Clutch resting distance/throw e36, 540i

[vapid.order]

Hello, I have an E36 with a Volvo T5 engine mated to the stock 250 Getrag using a PMC transmission adapter and a self-adjusting pressure plate from a 540i (which I believe is the same as the pressure plate for the M57). The combination seems to have significant throw issues, with the bite point being only an inch or two down from the top of the resting position of the pedal and then a very strong "over center" feeling in the pedal after. With the high bite point, I believe the clutch may not be fully releasing.

Does anyone know the distance from the slave cylinder mounting flange to the clutch fork with a stock Getrag 250 installation, and the stock amount of "preload" that the pin recesses when installing the slave?

Assuming the slave cylinder pin can retract enough without bottoming out, does cutting the spring in the slave set the "default" position adequately to accommodate changes in fork position?

Anyone have any other ideas for fixes?

[vapid.order]

A few updates:

I removed the spring from the clutch pedal to confirm the "over-center" feeling is not related to the helper spring setup in some cars. Issue remained. This is a self adjusting pressure plate, which I could see causing the clutch to not fully disengage but wouldn't explain the over-center issue.

With the slave removed, there is a small amount of play in the fork before it hits the pressure plate, meaning there isn't inherent interference in the flywheel, clutch pressure plate, throwout bearing, fork, pivot stack, so this should be solvable from adjusting slave cylinder engagement and throw. I realized the head of the adjustable slave cylinder pin I was using was bottoming out on the slave cylinder seal retainer, which was likely causing the clutch to partially release with the pedal fully retracted. Removing the adjustment part completely now provides a bit of a dead zone at the top of pedal travel, so I'm thinking that fixes this portion of the issue.

The distance from the slave cylinder flange to the fork with my transmission adapter is 2.62" I'm wondering if a 1990 e34 535 22.2mm diameter slave cylinder (versus e36 20mm diameter) might fix both the slave pin fork resting distance issue and decrease the clutch movement relative to the pedal. I'm not finding information on the pin stickout for the e34 slave, but in photos it seems to have a shorter distance to the flange. Cutting the pin wouldn't be the end of the world, but I am generally trying to keep from customizing maintenance items, so I can buy parts from an auto parts store should the part fail far from home.

Table of various clutch cylinders below. My clutch pressure plate is originally from an E39 2000 540i, but without knowing 540i clutch pedal throw distance, fork length/pivot geometry, it's not necessarily just a case of replicating this ratio.

		Master (mm)	Slave (mm)	M/S area Ratio	% change in clutch throw
E36	non-M	18.11	20.64	0.77
E34	1990 535	19.05	22.2	0.74
E34	1995 540i	19.05	26.99	0.50
E39	2000 540i	19.05	22.2	0.74
E36 master/E34 353 Slave		18.11	22.2	0.67	86%

Example of the measurement (and a random photo of the swap for those curious).

Attachment 730000PXL_20240217_231546652.MP.jpg

[nonsensebureau]

I'm currently going through the exact same issue with a slightly different setup, K24 mated to ZF 5 speed (e36) using a PMC adapter kit. Clutch engages at the top of the pedal and never fully disengages, fork grinds on pressure plate if I floor the pedal... I tried PMC's recommended pressure plate M57/ 540i and that made it even worse (PP fingers had like 14mm preload on the throw out bearing). I found out the E46 clutch/pressure plate seems to be the correct thickness when torqued down assuming the TOB will have about 1.5mm of preload, which is another measurement I'm unsure of.

I haven't messed with the master/slave bore sizes yet because the setup I have worked perfectly on my S52/ZF5 combo. There are 2 different factory pushrod lengths, E34 i believe is about 3/8" shorter which when paired with the E46 pressure plate, everything seemed to line up. I know the getrag is different but maybe using an E34 or similar style pressure plate will solve at least one of your issues while retaining factory parts?

Ill be installing everything this weekend to see if these parts are correct, also any insight would be appreciated!

Btw i tried cutting the original pushrod down to length and it ended up falling into the bellhousing after a clutch kick so.. I will be installing some sort of stopper on the clutch pedal.

Also, awesome setup! Looks like it compares to the K swap but with some actual torque lol.

[vapid.order]

What clutch plate exactly did you use and do you have the measurement for from the friction surface to the ends of the fingers available ? Did you have to bore out the holes for the pins?

I just ignored the poor action for a while and figured any problems would make themselves apparent and sure enough, the release bearing broke as well as the pressure plate rubbing the bellhousing (perhaps from the broken release bearing allowing more movement). Measuring all the parts individually, I think the stack height of flex plate, flywheel, pressure plate, release bearing, and fork is deeper than the bellhousing and adapter plate depth. I'll draw it up later today.

[vapid.order]

I took the time to dimension everything. The fork is an estimation as the shape is pretty complex. What I see is that without considering the pivot pin or slave cylinder, the fork will pre-load the pressure plate 0.12", and when taking the pivot pin into consideration, the preload is about .17", placing all components flush with each other until the fork, and then placing the fork flush with the guide tube base and measuring the interference with the release bearing contact surface and the fork. I assume the pressure plate compress in overall depth a touch when the clutch is installed that there is just barely not an interference, but clearly something went wrong to cause my release bearing to break.
PMC Exploded Reduced.jpgPMC Collapsed Reduced.jpg