Best place/price to get standard 350i front discs
Discussion
Hi All. Just replaced the rear braking setup, discs pads (main and parking brake) seals etc for less than £100. Now thinking of front brakes, anyone point me in the direction to get sensibly priced front discs for 350i. I have not tried a Ford garage yet but Halfords quoted £80 per disc (4 times more than I paid for the Jag rears). Thanks.
I paid £130 for a pair of Black Diamond grooved and cross drilled disc's which I'm very impressed with, I can try find a link if your interested?
Here's a link:- www.motorsportworld.co.uk/frame-detail.asp?PAGE=/black-diamond-brakes.htm
>> Edited by taff_o on Tuesday 27th April 15:33
Here's a link:- www.motorsportworld.co.uk/frame-detail.asp?PAGE=/black-diamond-brakes.htm
>> Edited by taff_o on Tuesday 27th April 15:33
I understood that the reason for grooved and drilled discs was to de-gas the pads thus preventing a build-up of gas between pad and disc which affects efficiency. This was with asbestos-based pads which of course none of us use anymore 
With todays asbestos-free pads I believe this isn't the case and boggo vents should be fine. If this is rubbish I expect someone to put me right
Of course having said all that the bluewedge has drilled, grooved and vented discs
J
With todays asbestos-free pads I believe this isn't the case and boggo vents should be fine. If this is rubbish I expect someone to put me right
Of course having said all that the bluewedge has drilled, grooved and vented discs
J 
jmorgan said:
Arn't the bog standard around £25 each?
I tell a lie, 21 squid.
Wedges stopper
I'll get me life jacket........
I've raided the stoptech site for this info ..
it's a superb site and they know their onions ..
www.stoptech.com/
Drilled or cross-drilled rotors: Disks that have been drilled through with a non-intersecting pattern of radial holes. The objects are to provide a number of paths to get rid of the boundary layer of out gassed volatiles and incandescent particles of friction material and to increase "bite" through the provision of many leading edges. The advent of carbon metallic friction materials with their increased temperatures and thermal shock characteristics ended the day of the drilled disc in professional racing. They are still seen (mainly as cosmetic items) on motorbikes and some road going sports cars. Typically in original equipment road car applications these holes are cast then finished machined to provide the best possible conditions by which to resist cracking in use. But they will crack eventually under the circumstances described in another section (see Cracking). Properly designed, drilled discs tend to operate cooler than non-drilled ventilated discs of the same design due the higher flow rates through the vents from the supplemental inlets and increased surface area in the hole. That's right, inlets, the flow is into the hole and out through the vent to the OD of the disc. If discs are to be drilled, the external edges of the holes must be chamfered (or, better yet, radiused) and should also be peened.
Cracking: Cracking is primarily due to heat cycling that weakens the cast iron discs. The exact mechanism of this failure is disputed. Cast iron discs are formed with the excess carbon being precipitated in the form of carbon plates or flakes dispersed throughout the ferrite (iron) matrix. What is believed to happen is that when discs are operated above about 900º F, the carbon becomes more flexible or "fluid" in its shape partly due to the thermal expansion of the enclosing ferrite matrix. Then, as the disc cools relatively rapidly back below about 900º F the carbon is trapped in a changed more random shape then when it was first cast. This creates internal stress on the part and continuously transforms the disc by relieving the stress through the cracking. The cracks begin by appearing between carbon flakes. Nodular or ductile iron would resist this cracking due to the excess carbon being precipitated in a spheroidal form, but it, like other alternative materials do not have the mechanical properties needed to function ideally in a brake disc application. In discs that are cast to resist cracking through chemistry and controlled cooling at the foundry, cracking will still occur, but more slowly and take the form of heat checks on the surface. In some cases cracks will begin at the periphery of the disc and propagate inwards. In this situation, propagation can be delayed by drilling small holes at the end of the cracks (stop drilling). We do not recommend this however, because if the cracks continue to propagate unnoticed, catastrophic mechanical failure will result. Replace disc at the first sign of cracks at the outer edge of any size. A historic note, the original purpose of the curved or angled vane disc was to prevent cracks from propagating by imposing a solid vane in the path of the crack. The cooling function was secondary.
Slotted:
1. Disc: Shallow, sharp edged but radiused bottom grooves milled into cast iron discs to provide leading edges for bite and a path for the fire band of gases and incandescent friction material to be dissipated through. If the slots fill up with pad material, the system is operating at too high a temperature.
2. Pad: Radial grooves molded or cut into the surface of the pad to provide a path for fire band dissipation and to double the number of leading edges and improve bite. Some long pads also have a longitudinal groove
Should all be as clear as mud now...
it's a superb site and they know their onions ..
www.stoptech.com/
Drilled or cross-drilled rotors: Disks that have been drilled through with a non-intersecting pattern of radial holes. The objects are to provide a number of paths to get rid of the boundary layer of out gassed volatiles and incandescent particles of friction material and to increase "bite" through the provision of many leading edges. The advent of carbon metallic friction materials with their increased temperatures and thermal shock characteristics ended the day of the drilled disc in professional racing. They are still seen (mainly as cosmetic items) on motorbikes and some road going sports cars. Typically in original equipment road car applications these holes are cast then finished machined to provide the best possible conditions by which to resist cracking in use. But they will crack eventually under the circumstances described in another section (see Cracking). Properly designed, drilled discs tend to operate cooler than non-drilled ventilated discs of the same design due the higher flow rates through the vents from the supplemental inlets and increased surface area in the hole. That's right, inlets, the flow is into the hole and out through the vent to the OD of the disc. If discs are to be drilled, the external edges of the holes must be chamfered (or, better yet, radiused) and should also be peened.
Cracking: Cracking is primarily due to heat cycling that weakens the cast iron discs. The exact mechanism of this failure is disputed. Cast iron discs are formed with the excess carbon being precipitated in the form of carbon plates or flakes dispersed throughout the ferrite (iron) matrix. What is believed to happen is that when discs are operated above about 900º F, the carbon becomes more flexible or "fluid" in its shape partly due to the thermal expansion of the enclosing ferrite matrix. Then, as the disc cools relatively rapidly back below about 900º F the carbon is trapped in a changed more random shape then when it was first cast. This creates internal stress on the part and continuously transforms the disc by relieving the stress through the cracking. The cracks begin by appearing between carbon flakes. Nodular or ductile iron would resist this cracking due to the excess carbon being precipitated in a spheroidal form, but it, like other alternative materials do not have the mechanical properties needed to function ideally in a brake disc application. In discs that are cast to resist cracking through chemistry and controlled cooling at the foundry, cracking will still occur, but more slowly and take the form of heat checks on the surface. In some cases cracks will begin at the periphery of the disc and propagate inwards. In this situation, propagation can be delayed by drilling small holes at the end of the cracks (stop drilling). We do not recommend this however, because if the cracks continue to propagate unnoticed, catastrophic mechanical failure will result. Replace disc at the first sign of cracks at the outer edge of any size. A historic note, the original purpose of the curved or angled vane disc was to prevent cracks from propagating by imposing a solid vane in the path of the crack. The cooling function was secondary.
Slotted:
1. Disc: Shallow, sharp edged but radiused bottom grooves milled into cast iron discs to provide leading edges for bite and a path for the fire band of gases and incandescent friction material to be dissipated through. If the slots fill up with pad material, the system is operating at too high a temperature.
2. Pad: Radial grooves molded or cut into the surface of the pad to provide a path for fire band dissipation and to double the number of leading edges and improve bite. Some long pads also have a longitudinal groove
Should all be as clear as mud now... 
jmorgan said:
Arn't the bog standard around £25 each?
I tell a lie, 21 squid.
Wedges stopper
I'll get me life jacket........
Thanks for the advice all I will see what I can find. May find some up at Stoneleigh this weekend.
Regards releasing the brakes after comming to a stop I was also told the same back in the 70s, this used to be particularly important with automatics (not something that affects us wedgers to a great extent) as most people leave them in drive and hold them on the foot brake at traffic lights etc. Have not heard of the problem for quite a while so perhaps modern materials and vented discs have overcome the problem.
Regards releasing the brakes after comming to a stop I was also told the same back in the 70s, this used to be particularly important with automatics (not something that affects us wedgers to a great extent) as most people leave them in drive and hold them on the foot brake at traffic lights etc. Have not heard of the problem for quite a while so perhaps modern materials and vented discs have overcome the problem.
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