Diagnosing clutch issue - 95 540i/6

[papa t]

I've been trying to troubleshoot my clutch problem. I have a '95 540i/6 with 220k+ miles on it that I've owned for about 18 months. I have no idea of the history of the clutch. Earlier this summer I noticed the clutch slipping when accelerating in 6th gear. It's gotten progressively worse over the last few months. I changed the slave cylinder and noticed the stamped number on the old slave (FAG) didn't match the new one (Sachs). I figured it was because they were different manufacturers. The clutch still slips so I ordered a 265mm clutch kit but then I started wondering. If the previous owner installed an 240mm E39 clutch and flywheel and slave, would the new slave I installed have trouble moving the clutch? Is there a big difference in the flow rate of the fluid in an E34 540 slave than an E39 540? I was assuming the previous owner(s) had to replace the clutch at some time and that they used a 265mm kit. Now I'm not so sure. Is there a way to tell without removing the transmission? Sorry for so many questions. I'd like to have all of the parts I'll need before I start the repair.

Thanks in advance!

[AHenry014]

The e34 265mm clutch uses a larger, 27mm diameter slave. The e39 240mm clutch requires the use of the corresponding e39 slave (22mm), which happens to be the same as the e34 525i (m50)/530i slave.

[papa t]

Thanks for the response. Could using a 27mm slave affect the performance of an E39 240mm clutch? I'm wondering if the previous owner installed a 240mm clutch/flywheel and an E39 slave, would my installation of a 27mm slave give me the same symptoms as the bad old slave (it was in pretty bad shape when I pulled it). Does anyone have any thoughts on the matter? It seems to me that the larger the diameter valve pushes more fluid but at less pressure than a smaller diameter valve.

[Bimmerick]

In a recent thread this guy went from a 265mm to a 240mm clutch without "downsizing" the slave cylinder and experienced a very light clutch pedal; it was so light that the ended up swapping the E34 slave out for an E39 slave cylinder. So, would you describe your clutch pedal feel as super light?

Also, your flywheel may need refinishing as well (or replacing if it's a dual mass flywheel).

[papa t]

Thanks for the link. That's actually the post that got me wondering about my slave cylinder. My clutch feels a little lighter but not too much different. It engages fine but slips under load in most gears. I was hoping for a "simple" solution but it looks like I'll be dropping the transmission to see what is there. Is a bad flywheel readily visible? Also, assuming its a 265mm DMF and will need to be replaced, is there a problem using the OEM clutch with a solid flywheel? I have the 265mm Sachs clutch already and will need to order a flywheel. From my research, it seems the general consensus is, it will work but there will likely be some chatter. Am I correct?

[AHenry014]

An unsprung disc with a solid flywheel engages a bit more suddenly than a sprung disc. I daily drove a JBR solid lightweight flywheel with a OEM replacement LuK 240mm clutch kit. drivability was fine, no chatter. This was a full faced organic disc. I cant say how a pucked clutch would drive.

[uscharalph]

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