Disassembly and Assembly

Complete removal and installation of input and output shafts (S5D 20OG/250G)

Transmission removed.





Unscrew drain plug.
Drain off fluid.
Secure special tool 23 0 100 on the bore of the drain plug.
Fit transmission to assembly frame 00 1 490 with special tool 23 0 100.
Removing clutch release mechanism and release lever, refer to Clutch M/T.





When fitted: Lift out lockplate (1).





Block output flange using special tool 23 0 020.
Unfasten collar nut with special tool 23 1 210.





Pull off output flange.

Note: If ease-of-movement is impaired, remove output flange with special tool 33 1 150.





Remove radial seal with special tool 00 5 010.





Remove cap (1).





Remove compression springs (1) and cylinder pins (2).





Remove locking stops and ball stops (3) (5 off) with help of a magnet (4).





Note: Note locking pin (1) in the central selector rod'.





Locking pin (1) on middle selector rod (2) must locate in center of selector rod.

Note: To secure the position of the locking pin (1), the transmission must be shifted into 2nd gear.





Shift into 2nd gear:
Insert splint driver or screwdriver (1) in bore of selector shaft (2).
Twist selector shaft (2) up to 1st left detent and press into the transmission.





Unscrew bolts.





Remove sealing ring.





Unfasten screw (1) and reverse gear switch (2).
Lever out cap (3).





Remove spring (4) and arrester bolt (5).





Unscrew screws (1 and 2).





Drive dowel pin (1) out towards clutch case with a cotter pin extractor.





Drive out cotter pin (2) with a cotter pin extractor.





Unfasten screws on transmission case (9 off).





Remove transmission from assembly frame 00 1 490 and put down with the output side facing upwards.
Fit special tool 23 1 141 together with 23 1 142 and 23 1 143 and install on rear case section.
Pull off rear case section.





Remove middle selector rod until all 3 selector rods are at the same height.





Remove retaining plate (1) and magnetic disc (2).





Withdraw pin (3).
Remove pivot lever (4).
Remove gearshift rail (6).

Note: There are 4 rollers at the lower end of the selector shaft (5) and these can fall out when the selector shaft is removed.

Pull out shift shaft (5).





Position gears and shafts with front case section on special tool 23 2 400.





Unfasten screws and remove guide tube.





Note: Two covered removal holes (1) are located on front end of radial sealing ring.





Screw special tool 23 0 490 into one of the two removal holes.
Pull radial sealing ring out of transmission housing with impact weight.





Caution: To avoid damaging input shaft, special tool 23 2 460 must be inserted on the input shaft during removal of the circlip (3).

Lift out circlip (3) and pull off over special tool 23 2 460.





Remove closing ring (4).





Caution: To avoid damaging input shaft, special tool 23 2 460 must be inserted on the input shaft during removal of the circlip (6).

Lift off circlip (6) and secure to special tool 23 2 460.
Pull special tool 23 2 460 with circlip (6) from the input shaft.
Lift out shim (5).





Secure special tool 23 1 141 to front case section with 2 screws.
Pull front case section from gears and shafts.





Take off needle bearing (1).
Remove reverse gear (3) with reverse gear pins (2).





Remove complete gear train with selector rods (1) from special tool 23 2 400.





Assembling transmission: Install complete gear train with selector rods in the special tool 23 2 400.





Install reverse gear with collar (2) facing upwards and reverse, gear shaft with long extension (1) in special tool 23 2 400.
Coat locating face of short extension (3) on reverse gear with Loctite 574 seals compound.
Liquid seals, see BMW Parts Service.





Check end float of the input shaft.
Apply special tool 23 2 420 on the input shaft.
Insert shim (2) and new circlip (1) in the groove.
Check end float with a feeler gauge.
End float 0.04 mm.

Note: Shims (2) can be obtained from Parts Service in thicknesses (X) of 2.3 - 2.65 mm.





Heat input shaft inner bearing race (1) in the front case section to approx. 110 - 120°C (hot air blower).
The heating temperature must be precisely maintained. Check with a suitable thermometer.
Align selector rods with one another.
After heating, insert the roller bearing (2) with thick grease into the bearing sleeve with large diameter facing upwards.





Carefully attach the front case section.

Note: The 5th gear synchronizer ring can jam.

After completely assembling the transmission, the 5th gear synchronizer ring can be loosened again by twisting the output/input shafts against each other.





Install spacer (5).

Caution: To avoid damaging input shaft, special tool 23 2 460 must be inserted on the input shaft while installing the circlip (6).

Slide new circlip (6) over the special tool 23 2 460 and install in the lower groove.





Install closing ring (4).

Caution: To avoid damaging input shaft, special tool 23 2 460 must be inserted on the input shaft while installing the circlip (3).

Slide new circlip (3) over the special tool 23 2 460 and install in the upper groove.





Coat the radial seal sealing lip with ATF-oil. Push radial seal (1) over special tool 23 2 460 up to case.
Remove special tool 23 2 460.





Drive in radial seal (1) with special tool 23 2 430.
Use plastic hammer to drive in.





Install guide tube.
Install screws with Loctite 243 screw locking compound.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.





Secure reverse gear shaft in front case section.
Install screw (1) with Loctite 243 screw locking compound and tighten.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.
Loosen screw (2) from special tool 23 2 400.





Remove front case section and gear train from special tool 23 2 400 and place to one side with output end uppermost.





Attach 4 rollers to the selector shaft with Vaseline.





Insert selector shaft (1) into front case section.
Insert gearshift rail (2) with the opening upward into the case





Install pivot lever with wider head (1) facing the selector rod (2).
Polished side must face towards case.
Attach pivot lever with the pin (3).





Install locking pin (1) in the selector rod (2) with Vaseline and secure in the centre.





Clean case sealing surfaces and coat with Loctite 574 seals compound.
Place retaining plate (1) with flat side uppermost on 2nd gear on countershaft. Screw special tool 23 2 440 into the retaining plate (1)
Install magnetic disc (2) in the case. Align selector rods with one another. Coat locating face of reverse gear shaft (3) with Loctite 574 seals compound.





Lift radial seal on selector shaft out of rear case.
Heat inner bearing race (1) and rear case section in area around bearing to 110 - 120°C (hot air blower).
The heating temperature must be precisely maintained.
Check with a thermometer.





Insert rear case section up to limit stop. Install 3 screws with new sealing rings. Remove special tool 23 2 440.
Screw in fourth screw with new sealing ring.
Tighten down all screws.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.





Lightly secure front and rear case sections with opposite two screws.
Place rear case section on support 23 0 100 and again lift with the assembly hoist 00 1 490.





Drive in cotter pin (1).





Drive in cotter pin (2).





Screw in all case screws and tighten down.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.





Loosen bolt (1).
Install screw (2) with Loctite 243 locking varnish.
Tighten the screws (1 and 2).
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.





Install radial seal for selector shaft and output shaft.
Coat sealing lip with ATF-oil.
Push in output shaft radial seal with special tool 24 0 110 and selector shaft radial seal with special tool 23 1 240.

Note: Use a plastic hammer to drive in seal.





Heat output flange to approx. 80°C (hot air blower) and fit to output shaft.
Coat thread and locating face of collar nut (1) with Loctite 24: locking varnish.
Block output flange using special tool 23 0 020.
Tighten collar nut (1) with special tool 23 1 210.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.





Install arrester and locking balls.
Order: Locking ball (1), arrester ball (2) and locking pin (3).





Install springs (1) and cylinder pins (2).





Attach cap (1).
Install screws with Loctite 243 screw locking varnish and secure.





Install arrester bolt (1) and spring (2).

Note: Roller (3) must be positioned horizontally.





Install shear-off screw (1) with Loctite 243 locking varnish and tighten down.
Install the reverse gear switch.
Tightening torque, refer to Manual Transmission/Transaxle, Specifications.
Knock in plug (3).
Installing clutch release mechanism and release lever, refer to Clutch M/T.