technicalninja

OK, I'm new to the forum and am rapidly getting "spun-up" on Miata knowledge but have not really been able to provide new knowledge to the MT community...
Here's my two cents
I also have a 1998 BMW E36 M3 5spd and have insight to a transmission issue that should be addressed BEFORE you install an old BMW trans.
The shift detents gall in their aluminum bushings inside the rear case.
This causes increased resistance to rotation of the shift linkage during shifts that change internal shift rods in the trans. ie 2-3 and 4-5.
What usually happens is what's known as a "money shift" .
During spirited driving you try to get 5th and end up back in 3rd.
The trannys are STRONG. It never hurts the transmission...
The syncros work GREAT you always make it back into 3rd...
What ever is attached to the transmission is usually destroyed...

I had the driveline out of my M3 when I found out about this problem and decided to do mine as a preventative maintenance.
My car is a 133K 2 owner (both old people) nice M3 that had perfect shifting qualities. This car has been well maintained and not beat on. I expected I was fixing a "non-problem".
My shift plungers were completely jammed in their bushings. They should just fall out after the clips and plugs are removed. I had to pry mine out with a modified pilot bearing tool.
The original bushing were plain aluminum and the BMW "upgrade" bushings have a Teflon like coating on them. It looked to me like the bushing/plunger assemblies receive no or very little oil and BMW didn't oil them when installed originally...
As I remember there were two diameters of bushing (total of 5 maybe 6 bushings) and they have to be installed at different depths in their respective bores.
There was pretty good info on the net regarding making a set of bushing drivers (technical enough drawings to recreate on your own).
I'm very frugal and came up with an alternate method for installation...
A Honda H23 head bolt.
I chucked it up in a drill press and machined a bit of the flange under the head until it just fit into the bores in the transmission.
Cut it off 2" below the flange and found vacuum tubing to slip over it. It was close to fitting the new bushings and a couple of wraps of electrical tape filled the extra space.
You want it to fit the new bushing loosely so you can remove tool after you install the bushing.
I measured and recorded the depths of the original bushings.
Removed them. I hadn't worried about removal, I was wrong. They are very difficult to remove without an expanding remover that fits a slide hammer. It can be done however and two hours later and some blood and mass profanities I got them puppies OUT!
Installing the new ones took 10 minutes. The new bushings could be installed with a small tap hammer and control was easy. The Honda/BMW bushing driver worked great.
The new stuff from BMW was not expensive (50-60) and besides removal the job was very simple.
Hope this helps...
Rick

DaWaN

I think I saw a video about this issue some time ago:

It is in Finnish, but there are subtitles.

How many of these pins are really troublesome? In the video above only one pin gets replaced.

Edit:
A total of 5 of these according to this manual: https://webspace.ringling.edu/~dplas...hift_pins.html

KMiata

Good info, thanks for sharing. It will be helpful to the guys who'll be running our trans upgrade.

m2cupcar

iTrader: (5)

Prop cat awarded.

MartinezA92

iTrader: (4)

Actually happened to a friend of mine with an E36 M3. Legend has it you can still hear his timing chain getting ripped off the block on warm summer nights.

chicksdigmiatas

iTrader: (11)

Nice, thanks for the post. Prop cats awarded. I am considering doing this instead of a swap so great timing.

KMiata

For what it's worth, you're looking at $82 in BMW parts to correct the shifter centering. Just ordered to set to throw in a ZF 5 speed here, and I'll put together a DIY of some sort for any customers. It does seem pretty straightforward to do with the trans out of the car. $200 trans + $82 in replacement in fresh pins. No big deal.

Bimmerworld even sells all the parts in a nice little kit:
ZF Transmission Detent Repair Kit

motorphile

iTrader: (1)

I just wanted to confirm that this is a very real issue on these transmissions. When I bought my E36 M3, the shifter's neutral resting place was between 1-2, not 3-4 as it should be. This obviously made shifting "interesting". Fifth was nearly impossible to find. My pins and bushings were so seized up that it took literally every tool I could throw at them to get them removed. Even a slide hammer was no match for these bad boys. If you're planning on throwing one of these transmissions in your Miata, save yourself some time and just do them now.

That being said, I actually have a complete set of the "proper" drifts to install the bushings. Some of the bushings can be driven in too far, which means you'll be ordering another as you can't get them out without screwing up the nice teflon coating. I would be more than happy to rent them to forum members if that isn't against the rules here. If there is enough interest, I'll work on the details.

technicalninja

Thanks for the litter of kittens guys, I'm glad I could help.
Motorphile is correct, the kicker is the depth of the bushings. I was worried enough about trashing bushings that I ordered 1 extra of each part # (I think it was 3 different #s).
Ended up throwing those extra bushings in my bushing stash. They are very easy to install.
The M3 forums had people renting drivers. By the time you were done with rental fee and shipping you had $45 invested...
I found a couple of threads where members made a batch (Group buys). The sets were usually 45-50...
The set is worth $50 to own not rent IMO.
It could be made out of anything.
A wooden set would probably work fine for limited use.
A set machined out of hard plastic (nylon) would be best IMO.
KMiata will need a set as they will do many.

If you're only going to do 1/2 just machine a flanged bolt (Miata head bolt might work better than Honda as the Miata has a raised shoulder under the flange- might fit perfect)
Record installed depth and put the new ones in that deep. Tap-tap-measure, tap-tap-measure---easy---does NOT require a heavy hand.
Install was gravy... Way simpler than I thought.
Removal was the problem.
If someone comes up with a easy extractor please post...
DaWaN's link is a good one. Gives the normal "distort bushing and pry out" method. It will work. Be very careful to not gouge the bores.
A internal expanding collet that can be attached to a small slide hammer would make the removal process much much better.
Sadly I did this over 5 years ago and the M3 is still a dead puppy. Life got in the way. I really ought to finish it.
Way too many irons in the fire...
Rick

dradernh

While the 4-3 shift will frequently money shift the BMW motor, the 4-1 will always money shift it unless the motor is built to live through a large RPM over-rev. I felt fortunate that mine lived through a 1500 RPM over-rev on a 4-1 downshift. I caught it somewhat quickly, but not before it had spun up to 9107 RPM. And as you suggested, the transmission slipped from 4th to 1st at 70 MPH just as smoothly as if it had been purposely shifted from 4th to 3rd.

The solution on the M3 I ran (with transmissions in excellent condition) was to ensure that the motor and transmission rotated as little as possible relative to one another. This meant stiffer than OEM motor and/or transmission mounts a la Rogue Engineering Transmission Mounts, or for race cars: E36/E46 Lowering Solid Engine and Transmission Mount Set. After the over-rev incident, I went with the solid mount set and had no further issues. However, I never again attempted downshifting while turning, which I understand is the circumstance under which the money shift typically occurs in the M3s.