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View Full Version : FAO Pooky - bedding in Pagid RS pads



GVK
25-08-2006, 09:32 AM
What's the crack for bedding these in Dave?

http://i74.photobucket.com/albums/i270/GVK34/pagidyellows.jpg

Gary Kinghorn
25-08-2006, 09:44 AM
I ran them in my Subaru.

From memory the advice I got was

1. On a dual carriage way 5 gently slows from 70 down to 50mph
2. Same again but 5 hard slows from 70 down to 30mph
3. Drive the car for 10 mins without braking allowing the pads to cool.

Your now ready to rock and roll :thumb:

Gary

GVK
25-08-2006, 09:47 AM
Ta Gary, nice and simple and similar process to DS3000s etc..

Just need a fooking engine in it now :lol: :lol:

Gary Kinghorn
25-08-2006, 09:50 AM
sounds like you need to bed them in on a big hill then :thumb:

Nick would have been able to do it on the no engine run from the ring haus to Adenau no problem :lol: :lol:

Pooky
25-08-2006, 01:21 PM
To be honest just made sure they had plenty of road miles on them before I went on track and it seemed to work fine.

Dave G
25-08-2006, 01:29 PM
I set fire to my DS2500s (which I prefer to 3000s!) when bedding them in when I bought my first set. Had to swiftly drive off again. :shame:

gsxrthou
25-08-2006, 03:09 PM
Here is stoptechs advice on bedding pads / discs in...
Here is the full webpage, below is a disc with uneven pad deposits commonly called a 'warped disc' (http://url=http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml)

http://www.stoptech.com/tech_info/img/warped_4.jpg



PREVENTION
There is only one way to prevent this sort of thing - following proper break in procedures for both pad and disc and use the correct pad for your driving style and conditions. All high performance after market discs and pads should come with both installation and break in instructions. The procedures are very similar between manufacturers. With respect to the pads, the bonding resins must be burned off relatively slowly to avoid both fade and uneven deposits. The procedure is several stops of increasing severity with a brief cooling period between them. After the last stop, the system should be allowed to cool to ambient temperature. Typically, a series of ten increasingly hard stops from 60mph to 5 mph with normal acceleration in between should get the job done for a high performance street pad. During pad or disc break-in, do not come to a complete stop, so plan where and when you do this procedure with care and concern for yourself and the safety of others. If you come to a complete stop before the break-in process is completed there is the chance for non-uniform pad material transfer or pad imprinting to take place and the results will be what the whole process is trying to avoid. Game over.

In terms of stop severity, an ABS active stop would typically be around 0.9 Gs and above, depending on the vehicle. What you want to do is stop at a rate around 0.7

to 0.9 G's. That is a deceleration rate near but below lock up or ABS intervention. You should begin to smell pads at the 5th to 7th stop and the smell should diminish before the last stop. A powdery gray area will become visible on the edge of the pad (actually the edge of the friction material in contact with the disc - not the backing plate) where the paint and resins of the pad are burning off. When the gray area on the edges of the pads are about 1/8" deep, the pad is bedded.

For a race pad, typically four 80mph to 5 and two 100mph to 5, depending on the pad, will also be necessary to raise the system temperatures during break-in to the range that the pad material was designed to operate at. Hence, the higher temperature material can establish its layer completely and uniformly on the disc surface.

Fortunately the procedure is also good for the discs and will relieve any residual thermal stresses left over from the casting process (all discs should be thermally stress relieved as one of the last manufacturing processes) and will transfer the smooth layer of pad material onto the disc. If possible, new discs should be bedded with used pads of the same compound that will be used going forward. Again, heat should be put into the system gradually - increasingly hard stops with cool off time in between. Part of the idea is to avoid prolonged contact between pad and disc. With abrasive pads (which should not be used on high performance cars) the disc can be considered bedded when the friction surfaces have attained an even blue color. With the carbon metallic type pads, bedding is complete when the friction surfaces of the disc are a consistent gray or black. In any case, the discoloration of a completely broken in disc will be complete and uniform.

Depending upon the friction compound, easy use of the brakes for an extended period may lead to the removal of the transfer layer on the discs by the abrasive action of the pads. When we are going to exercise a car that has seen easy brake use for a while, a partial re-bedding process will prevent uneven pick up.

The driver can feel a 0.0004" deposit or TV on the disc. 0.001" is annoying. More than that becomes a real pain. When deposit are present, by having isolated regions that are proud of the surface and running much hotter than their neighbors, cementite inevitably forms and the local wear characteristics change which results in ever increasing TV and roughness.

Other than proper break in, as mentioned above, never leave your foot on the brake pedal after you have used the brakes hard. This is not usually a problem on public roads simply because, under normal conditions, the brakes have time to cool before you bring the car to a stop (unless, like me, you live at the bottom of a long steep hill). In any kind of racing, including autocross and "driving days" it is crucial. Regardless of friction material, clamping the pads to a hot stationary disc will result in material transfer and discernible "brake roughness". What is worse, the pad will leave the telltale imprint or outline on the disc and your sin will be visible to all and sundry.

The obvious question now is "is there a "cure" for discs with uneven friction material deposits?" The answer is a conditional yes. If the vibration has just started, the chances are that the temperature has never reached the point where cementite begins to form. In this case, simply fitting a set of good "semi-metallic" pads and using them hard (after bedding) may well remove the deposits and restore the system to normal operation but with upgraded pads. If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. 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.

The only fix for extensive uneven deposits involves dismounting the discs and having them Blanchard ground - not expensive, but inconvenient at best. A newly ground disc will require the same sort of bedding in process as a new disc. The trouble with this procedure is that if the grinding does not remove all of the cementite inclusions, as the disc wears the hard cementite will stand proud of the relatively soft disc and the thermal spiral starts over again. Unfortunately, the cementite is invisible to the naked eye.

Taking time to properly bed your braking system pays big dividends but, as with most sins, a repeat of the behavior that caused the trouble will bring it right back.

GVK
30-11-2006, 11:54 PM
Well, done about 1000 road miles and a track day at Donny on these pads, yes they are expensive but they are 'kin excellent :thumb:

Boy do they squeal on the road tho :lol: :lol: :lol:

Stopped at some lights in town earlier with a squeal akin to a double decker bus :lol:

Bloke sat in his Saab in the left lane with window down halfway, quickly turned round and made some kind of spacker face at me :lol: :lol: :lol: :lol: :P

Simon
01-12-2006, 08:43 AM
^^^
you should have stuck your little finger in the corner of your mouth & set you cat on him :lol:

Tony
01-12-2006, 11:58 AM
Originally posted by Simon@Dec 1 2006, 09:43 AM
^^^
you should have stuck your little finger in the corner of your mouth & set you cat on him :lol:
LOL :lol: :lol:

T

GVK
02-12-2006, 03:47 PM
Originally posted by Simon@Dec 1 2006, 08:43 AM
^^^
you should have stuck your little finger in the corner of your mouth & set you cat on him :lol:
I would have Simon, but the cat is zip-tied to the roll cage. :blink: