Mercedes W124 5 Speed Swap Guide

Mercedes Benz 300E/300CE/300TD 4 Speed Automatic to 5 Speed Manual Swap

List of Parts Needed:

103 030 1205 - Single Mass Flywheel

011 250 0903 - Clutch Disc 8.5"

004 250 3104 - Pressure Plate for 8.5" Clutch Disc

912004-008102 - Pressure Plate Screw washers - NOTE: You need six (6) of these

000912-008012 - Pressure plate screws - NOTE: You need six (6) of these

001 250 2415 - Throwout Bearing

115 980 0115 - Pilot Bearing

201 260 23 33 - Shift Linkage 5th/Reverse

201 260 22 33 - Shift Linkage 3rd/4th

201 260 21 33 - Shift Linkage 1st/2nd

000 994 29 60 - Shift Linkage end clips - NOTE: You need six (6) of these

201 540 1568 - Speedometer Cable 1490mm - Note: Some models already have this length of cable.                                        Remove from auto trans and install on 5 speed. They are interchangeable

001 295 6806 - Clutch Master Cylinder

201 290 0311 - Clutch slave cylinder

129 410 0601 - Front Driveshaft for COUPE

124 242 0501 - Transmission mount for 5 speed manual - NOTE: auto and manual use different mounts!

304017-010036 - Bellhousing Bolts - NOTE: You MAY reuse removed bellhousing bolts

304017-010035 - Bellhousing Bolts for starter - NOTE: You need two (2) of these. You MAY reuse bolts.

124 267 0097 - Shifter boot

B6 6 26 8109 - Gearshift Knob with leather boot

124 295 0513 - Clutch Line

203 997 3182 - Hose From Reservoir to Master Cylinder 270mm

124 683 0306 - Shifter Frame for Shift boot to center console wood (5 speed version)

XXX XXX XXXX - Shifter - NOTE: Will need corresponding shifter for particular transmission. They have                                    different shift patterns that the shifter assemblies are designed for

XXX XXX XXXX - Brake Fluid Reservoir - NOTE: The brake fluid reservoirs ON ALL W124 and W201 cars have a nipple on the side of the reservoir. Simply cut off the edge of that nipple and attach your hose to the master cylinder to this nipple.

XXX XXX XXXX - Brake/Clutch Pedal Assembly - NOTE: All W201 and W124 use the same pedals.

NOTE: There are some miscellaneous small parts that are not on the list. This is due to myself not wanting to take the time to find them and write them down. These omitted parts are small clips and attachments that are already used on the attachment parts to the automatic transmission.

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Now that you have your parts, it's time to dig in

1) Remove exhaust system - from the Cat Converter back should be enough, but for mobility purposes, remove entire exhaust. 4 bolts at the exhaust manifolds, a few at the transmission, and 4 more exhaust hangers and you can drop the exhaust as one piece. Have a jack up front and have a helper "bench press" the rear of the exhaust while you remove exhaust hangers.

2) Remove the driveshaft - Note: The automatic transmission is around 25"-26" in length, while the manual is around 18"-19" in length. The difference is made up in the driveshaft. Notably, the front half. Because I had a front driveshaft off of a 84 190E, the spline was a smaller diameter than the one used on my 300CE, so the two drive shafts would not mate up.  I had the front half of my driveshaft cut and the front tip of the 190E drive shaft welded onto the front portion of my 300CE driveshaft. The shafts are the same diameter at their thickest point, but have different size yokes at where they meet at the transmission. The 190E yoke was retained and used with the transmission. I also had a tube machined and put inside of my new front driveshaft for extra strength. Driveshaft is neutral balanced.

3) Remove the automatic transmission. To get to the top two bolts, jack up the front edge of the oil pan slightly, with a 2x4 on the jack to prevent damage to make accessing the top two bolts easier. You will need a bunch of 3/8 extensions with a swivel  17mm socket. Make sure you have unbolted the torque converter from the flex plate and make sure you have unscrewed the speedo cable from the back of your cluster! Follow all cables from the transmission and unplug/remove them all.  Once all 17mm bolts are removed, find a 2x6 and place it on the jack and have a helper work the jack while you wiggle the transmission towards the rear of the car. Having a pry bar will make life easier.

4) Once transmission is removed, remove all unnecessary auto transmission cooler lines and all other parts associated with the auto transmission. 

5) Remove flex plate. While I was in there, I removed and replaced the rear main seal. Mine was slightly leaky, I don't know why as it was replaced by a shop a few years ago. I suppose instead of tapping it in gently, they whacked the thing in just to get it over with. I highly suggest doing your rear main. You're in there already, why skimp out on the extra $10 or so for the seal?

6) Install flywheel. Torque flywheel bolts to 30Nm followed by a 90 degree turn. The bolts used for the flywheel are stretch bolts. I do not know specs for reuse, so renew them! Better to be safe than to be sorry, these bolts are not expensive, don't skimp out and cause yourself problems.

7) Install your clutch

8) Install pressure plate and torque pressure plate bolts to 18 ft lb.

9) Fill your trans with fluid if you haven't done so already. Auto trans fluid is OKAY to use.

10) Install transmission - make sure you have a helper or a jack to lift the front edge of the oil pan to install the manual transmission. Either jack the transmission into place or put the trans on your stomach and "bench press" the transmission into place. Benching the transmission into place is far more accurate and much more effective. Have a helper if you need it.

11) Remove auto shifter and replace with manual shifter. Just for giggles, I replaced the factory rubber shift bushings with solid brass bushings. The result is a more solid shift. The auto shifter will be a PITA to get out, but if you pry away the covers, you will reveal all 4 10mm bolts. Those wires on the side of the shifter are now useless. They prevent the shifter from being shifting while the car is off or the brake pedal  pressed, simply move them off to the side. There is a difference between the shifter console wood pieces as the stick shift cars had a larger area cut out for the shift boot to be held in place. The automatic piece is fine, you'll just tuck the shift boot underneath and find a way to secure it to make it look good. I found gray leather and had a shift boot sewn together, than I upholstery glued it to the underside of the shift console wood. Looked good, looked factory and held together great.  

12) Line up the shifter arms by putting a small, but thick enough allen wrench into a slot already in the shifter assembly arms. This lines up the arms so the shifter can be moved side to side. Make sure the manual trans has all 3 of its arms in the upright position (neutral) and adjust the shifter rods to fit. This will ensure the shifter up top will be shifting solidly and smoothly. Because Mercedes decided to have aluminum shift rod ends that are incredibly fragile and mate them to steel rods (what were they thinking), I decided to make a beefier set that will outlast these destined to fail rod ends.

You can see the crappy MB design next to my beefy design.

Shift linkage ends are the exact same dimensions width wise and height wise, just with a little more effort put into the design.

Shifter Linkage Ends

14) Bleed your clutch/brakes. You will need a small diameter hose to attach to your right front brake caliper. Make
sure this hose is long enough to reach the right side of the transmission where the slave cylinder is. Just pump the brake and fill the reservoir. To bleed the clutch, you have to reverse bleed the system.

15) Put everything else back on and go for a drive. Hopefully you'll be good to go.

Now, if you wanted to put a 5 speed behind your HFM M104, there's going to be a little playing around to do. The M104 uses a small TDC magnet on the outer flywheel segments. You can use a standard M103 single mass flywheel, drill a hole in one of the segments and install the magnet

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You can see the magnet on the top right timing segment.

The HFM M104's absolutely need this magnet in order to run. The CIS M103 and M104 do NOT need the magnet to run, they simply run using the segments themselves. 

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Thanks for taking the time to read this. I hope it helps you, because I sure had a hard time putting everything together and figuring out what worked and what didn't. I did this swap some time in 2009 and the car is still driving great (with a new owner though). If you need any help or have any questions, feel free to leave a comment below or shoot me an email allenkrolik@gmail.com 

Take care,

Allen

(bsmuwk on benzworld and peachparts)