E30 M60 Clutch Engagement

[Garageaholic]

You M60 guys: when in your clutch pedal throw do you start to feel engagement?

For me, it's always been very close to the floor (1/2"). And this worries me because I have bled the system numerous times with 100% certainty that there is no air in the system. The MC is new, but the SC is from the original 540i/6 that I took it from and it worked fine for the entire time I drove the damn thing. I have no leaks and can't diagnose why the clutch engagement is so off. I have a Lightweight single mass flywheel with new clutch and PP from UUC, but I was told that the "stack up" was the same.

I bring this up because under hard shifting, I can't get into gear and for an E30 with a V8 engine, it really harshes my mellow.

What ideas can I try to get this thing working like it should?

[Jean]

Hey Frank, so you basically re-used the slave from the 6spd you've installed in the e30 with your swap and that slave worked fine before right?

What about the master? Anyway you can confirm if the master you are using isn't maybe a good match for the slave from the e34 or is the master from e34 as well?

[Garageaholic]

Jean,

You have a great point and I had that "a-ha" moment this morning. The MC is brand new and is an e30 type...Perhaps they are not matched correctly...i.e. the volume of fluid displaced be the MC is not enough to move the SC far enough to fully disengage the clutch.

Tonight, I'm going to try to remove the slave and slightly extend the push rod by cutting/welding to see if that gets me the throw I need....1/4" extension should get me there.

[JGood]

Hey Frank, got your text, unfortunately my setup is totally different. I'm using the ZF trans, which uses an aftermarket m52 clutch setup.

Anyway, a couple things:

Jean is correct, the slave cylinders are different. Both the e30 325 and e34 540i master cylinders are 19.05mm, but the e30 slave is 20.64mm and the e34 slave is 26.99mm. I don't know if this would cause your problem, I don't know the math off the top of my head to determine if that would increase or decrease slave cylinder movement in relationship to pedal travel, or if the difference is even significant. The 530i slave cylinder that I'm using is 22.2mm, closer to the e30 size, but still bigger. My clutch releases pretty far up in the pedal travel.

I'd be very hesitant about welding an extension on to the slave cylinder rod. You may end up with a clutch that won't fully clamp, or a burnt up SC seal, or it may break, etc... Maybe try to get in touch with Jonsku, he's done a lot of these swaps with 6 speeds and I'm sure can tell you if the e30 MC and e34 SC work together.

Check to make sure you are getting full pedal travel. I had an issue with my modified pedal box where the MC was binding up, and the pedal wasn't depressing the whole way. I had the same problem, I could barely get the clutch in far enough to shift. It turned out the rod was sliding over on the spacer I made to relocate the MC, and the angle was so much that it binded up the MC. Just make sure your pedal is actually traveling the whole way, and nothing is stopping it.

I know you don't have the typical symptom of a bad slave cylinder, but I'd replace it anyway, if everything else seems good. It's the next easiest thing to do.

[The Dark Side of Will]

Jean,
Tonight, I'm going to try to remove the slave and slightly extend the push rod by cutting/welding to see if that gets me the throw I need....1/4" extension should get me there.

Don't do that.

Jean is correct, the slave cylinders are different. Both the e30 325 and e34 540i master cylinders are 19.05mm, but the e30 slave is 20.64mm and the e34 slave is 26.99mm. I don't know if this would cause your problem,

It would.

[Garageaholic]

True, but I checked realoem and it shows that exact configuration present in my 540i. I think that the modification I made to my pedal assembly somehow yields less throw on my MC than before.

Now what could be some ideas to modify the throw on my MC without disassembling the entire pedal assembly?

[JGood]

True, but I checked realoem and it shows that exact configuration present in my 540i. I think that the modification I made to my pedal assembly somehow yields less throw on my MC than before.

Now what could be some ideas to modify the throw on my MC without disassembling the entire pedal assembly?

Yeah, I don't know what I was thinking... the master cylinders are the same, so you should be good with that combo.

I wouldn't worry about modifying pedal throw. Unless you can physically see that the MC is not compressing the whole way. It should be obvious to see.

What clutch/flywheel are you using?

[Garageaholic]

I have a Lightweight single mass flywheel with new clutch and PP from UUC (the package that they offered), but I was told that the "stack up" was the same.

And I do believe it is...

[Garageaholic]

Due to my previous mods to the clutch pedal assy, I think I'm going to extend the MC pushrod slightly.

If this is all a result of a misaligment of my relocated MC, then this is the only realistic option (and low risk at that).

[Garageaholic]

Well, after getting home from work and investigating further, I realize that I cannot extend any pushrod any further than it is. I bled the system again and it's engaging better. It's not what I'd expect, but it's better. Better to the point where I can have effective money shifts, which is what I really care about.

Thanks for your help, but I think that I might end up waiting until the winter to perfect this.. Until then, It works "fine" and will take me to bimmerfest and back this weekend.