So, here you are, looking for answers for your questions! I was on the same lane one year ago, trying to figure out how to crack open this BMW ZF GS6-53DZ gearbox. The real problem is that there is literally no proper tutorial out there in internet, how to do it properly. No worries, I will try to do a proper writeup based on over year collected information, my experience & some extra info by ZF factory itself!  

So, whatever is the reason, replacement of bearings or welding the bellhousing like I did, you must open it up to do it properly. It would be also nice to change the bearings while you are at it. Let’s begin!

Probably there is some extra tools what you will need while on it… this is the basic list what came in my head first:

1. Torx 30, 45 & 50
2. Ratchet
3. Extension for ratchet
4. Torque wrench (20 Nm)
5. Straight nose lock ring pliers for inner & outer rings
6. …..
7. Socket (sadly can’t remember was it 17 or 18)
8. Heat gun
9. Grinder
10. Infrared thermometer would be useful to monitor bearing temperature
11. Shaft seal remover
12. Flat end screwdriver
13. Tools to build a puller for housing or it is also possible to remove housing via preheating the bearings! It is a best option if you can heat bearing up to 110 Celsius, in this case housing will come off with slight tapping on input shaft)

List of spares:

1. Sealing cap with original ZF spare number 0501 317 873* as shown on Diagram No.1 with number 01.130 (price aprox 8 euros)
2. Shaft seal with original ZF spare number 0750 111 403* as shown on Diagram No.1 with number 01.030 (price aprox 10 euros)
3. Ang. Cont. Bearing with original spare number 0735 340 180* as shown on Diagram No.1 with number 01.100 (price aprox 60 euros)
4. Ball bearing with NTN code 6308X35CS26 (you can find this roller bearing from any decent bearing dealership for 25 euros aprox. On diagram marked as 01.070.)
5. Some liquid gasket (Victor Reinz is one of the best out there with price tag aprox 10 euros)
6. Oil BMW MTF-LT-2 1.6 liters.

NOTE!

Spare parts with * after number would be best & cheapest to order directly from ZF factory! Just contact with local ZF dealership & they will hook u up! Ball bearing can be found at any decent local bearing shop! You don’t have to stick with SKF ball bearing but, in my opinion, it is best to go for premium if you have higher torque engine build in your hand!

So, let’s begin with disassembly! First thing first I assume that oil is still inside the gearbox so begin with removing plug 01.230 & drain it in clear oil pan or something similar (it is always good to check old oil for metal ships etc. to get some idea from gearbox condition).  Remove bolts 01.050 with guide tube 01.040. Seals 01.030 & 01.130 will be changed anyway (I just don’t see any option to take them out without destroying them) so take a flat end screwdriver and hit it inside seal to make some prying hole for shaft seal puller, you can also drill the hole but be careful not to damage bearing seals!

        After successfully removing both seals, you will need to remove bolt hidden below seal 01.130 with retaining ring 01.120. Same goes with input shaft expect there won’t be any bolt and only retaining ring.

                Now, when bellhousing end is cleared there are some extra bolt’s & bits on side what need to be removed next:

It’s a easy task to remove 06.060 and 06.480 (below 480 there will be spring with detent pin also hidden), just screw them out & that’s it. To deal with 06.830 &              06.780 I will strongly recommend to clean those surfaces with brake cleaner or something similar before. After that remove retaining rings on both. If there is no dirt on the way there’s a possibility that sealing caps will just pop out thanks to spring force. If not then take 2 small screwdrivers and try to pry them out gently.  Springs with pins should come out easily afterwards.

                And now the final bolts before fun begins. On Diagram No.1 they are indicated as 01.220. Those are aluminum bolt’s so be 100 precent sure that torx bit will fit nice & snug in this socket, cleaning wont do any harm! After 15 bolts has been removed we are finally ready to split the casing!

                So, like mentioned previously there are two ways to split this casing. If you are planning to build a puller keep in mind that it have to be quite bulky to keep up with forces. Both input & aux shaft are fixed to shaft via tolerance fitting so in normal condition there is no way you can just pull it off from shaft. Same thing goes with clearance between housing and bearing. Because there is two shafts you have to use 2 pushing points on puller to equalize the forces as indicated on diagram No.3!

There are some topic’s out there where guys just pull it off brutally via input shaft but I strongly advice you not to do it to avoid any possible damage to the housing, bearings & and list goes on.  That’s the puller what I used, beams where bolted to the housing and 2 bolts in center where use to push on shafts:

Always protect the shaft ends by adding washer or something similar under the bolt tip!

There is also possibility to split it gently but it requires a lot more patience . Idea is to heat up bearing inner ring so it will expand enough to clear clamping force on shaft, revers via how those things are installed. In this case it would be perfect to have 2 heat guns on your hand to heat those bearings simultaneously & laser thermometer to keep eye on temperatures. If you are planning to install new bearing anyway you can go over 120 °C with no problem- in this case grease just starts to melt out and seal can be damaged, nothing else. If you still want to use those bearings later just don’t go over 120 °C and try to direct airflow straight on both bearing inner rings regularly measuring it’s temperature. After achieving 120 °C on both rings try to fix bellhousing somewhere (I was just holding it between my legs on ground) and hit the shaft end with hammer holding some wooden block at tip of shaft end to protect it from hits. If everything done properly housing should come off relatively easily.

Both bearings should stay inside bellhousing after separation so if you are planning to change those like I did remove the bolts 01.090 with fixing plate 01.080 and tap them out as shown on Diagram No.4.  There will be small issue with bearing 01.100- Because it is angular contact ball bearing then inner ring is made from 2 parts. One part will be left behind (as seen on picture No.5) on aux shaft and will require some heating or grinder to get it off. Grinder is a good quick way to do it but everything has to be covered up to avoid metal dust accumulation inside the gearbox and it requires precision not to damage shaft it self. You don’t have to grind it all way trough- you will only need one groove, hammer and chisel to hit a crack inside this ring. After that it can be removed easily. Other option includes heating again and should work fine in theory but I haven’t put it in practice.

So, now you are here thinking how to put it back together. Let’s assume that you are planning to replace bearings in process. There is a specific order how to make it happen.

As shown in diagram No.5 install bearing 01.070 by tapping it in to the casing. Secure it on place using locking plate with bolts. 

Take Bearing 01.100 one inner ring, heat it up to 120 °C, put some oil on aux shaft end and slip the ring on shaft like shown on picture No.5.

Tap the bearing 01.100 into casing. Bearing in place remove other inner ring from bearing- it will be installed after gearbox casings are back together.

One tip before you install the bellhousing- check & clean magnet next to drain plug before you install it.

Now the fun part will begin!

                Putting casings back together is not an easy task- took me several attempts until I got it right. Gear shifting shaft must be in correct place so that bearings inside casing would accept shaft ends & shifter itself would work properly later. It would be very nice if you can heat up whole casing with bearings installed in place up to 120 °C. (wait until you wife goes to work & use electric oven in kitchen but make sure casing is clean from oil & dirt, otherwise you won’t survive when she comes back home :D! NB! This is not good advice, but it would work!)

                Don’t forget to clean casing ends from old sealant & apply new sealant before installing it back on place! With heating or without the principle is same: make sure that fork ends would fit right into the rollers as shown in Diagram No.6. Also, it is important to align up locking bracket 06.170 with pin on fork 06.050 & make sure lever on fork 06.300 would fit into the gap on fork 06.050 as indicated on Diagram No.6.

If you didn’t heated the casing would have to press it back together. Casings back together install bolts aluminum bolts 01.220 as shown on Diagram No.1. Make sure that threads are clean and in good order, it is very easy to damage those bolts! Max toque spec for those bolts is 20 Nm!  Some may say that bolts have to be changed after removal but there is no requirement from factory itself!

                Casing back on install bearing 01.100 inner ring on place via bolt & everything else can be installed back together in reverse order as described at beginning.  Make sure all gears engage with ease, fill the gearbox with new oil and you are good to go!     NB! Drain and fill plug toque specs for M12x1,5 plug is 25 Nm and M18x1.5 35 Nm.

Special thanks for readers and don’t forget to leave comments down below! I’m also grateful if point out any mistake in this tutorial! Pictures are taken from ZF spare parts catalogue. Please contact me via kasutamucustoms@gmail.com if you want me to share it with you!