DIY - E46 Flex Disc (Guibo)

[bimmer]

Credit to original author: http://www.bokchoys.com/differential/diy_guibo.htm

"These instructions are only as a guide for people to replace their flex disc (universal joint). Please read through all the instructions before attempting to install on your own. I take no responsibilities for any inaccuracies or problems/damage /injuries you may encounter from using these instructions. Please consult your shop manual.

When the Flex disc goes bad, you'll start to have vibrations in drive train. You can quickly check to see if your flex disc is bad by looking under the car. The flex disc is located between the transmission and the drive shaft. You'll see cracks in the rubber when the flex disc starts to go bad. In my case, chunks of rubber started flying off.
(Figure A).
Replacing the Flex disc involves dropping the exhaust and part of the drive shaft.


Parts Needed
1 Flex Disc (Figure B)
- Part # 26-11-1-227-410 manual transmission
- Part # 26-11-7-511-454 automatic transmission

6 Nuts M12x1 (part # 07-12-9-900-047 )

Tools Needed
10mm Socket
13mm Socket / wrench
15mm Socket
18mm Socket / wrench
Screw driver
Jack & Jack Stands / Lift


1. Raise the car and place on jack stands. Never work on a car that is only supported by a jack.

2. Remove exhaust. The exhaust needs to be removed to gain access to the drive shaft.

A. Remove (4) 15mm bolts that connect the exhaust to the headers. (use penetrating lubricant to help loosen bolts, they'll be really tight)

B. Remove (2) 13mm bolts from the front exhaust bracket.

C. Remove (8) 13mm bolts from both center reinforcement places. 1 reinforcement place is connected to the center to the exhaust with rubber mounts.

D. Support both ends of the exhaust before removing the final bolts holding the exhaust. Unscrew the 2 rubber hangers on the exhaust. (4) 13mm nuts. Exhaust will fall when you remove the hangers. Remove exhaust.

3. Remove drive shaft heat shield. There are (2) 10mm screws on the front and (2) 10mm screws on the back. (Figure C)


4. With the heat shield out of the way, you can inspect the drive shaft center mount bearing. Make sure it looks good before continuing. (Figure D) If it looks bad, you'll need to replace it. Drive Shaft Center mount bearing replacement is not covered in this DIY).


5. Remove the (6) 18mm bolts on the Flex Disc. (3 are for the drive shaft, 3 are for the transmission). Remember to release the parking brake so you can rotate the drive shaft. (Figure E)


6. Remove the center mount bearing to allow slack in the drive shaft to remove Flex Disc. Make note of the position of the center bearing mount. When reinstalling the drive shaft, you need it is aligned correctly. Support drive shaft with wire or stands. (Figure F) Remove (2) 13mm bolts from the center mount bearing bracket. (Figure G) (Tightening torque - 13mm bolts 15 ft-lbs) Pry old Flex Disc off with a screwdriver. (Figure H)


7. Install new Flex Disc. 3 arrows on flex disc MUST POINT TO FLANGE ARMS! (Figure I) Use new self-locking nuts when installing Flex Disc. (Tightening torque - 18mm M12 bolts 74 ft-lbs)


8. When reinstalling center mount / drive shaft, make sure center lines of the universal joints are lined up. (position of drive shaft center mount should be similar to what it was before you took it off)"

[sapote]

6. Remove the center mount bearing to allow slack in the drive shaft to remove Flex Disc. Make note of the position of the center bearing mount. When reinstalling the drive shaft, you need it is aligned correctly. Support drive shaft with wire or stands. (Figure F) Remove (2) 13mm bolts from the center mount bearing bracket. (Figure G) (Tightening torque - 13mm bolts 15 ft-lbs) Pry old Flex Disc off with a screwdriver. (Figure H)

This omits one important step: With the center support bearing off the studs, you have to push the driveshaft rearward to shorten it (the front half slides into the the rear half via the splines); if not there is no way the driveshaft could get off the tranny output flange's pilot pin even pulling down hard on the CSB. To make this easy, you can loosen the big nut just behind the CSB for the splines to move easier.