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

taiden · Post by **taiden** » Mar 08, 2012 11:57 PM

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

demetk · Post by **demetk** » Mar 09, 2012 7:43 PM

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 · Post by **taiden** » Mar 09, 2012 8:12 PM

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 · Post by **taiden** » Mar 10, 2012 2:22 PM

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.

Post by **mooseheadm5** » Mar 10, 2012 6:50 PM

Don't do that. Shift gears in neutral.

taiden · Post by **taiden** » Mar 10, 2012 8:36 PM

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

Post by **mooseheadm5** » Mar 10, 2012 9:10 PM

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

taiden · Post by **taiden** » Mar 10, 2012 9:27 PM

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.

Post by **mooseheadm5** » Mar 10, 2012 10:01 PM

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 · Post by **taiden** » Mar 10, 2012 10:24 PM

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.

Post by **mooseheadm5** » Mar 10, 2012 11:25 PM

No, I get what you are doing. You are trying to get the input shaft to spin a little right before you shift and then shift into first quickly while the shaft is still spinning thinking that it helps line things up. Don't.

taiden · Post by **taiden** » Mar 10, 2012 11:51 PM

Engine off, on a slight incline, in a situation where first gear isn't going in with the clutch in. Let the car roll with the clutch in while you feed it first gear. It slips in. I'm doing the exact same thing.

"Don't"? Really?

Post by **mooseheadm5** » Mar 11, 2012 1:50 AM

If you can't engage first gear with the clutch pedal down by simply moving the shifter into place, the clutch is not disengaging fully. In the context you give in this last post, you may make it ever so slightly easier by providing some movement, but it should not be necessary. If you are trying to do this in real life with the engine running by spinning the shaft up in neutral and then quickly shifting it, you are not giving the synchros enough time to match speeds.

taiden · Post by **taiden** » Mar 11, 2012 5:26 PM

What I'm doing is no different than shifting into first from neutral. Some people hold the clutch in and keep trying over and over again. The trick is to let the clutch out in neutral and then try again. This doesn't really apply to cars with a syncro on first gear. I wasn't aware the e28 had a syncro on first gear.

taiden · Post by **taiden** » Mar 17, 2012 10:13 AM

Finally got my fasteners in. I had to buy in packs of five, so if anyone wants one I'll sell it for $10 shipped.

3/8" x 16 tpi
2" long set screw with inset allen head
thin and skinny nut for better clearance to bellhousing
316 stainless steel

marked for OEM clearance (compared to a new plastic pivot pin)

head rounded to match the contour of an OEM pivot pin

(fasteners before any modifications)

m535is · Post by **m535is** » Mar 17, 2012 11:07 AM

The E28 as with all BMWs from the well, the mid-70's has a synchro on first. Moose is correct. With the clutch disengaged you should not need to do anything, move the car, etc., to put it into first. I have never had this problem on any of the 20+ manual transmission BMW's I have driven. The only time I have ever had an issue putting it into first is with the engine off and rear wheels locked in position and without disengaging the clutch trying to put it in first. This sometimes will not work because the input and output shafts are not oriented correctly. If you are having trouble putting it into first, this is typically a sign of the pilot bearing being worn out causing the input shaft to spin more than usual which makes the 1st synchro work harder or the clutch is not fully disengaging which could be caused by a number of things.

Here is another way to think about it. The output shaft is stationary. Why would you spin the input shaft if you have a synchro? The goal of the operation is to get the gears engaged and in that situation the input and output shafts won't be moving. So that would mean that the synchros now have to work even harder to stop the input shaft, which doesn't make any sense.

If you are having trouble with the into first shift than you should look at if your clutch is fully disengaging and see if your pilot bearing is bad. Seeing as you have a completely flattened, or unuseable pivot pin, it makes me think that the clutch might be well overdue for a service even if the pressure plate and disk are good. I would say get in there and replace it all. You have spent so much time under the car working on this that you probably could have pulled the trans and replaced all these parts by now and have little to no further problems.

Just my $0.02

taiden · Post by **taiden** » Mar 17, 2012 11:29 AM

m535is wrote:You have spent so much time under the car working on this that you probably could have pulled the trans and replaced all these parts by now and have little to no further problems.

Story of my life.

MyE28.com

MyE28.com

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