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Discussion Starter #1 (Edited)
For the better part of the week, while I was replacing the clutch and installing a Dinan 3.45 Differential, I took on the project to address leaks between the transmission casings, replace transmission seals, and change the oil.


I got a few DM over Facebook from the E39 M5 owners group with the same issue interested in how to remove the rear casing. As some may have looked into this there are a few out there who’ve done it, but do not provide pictures to assist with steps on how to, deterring one away from doing it; especially since it is not recommended to do so.


So since I also found my self struggling to understand the little information out there- with no experience on transmission work, I decided to share and provide the steps with pictures that I gathered on how to disassemble and re-assemble the transmission.


This is steps on ONLY removing the cases. Anything beyond that you will need special tools. I used basic tools you would need to take off housing bolts and sensors, aside from that, make sure you have a telescopic magnetic pick up tool, flashlight, basic tools on hand, as well as second set of hands to hold the middle casing for re-assembly of rear casing.


I found it easiest to remove the rear casing by removing the front bell casing first. The front bell casing comes out easily. You may hear the 2 shifter pins and 4 rollers come off, if you don’t, remove them with your telescopic magnet- you’ll notice that there magnetic as well, they’re located in the very front of the shifter rod on page 5 with the blue square.


Then on to removing the rear casing; here’s the part that can get tricky, but if you follow thoroughly you should not have any problem as I disassembled and reassembled mine 3 times in between losing a roller washer I was waiting on (thanks to @technician117) and washing the transmission. Make sure to be very careful in placement of these parts as some are not attainable.


  1. Remove cover on page 1 with green circle.
  2. Remove springs and sleeves located on page 2 with black squares, use telescopic magnet to assist you and if need be use a small flat head and pry out carefully.
  3. Remove pins with telescopic magnet on page 3 with yellow squares and then stick telescopic magnet into the yellow slots and fish out the ball bearings.
  4. Remove yellow circle sensor, red circle bolt with spring and ball bearing following it, then blue circle sensor with “locking pin” behind it on page 4.
  5. Remove black circle assembly on page 5 with the right size Allen key and slide the assembly out. Make sure not to lose the roller/washer as that is what I lost and set me back a few days.....
  6. Remove the long rod with the red arrow on page 5 out and towards the direction of the yellow arrow.
  7. Revert back to page 4 with the red circle bolt and with the rod out of the way stick telescopic magnet tool and pull out the long pin with green arrow on page 6 to the direction to the blue arrow also on page 6. You may need to tap the rear casing with a rubber mallet to slide the pin close enough to catch the telescopic magnet but DO NOT smack it or you will knock the pins on page 7 with white arrows out of the rods.
  8. Revert back to page 3 and in the slots for the yellow squares shine flash light in slots and ensure the pins did not slide out of the rods. If it did a little bit use a small flat head screw driver and on the left square slide the pin to the left until you can not see it and do the same for the right square.
  9. Now the rear casing is ready to be removed. Use a flat head and pry if need be but at this point the casing should slide right off. Use a rubber mallet or small 2x4 block to hold the gearbox level and off the gear at the end of the bottom drive shaft shown on page 7.
  10. Remove 2 pins with white arrows on page 7 with telescopic magnet.
  11. Replace necessary seals and prepare for re-assembly.
  12. Clean the back side of the middle casing and front side of the rear casing where a Grey 100% RTV silicone will be applied, use rubbing alcohol or brake cleaner. If the outer casing was marred or nicked in the process of removal use WD-40, fine grit sand paper, and smoothen the surface then apply silicone. Give 5 minutes to let silicone dry and on this step be prepared to reassemble. In the meantime reinstall the 2 small pins on page 7 with the white arrows using grease or PTFE lubricant to hold pins into place. Make sure that all 3 long rods on page 7 with yellow square maintain the same height, adjust rods if need be. Put the “transmission circle magnet” in its slot that it goes right next to the bottom drain plug.
  13. Install rear shaft bearing with red arrow on page 7 into the rear casing. Remove your mallet or block that’s holding your gearbox level and have your second set of hands holding the middle casing with gearbox slightly declined towards the back of the rear casing to ensure the bearing does not fall out of place because that will stop you from re-assembling the rear case, then align rear casing to rods and slide in. If it stops or gets stuck right before they mate and the bearing did not fall, spin the front shaft to engage with the small gear connected to the rear casing. If still no prevail, slide case off and verify the 2 small pins are still in place. If followed precisely, should work the first time. Finally screw in housing bolts.
  14. Install ball bearings and pins on page 3.
  15. Install sleeve and springs on page 2 and then bolt on the circle green cover on page 1.
  16. Slide through the long pin located page 6 through the hole where the bolt goes with the red circle on page 4. Use small flathead to push rod all the way through and ensure by shining a flashlight.
  17. Slide long rod with red arrow on page 5. Rod will only go one way.
  18. Install black circle assembly on page 5.
  19. Install yellow circle, blue circle with your “locking pin”, and red circle with ball bearing on page 4. Rear casing is finally assembled.
  20. Prep your front housing for silicone to be applied then apply silicone. In the meantime on waiting for the silicone to cure some install 2 pins and magnetic washers that go on to the front of the shifter rod located on page 5 with the blue square.
  21. Align front bell casing to shifter rod and slide in. Screw in bolts and torque all bolts to specs. Be real careful in the process of doing this because casings are aluminum and are notorious to crack.
  22. Add your desired up to spec brand oil. You will more than likely use 2 quarts of transmission fluid as you will allow the tranny to completely drain.
  23. Install transmission!
With all this in mind, the transmission needs to be drained, laying flat; from its bottom side, rather than standing up from the front bell casing (like the YouTube video out there and some of my pictures before I figured out the hard way), all the housing bolts removed, knock out dowels half way punched out, rear flange and front guide bushing off, and in neutral.


I would also like to add that it’s a great time to replace the transmission mounts. I was in denial that mine needed to be replaced by a visual inspection until my dad surprised me with a new set and when comparing, I was appalled to see a night and day difference!


Enjoy a leak free gearbox.
 

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Hey, this is fantastic and so glad someone finally documented how to take the rear casing off as I have a good trans (though has a crack in the rear casing from shipping) and a new rear casing to install and I've been dreading trying to replace it since I didn't have any step-by-step instructions.

One suggestion, you might want to consider doing this in a PDF or something that can be updated and reuploaded to the same link, that way if there are changes that need to be made past the first 24 hours, you'll be able to make them. Also, it would be immensely more helpful if the pictures were in-line with the text, so we don't have to constantly skip back and forth between the description and the picture that applies. Just a thought.
 

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Thank you for the feed back and suggestion. I understand that it would be extremely more helpful if all the pictures were in line with the text, which I tried my hardest to do so. However, I did not take many pictures and it’s why I mention that I used pictures from another member to put the how-to together. I figured gathering pictures together was better than having none.

Hey, this is fantastic and so glad someone finally documented how to take the rear casing off as I have a good trans (though has a crack in the rear casing from shipping) and a new rear casing to install and I've been dreading trying to replace it since I didn't have any step-by-step instructions.

One suggestion, you might want to consider doing this in a PDF or something that can be updated and reuploaded to the same link, that way if there are changes that need to be made past the first 24 hours, you'll be able to make them. Also, it would be immensely more helpful if the pictures were in-line with the text, so we don't have to constantly skip back and forth between the description and the picture that applies. Just a thought.
 

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Thank you for the feed back and suggestion. I understand that it would be extremely more helpful if all the pictures were in line with the text, which I tried my hardest to do so. However, I did not take many pictures and it’s why I mention that I used pictures from another member to put the how-to together. I figured gathering pictures together was better than having none.
Yeah, pictures are the necessary part of the DIY and what we haven't had with descriptions until now. M5board doesn't let you do attachments in-line, but if you use a site like Flickr to host the pics, you can link the pictures in-line and it works much better.

Again, after 24 hours, you won't be able to edit the post anymore.

Sent from my SM-G965U using Tapatalk
 

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Duly-noted. Thanks for the heads up, I wasn’t aware of that. Will look into it this weekend.
Sometimes you can get a moderator to either open it back up for changes, or at least you can provide the changes and they can make them for you. I believe the moderator in here is ARD, so you might want to message him for more info.

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Yeah, pictures are the necessary part of the DIY and what we haven't had with descriptions until now. M5board doesn't let you do attachments in-line, but if you use a site like Flickr to host the pics, you can link the pictures in-line and it works much better.

Again, after 24 hours, you won't be able to edit the post anymore.

Sent from my SM-G965U using Tapatalk
Paul, it does allow it. It’s how I do all my posts with multiple pics. Basically, just upload your pics in order, then click on the paperclip-

D9AC24E2-BC81-436C-9DF7-639F78E1F792.jpeg


Then the list of your pics drops down (in order)and you choose the appropriate pic, then continue writing, then choose the next pic, etc.

CBCDC8B1-A1DE-4F6E-B87F-69D9E2BE43ED.png


It’s probably more complicated then using Flickr, but just wanted to say it is possible and it’s the only way to ensure your pics will stay here as long as the forum is up.
 

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Paul, it does allow it. It’s how I do all my posts with multiple pics. Basically, just upload your pics in order, then click on the paperclip-

View attachment 868874


Then the list of your pics drops down (in order)and you choose the appropriate pic, then continue writing, then choose the next pic, etc.

View attachment 868882


It’s probably more complicated then using Flickr, but just wanted to say it is possible and it’s the only way to ensure your pics will stay here as long as the forum is up.
Good to know! I always use Flickr so I haven't messed with that much.

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I know that this post is from a long time ago so I’m praying that someone here can help me out. I’m having some frustrating issues as I do not know what I’m doing improperly trying to follow along to these instructions, This is my first time tinkering with a transmission and I’m looking to do a manual conversion. In the heat of my excitement I misunderstood that I didn’t have to take the rear case off to properly remove the front bellhousing, In doing so I made a major error and broke the bolt head off of the threads for the reverse sensor. I now need to get it tap and died out but I am still struggling to remove the rear case. Some of the pins in page 7 have seem to come out and I cannot get them back in, along with that I can’t seem to find the pin in page 6. If anyone could help it would be extremely appreciated as I’m extremely frustrated and stressed out. I have linked images so someone can hopefully tell me what to do, also one of the bolts on page 3 seems to have bondo on it, any ideas?. Thank you.
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