C43 Transmission Q's
 

Hi All,

I have a 98 C43 that has 105k miles on it and the transmission finally decided to break. I have a HPS supercharger and drive it spiritedly sometimes, but not often.

I spoke to Mark at Sun Valley Mercedes and he wants to sell me a new rebuilt transmission (631). I've told him about possibly getting a (636) because it can hold more power, but he said they are the same. Even the clutch packs are the same and you can only put a certain amount of clutch plates for them to fit.

Now, i'm confused in what's the difference between the 631 and the 636 transmission.

Any help would be appreciated...

Thanks GP

636 tranny must be stronger holding a bit more TQ than 631

I don't think so Dennis,, they're Exactly the same out-put..!!

,,ZAYED,,

why did MB have different trannies for c43 and e55?
why do c43 tranny blow out and I rarely hear about e55 tranny go to hell if maintained properly?

there's some weak parts on c43 tranny going bad.

When i swapped the Engine to 5.4l, i kept & used the stock C43 gearbox "3" years without any issues..!

it depend to the gearbox condition, during to the service & mileage..!!

,,ZAYED,,

So Zayed, in your opinion, go with the newly rebuilt 631 or a used 636?

Prefer new good rebuilt "631" than used "636"..:)

ZAYED,,

so it's mostly matching numbers for 636 tranny and m113980 engine

if 631 is as strong as 636 i don't see a point why some c43 owners on this forum bought the 636 tranny as a replacement when their original 631 blew

I have a trans with 68k from a 99 c43 for sale...

As you know bro, i supercharged my C55 and still used stock "631" around "2" years, NO issues,,

also, my friend have Clk430 with 5.4l, he still using his stock "632" gearbox since around "4" years, still Brilliant..;)

,,ZAYED,,

PJmak: email me LJV2013@yahoo.com

Its weird, ive heard that 636 trannys are better than 631 too....
Ive owned my supercharged c43 for 14yrs now and still love it, so maybe a 641 or 643, or even a 649 would be better? I plan on keeping the car for awhile.

Guess if you keep the ATF and filter fresh, that should keep things running fine.

+1 Daniel,

Me & my friend change the "oil/filter/pilot spacer" every 4-5 months with converter,,

good service is the [[---MAIN TRICK---]]..:)

,,ZAYED,,

Every 4-5 months?:eek:

Thatll add up

The C43 gearbox is a bit of a "hybrid" box, it has the larger output shaft and extra clutch packs but still has the bronze bush where the input and output shafts meet which was only found of smaller gearbox's and not behind a V8 in any other model. The E55 gearbox is largely the same but has a roller bearing instead of a bronze bush which was only on high torque engines at the time (V8's and Diesels), it was later fitted to all 722.6's due to increased longevity.

The roller bearing and bronze bush aren't interchangeable.

Fit the E55 box.

Thanks mate for the explanation. Guess that explains perfectly.

Did MB do anything to the box after the many problems they had in 98'? It does seem that the later boxes 99' had no major (less) problems.

+100000000 with Daniel,

Excellent Explanation, didn't know about that,,

Thankss for sharing..:y

,,ZAYED,,

The cut off point on EPC for transmissions ending in 1-596204 (722.6XX-1-596204). My guess is this when it was changed ex-factory. Apparently early 722.6 V8's, bigger diesels and factory taxis had the roller bearing from start of production (that's what I was told on the 722.6 training 10+ yrs ago). They quickly changed it to all .6's having the roller bearing but early C43's missed out.

Whilst it can be upgraded by changing both input and output shafts to later ones but not worth the cost. If the gearbox is apart then a new bushing and regular oil changes should be fine to keep it going a while yet (this is what I did to mine). If it's already gone bang then just get a E55 box and call it a day. The E55 and C43 torque converters have different stall speeds but are interchangeable so use what suits your driving/setup.

-

at stealership, can i check the tranny serial number if I have an early tranny with brass bushing or the improved roller bearing?
my car is a late built MY1998 with facelift interior details which was sold as MY1999

after this serial number did MB use roller bearing as added strength on all trannies?
722.631-596204

I have recently bougth a spare tiptronic tranny MY2000.
tranny is the same mileage as my car 110.000km's
did all 722.636 trannies from all years 1998 - 2002 have the stronger roller bearing design?
did 636 trannies have the improved design conductor plate?
did MB fit a magnet in the oil pan as a standard part from MY2000?

what do you recommend using, the C43 torque converter in the new E55 tranny or use the E55 TQ converter as it is when I swap trannies when the old tranny dies?
please explain further, didn't quite understand what you mean?

If you have access to EPC you can enter your VIN and it'll give you the transmission number. It's also stamped on the side of the gearbox just above the oil pan as well as on the data card in your owners manual.

The same conductor plate is fitted to all 722.6 from a C180 to the SL65. The improvements where a date thing, all plates you buy now are the latest design.

I can't find an exact break point but that is the serial for the change in input and output shaft designs and they only changed together to allow the roller bearing to be used. There was an earlier change to the output shaft on some smaller version .6's due to noise. It's my best guess.

Magnets are a strange one, they never made up their mind what to do there, including the numerous changes to the later 722.9's. I put 2 of the later round magnets in the back of the pan as they are much stronger than the original flat magnet (new version A169 371 0003).

I've got both the C43 and the E55 so I'll check what the stall speeds are this weekend, I cant remember which one was higher but I do remember I wasn't going to swap them from what I found.

Question from a simple mind: what is stall speed in a transmission?

please check your inbox
thanks

Stall speed is basically the maximum amount of "slip" the torque convertor can allow by design. IE If you hold the car stationary on the brakes, what is the maximum rpm attainable at full throttle. Engines with lumpy cams and torque only available at high rpm have high stall speeds but generate a lot of heat compared to a low stall speed.

The W210 E55 I tested has a stall speed of approx. 2200rpm. My C43 has a stall speed of about 1900rpm. The lower stall speed means it is "more direct" and better for circle track due to the higher efficiency/lower heat generation but not as good for the drag strip. Because we have a lockup clutch having a high stall speed isn't as much of a disadvantage as on American muscle cars (fuel efficiency wise). High stall torque convertors (in MB world a high stall would be 2400-2800rpm, in aftermarket world it would be 3000-4500rpm) trade off slip for higher torque multiplication and allow engines to get into their powerband more easily and stay there.

The differences in stall speed aren't big enough to worry about for a road car unless you had a lot of mods. Because mine does a lot of circle track driving the lower heat is a big consideration for me.