Separating the Case on ZF 5 speed

[RagnarDanskjold]

I've been searching for a while on info for rebuilding the ZF five speeds, and know it's possible, but have had little success in finding any info, so I'm fishing again.

I've got my original unit in my shop, a second used unit on the shelf and a third used in my car that was far more beaten on than the seller led me to believe. In short, I've got a few units to play with.

I've stripped one unit externally and I'm trying to separate the case halves, but it appears the input shaft bearing is a press fit on the shaft as well as the case. I'm looking for confirmation of this before I go nuts and start pressing the case off. (I've built a jig to anchor the bell housing allowing me to press the shaft aft, thus pulling the front of the case fore).

So, if anyone has ANY information on these transmissions and splitting/rebuilding I would be greatly appreciative. I've got a modest shop, access to two other machine shops and the desire to unravel this mystery. Before the expected "you're crazy", "why, dude?" or "just send it to Jim Blanton" comments, yes I am crazy, because I want to, and Jim (who used to have a shop 1mi. from where I lived) is in AZ now, I don't have the budget for someone else to rebuild one and I'm leery of getting another used unknown. So again, any helpful input will be greatly appreciated and the wisdom garnered will be shared with the community at large.

Thanks in advance,
Steve

[Mr Estoril]

You are correct, you have to press the shaft out to seperate the halves. Obviously remove the bolts first.


I had already ruined this one (another story on how) but I wanted to open it up for kicks.





Yeah... that black junk shouldn't really be there in a healthy or even worn trans. Anyway... I seems like getting some of those forks aligned would be the tough part but honestly I never tried to reassemble so maybe had I kept at it, I would have come easily?

For the little black seal on the back. Make sure you give plenty of time for that order. I had to replace one on another trans and on that occasion it had to come from Germany.

[NeilM]

Steve,

Hope you'll post follow-ups and photos. Nobody seems to rebuild transmissions any more, so it would be fun to see what you find.

Neil

[RagnarDanskjold]

Neil, that's exactly my plan! Given how many are out there, this has to be of benefit to several people, myself included.

And Mr. Estoril, those pics are a HUGE help to get me started. I was working from the front end, but I think starting at the back of the case first will make more sense.

There's a lot going on at the tiger park right now so it may be a bit before I've got some more time to put in to it, but I'll definitely be posting up what I find and documenting everything as thoroughly as I can.

Thanks, gents!

[purduinaM3]

I've heard that you need a jig to reassemble them, but I'm not sure how true that is. Definitely keep us updated, I've always been curious!

[Mr Estoril]

I have a few more.









- - - Updated - - -

As I recall, and this was a long time ago so who knows, I got to a point where I wanted to separate the components on the shafts and I wasn't sure how to do it. I may not be recalling that correctly and I probably also didn't try very hard because I knew the trans was ruined anyway.

- - - Updated - - -

I've heard that you need a jig to reassemble them, but I'm not sure how true that is. Definitely keep us updated, I've always been curious!

This wouldn't surprise me. As I recall what seemed like it would be really difficult was keeping everything in place while it was going together. Then again... it had to be put together somehow the first time.

[aga080]

not sure, but this one popped up on my local craigslist the other day

http://allentown.craigslist.org/pts/3978701909.html

[JonTheGreek]

So whats going on with your trans man. Looks really interesting. I want to do my detents that go bad and thought that i might try and tackle this as well. Although i would have some help with my local trans shop too. I tried to find something about this almost a year ago but came up empty handed. I figured all the people that had knowledge about it didn't want to share

[99MPower]

Drive Gear does rebuilt ZF trans

its very difficult, and the information is even more secret than the differential setup info (that info has finally surfaced)

[Randy Forbes]

The repair manual is ZF part # S531REP and available from ZF for about $15.00. It outlines the tear down and rebuild, but makes references to many special tools.

Several years ago, a guy brought me a car with the trans case cracked around the drain plug, so I looked into getting ALL the required tools. At that time (2007?) buying all the special tools was going to cost me $2600.00 (through the local BMW, from which I get deep discounts__though the margin on tools is pretty small anyway); at that time a new/reconditioned ZF S 5 gearbox (through the dealer) cost about $1500.00.

I wound up grinding out the crack and TIG welded it instead. It's still holding, and I regret that I didn't buy the tools back then, as they'll only cost more now.

But, the manual is a good start!

[Piner]

Im interested in this as I'd like to take the internals out and have them cryo/WPC treated. Im looking forward to seeing your progress.

[JETninja]

Cool stuff Steve, wish you luck! 223K on mine and still works great....time to replace the shift linkage bits (bit loose again after 125K since I last replaced it all) but the tranny is fine...

But the more DIY's the better. To many stupid secrets on things like this and diff's....

[BeachMedic]

20200111_101602.jpg
So, to split the case you need to remove all the bolts from the rear half of the transmission case. It would also help to remove all the detent pins and the fifth and reverse gear springs. This will make sure nothing is pushing on the selector rod.20200111_101719.jpg

[BeachMedic]

Here's what it looks like when you finally get it apart.

Attachment 664817

Of note, when I finally got it apart I saw a bunch of black stuff stuck to a dark blob on the wall of the casing. It turned out to be the OEM magnet the BMW installs in a slot in the floor of the transmission. The magnet had broken and come out of the slot, then stuck itself to the wall with all the metal debris it collected. I pulled it all out and replaced it with a rare earth magnet drain plug I bought from ECS tuning.

20191226_132239.jpg

Attachment 664818

[BeachMedic]

Getting it all back together isn't easy, but it's also not impossible. I didn't have the ZF manual so I relied on the schematic on RealOEM's parts page. https://www.realoem.com/bmw/enus/sho...diagId=23_1291

20200111_113553.jpg

The biggest difficulty comes from getting part #29, what I call the z shaped linkage, to all line up properly and move smoothly. If you don't line the holes up correctly the linkage won't spin on the bolt shaft and instead it will remain stationary.
To line the holes in the shifting forks up with their respective bolts (like part #22 & #23), I used thin string (the guts from 550 cord) and half hitched a short length of toothpick to it. I then routed the string out through the bolt hole in the transmission case. Once the halves were back together, I pulled the string taut to line up all the holes and then slid the bolt in.

20191212_160233.jpg

20191212_160654.jpg

I found it worked best to top leg or bottom leg of that z linkage connected first. If you do that, the middle portion will line up way easier, but if you try for the middle first and then do the top or bottom, things don't want to line up.
Making sure the bolts get far enough into the holes on the z linkage is the difficult part. Either using your fingers or a small shaped tool like a pick or an Allen wrench, you'll want to try and pull the back side of the linkage towards the exterior of the case. It will 'snap's into position and then you know it will rotate freely on the bolt.

Once the z linkage is all connected, you can line up the lower bolt (part #22 connecting through part #21 to part #20, in the schematic in the below reply) and tighten it.

20200111_112256.jpg



The other bolt must be placed after the transmission halves are back together.

Tag: ZF S5D 320Z

[BeachMedic]

To get the halves back together, I basically just pulled them together with the bolts. The reverse gear packs bolt is very helpful here. Before I cut it to the proper length (35mm), I actually used the full length to help pull the halves together.

20191226_125457.jpg

Once the halves were reasonably lined up, I placed a bead of high temp RTV silicone around the mating surfaces. I waited about 15 minutes and then tightened the halves back together.

20191226_125504.jpg

20191226_131633.jpg

20191226_131615.jpg

I would turn each bolt about one full turn and then move to the opposite side and tighten that one, kind of like doing a star pattern when tightening lug nuts on a wheel.
Once the halves were together all the way around, I wiped up the excess RTV that had been squeezed out. Since I didnt have a manual and couldn't find any specs anywhere, I then torqued the bolts to around 40 ft lbs since that seemed to be an average for other bolts of the same size when used in other applications.
The final bolt (part #22 connecting to part #20) can then be tightened.

20200111_115613.jpg

[pbonsalb]

Good job! What did you fix or replace while you had the trans apart?

[BeachMedic]

Thanks!
I replaced:
Selector rod seal.
Transmission output shaft seal.
The pilot bearing, since the old one disintegrated.
The rear main seal.
Clutch throw out bearing.
Clutch friction plate.
Driveshaft center support bearing.

20191130_143112.jpg

20191130_143055.jpg

[pbonsalb]

All those things you can do with out disassembling the trans. Why did you disassemble the trans?

[BeachMedic]

While attempting to remove the old shift detent bushing, it was pushed inside the transmission case.

[BMWManiac]

The guts of 550 cord finds yet another use!

The older these cars get, the more important this skill will become

You're telling me "Mr. Transmission" can't fix these :-)

[pbonsalb]

If you have big power and you are actually putting it to the ground, the ZF320 won’t hold it. I gave up after breaking 2. The GS6-53 can be fitted and will take big power (it was used in the F10M5).

[MauiM3Mania]

20191130_143055.jpg

bro...
Western-Safety-Heavy-Duty-Disposable-Gloves.jpg

[golgo13]

Damn. That's awesome. Good to know it's possible. I'm anxious to see if everything works fine once you put it back together.

That's a lot of work for a $400 used transmission.

EDIT: This aged well. Now used trans are $700+ lol

[BeachMedic]

Yeah, I got a lot of people ragging on me for not wearing gloves. Especially since I can just get them free from work....

- - - Updated - - -

Damn. That's awesome. Good to know it's possible. I'm anxious to see if everything works fine once you put it back together.

That's a lot of work for a $400 used transmission.

Yup, everything works great!
At a certain point, I just decided to see if I was capable of fixing it and I hoped to learn a bunch in the process. I did!
It also made the wife happy I didn't have to spend another $400.