army_greywolf

iTrader: (2)

Much like engine break in procedures, there is a HUGE controversy about how to go about bedding an organic composition clutch. It also covers kevlar impregnated resin clutches. This procedure is not for race or puck type clutches, it isn't for dual disc clutches either, there is a different procedure for it and you should follow the instructions that came with the clutch in those cases.

For those of us whom use kevlar full disc or ORGANIC factory clutches, and for those who don't understand wtf is the big deal, I will tell you now a properly bedded clutch WILL hold at or slightly more than 400 lb-ft torque.

Now the procedure.

First off, your not attempting to slip your clutch at high speeds, this procedure is done at low engine speeds of 1.5 to 3k. Quite simply it's easy to screw this part up so be careful or just don't do it. Also, since it is a break in procedure, obviously if your car is already broke in this probably isn't a good idea.

Slip the clutch gently at low speed in 2nd or 3rd gear while traveling at 15-20 mph. Slip the clutch at 20-30% load for no more than 5 seconds at a time. At this point you want your heat and cooling cycles to travel upwards like a sawtooth, until you reach the point where you can smell the clutch. THIS is the point where the resins are flowing and here is where you want to do your bedding. For the next slip cycle you want to apply more load and slip for less time, gradually increasing speed until your slipping the clutch at 40-50 mph in top gear. Again, you want to maintain clutch temperature without going too far, this is done by feel, you should NEVER experience visible smoke, if you do, you went too far. The reason your not bedding the clutch harshly like brake pads is because while the brakes are designed to apply over and over at very high temperatures, a clutch is not, you simply want to maintain the clutch operating temperature at its upper limit for at least twenty consecutive engagements at low speed, medium speed and just a few at high speed. Then during the clutch COOLDOWN cycle you want to bring the clutch temperature down in the same stages you brought it up, which means you will disengage the clutch WHILE MOVING at low speeds, travel until you must bring the car back up to speed, gently reengage clutch and repeat until the clutch has been cooled significantly. Do not simply drive at speed without using the clutch the entire point is to seperate the friction point in stages during the heating process and cooling process, this way the clutch beds the materials as precisely as possible, this will eliminate high spots in the material, remove machine marks in the pressure plate and flywheel and bed the clutch's rotational centerline (the span of distance the friction material travels during a 360 degree rotation, I forget what the correct term is but you get what I'm trying to express.

So to recap, to bed the clutch, you want to take the operating of the temperature of the clutch up in stages from full cold right to the point it starts to smell but DOES NOT emit smoke, during this particular stage you want to make twenty engagements at low speed at increasing loads while decreasing engagement times. The temperature must stay at the upper limit as this is your actual bedding. Finally you want to REDUCE temperature in stages, disengaging the clutch often so it doesn't transfer heat to the friction material unevenly (the friction material will reduce temperature SLOWER than the flywheel and pressure plate, you want everything to cool down together at the same rate thus separating the three components in stages helps this process).

I pulled the above procedure from an old GM High Performance magazine, an M3 forum and a phone call to a friend I race with who bedded my clutch for me and taught me how to do it. I'm not comfortable repeating internet here say so I won't provide links, but google can net you what your looking for anyways. I had success with this process and I feel my clutch is in excellent shape because of it.

If anyone has anything to add, or if a mod feels this would make a good how to (I can edit this later to make it a better step by step.)

Oh and obviously if you don't have a decent understand of what I talked about, don't do this ok? You can honestly ruin a perfectly good clutch in the span of an hour.

RyRidesMotox

Thats interersting. sub'd for later, thanks for the info.

ronn

iTrader: (3)

Question:
What about new cars? I mean there's no *procedure* to speak of in the owners manual. Are these *pre-bedded* at the factory? If not, then I don't get this. My clutch with 16K Mi is PERFECT, of course I never abuse it either. BTW, when got my Clutchmasters for my previous car (Full face Kevlar), the instructions only stated to take it easy for the first 700 Mi..no hard acclertation or dropping the clutch. Just *normal* driving..taking it easy. After that, I had NO problems at all for the next 70K miles (when I sold it..still rock solid then too).

army_greywolf

iTrader: (2)

I'm told this increases holding ability by about a quarter and may affect life positively. Kevlar clutches last FOREVER I had one with a couple hundred thousand miles on it come in for a throw out bearing (but he didn't want to touch the clutch).

Anyways, it's supposed to make the clutch feel smoother, hold better and in theory, last longer because of the aforementioned. This would be for those people with factory clutch or a new car that plan on power adders. Also for those whom have low mileage and plan for a semi aggressive tune.

Some people on here have done this "procedure" entirely by accident by slipping their clutch repeatedly on an agressive tune. If it didn't overheat they may have noticed that after a couple times of it slipping it no longer slips. I believe BYT may have mentioned this in another thread, not sure.