Transmission rebuild

[skubasteve]

As far as tools go, you do need a wide assortment of standard tools including:
- Oxygen sensor socket (you might be able to get away with a 22mm wrench for this)
- E12 and E10 sockets for the bellhousing bolts, preferably standard depth. I bought the Harbor Freight sockets which are deep well; this complicates the job due to tight clearances on some of the upper bolts
- 3' or more of 3/8" or 1/2" drive extensions for the E12 and E10 sockets (I used about 3'; others have said they used 4'-5')
- Transmission jack
- An E12 wrench for removing the transfer case bolts. Some of these have tight clearance and the 3/8" drive E12 socket used for the bellhousing bolts won’t fit. You can also try and cheat with a 1/4"-drive 3/8" socket, which worked for me on one particularly cramped bolt but of course there is risk of stripping. I finally bought a combination E12/E10 wrench in order to do it right (Amazon Prime is your friend when doing a job like this).
- Torx and Allen sockets in various sizes for disassembly of the transmission itself. I ended up needing quite a few 3/8" drive torx and allen sockets; I bought Husky items from Home Depot for this. $2 apiece. Same items are $6 each at Lowe's. Don't use cheap tools on the torx and Allen heads or you will end up spending time with your Dremel and drill trying to remove bolts with stripped heads. At least that’s what I’ve heard.
- 1/2"-drive breaker bar comes in handy, but maybe not required if you are really strong or have a pipe for your ratchet
- Large snap ring pliers. I broke my Channellock 927 tips trying to remove the snap ring on the output shaft carrier; this snap ring needs a bigger tool. I bought the Lisle 49200 heavy duty pliers but they were defective; a replacement is in the mail from Amazon. I think these will work based on my almost-successful removal attempts with the defective pliers.

I’m only part of the way through the job so the above list might grow.

As far as special tools, I think these fall into two categories: Press fixtures for removing the clutch pack springs, and measuring devices to check thicknesses and clearances.

Getting the clutch packs apart without the BMW tools (or fabbed tools of similar design) is tricky but doable. There are several threads covering different approaches. I tried to locate a 1/16” strip of aluminum per one of the threads I read; that person wrapped the aluminum into the needed diameter and used a clamp to provide the needed force (if I find that thread I’ll post it). Another person used PVC piping pieces. I’ve successfully removed 3 of the clutch springs (C, E, and F) with a “3 in. PVC DWV MIP Adapter” from Home Depot (NIBCO 3 in. PVC DWV MIP Adapter-C4804HD3 - The Home Depot). I think I can use it for the A clutch as well. The B clutch spring is much bigger and I will have to figure that out. I removed the D clutch spring when doing initial disassembly; I just pried the snap ring out. This is a dangerous way to do it; I thought it needed to be removed to get the trans apart. I will have to figure out what is needed to reinstall it. For the 3 I’ve removed with the PVC peice, I’m using a large c-clamp and some pieces of wood. It’s pretty redneck.

Measurement tools have been covered elsewhere; I think I am going to forego most of the thickness measurements which require preloading the clutch packs. It sounds like the end play measurement is key, so I will be investing in a dial indicator gauge and magnetic base.

[skubasteve]

Phil,

In another thread you recommend removing the bearing cages from the races in order to inspect for pitting on the races. Can you give me any tips on how to do that? I'm afraid to go prying at it with a screwdriver.

[RRPhil]

Yes, you can never be sure what’s lurking underneath so I always check each one. I separate them using a hard plastic implement, prying as close to the centre as possible where the metal is peened over to retain the cage. If you look carefully at the design of the needle cages you’ll see that they only fit one way up.



Phil

[skubasteve]

How do I go about removing the output shaft extension? I've removed the snap ring but it feels like the shaft is pressed into the bearing. Do I need to remove it to replace the rear seal?

[RRPhil]

Yes, you need to press out the adapter shaft so that you can prise out the old seal and replace it.



Phil

[skubasteve]

Thanks as always Phil.

How important is it to use petroleum jelly/assembly lube on the various soft parts (and bearings) during assembly?

[RRPhil]

They’re useful to hold parts (bearing washers, etc.) in place during assembly but otherwise I generally just use transmission fluid if the transmission will be run soon after the rebuild i.e. it’s not going to sit on a shelf for months.

Phil

[skubasteve]

Question on reassembly process:

I have my D/E assembly back in the transmission, and I’ve installed the large snap ring that has a bevel on each side. The snap ring is engaging the groves to about half of the groove depth. The manual describes using a tool and hammering the snap ring towards the case in order to get it seated. I am concerned about doing this because this would force the D/E assembly further into the housing, and I can’t be 100% positive the D/E assembly is fully engaged with the planetary gearset. I put the gearset in first then put the D/E assembly in (the manual says to put the gearset and the D/E assembly together first before installing both into the housing, which would allow verification of engagement before installation). The holes in the housing look like they are lined up nicely with the holes in the D/E housing.

Has anyone been in this spot? Is it okay to bang away at the snap ring?

[Clockwork]

interesting ZF guide on doing the tranny filter
https://s3.amazonaws.com/fcp-promoti...6198-204779609

[skubasteve]

I tapped on the snap ring some to no avail. I asked about this because the control dimension on the A/B assembly was measuring about 2mm greater than the required 20mm, so I was afraid the D/E assembly wasn't seated.

I was able to seat the A/B assembly properly by tapping on the input shaft with a rubber mallet. If you do this make sure all of the clutches are engaged; I was measuring 22mm on the control dimension instead of the prescribed 20mm. Some light taps on the shaft and it bottomed out at 20.

Lots of detail there on the fluid change. Thanks for posting.