M52 swap with ZF trans, the clutch pedal travel is short, like I'm hitting something

[Chilezen]

I'm almost done with the swap, and last night I bled the clutch line after doing the brakes. For some reason, the pedal doesn't feel right. The travel seems short, like 4 inches or so. Plus, the pedal feels kinda soft, which to me feels like an easy clutch, up until it stops earlier than I am used to (coming from an M20 with the getrag). So the pedal goes down with some resistance as normal, up until I feel a stop, which seems early to me. And it returns like normal. It kind of feels like it might not be doing anything, but it doesn't feel like there's air in the lines.
I don't know yet if the clutch disengages with the car running, because I haven't finished the swap yet. I bled the line after swapping the slave cylinder by letting the fluid drain out, and pumping the pedal a hundred times because I'm told it is self-bleeding like that.
Parts I've used are an FTE brand slave cyl, pn 21521159045, and the UUC lightweight flywheel + clutch combo, using the M5 sprung disc + pressure plate + associated TOB. I did also have to buy a new fork lever, spring clip, and pivot pin because my trans didn't come with those.

Am I missing something? Did I bleed incorrectly? Why would it feel like I'm hitting something/reduced travel? Could something have been installed incorrectly? Maybe it's okay and I don't know until I start the car. But I'm looking for insight first, based on this speculation. Thank you!

[jbontke]

I have never had good luck bleeding a clutch unless I use a power bleeder of some sort (I use the motive unit). It sounds like its not bled all the way. There is a spring that helps pull the clutch pedal back up to the top. If you clutch still has air in the line, the combination of air and return spring could be causing the "stop" you are describing.

[Chilezen]

the combination of air and return spring could be causing the "stop" you are describing.

Would you please elaborate as to how the return spring my be causing the "stop" sensation?

[e30austin]

i had a sorta similar problem last week, with an e30 with s52 and ZF box. F1 racing single mass flywheel (the dual mass replacement style, not the thin one). the car needed a clutch replacement and it had a hodge lodge combination of parts.

i ordered an e34 m5 sprung clutch disc and an e36 m3 pressure plate. some asshole either mislabeled or mispackaged the pressure plate, because it was for an e34 535i (dual mass). unfortunately, i didn't catch it until i had already finished.

the problem i had, the pedal felt normal til about halfway through the pedal and it felt like i hit a wall. for fun, i started it up and heard this awful noise from the bell housing. what ended up happening was, the clutch fork was contacting the pressure plate before the throwout bearing had enough chance to contact the finger springs. tore it down and saw what happened, so i ordered another pressure plate and it was the correct unit. problem solved.

tl;dr, make sure you have the correct combination of parts. you can also do the "one man method" of bleeding the slave by depressing the plunger on the side of the bellhousing about 20 times or until you feel good pressure. this forces the air bubbles up to the reservoir. good luck.

[Chilezen]

So, update...
I did start the car, which I didn't want to do but I needed to know. It has open headers, so it was loud obviously, but I didn't hear anything astray from the bell housing. I pushed the clutch in, and definitely didn't feel right. Like I could feel the fingers of the pressure plate, or something like that. Just the constant little thumping of metal fingers felt through the pedal.

This sounds similar to what you described.
Since I ordered the kit from UUC, I'll call and see what they can do.

In fact, looking at the product webpage, it says the kit uses an E34 M5 plate.

It also warns against their vendor sending out the wrong units.

Unfortunately I don't quite have the means to tear it back open and actually see what parts are in there. I'm really SOL at the moment.



This freaking sucks.

[e30austin]

i'm guessing the vibration is the rivets on the pressure plate contacting the clutch fork. that's a bummer. sorry to hear.

[Chilezen]

UUC has not answered their phone for the past 3 days. I'm livid.

i'm guessing the vibration is the rivets on the pressure plate contacting the clutch fork. that's a bummer. sorry to hear.

How did you end up pinpointing that the problem was the pressure plate? Is it only a matter of part numbers?
I'm wondering if this kit is supposed to include a PP from an E34 M5, and you're saying that it should be an E36 M3 plate, what's the difference? Since I can't talk to UUC, I'm trying to find out what I should be looking for. Maybe I was given a regular E34 plate, not the M5 plate? If I have to order a plate myself, why choose the M3 over the M5 plate?

Thank you!

[e30austin]

UUC has not answered their phone for the past 3 days. I'm livid.



How did you end up pinpointing that the problem was the pressure plate? Is it only a matter of part numbers?
I'm wondering if this kit is supposed to include a PP from an E34 M5, and you're saying that it should be an E36 M3 plate, what's the difference? Since I can't talk to UUC, I'm trying to find out what I should be looking for. Maybe I was given a regular E34 plate, not the M5 plate? If I have to order a plate myself, why choose the M3 over the M5 plate?

Thank you!

i have had decent luck contacting them through email.

it was my fault why i had issues, but it was incorrectly boxed and i didn't catch it. i ordered an e36 m3 pressure plate. i received an e34 535i dual mass reassure plate. they look identical from a quick glance, but they are 100% different. i only realized this after the car was all reassembled and back together. i removed the trans and saw some light scarring on the pressure plate face that matched up with some witness marks on the clutch fork, none of which were present prior to reassembly.

i dont know which style flywheel you have so i'll try to make it easy for you:

if your flywheel thickness replicates the thickness of the original twin-mass unit, you use e36 m3 pressure plate and e34 m5 clutch disc (the e36 m3 clutch disc is unsprung due to the twin-mass flywheel having springs built in).

if your flywheel thickness replicates the thickness of an e30 single mass flywheel, you use a full e34 m5 clutch kit. reasoning for this is you retain the correct diameter pressure plate and clutch disc (240mm) and ensure the stack height is enough to allow for proper clutch engagement/disengagement.

hopefully this sheds some light. sorry you've got to deal with this.

[Chilezen]

hopefully this sheds some light. sorry you've got to deal with this.

Thank you for the details! It does shed light on this.

They have not responded to my email. I am on my own.

I've been trying to figure out what plate/clutch I received. UUC used a third party, Clutch Masters, who sent me the (possibly) mistaken items. I looked through my receipts but none show the details of the products sent.
So I have looked through my photos from the installation months ago, and these are all I've been able to find:



I absolutely cannot figure out what the part numbers are on these. I can almost see the white letters on the clutch disc, which I think says "1849 0 1 183" but I can't be sure. The pads of the disc and the rivet intervene with the print. The rest is illegible to me. But it looks like the clutch is the correct size (240mm) based on the first photo.

Aside from the part numbers, just going by shape/design, can you guess, or at least rule out, what I have/don't have?

I browsed the realoem catalog, comparing all part numbers between the E34 M5, 525, 535, E35 M3, 328, and so on. I've also looked through the FCP Euro site, trying to compare pictures of the clutches. There are none that I've seen with both 4 large springs and the clutch pads (they're typically smooth). This is what they show in the M5 kit:



Very similar to what I have, but I can't be sure. I may just have to buy it, rip out the trans, and then compare/replace. I wish there was a better way.


What is the fastest way to take out the trans?

[e30austin]

looks like an e34m5 pressure plate to me, so presumably, that'll be the matching clutch disc. that's the correct setup for the flywheel you have.

what release bearing does the kit come with? did you make sure the clutch disc was installed correctly? with the aftermarket flywheels, there is a right and a wrong way to install them, and it isn't always clear. if the flywheel has a machined "pocket" that's large enough for the clutch disc hub to fit into, that is the correct direction for it, even if it doesn't seem correct.

as far as pulling the trans... no "fast" way to it. not a ton of clearance in the tunnel with a ZF. hope you have small hands/forearms and plenty of u-joints, you will need them.

[Chilezen]

looks like an e34m5 pressure plate to me, so presumably, that'll be the matching clutch disc. that's the correct setup for the flywheel you have.

Interesting. Based on that speculation, that's good news.
I can't say for certain what bearing it came with, only that it came with one. I do recall installing the clutch correctly, it's as simple as "this side to engine" printed on one side (or something like that). I do remember the clutch disc saying which way was which. And, just looking at the picture I have, it looks like the flywheel orientation is correct.

I could be wrong, since something is wrong. Maybe the TOB was installed incorrectly? Maybe the fork isn't seated on the pin? Wrong pin? Those are the only other things I can think of.

I'm going to see about dropping the front subframe to gain clearance.

[Chilezen]

Good news, finally found the problem.
I sent the car to a shop to have them pull it apart since I couldn't make the time.

They said the TOB was installed incorrectly! It was behind the fork, instead of in front. I don't even know how that kind of dumb mistake could be made.
My friend helping me is to blame, he was the one assembling that, but I should have double checked his work. Blame aside, that was the problem. Everything else was fine after reinstallation, and the car runs good so far!

[e30austin]

oops! that'll certainly do it. glad it was nothing severe and you're back on the road!