myblkc63

I was at the track yesterday driving very hard and on my 3rd session on the second to last lap the car switched to sport mode on it's own and took away the option for me to put it back in manual mode. When I finished the session I turned off the car let it set and now the Manual mode is back.

Any ideas? Has anyone experienced this?

Thanks for the help.

dmyrick

Thats a damn shame. were your laps as good in S mode

myblkc63

I don't know. Thinking I might have broke something, I took a semi light lap then brought it in. It was shifting at mostly the right points though but you don't have the same control.

I am going to call Mercedes tomorow morning but wanted to post here in hopes that someone has experienced this already and/or might know what the cause could be.

1st amg

Perfectly normal, on my track sessions this has happened when the tranny seems to get a little hot, other members here who track their car have experienced the same thing. There is no harm done, when the car cools off a bit then all is back to normal.

myblkc63

Really? Well that's a little disheartening. There should be a way to direct more air or use a better transmission fluid to keep it cool. I hope to track the car more often and for longer seasons and definately don't want this to be occuring.

Im gonna see what I can find out and will post it here.

Thanks for the confirmation that I didn't break my car.

LZH

Agreed - I had the same thing happen in my Black Series at Willow Springs on a VERY hot day (115 degrees). When it happened I was in the middle of turn 8 well into triple digit speeds holding a tight line in 5th gear and all of a sudden the trans goes into C mode and upshifts to 7th sending the car sideways and drifting into turn 9...Not fun at all and could have turned into a huge off.

azlane

At what kind of oil temp does this happen? I'm wondering if this is the car going into limp mode.

Here in AZ my oil temp has gotten in the 245 degree F range but so far no limp mode.

LawRens

Does this not become more of a potential hazard than anything else? Going from M mode to C during some hard driving could be disastrous...

myblkc63

Yes this seems like a pretty big risk especially since there is no warning.

It doesn't appear to be oil temp related but transmission temp. It wasn't limp mode as the car contined to shift in sport mode and their didn't appear to be a drop in power.

It's really frustrating and a little scarry that this can happen at any moment. I going to call Mercedes and get to the bottom of this.

justthebest

I remember a thread a couple months back about an extra available heat sink either on the transmission or somewhere around there. Maybe those that seriously track their cars would be willing to go through the moderate time investment to add an extra heat sink on.

LZH

Correct, it is trans temp and there was no warning whatsoever. There should at least be a dash light telling the driver that the trans temp is approaching levels where driving conditions will be altered by the tcu. Perhaps this should be a reason for amg to reflash our cars with a message that comes up in the center display and also give us the rev matched downshifts! ( for those of us 63 owners who don't have it)

ATL_MB

You may be thinking of the rear diff, which has a heat sink / fins for factory LSD units.

justthebest

Yep, rear diff - nevermind - Thanks ATL.

Quadcammer

shouldn't be too hard to plumb in an external tranny oil cooler.

myblkc63

I amhoping that one of the tuners has already developed one. I am going to look around.

Blk04cobra1

I have to agree with you guys that the potential for something hazardous is out there, but you have to step in to MB's shoes for a moment. It is a fail safe mechanism probably for warranty purposes. If it's triggered to come on at a certain temp, then that means that is probably the limit of the trans and it doesnt want you to go over that.

myblkc63

It's a known issue. Read the last 2 paragraphs on this article.

http://www.carracing.com/CarReviews/...html?s=driving

My point is there has to be something we can do to keep it cool and that is what I am going to look into.

LZH

It shouldn't be difficult to just upgrade the stock transmssion cooler to a larger one.

Jons95c36amg

What was your oil temps on the dash? Too bad it doesnt have a tranny temp.

justthebest

I wonder if AMG fiddles with the AMG Academy cars to address this problem somehow - the instructors do hot laps in the Cs, and I would think that they would be comparable to most of the guys that track their cars on this forum.

MB_Forever

My understanding was that the CLK63 Black Series already has an additional tranny cooler to address this problem?

ATL_MB

I believe the car already has a transmission cooler. As LZH says, it should be pretty easy to upgrade it.

If you really wanted to do it right, though, you could probably put an extra tranny cooler into the left bottom bumper cover with a fan, and cut out those fake air vents to work like they do on the right (where an engine oil cooler lives).

Blk04cobra1

I know they have a cooler for the rear end, but didnt know they had an additional tranny cooler.

miami1lt

Tranny switching under hard-driving is not a good thing...it should NOT happen on its own...and if it does, it should go to "S" mode....

I hate that you have to go through C to get from M to S anyway. Seems to me that it should go M, S then C...as most people that are driving in M mode that want to switch don't want to go through C. In fact, you should have to push and hold to get C.

LZH

The Black Series has a larger main radiator for the coolant, another for the power steering as well as an additional transmission cooler which are built into the left front wheel arch. The engine oil cooler is located in the right wheel arch. I had my front bumper off at one point and the car looks very much like a race car with barn door size radiators. But, we all know it is NOT a true race car, but better yet a street car that can handle track duty.

I would say that when my transmission kicked me out of M mode, I wasn't too surprised...it was very hot as I mentioned before, and I only know of a few other street legal cars that could have gone as long as I did without overheating something in those conditions. IIRC the track temp was in the 130's....So, I guess my point is that it's no wonder the C63's are having the same issues under even more favorable conditions as they are not setup to take the abuse that the Black Series can handle. Again, someone should looking into putting the CLK Black Series transmission cooler setup in to the C63. Im sure it would be an easy intall and you'd have all factory parts - the only thing I could see being an issue is fitment and space. You would probably have to have a few brackets custom made and perhaps move a few lines around.

To the OP - what was the ambient temp while you were running ? You cannot just "get more airflow" or use another trans fluid to keep this from happening. If you do plan on tracking your car more you REALLY need a larger transmission cooler or an additional one installed in the left bottom bumper cover as ATL MB suggested. If there is space there, that's what you should do.

Something like this:



http://www.streetperformance.com/par...-db-30216.html


Also, if your car has an ECU tune AND you are planning on headers and a pulley...I'd strongly suggest going with an additional trans cooler. Take a look at ths thread and you will see what I mean:

https://mbworld.org/forums/c63-amg-w...mea-culpa.html