// Renaming thread to focus on the real problem I'm having: Maytag's clutch pedal disengages the clutch within 1" of me pressing it
I confused myself about which T/O bearing I put in Maytag when I did the swap. Amazingly the 700 pages of threads on the car never say whether I put the tall or short T/O bearing in. I checked tonight and it's the taller one, which is correct given my flywheel is a lightened 82 528e flywheel. The idea being the taller TOB will engage the pressure plate fingers earlier, compensating for the thinner flywheel. I also have a shorter one that I ordered at some point for some long forgotten reason.
(This info is spread all over mye28, so consolidating it here for others' benefit...)
Left: Taller Throwout Bearing (H=30MM, e21 323, 528e, and 325i): 21 51 1 204 525
Right: Shorter Throw-out Bearing (H=25MM, 533, 535i) : 21 51 7 521 471
Interestingly, I found a another thread where Paul "Kick him off Facebook" Muskopf wrote this here
mooseheadm5 wrote:There are two different lengths of 260/5 M20 transmissions. Ones with the shallow bell housing for the single mass flywheel and a deeper one for the heavier dual mass. The DM flywheel is thicker than the SM. As a result, if you use a SM FW and clutch with a DM trans, you will have issues. There are a couple of ways to get around this. One is to make a longer slave pushrod, but this isn't the best way because it gets the clutch arm into a weird angle. Another is to make a slightly longer slave pushrod and a longer pivot stud (they would both need to be lengthened the difference in thickness between the DM stackup and the SM stackup, but I don't know this dimension off the top of my head.) The last way is to use a longer throwout bearing, but I don't know the part number, if there is one, for a BMW bearing that will work.
This is the first I've heard of there being two different lengths of 260/5 M20 trannies!
On 528e models, two different types of flywheels
are installed on the models covered by
this manual. Models built up to May 1986 have
a conventional plate-type flywheel. All models
built after this date have a dual mass flywheel.
Maytag's transmission came from an 86 325e, and that car was built 7/1986. Bentley does not list different M20 transmission housing #s between these years.
I measured my lightened 82 523e flywheel tonight to see how thick it is. It's 23mm thick.
Bentley says the Minimum flywheel thickness for the 528e "1984" model is 25.0mm (32.0mm for the 1985-1988 528e).
Anyone know what the the stock 82-84 528e flywheel thickness is?
Here's what I'm now thinking, based on all of this:
To address my "clutch disengages too early" problem I need the throwout bearing to engage the PP fingers LATER than it currently does. This means I need the shorter throwout bearing.
The difference in length of the TOBs is 5mm. Does not seem that the difference in length of the two variants of ball pins being 5mm is a coincidence.
The 5mm difference in ball pins means 2.5mm in travel of the throw-out bearing (it also means the fork will be cockeyed, but i doubt that will make a difference in anything.
The advice to use the taller TOB was derived from the assumption that my flywheel was thin.
Now I'm wondering if
The flywheel is not "thin enough" to "justify" the taller TOB?
The bell-housing I have is the shorter version (pre-dual mass flywheel)?
Regardless, it seems like I have 3 choices:
- Just replace the ball pin (2.5mm shorter)
Just replace the throwout bearing (5mm shorter)
Replace both (7.5mm shorter)
I'm afraid if I do #3 I'll "go to far" and end up with the clutch disengaging near the floor. I certainly don't want to get this wrong and have to pull the transmission...
So getting the stock width of a 82 528e flywheel seems like it would be helpful.
(For reference, this is a good, related thread: http://www.mye28.com/viewtopic.php?f=3&t=102734
, focusing on the other end of the spectrum where the pedal disengages the clutch too close to the floor. It makes it clear a really short [worn out] pivot pin will cause the pedal to disengage the clutch closer to the floor).