C43 with 55 engine swap
The swap is not hard but have some stories. And it was done a few days ago! Car start up fine, idle seems a little bit low on 600rpm
Using the old 43 ECU and the wiring harness and did some modication for the coolant pipe.
So last night finally can test drive the car. Here are the problems
1. Car drives ok under 2000rpm, shift no problem
2. Sometimes car do not want to shift until 2500rpm
3. Once the hit higher rpm, say 3500rpm, the car will not shift anymore, feel like enter into limp home mode.
4. When this occur, if I hit the gas hard, the rpm will go up but the speed did not catch up (feel like the tranny is slipping, no ESP light on at that time)
Mechanic try to pull out the fault code and said my tranmission cannot handle the torque from the new 55 engine. He suggest me to upgrade the tranny.
So I would like to know, is the 722.631 (NON tip) tranny is not able to handle the 55 torque? If so what other tranny I can swap to? Can the one from a W220 S500 (with tip) can be swap?
Or I can only limit my option to 55/600 tranny?
Sorry for my poor english and look forward to your opinions. Thanks!




I've been driving my 55 swapped C43 with my original 43 transmission very aggressively for 15k miles, it's fine. Had 200k miles since last rebuild on it before the swap. Just service normally and all is fine.
you have an electrical issue. Fluid in the tcu connection or cracked conductor plate. Do not throw money at a new transmission.
my mechanic has a number of test drive and every time when the car won't shift after the mechanic hit the gas harder, which mean the rpm pass 3000. The 722.631 shift fine if he treat the gas paddle gently. Once the car wont shift, mech will need to pull the code. Every time the code is different.
I will have him to check the granny again.
Thanks for your information !
really hope to get the c43 ready with the 55heart!




I've been driving my 55 swapped C43 with my original 43 transmission very aggressively for 15k miles, it's fine. Had 200k miles since last rebuild on it before the swap. Just service normally and all is fine.
you have an electrical issue. Fluid in the tcu connection or cracked conductor plate. Do not throw money at a new transmission.

Brass bushings are made of weak material on early 631 transmissions 1998.
From 1999-2000 trannies were better.
Change tranny oil and filter on regular basis.
You can also buy the extra magnet which came on newer cars.
C43 never had this magnet.
It's rectangular shaped.
Don't thrash your tranny when it's still cold.
In city driving use only the 4th speed not in D-mode.
Some peepol used to claim tranny oil heats up more in D-mode in city driving?!
Don't know if this is true or just an urban legend, maybe our spezialists can confirm this?





Brass bushings are made of weak material on early 631 transmissions 1998.
From 1999-2000 trannies were better.
Change tranny oil and filter on regular basis.
You can also buy the extra magnet which came on newer cars.
C43 never had this magnet.
It's rectangular shaped.
Don't thrash your tranny when it's still cold.
In city driving use only the 4th speed not in D-mode.
Some peepol used to claim tranny oil heats up more in D-mode in city driving?!
Don't know if this is true or just an urban legend, maybe our spezialists can confirm this?

My 99' has the magnet, but don't know if it was added after construction, or came as standard.
Never heard about blocking the transmission in 4th gear. Mine stays in D and works perfectly.
Agree that you need to get things hot before hard acceleration. Same principle for all machines
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So the shop tested the car again, changed all fluid and said there is nothing related to the electrical. They said the tranny was gone bad.
So here is my options:
1. Get a tranny from the 55 or 600 car... which is very difficult to locate one. Even if I can the price will not be cheap. EST price around USD 800-1000 tranny only
2. Use a M113 S500 gear box from W220, price is around USD400, plus parts and the EST price is around USD1000-1200 with labour
3. Rebuilt the C43 tranny. EST price around USD1600. Which I think I will go this way. The only thing I can think of if there is any parts I can get upgraded if I told the shop to rebuild the tranny?
Thanks again for everyone's input!
really cant wait to feel the 55 in C43!
The Best of Mercedes & AMG




BTW have you seen this 722.6 manual? Guess it's the bible regarding this transmission
Last edited by DRBC43AMG; Sep 28, 2017 at 04:25 AM. Reason: Added file
Reading your post, you mentioned This was solved by stopping, cutting the engine, starting again and driving away with a light foot on the throttle going up the gears to 5th.
Exactly the same as mine. if light foot the tranny shift ok... not 100%normal but it still shift. Once with heavy right foot. The tranny wont shift anymore......
Then after stop sign, the tranny will shift from 1st to 2nd, and that's all.... and kinda feel the tranny was slipping too




From my experience, I would say the conductor plate is faulty and needs to be changed. If you want more info, go read my 2017 Spring preparation thread (see signature below)
Forgot to add that if you have codes related to the conductor plate, the mechanic will need to erase the code, otherwise the tranny will remain in limp mode. Why? I serviced everything and forgot to to erase the code. Plug in, erase, plug out, drive away
Last edited by DRBC43AMG; Nov 2, 2017 at 10:15 AM.




compared to get many models of 55K dolls,,
55N/A with good mods., will be great to poping with..
,,sorry, it's my own IMO..

-;ZAYED;-




Turn out the tranny gone south.... It is not easy to get an 55/ 600 tranny so my mech. just swap the tranny from a W220 S500 first. He said the car is working fine now. I will pick up the car tomorrow and let you guys know!
Thanks for all the input!
J




He is a good mechanic and he used to drive a W202 230K
The power, or I should say the torque, was so powerful and it really give a different character to the C43!
My mech show me my old tranny. He dropped the pan and found tiny bronze shavings on atf and the pan. He also mentioned and suspected K2 clutch drum bushing since the car was produced in 1998, having the old design K2 drum bushing.
Anyway the car drive ok but he said give some time for the tranny to learn. I will keep you guys update!
I love the NA 55 engine and I should have enough fun with this powerplant.
Also it is not legal to drop the 55 engine into a 43. However it is not easy to tell and the cops will usually let you go coz the engine bay looks original.
Will be a different story if you put the M113K in it........... too obvious




Also it is not legal to drop the 55 engine into a 43. However it is not easy to tell and the cops will usually let you go coz the engine bay looks original.
Will be a different story if you put the M113K in it........... too obvious
So here is my questions:
1. Is the 2001 CLK 55 brakes better than my 98 C43 brakes?
2. Both of the side mirrors are not working except for the folding function, should I swap the mirror with the CLK one?
3. The CLK has the +/- transmission. Is it hard to swap that? Can the CLK instruct cluster direct fit the W202?
Thanks!


