[Vetracr]

Running at Sebring this weekend I discovered a problem on manual shift E89 Z4's. Problem has existed for a long time on other BMW's but I didn't know about it until I discovered it the hard way on track. I have a 6 speed 3.0. At the end of my first 30 minute session on track I went to shift from 5th to 4th. I let out the clutch, put my foot on the gas, the engine revved in neutral and I smelled the clutch burning. I thought I had burned up the clutch. I made my way back to the pits. As I had a 120 mile trip home I packed it in for the day and drove home. Car and clutch felt ok on trip home. Once home I started doing some research and discovered the manual E89's have the dreaded clutch delay valve (CDV) installed. This is a one way valve in the clutch line just before the clutch cylinder. It slows down the actuation of the clutch. Thats why when I released the clutch the clutch didn't engage. I made a quick shift but the valve delayed the engagement of the clutch causing it to slip. Problem showed up at end of 30 minutes on track. Pretty tough environment. I don't know if CDV failed due to heat of track use but it was first time I encountered problem. I plan to switch out valve for one with valve internals removed so clutch works like normal clutch. If you have manual xsm and track your car I recommend you do the same.