new clutch problem

hello

i've got a supra single turbo (xs T61 at 1.2bars) and just fit a r154 gearbox with a new flywheel and a news clutch.

The clutch is a spec stage 3 rated to 520 fts /lbs at mvp's store.

my problem is the clutch is slipping in 4th and 5th gear at 0.6-0.7bars

so at this pressure i think that i am under the max torque of the clutch

Is this thing normal? does the clutch needs a break in? or i have underestimate the clutch i need?

thanks a lot

Clutches DO need a bed in period, just like brake pads and discs. As an aside this is ESPECIALLY true if the new clutch is fitted to a used flywheel with a less than 100% perfect surface finish. If the engine is really putting out over 520 ft lbs of torque and the clutch grips, and you get decent traction, the gearbox will fail IMO at those sorts of torque levels you need either a custom flywheel and single plate clutch of much greater surface area, or a multi plate clutch.

it's a lightened spec flywheel which is brand new and this is a 6puck disc

Either you are putting over 520 ft lbs of torque through the drive train, the installation of the clutch and flywheel is less than optimal, or the torque capability figures for the clutch are optimistic. You could pop the clutch out and see it has bedded to give full friction face contact, and also double check everything is good with the installation like the release bearing isn't in contact with the fingers and not allowing full diaphragm pressure. To be honest unless you have amazingly good traction that sort of torque should light up the tyres, even on a dry road, and will definitely give an R154 palpitations.

ok i think i m gonna double check everything in the installation of the clutch,

i ve just done 60miles today particulary in town and it seems to get a little better!

maybe it just needs a good 400-500miles of break in?

150 miles of normal town / country should see it bedded. Are the pucks cerametallic or fibrous?