years now and every set of disks I have had have been like that, its nothing to worry about. If the cracks are anything other than radial they you should change the disks.
Simon
BTW I've had a few road cars with the same feature and had no issue wth MOTs either
Joe, as Simon says like I said.
That said (and it'll come as no surprise to the Big R as I've said it to them direct more than once), personally, I'd prefer to have discs without any cracks at all even if these hairline radial cracks less than 10mm long are apparently 'OK' and not to be worried about.
I'd be interested to know whether anyone has used alternative disc makers/suppliers (like Black Diamond, EBC, Brembo etc) which have remained crack free.
I may just be lucky but I've never had cracked discs on a road car (to be fair I've always stuck to OEM) and if I did, there's no way I'd want to use it; that's in road conditions far less demanding than on a track.
That said (and it'll come as no surprise to the Big R as I've said it to them direct more than once), personally, I'd prefer to have discs without any cracks at all even if these hairline radial cracks less than 10mm long are apparently 'OK' and not to be worried about.
I'd be interested to know whether anyone has used alternative disc makers/suppliers (like Black Diamond, EBC, Brembo etc) which have remained crack free.
I may just be lucky but I've never had cracked discs on a road car (to be fair I've always stuck to OEM) and if I did, there's no way I'd want to use it; that's in road conditions far less demanding than on a track.
splitpin said:
I may just be lucky but I've never had cracked discs on a road car (to be fair I've always stuck to OEM) and if I did, there's no way I'd want to use it; that's in road conditions far less demanding than on a track.
This may helphttp://www.winnard.co.uk/downloads/service_guide.P...
I'm talking about heat crazing, are you?
It's down to hard they are used, the only time it becomes an issue is when you have cross drilled discs then the holes act as foci for the stresses created
S
Edited by Simon T on Wednesday 7th April 19:12
Hi Simon
Yep, that's it: think some people call it heat chinning?
Don't get me wrong, not for a minute do I think there's a fundamental safety issue involved here, no way would Radical allow that. What I'm saying is that given the choice, I wouldn't have any sort of cracks on brake discs; on most cars that radial crazing appears when the disc is getting down towards it's minimum thickness, but from what I've seen, it appears way earlier than that on a Radical's discs.
That causes me a bit of unease in terms of worse case scenario, if and when they could change to full on cracks.
Here's a paste-in from that piece, certain parts made bold >
"Heat crazing, as illustrated, is the result of normal heating and cooling of the brake disc during service. These fine heat cracks are not detrimental to the performance of the brake. However, heat crazing can develop into deeper cracks. Therefore, any discs with radial cracks deeper or wider than 1.5 mm should be machined, as long as the minimum thickness allows, or replaced. The early development of heat crazing can be an indication of an operational problem."
Fair enough one can see the width of a crack, but it's depth isn't so easy and having read some technical stuff from Brembo, from what I gather the depth of (tangental to pad direction) radial cracks increases more aggressively than their length on a proportional basis.
That's the reason I'd rather have discs that don't crack in any way at all until they ready for immediate despatch to the bin; if there's no cracks, there's no pondering at all to be done about their length, width or depth. I'm interested to know why we still have radial cracks on our discs, particularly on 15 fronts and 16 rears on such as SR3s where's there's much more room to play with. Rightly or wrongly, I always thought those crazings were sort of inevitable on the chain driven Rads - with their 13" wheels and Ford dimensioned discs - on the basis of OK very much lighter but immensely quicker than what they were originally designed to stop.
There must be a reason or reasons that could be overcome; whether it's because of the metal composition or the disc design (for example the way the two halves of the vented disc are 'cast apart') or because the discs aren't thick enough (I doubt it having seen those on a Formula Renault) I have absolutely no idea. That's why I was asking whether anyone had used discs from other reputable manufacturers and whether they had or had not crazed the same way.
Take the point about fully cross drilled brakes; if anyone has got them on their Radical (or most anything else as a non OEM 'improvement') get rid asap. Ceramics/carbon composites aside, a few diagonal grooves (like Radical's original parts have) to clean-up pads and release gas is all anyone could ever need on a Radical.
Yep, that's it: think some people call it heat chinning?
Don't get me wrong, not for a minute do I think there's a fundamental safety issue involved here, no way would Radical allow that. What I'm saying is that given the choice, I wouldn't have any sort of cracks on brake discs; on most cars that radial crazing appears when the disc is getting down towards it's minimum thickness, but from what I've seen, it appears way earlier than that on a Radical's discs.
That causes me a bit of unease in terms of worse case scenario, if and when they could change to full on cracks.
Here's a paste-in from that piece, certain parts made bold >
"Heat crazing, as illustrated, is the result of normal heating and cooling of the brake disc during service. These fine heat cracks are not detrimental to the performance of the brake. However, heat crazing can develop into deeper cracks. Therefore, any discs with radial cracks deeper or wider than 1.5 mm should be machined, as long as the minimum thickness allows, or replaced. The early development of heat crazing can be an indication of an operational problem."
Fair enough one can see the width of a crack, but it's depth isn't so easy and having read some technical stuff from Brembo, from what I gather the depth of (tangental to pad direction) radial cracks increases more aggressively than their length on a proportional basis.
That's the reason I'd rather have discs that don't crack in any way at all until they ready for immediate despatch to the bin; if there's no cracks, there's no pondering at all to be done about their length, width or depth. I'm interested to know why we still have radial cracks on our discs, particularly on 15 fronts and 16 rears on such as SR3s where's there's much more room to play with. Rightly or wrongly, I always thought those crazings were sort of inevitable on the chain driven Rads - with their 13" wheels and Ford dimensioned discs - on the basis of OK very much lighter but immensely quicker than what they were originally designed to stop.
There must be a reason or reasons that could be overcome; whether it's because of the metal composition or the disc design (for example the way the two halves of the vented disc are 'cast apart') or because the discs aren't thick enough (I doubt it having seen those on a Formula Renault) I have absolutely no idea. That's why I was asking whether anyone had used discs from other reputable manufacturers and whether they had or had not crazed the same way.
Take the point about fully cross drilled brakes; if anyone has got them on their Radical (or most anything else as a non OEM 'improvement') get rid asap. Ceramics/carbon composites aside, a few diagonal grooves (like Radical's original parts have) to clean-up pads and release gas is all anyone could ever need on a Radical.
(YHM@Work)Gassing Station | Radical | Top of Page | What's New | My Stuff