MyE28.com

Facts:

• RealOEM lists PN 21511202659 for the clutch "Ball Pin" for a E28 535i *and* E28 528e. This ball pin is 15mm long.
• RealOEM lists PN 21511223281. This ball pin is 20mm long and has a 10mm shaft and comes on the E31, E34, and E39.

The SS/aluminum one is 21511223281 (E31) and the brass one was purchased from Ireland Engineering, I believe. It is 15mm long and has an 8mm diameter shaft.

When I did the 5-speed conversation on Maytag (1987 528e) I put an E31 ball pin in. Because the pin is longer, my clutch engages very near the top of the pedal travel. That 5mm makes a big difference. I want to go with the shorter 15mm pin. However, the hole in the bellhousing is 10mm in diameter, so the brass pin just slops around.

The question:

Did I drill out the bellhousing when I did the 5-speed conversion? I don't remember doing that (and I didn't mention it in my thread).

The follow-up question:

Can someone suggest a way of making the smaller diameter pin snug? I need a 8mm ID/10mm OD sleeve or something.

Or I could shorten the E31 pin by cutting the round part down on the grinder, but that seems sketchy.

I would check mcmaster (or similar ) for thin walled metric tubing. Press the pin into the tube with a little loctite. I could make one if you can't source it. Just need to know the length. PM me if needed.

George wrote:I would check mcmaster (or similar ) for thin walled metric tubing. Press the pin into the tube with a little loctite. I could make one if you can't source it. Just need to know the length. PM me if needed.

Good suggestion on McMaster-Carr. If there are no intermediate sizes, drilling the housing even bigger to get a bushing that will fit might be necessary.

Sleeve/McMaster Carr was a good suggestion. But after sleeping on it, I went the other way and shortened the 20mm pin to 15mm.







Dremel for the win!

Now my question is, why is the E31 pin so much longer? What's different about the transmission/clutch in the E31/E34/#39 that requires a longer pin?

// 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


30mm


25mm


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!


Bentley says:

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?

OR

The bell-housing I have is the shorter version (pre-dual mass flywheel)?

Regardless, it seems like I have 3 choices:

1. [1]Just replace the ball pin (2.5mm shorter)
   [2]Just replace the throwout bearing (5mm shorter)
   [3]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).

Firs off I'm not a mechanic and know shit. I could be totally wrong, but I think you are on wrong path. If there is no slop in the pedal, then the pin and TO bearing has nothing to do with point of engagement.
I think the issue is in pressure plate preload / disc thickness.
The arm thing is swinging in an arc. Pin length allowed you to adjust the arm hitting the clutch square.
Again I'm making this all up as I write but sounds good to me

Tiit wrote:Firs off I'm not a mechanic and know shit. I could be totally wrong, but I think you are on wrong path. If there is no slop in the pedal, then the pin and TO bearing has nothing to do with point of engagement.
I think the issue is in pressure plate preload / disc thickness.
The arm thing is swinging in an arc. Pin length allowed you to adjust the arm hitting the clutch square.
Again I'm making this all up as I write but sounds good to me

The TO bearing is mechanically attached to the fingers on the pressure plate. If there's no slop (in my case there isn't) and increased pressure in the hydraulic system presses the slave rod out the PP fingers will start compressing. If the PP fingers are ALREADY compressed because the distance between the rear of the transmission (and the slave) is less than per-design, the amount of pedal travel required to compress it to the point where the PP moves away from the flywheel is LESS.

The Ball Pin has the same effect. A taller Ball Pin is exactly the same as a taller TOB.Yes, it's primary design is to ensure the fork is level.

Both are exactly the same as a fatter flywheel, which would move the PP and thus fingers of the PP back towards the rear, increasing tension on the PP fingers.

Makes sense. Thanks.

I have a "spare" 260/5 that I got along the way. Today I decided to measure things to see what was up. Imagine my surprise when I discovered that Maytag's transmission is the LONG variant and my spare is the SHORT variant (I have confirmed there are, in fact, two variants of the Getrag 260/5!).

Transmission on Maytag
PN on Bellhousing: 260.0.1270.90
VIN: WBAAB5407H9696074
Model: 1986-07-31 US 325E (not a 528e as I had previously thought)
Housing PN from RealOEM: 23111222657
T/O Bearing PN from RealOEM: 21517521471
OAL (output shaft to bell-housing face): 55mm
Bell-housing length (rear casing front to bell-housing face): 37.5mm
Bell-housing depth (slave face to bell-housing face): 17mm

Spare transmission
PN on Bellhousing: 260.0.1346.90
VIN: WBAAA130XK4143310
Model: 1988-08-18 US 325i
Housing PN from RealOEM: 23111222658
T/O Bearing PN from RealOEM: 21517521471
OAL (output shaft to bell-housing face): 55mm
Bell-housing length (rear casing front to bell-housing face): 37mm
Bell-housing depth (slave face to bell-housing face): 16.5mm







So this odd situation with the pedal engaging too high is NOT due to a shorter bell-housing. Darn. I wish that were the case because it would explain everything perfectly!

It is odd that RealOEM specifies the same T/O bearing (the short one) for both variants of the 260/5.

Regardless, I'm making the call now to assemble this thing using the shorter T/O bearing and the shorter longer ball pin (5mm difference). Joel323 has told me that 5mm in stack height will move engagement about 1/3 of the pedal throw.

cek wrote:I have a "spare" 260/5 that I got along the way. Today I decided to measure things to see what was up. Imagine my surprise when I discovered that Maytag's transmission is the LONG variant and my spare is the SHORT variant (I have confirmed there are, in fact, two variants of the Getrag 260/5!).

Granted I play with M30s, but that's news to me. But our bible Realoem does list one as up to 6-86 and another from 6-86. What the difference is isn't obvious. And it shows a different driveshaft with 5-86 being the changeover point. It also shows the later driveshaft as interchangable with 9-85 and later 5 speed cars and lists the length at 1522 early and 1566 late. Interesting. Where is it that you're measuring, either 163 or 171?

Lastly a favor if you could, since it appears you must have the driveshaft out, could you measure the D/S length? And specify from where to where. I've got 3 driveshafts, that I think are E12/28, but I don't know what they go to and the measured length doesn't jive with what I've seen. Metric or fractional measurements are welcome.

Mike W. wrote:

cek wrote:I have a "spare" 260/5 that I got along the way. Today I decided to measure things to see what was up. Imagine my surprise when I discovered that Maytag's transmission is the LONG variant and my spare is the SHORT variant (I have confirmed there are, in fact, two variants of the Getrag 260/5!).

Granted I play with M30s, but that's news to me. But our bible Realoem does list one as up to 6-86 and another from 6-86. What the difference is isn't obvious. And it shows a different driveshaft with 5-86 being the changeover point. It also shows the later driveshaft as interchangable with 9-85 and later 5 speed cars and lists the length at 1522 early and 1566 late. Interesting. Where is it that you're measuring, either 163 or 171?

Lastly a favor if you could, since it appears you must have the driveshaft out, could you measure the D/S length? And specify from where to where. I've got 3 driveshafts, that I think are E12/28, but I don't know what they go to and the measured length doesn't jive with what I've seen. Metric or fractional measurements are welcome.

Will do in the AM. Note I measured the OAL of the transmissions and they are the same OAL.

Mike W. wrote:Lastly a favor if you could, since it appears you must have the driveshaft out, could you measure the D/S length? And specify from where to where. I've got 3 driveshafts, that I think are E12/28, but I don't know what they go to and the measured length doesn't jive with what I've seen. Metric or fractional measurements are welcome.

From front side of front flange:


From back side of back flange:

Outstanding, now maybe I can try to figure out what I have.

Following up based on what I learned since re-installing this transmission with the

- shorter ball pin
- shorter throw out bearing

After installation and first start / break-in of the newly built M20B7 (which runs very well, woot!) I noted a clear 'death rattle' from the transmission when in neutral (clutch engaged). It sounded an awful lot like Vlad's 260/6 does. Classic death rattle,but a bit more pronounced, I thought.

This transmission was super silent in this regard before the engine swap. I immediately decided the shorter TO bearing was 'the cause' and the rattle was it and/or the fork banging around (everything being lose given the ~7.5mm 'shorter' stack).

So, with the help of my buddy we yanked the transmission, put in the old, taller TO bearing and get the car back on the road in record time (for me; 4 hours). After driving enough to get the transmission hot, the death rattle was there.

So the shorter/taller TO bearing has nothing to do with the death rattle...

However, this was also true: There was no noticeable difference in where the clutch dis-engaged in terms of pedal travel between the two.

cek wrote:
However, this was also true: There was no noticeable difference in where the clutch dis-engaged in terms of pedal travel between the two.

Due to the self adjusting clutch I was wondering if it might turn out that way. That said, I'm not sure how to fix it.

cek wrote: The question:

Did I drill out the bellhousing when I did the 5-speed conversion? I don't remember doing that (and I didn't mention it in my thread).

I put the e31 pin in my G260/6 and I had to drill mine out to get it to fit.


Also, concerning clutch engagement point and pin length - if the pin is absent, the clutch pedal will be unable to completely (dis?)engage the clutch when the pedal is pressed all the way to the floor.
I can't say if this is due to some limitation in the slave cylinder's throw or somesuch, but that's what I personally experienced in my car.