low pedal engagement, not bracket, not master, not slave

[taiden]

Hmm. I haven't started pulling the transmission yet. Is my idea insane? My fasteners book is MIA so I don't have the resources to calculate acceptable axial load for a threaded steel fastener in a cast aluminum assembly.

[demetk]

Sounds interesting. Waiting for what you come up with as a solution. This comes to mind.

[taiden]

The metal pivot pins seem to all be silicon bronze. If my memory serves me, this material's surface is naturally low friction. I haven't seen anyone use steel for this part, and I assume it's because it would increase wear on the clutch fork. Clutch forks are cheap. The plus about having a threaded pivot is it would be adjustable. I don't know. I'm still on the fence.

[mooseheadm5]

The 850i pivot is stainless steel.

[taiden]

Whoa! That's good enough for me. Thanks again moosehead.

Quick question, what's the function of the spring? Just to keep it in place?

[mooseheadm5]

Keeps the clutch fork in contact with the pivot to keep it from rattling.

[Mike W.]

Broken record, but if you tap it and screw something in from the back use locktite. Preferably with a locknut. You don't want any movement, it'll strip the aluminum as often as you push the clutch in.

You might wear thru in a couple of years, but release arms are cheap if you don't already have any spares. Grind the end to a ball shape, polish, maybe add a dab of grease and drive away.

[mooseheadm5]

I wonder if one of these would work.

http://www.sdp-si.com/D785/PDF/D785HW019.PDF

[taiden]

That's pretty much what I'm imagining. I have both a 1/4x20 tpi and a 3/8x16 tpi tap. If either will match the hole I'm going to use a hex head stainless bolt with a locknut.

[1st 5er]

This I gotta see.

Pics please.

[taiden]

I'm doing it.

First I pushed the remaining bit of plastic into the bellhousing. I figure another small bit of plastic bouncing around in there isn't going to hurt.

Hole is 0.305" in diameter.

3/8" x 16 tpi tap was $8 and takes a 0.313" (5/16") hole.

I am confident this fastener size is more than enough for this job.

Updates as I continue...

[taiden]

Just did a test run with a 0.297" hole in a junk cast aluminum water pump. Tapped just fine. I'm going to run the 3/8" x 16 tpi tap without any extra drilling.

[taiden]

Got the hole tapped and got an allen head bolt in there. Clutch disengages beautifully now and the action is silky smooth.

Cost: bloody knuckles and $15

[1st 5er]

This I gotta see.

Pics please.

[taiden]

I'll snag some pictures when I go to do the guibo.

The point is that if anyone else decides to do this, the hole is perfect for a 3/8" x 16 tpi tap. Figure out how to hook the tap up to a stubby ratchet though. Otherwise it's impossible. I did this by holding the tap in a backwards 3/8 drive (male) 1/4 drive (female) adapter and an 11 mm 12 point socket.

Also, the locknut interferes with the bellhousing, so if you can source a smaller nut for the 3/8" fastener, it will probably work best. And finally, if you get the 'set screw' style fastener from McMaster in a good length, this will be the ultimate best.

I doubt this has anything to do with it, but there was an on/off throttle clunk before and it seems to have gone away since I did this?

awkward.

[Mike W.]

Got the hole tapped and got an allen head bolt in there. Clutch disengages beautifully now and the action is silky smooth.

Cost: bloody knuckles and $15

[taiden]

I'm ordering 2" long set screw style fasteners with skinny jam nuts. Should clear the bell housing just fine.

They only come in packs of five, so if anyone decides to do this to their transmission let me know. I'll sell the fasteners for cheap.

[mooseheadm5]

I'd go ahead and use loctite as well. Just make sure you are not accidentally preloading the release bearing. That would be bad.

[taiden]

Valid point but isn't the slave cylinder supposed to relax enough to avoid that issue?

[mooseheadm5]

Valid point but isn't the slave cylinder supposed to relax enough to avoid that issue?

It gets to the point that it is bottomed out if you move the pivot too far forward. It can also make the clutch feel funny.

[taiden]

I see what you're saying now. I could score the slave pin thingy and check it's throw.

[demetk]

This thread made me check on my problem. I had a cracked bracket that I welded. After replacing the master and slave and bleeding multiple times I still have problematic 1st gear engagement.

Here's my slave at only .68" travel. I highlighted the scribe mark with a marker.



ate part number.



Is your scribe mark at the same location?

I'll be checking on the pivot pin tomorrow.

[taiden]

Mine was all the way up against the rubber boot. Much further in than yours. I had about the same travel, but that was BEFORE I had the system totally bled.

[taiden]

Also, for what it's worth, I have 1st gear problems too at a stop. In most cars you can let the clutch out in neutral and then quickly shift to 1st, this helps the gear stacks align because they will still be spinning under no load... but this doesn't seem to help in the e28.

[mooseheadm5]

Don't do that. Shift gears in neutral.

[taiden]

Well, I push in the clutch when I go to first. I don't mean just slam it in.

[mooseheadm5]

Then what are you talking about when you say you let the clutch out in neutral and shift into first?

[taiden]

If you let the clutch out in neutral it spins the input shaft, if you throw the clutch in and quickly shift into first the gear stack connected to the input shaft will still be moving slightly. This movement under no load allows the gears to click nicely into place. That's the long version anyway...

Give it a shot the next time you can't get a car into first at a stop. Another way is to allow the car to roll slightly while maintaining slight pressure (clutch in) into first gear. You'll feel it *SNICK* nicely into gear when they are properly meshed.

[mooseheadm5]

Yeah, that's not how the synchros work. The gears are always meshed together. With the car stationary and the clutch completely disengaged, the input shaft will turn a tiny bit due to drag in the pilot bearing. The output shaft is stationary. There is no load with the clutch disengaged. Shifting moves the synchro sleeve to engage the gear to the shaft. Since the output shaft isn't moving and the input shaft has no load on it (even if it is turning a tiny bit) the synchros do what they are supposed to do. Trying to move it quickly into gear makes the synchros work harder. Transmission fluid properties also affect this interplay of synchros and sleeves.

Just shift slowly into first like a normal person.

[taiden]

Does the 535i have a syncro on first gear? Most cars I've owned do not. Maybe that's why this method doesn't work on this car.

And we are both understanding the situation the same way, but I don't want to waste 'breath' on arguing/discussing it because there's no point. I think you assume I'm jamming it into first gear. Text cannot explain the feel of the motion unless I wrote way too much on it.