ChrisW
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| posted on 6/5/08 at 06:58 PM |
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Brake discs - do grooves make any difference?
As subject really. Is all this stuff about grooved discs actually true? Or just marketing bull?
Reason I ask.... discs for my tin-top project are £35 for an OEM set, or £135 for a 'performance' grooved set from EBC.
Is it actually worth spending the extra £100 or do they just look nice?
Chris
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BenB
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| posted on 6/5/08 at 06:59 PM |
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Yes, they wear down your brake pads quicker 
I think the general consensus is that for a 7 they're not necessary.....
Cross-drilled are definately a bad idea as they just produce areas for cracks to appear....
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Hellfire
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| posted on 6/5/08 at 07:04 PM |
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Bit of both I reckon. They do perform better than standard equipment and you're also paying for the machining and labour costs. There is a
premium to pay for the bling factor though.
There are alternatives cheaper than EBC. Try CRN performance on e-bay. They buy OEM stuff and machine the grooves themselves and are usually slightly
cheaper than most.
Phil
[Edited on 6-5-08 by Hellfire]
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Guinness
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| posted on 6/5/08 at 07:08 PM |
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Put one of each type on either side of the car and see if it pulls to one side under braking? 
Mike
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Fozzie
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| posted on 6/5/08 at 07:09 PM |
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Clears the dust a bit easier....
TBH, unless the tintop is heavily modded (power-wise) I doubt very much that you will see a great deal of difference........IMHO of course!
Fozzie 
BTW.....'we' (work-wise )would not go EBC.... (IOE) for owt..........
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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Mark Allanson
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| posted on 6/5/08 at 07:17 PM |
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Has any manufacturer ever fitted them where they couldn't be seen?
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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westf27
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| posted on 6/5/08 at 07:32 PM |
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you are probably better to invest in some pads which will stop you faster,say like the pagids.Run these on an elise 160 and its like hitting a wall
braking from speed
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short track 123
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| posted on 6/5/08 at 07:44 PM |
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Why are drilled disks a bad idea ?
Seems to be some bad press about drilled disks.
Drilled and grooved disks are made for a reason namely to help with cooling and to help stop the pads glazing ( which is why there eat pads )
Just interested in peoples views...
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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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carpmart
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| posted on 6/5/08 at 08:42 PM |
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quote:
Originally posted by short track 123
Why are drilled disks a bad idea ?
Seems to be some bad press about drilled disks.
Drilled and grooved disks are made for a reason namely to help with cooling and to help stop the pads glazing ( which is why there eat pads )
Just interested in peoples views...
I agree with this, to a point. I have had two separate experiences with drilled disks cracking. Grooved disks do a good job of shifting the gas
build up and de-glazing the pads so I now stick with grooved only. However, in many applications unless you need the last 10% that this set-up gives
you, standard disks will be fine.
You only live once - make the most of it!
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'94 MX5 MK1, 1.8
F10 M5 - 600bhp Daily Hack 
Range Rover Sport - Wife's Car
Mercedes A class - Son's Car
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mr henderson2
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| posted on 6/5/08 at 08:48 PM |
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I don't know about the dust clearance, but the cooling effect of slots or holes must be virtually zero. There's no way there could be a
cooling flow of air though a series of small holes, less through the slots, and the increase in surface area is negligible.
John
BTW, Chris, did you get my U2U?
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clanger
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| posted on 6/5/08 at 08:51 PM |
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I used to work in one of the major OEM's that made thousands of discs per day.
Drilled/cut discs need to be done professionally or they can be lethal. Do not buy from third parties who drill/cut discs without proper crack
detection facilites. We used to use magnetic field and die penetrant, which show up cracks not visible with the naked eye. The machining stresses even
from simple holes can set up microscopic cracks which can be disaster. DO NOT DIY !!!!
[Edited on 6/5/08 by clanger]
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novacaine
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| posted on 6/5/08 at 09:01 PM |
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quote:
Originally posted by short track 123
Drilled and grooved disks are made for a reason
yes, to make the business that sells them lots of money,
places claim that those chavvy exhausts stuck on the back of a saxo or a nova give it lots of extra power when they don’t
or that those electric turbochargers work
if people will pay a premium for it then businesses will make it regardless of the effectiveness of the product(s)
(That was not meant to be an attack, im just pointing out that just because the manufacturers claim it, it doesn’t necessarily make it true)
And you run and you run to catch up with the sun but its sinking, Racing around to come up behind you again, the sun is the same in a relative way but
your older, shorter of breath and one day closer to death
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saigonij
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| posted on 6/5/08 at 09:02 PM |
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in my opinion, drilled and groved both reduce the surface area that is in contact with the pad, which would make them less effective.
This was backed up when a friend of mine changed the discs on his R21 Turbo from drilled and groved to plain. His brakes were drastically improved -
ok, the new pads go some way to improve this.
I also think that the groves dont let the pads fully bed in as they are always being resurfaced.
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tks
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| posted on 6/5/08 at 09:15 PM |
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mhh i cant totally agree..
you will need to compare more situations...
what happens when there is water between the pad and the disk????
or snow???
i think they look nice and they work better... saying that they are more expensive and eat pads...
bike discs are also drilled... there must be a reason for it.. i think its for antiglazing..
Tks
The above comments are always meant to be from the above persons perspective.
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Coose
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| posted on 6/5/08 at 09:26 PM |
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quote:
Originally posted by tks
bike discs are also drilled... there must be a reason for it.. i think its for antiglazing..
Tks
You were right the first time old chap - for shifting water. Also, less unsprung weight and gyroscopic mass.
Spin 'er off Well...
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short track 123
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| posted on 6/5/08 at 09:30 PM |
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Cooling effect with drilled discs is not about the flow of cool air. It allows the air to expand into the pocket ( the drilled hole )
quote:
(That was not meant to be an attack, im just pointing out that just because the manufacturers claim it, it doesn’t necessarily make it true)
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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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skydivepaul
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| posted on 6/5/08 at 09:49 PM |
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Drilled and or grooved discs are there to help with cooling the discs and indirectly caliper and deglazing of pads. they do not help the car to brake
any better as they do have less surface area in which the pads use to apply the brake force.
They do however keep the brakes cooler under more extreme circumstance.
most supercars i.e porsche, ferrari, Lambo and nearly all race cars used some sort of drilled, grooved or otherwise discs for their cars so there has
so be some merit in them.
if you are only planning on steady road use you will not need them in a seven type car. If you are planning to use for trackdays and racing then i
would recommend you get them.
thats just my twopence worth!!
[Edited on 6/5/08 by skydivepaul]
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Fozzie
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| posted on 6/5/08 at 09:52 PM |
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quote:
Originally posted by mr henderson2
I don't know about the dust clearance..........
Sorry Mr H2, I was being a tad sarcastic.....hence the ...............
IMHO holes can get hairline cracks that the eye cannot see....... my personal take on it is, invest in a set of good pads, and bed them in, in
accordance to the manufacturers instructions...which must be followed to the letter......
Fozzie
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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charlierevell
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| posted on 6/5/08 at 10:11 PM |
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The holes are to reduce a gas build up between the pad and disc. Some of the new better ones dont drill all the way and others a chamfered to prevent
cracks.
Grooves get rid of water and help de-glaze the pads.
My 2pence worth!
Tango orange is an 'IN' colour!!
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chriscook
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| posted on 6/5/08 at 11:20 PM |
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I work with very experience vehicle braking consultants who do work for major OEMs and I once asked whether such things actually did anything.... I
think the response was laughter.
They knew of only one situation where I think it was grooves were used on a production car for reasons other than aesthetics. Even then it was because
it solved one very specific problem.
These guys have specified/designed/developed/tested enough brake systems that i wouldn't disagree with them.
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MikeRJ
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| posted on 6/5/08 at 11:29 PM |
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Brake disks can be designed to be drilled, with extra metal around the holes to reduce stress concentration, but many of the cheap ones are standard
disks with holes in them that will inevitably develop cracks.
AFAICT the silly grooves just make an annoying noise under braking, chew up pads and cost more. I'm certainly putting standard disks back on my
tintop when the current grooved ones are worn out. Horrible things.
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zetec7
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| posted on 7/5/08 at 07:30 AM |
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I wouldn't even CONSIDER using drilled or grooved discs that weren't OEM. If you find them cheap, they're most probably dangerous,
or at least prone to early and catastrophic failure. OEM brakes, if grooved or cross drilled, are designed and manufactured to be that way, and all
the engineering that goes into them can't be duplicated by somebody in Taiwan with a felt marker and a drill press (most probably how the cheap
discs originate). There are many things to consider...the metallurgy, cooling/gas and water dissipation, hole/groove pattern effectiveness, etc.
Stay away from anything not OEM!!
http://www.freewebs.com/zetec7/
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short track 123
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| posted on 7/5/08 at 08:54 AM |
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Where do OEM get there parts made ?
I have seen ( more that once ) OEM disc cracking and not just surface cracks.
Just think about the amount of recalls.
jason
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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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MustangSix
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| posted on 7/5/08 at 12:05 PM |
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Another Race Car part that simply is for looks on a street car.
Grooves and drilled holes are not there for additional cooling. They are there to help vent gasses that tend to outgas when pads are heated to
extreme temps, such as when you are attempting to slow your car from 200mph at the end of the Mulsanne Straight or entering Turn 3 at Talledega.
These gasses can prevent full contact of the pad with the rotor just like air holds a hovercraft off the ground. The slots and/or drilled holes give
the gasses a way to vent out.
But that situation rarely occurs on most cars. Probably almost never on a Locost. You'd be able to see the smoke from the pads and rotors.
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02GF74
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| posted on 8/5/08 at 08:38 AM |
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holes in discs.
firstly this will reduce the mass (less unsprung weight is never bad) so the disc will run hotter.
It does increase surface area but I would say that discs cool by convection - heat transferred to air - rather than radiation.
When running at speed, I doubt a lot of air will be able to flow through the holes so they aren't adding much in way of additional cooling, in
fact since the side surface area is smaller, they may in fact be worse.
Surely a disc with cross section like an I - so it presents a large front surface area, like a drum, would be more effective at cooling in the air
stream?
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