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2008 SLK55 manual swap complete

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5.4K views 27 replies 6 participants last post by  pklein  
#1 ·
Hi friends,

I'm happy to report the manual swap on my SLK55 is complete and the car runs!

I'll save myself a lot of typing by just saying the process was very similar to the one describe for this CLK320 swap. Since a manual version of the non-55s was offered by Mercedes, most of the parts for the swap are available, and the chassis has all the holes, mount points, etc., needed for the conversion. Josh at Mercedes Swap Shop did whatever needed to be done to the ECU. The only custom part I needed to make was bracket for the exhaust mount to the transmission. No, the transmission is not rated for the torque of the 55, but I'm not going to track this car or put tons of miles on it, so durability should be sufficient.

I was fortunate to get most of the donor parts from a 2005 SLK350 in a single go.
Gas Motor vehicle Machine Auto part Tool


The interior is a common site to those who already have a manual.
Gear shift Vehicle Motor vehicle Speedometer Steering part


Since the exhaust had to come off to remove the transmission, I took the opportunity to add a cat back system from QuickSilver. Combined with the transmission, the car is completely transformed. Here's a short audio clip.
 
M
#3 ·
HI,

I know this is an old thread but I was hoping to get an update.
It's been a couple years are you still happy with the car? Have there been any significant problems?
I would love to get any info as I'm considering the same thing on my 2008 :55 AMG

Thanks in advance
 
#4 ·
MShoemaker said:
HI,

I know this is an old thread but I was hoping to get an update.
It's been a couple years are you still happy with the car? Have there been any significant problems?
I would love to get any info as I'm considering the same thing on my 2008 :55 AMG

Thanks in advance
Click to expand...
Poster has not been back for 13 years.
 
#5 ·
It’s been not quite two years and I’ve got about 3-4k miles on the swap. No problems at all. It’s one of my daily drivers as well as a weekend car. The guy who goes by Anderzén on YouTube/Insta has many more years and tens of thousands of miles on his swaps, and the transmission holds up. The swap is mainly OEM parts (aside from a custom drive shaft in my case), and feels like it.

I much prefer shifting my own gears so absolutely no regrets. I’m in Northern CA. If you’re ever in the area, you’re welcome to check it out.
 
M
#10 ·
Ok, so I'll add the new driveshaft to the list.
What about the clutch, have you noticed any slipping? If there is an upgraded aftermarket clutch out there would it help or put more stress on the actual transmission?

What years SLK 350 should I be looking for? Will any with the W112 work?
Are there things you would have done differently doing it again?

Also, thanks for letting me pick your brain, I really appreciate it!
 
#11 · (Edited)
I've never noticed any clutch slip. I do tend to be pretty easy on clutches though, avoiding putting a ton of power through a partially engaged clutch, but once it's engaged, it doesn't slip. I went with this moderately upgraded part from Sachs. It claims 15% more hold, but that's a minor bump compared to the torque difference of an SLK55 and an SLK350. I think there are higher capacity units out there, but I haven't needed one.

It helps to have an R171 SLK350 VIN when ordering parts. The VIN from the car that donated the parts shown in the original post is WDBWK56F35F073699. I don't know what differences there are, if any, between R171 SLK280 and SLK350 driveline parts. The SLK350 engine is a little closer in output to the SLK55, so that's what I went with when sourcing parts.

What would I do differently? I tried to save some money with used parts, like the flywheel, transmission, driveshaft, on the initial build because I didn't know it would work. In the final form, everything from the rear main seal on the engine to the flex disc on the diff are new. I chased some gremlins that were all the result of parts being too worn. I don't know if you saw my other post on sourcing a brand new transmission.
 
#14 · (Edited)
Yes, the crossmember is different. The manual is a couple inches shorter than the automatic so it bolts to the chassis using a different set of holes present on SLK55 as well though it never shipped with the manual, and the tunnel is wider there. See pic.
Pipe Automotive Exhaust Exhaust system Engine Muffler


And yes, this means you need a different driveshaft.
 
#16 ·
Josh from MSS provided guidance on the wiring.

The clutch switch we need to use is the highest one, not the lowest mounted switch on the clutch pedal.
Pin 1 of the switch will go to ground,
Pin 2 will go to ECU connector 4 pin 4
White Text Font Diagram Slope


Now the reverse switch. Pin 1 will go to ground, pin 2 will go to the drivers side SAM connector 10, pin 6
Number Font Diagram Schematic Handwriting


I asked how I would know if the clutch switch was wired correctly, and he said you’ll know because the ESP light will stay on after you do a steering wheel lock-lock-lock reset if it's not right. I don't know what the clutch switch does. The car starts even if the pedal isn't depressed. My ESP light is off though.

I don't have working reverse lights. I wired to SAM connector 10, but they don't come on. It doesn't bother me enough to chase it.
Font Diagram
 
#18 ·
Ok, will definitely have to snag that mount. I see you also got the console trim, was the opening different from the auto? The look similar with the shifter removed so I was thinking of just reusing my existing piece to match with the rest of the interior.
 
#19 ·
It’s the same console piece. The trim for the AT pops out and you replace with a shifter boot. Thankfully, cost constraints probably favor their re-using as much as possible between models.
Center console Gear shift Steering wheel Carbon fibers Electronics
 
#20 ·
I hear you there, I look at the work required for some of the bigger body models (hello CLS) and am very glad I have a tarted up budget Benz. I’m still leaning towards lengthening the slk55 driveshaft and swapping to the 4 bolt output shaft (à la dc motorworks) because my car only has 30k miles on the clock and figure it will be easier in the future to order parts with less mix and matching.

due to the low mileage, finding a lower mileage transmission is proving fun, I almost bought the entire Swap from a manual ‘05 slk350 but it turns out it has about 4 times the mileage my car has, and doesn’t look like it lived an easy life. Here in Canada we have the c250 which was much more common to use a manual so I am trying to confirm it got the same transmission as the other v6 cars rather than the inline 4’s.
 
#21 ·
If I had it to do over again, I would have gotten the driveshaft made with the 4 bolt flange. I had sourced a 3 bolt front section from an SLK350 manual. It was only after I had vibration issues did I learn the central u-joint was worn out and decided to get one made that I could just bolt in. I think the flex ring for the 4 bolt flange is stiffer/stronger, and that can't hurt. When I get the chance, I'm also going to install a JXB center bearing carrier. Under high load, I think the OEM unit allows too much movement.

I think all the Merc's of the era have a variant of the NSG370 transmission. I've seen some rated for more torque, but don't know that the internals are actually any different. There is a cable actuated and a shaft actuated variant. The C-class cars use the cable. The SLK uses the shaft. I converted a brand new Mopar unit from cable to shaft. Details here in this other thread.
 
#22 · (Edited)
Interested to hear more about the jxb centre unit. the more research I do, it makes me think rebalancing the driveshaft as a whole while replacing all consumable parts is the best bet. in keeping the 4 bolt shaft I can also mark the mounting locations at the diff and transmission to the best shot at avoiding driveline vibration.

On Your note regarding the nsg370, my impression was that the w208/r170 cars had the cable shifters and nsg270 , but later manuals like the r171 slk350’s and w209/w203 cars were more likely to come with the nsg370/400. I know kangaroos mentions identifying the transmission can be done by the diameter of the output shaft flange, curious if you have any more knowledge on which cars ended up with the nsg270’s and how to identify. The w204 c250 piqued my interest as it has a 2.5L v6 but they seem to be much more plentiful which made me think they might be a better option to get an nsg370/400 that hasn’t been abused. Given the lighter weight of our cars, I suspect either transmission would suffice but always happy to gain more knowledge on the parts that are out there.
 
#23 · (Edited)
I'm not an expert in which units came in which cars. It does look like the NSG400 has reinforcing ribs on the case, and the NSG370 does not. Mine is a Crossfire transmission.

I'm going to try the JXB carrier because every now and then, it seems like the driveshaft gets excited into a wobble mode. The OEM carrier is very flexible. I went with the street bushing which is supposed to be stiffer than OEM, without much of an increase in NVH.

The consumable that caused problems in my case was the u-joint. It's not replaceable. Mine had about 65k miles at the time and had a pretty notable detent in the movement. By the time I had finally gotten all the gremlins out, everything from the rear main seal back to the flex disc on the diff was brand new.
 
#25 ·
Mine is a clutch line from an SLK350. I would be surprised if anything other than a line from a manual R171 is going to have all the exact bends. The screenshot below is from PartSouq which has been great for looking up numbers. It helps to have a VIN. The donor SLK350 that I sourced a lot of parts from was WDBWK56F35F073699.
White Font Screenshot Number Document
 
A
#26 ·
PKlein,

Thank you for sharing all the details of your successful project.

I am considering swapping 6 speed manual gearbox into my SLK55 2005. I am local to you, Foster City, and wonder if we could meet up?

I would really appreciate an opportunity to see your car, and get a bit of in person feedback.

Thank you. Ivica
 
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