Nissan 370Z Forum - View Single Post - New product review: CSC bearing sleeve for aftermarket clutches

Zat_Zuma · 04-10-2010, 04:38 PM

Let me start by educating the minority and explaining how a Concentric Slave Cylinder (CSC) works on a 2007-09 3.5 HR and 2009-10 3.7 VHR. It is a hydraulic cylinder that pushes on the pressure plate fingers to release the pressure on a clutch and allows the driver to shift gears.

It's construction is simple and straight to the point. Hydraulic pressure expands in the cylinder pushing the CSC bearing plate towards the fingers of a pressure plate and releases the pressure on a clutch. What you probably didn't know that it does this within a 15 mm stroke (just slightly over a 1/2" for the metric measurement challenged). I suspect full clutch disengagement is done within 10 mm. 15 mm is probably considered over extending the CSC and eventual failure.

The CSC rides and maintains a slight pressure on the pressure plate fingers at all times and as a result rotates roughly the same RPM's as the engine. The CSC face is made from a hard steel to prevent wear and to withstand the abuse of it's environment. It has a bearing surface width of 7 mm and inside diameter of 48 mm.

The OEM pressure plate has knurled fingers to allow to work properly on a flat bearing surface on the CSC. The pressure plate fingers have a opening of 49 mm and therefore makes excellent contact with the CSC bearing surface.

Now getting to the bearing sleeve for aftermarket clutches. Speed Performance has done some research on the relationship between the CSC's and the latest aftermarket clutches available for our 370Z's. They have developed a bearing sleeve for the CSC to correct the contact pattern on the aftermarket pressure plate fingers and corrected the spacing problem concerned with over extension of the CSC stroke. It is a thing of beauty

stock CSC for comparison

Now for the shocker ...........

I just happened to have a popular clutch/flywheel/ pressure plate combination on hand to compare the differences in CSC fitments. I won't mention the manufacturer but needless to say some members have this installed in their cars right now. I for one, will NOT be installing this into my car. after seeing first hand the CSC fitment and quality compared to a Speed Performance clutch offering. The space between the fingers of the un-named aftermarket pressure plate is 57.5 mm.
Let the pictures speak for themselves.

Aftermarket with stock CSC

As you can see the fitment is horrible and there is next to nothing for contact on the CSC bearing. It's a recipe for failure.

Aftermarket and CSC with bearing sleeve

For the record I did purchase a Speed Performance Stage 4 clutch package, solid steel flywheel, pressure plate and CSC with bearing sleeve with a stainless steel clutch line to eliminate the orifice block in the stock line. I had way too much trouble with the stock CSC and clutch lines on my 2007 3.5 HR with a aftermarket clutch not to replace the stock clutch lines and remove the orifice.

I'm looking forward to the install.