fixinbones

Well, after breaking my new car in I've started to explore the limits of the car. The one thing I noticed is that if you floor the car off the line or from a slow roll so that the transmission kicks down into first gear, the full throttle 1-2 upshift occurs way too early, like at 5-6k rpms. All other full throttle up shifts are close to redline. This happens with the transmission in S or C mode. I brought the car into the dealer and they said they all do this and there currently is no fix for this problem. Sounds kinda strange to me. Dont know if they're doing it to limit the load on the drive train? The only way to get the car to shift close to redline under full throttle is to put the transmission in M mode and do it manually which is a pain in the ***. Can anyone shed some light on this? Are other people experiencing this problem?

juicee63

Leave your car in d/s but downshift so gear 1 appears on the dash. Hold the gear to 7200 or 7100 then get off and throttle down. Your car will learn to shift out of first at 6800-7200 but you must downshift , display 1st gear then go WOT and only after you have trained the transmission to go past 6k rpm in first. Second gear should shift out at 7000-7200.

Manual is not the solution as your car will hit the limiter if you paddle out at 7k.

You can watch my videos on youtube, search juicee55,

fixinbones

I think I get what your are saying. With the transmission in S mode, down shift to 1st gear with the paddles, accelerate under WOT in first gear til 7100-7200, then let off the gas and let engine come back down to lower rpms as the car is decelerating.
My question is how many times do you have to do this for the engine to learn to shift at 6800-7200 on its own? Also, if I recall, I think I may have done something similar to this on my own a few times experimenting with the transmission to get it to upshift later. When I did it, I down shifted to 1st gear in S mode, and accelerated under WOT. I think the transmission up shifted on its own to 2nd gear at a higher rpm (but still not at 6800-7200rpms) then the typical 5,000-6,000 rpms shifts I was getting. With the transmission in S or C, it will upshift on its own and not let you get close to the limiter unlike the M mode where you could over rev the motor until the rev limiter kicks in. Im just curious if the transmission will hold 1st gear to such a high rpm is S mode. I will try your technique later today and report back. Thanks.

ATKM5

I think what he means is, you slowly and gradually build up your revs to 7000 rpm while in S mode. So basically you go to S mode, select 1st gear, and then gradually accelerate to the redline. If you go WOT, it will shortshift, so gradually is the way to go. At the redline you hold it for 1 sec and then either release the throttle or give it a bit more so it shifts into 2nd. I assume 5 minutes of this procedure is all it will take for the transmission to start shifting in the higher RPM range.

Hope this helps, I have to try it on mine when it comes back from the dealer...

fixinbones

This is the video hes referring to. Didnt get a chance to do it today, roads too wet. will try tomorrow.

http://www.youtube.com/watch?v=Il4lFYXYcTU

alx

not sure about transmission being trained to recognize upper rpms.

the problem is that the tach is slow. the car shifts at redline (or close to due to tq mgmt), but the tach cant catch up.

tach is made to smooth rpm reading especially at lower rpms and is neither sensitive nor accurate.

you want an accurate tach? unfortunately it will jump around at idle... and this is not behavior suitable for a merc... remember- there is also a clock - an effen clock on the dash... that sets the sporty level for sure...

my 2 cents

alex

fixinbones

Trust me the take is not slow. The car shifts too soon from 1st to 2nd, all other up shifts are close to redline about 7,000rpms. I will report back on my findings when I try it tomorrow.

ATKM5

Please keep us up to date!

alx

i know for a fact that the tach is slow.

on the slower-revving mb amg motors this is not a problem, but on the 63 motor it has been a problem in first gear (fastest revving) as the tach cant keep up.

fixinbones

ATKM5, whats your tranny in th eCLS doing with the 1-2 shift? Does she shift close to redline?

fixinbones

The tach may be slow but i'm not sure I understand how this effects the shift point of the car. If your are saying that my car is shifting from 1st to 2nd at close to redline but my tach is just showing a lower rpm I would have to disagree. You can see a big difference when you hold it out in M till 6,800-7,000 under WOT versus letting it shift on its own under WOT. When the car shifts on its own the motor is not in its powerband once it gets into 2nd gear due to the lower speed at which it has shifted into 2nd gear and wont pull so hard after the 1-2 shift due to this. If you hold first gear til 7,000 in M, the car pulls much harder after the 1-2 shift. There is no comparison in acceleration between the two, my car shifting in S mode would be smoked by my car shifting in M mode holding the revs til close to redline.

alx

how the engine sounds and the car feels has nothing to do with the slow tach.

i can guarantee you that if we have two identical cars and you manual-shift and i just mash the throttle in "sport" mode i will be faster. let me explain.

when in manual mode, tq mgmt and stability control have very high thresholds. this is done so you have some freedom do powerslide a bit, etc. thus you see the stability control (the yellow triangle) flash (and cut power) only in dire conditions where significant wheelspin is detected. you can further raise the limits by switching it off. unfortunately, this also means that your traction is not optimized for acceleration and significant wheelspin is presented when you shift at redline in first. you might or might not be aware of it as stability control does not interfere for a while. however, acceleration perception is solid as the engine roars to redline and the car struggles for traction.

now, when i auto-mode (even sports) you have active tq mgmt and stability control engaged. it is important to note that stability control will activate well before the yellow triangle flashes. one of the decisions that are made in 1-2 shifts is if it will be beneficial to redline the motor before the shift. if there is no traction and the stability control is actively breaking the rear tires (especially if no lsd is detected) a decision is elected by the tq mgmt software to short-shift the car as further acceleration in 1st gear is counterproductive.

so... there are three things at play when mashing the throttle in 1st gear- available traction and level of interference by stability control which determines tq mgmt decisions and shift points.

hope this makes sense... acceleration decisions are complicated, but in a nutshell thats what it is...

alex

WSH

Not clear that any human w/"placebo"shifters is faster/safer/smoother than a well-sorted latest-tech autobox (in Sport mode, not Manual) interlinked w/ESP, etc (human gearbox inputs often muck up the various computer networks of drivetrain/stability/braking, etc)

NBR times in SportPlus mode (not Manual) seem faster than Manual mode for even alleged "pro" drivers in 997S, 997TT, SL63 030, etc etc

Agree, 63 has weak tq for anyone addicted to fast, smooth, effortless mid-range accel....but get 65 if want such accel...."old"-tech 5-sp autoboxes work smoothly/reliably vs 738 lb-ft

juicee63

The car will shift how you drive and it adapts everyday.Most 63's shift out of first early. This can be avoided by keeping tthe he car in d/s downshifting to 1st and also turning off tc/esp. The car will also upshift if wheel spin is present.

My car has fantastic shift points in 2nd 3rd and 4th b ut first is still difficult to maximize.

On the race track in dyno mode it shifts out at 7k all day long.

Holding your gears allows the car to change where it shifts trust me this works. It seems crazy but holding first to 7k will teach the tcu to go to 7k. You can also change your ecu settings to increase your redline to 7400.

Let me know how you do, and keep in mind your engine will perform better after spirited driving many many miles. I have 35k and the car is smoother and faster than it was at 15k and at 5k.

good luck.

63 has plenty of tq, as witnessed by the fact my car has achieved the quickest 60ft time of any mercedes platform

fixinbones

Ok, so I gave my 63 a little lesson yesterday on revs to 7,000rpm as suggested by Juicee. The result of about 5-10 minutes worth of bringing the car close to redline in first gear on multiple occasions is that the car now shifts much closer to redline from 1st to 2nd, almost 7,000rpms, when in S mode and shifting on its own. So I must confirm that the teaching method for first gear 1-2 shifts works. As stated by Juicee, all other shift points on the car are perfect from day one.

Next question, do you leave traction control engaged all the time, even when racing off the line?

juicee63

On the street I leave it on but it dummies down performance. On my 07 tc is on even when turned off to a certain extent. The only real way to disable all your limitation is to run the car in dyno mode. Pre safe is still active but tc/esp, off the car.

Great job, the downshift is really critical use your paddles and or shifter often to downshift if you need more umph

How many miles on the CL?

alx

what you did is "force-conditioned" the tq mgmt software down the wrong path.

if your particular car was short-shifting out of 1st - that was the best acceleration under the given conditions (outside temp, tire traction, octane rating, etc.).

i can guarantee you that if you had the equipment to measure 0-60 you would notice that now your car is actually slower to 60...

but whatever makes you happy i guess?

alex

fixinbones

Thanks. Ive got 5,000 miles on her now. Just starting to drive it harder now.

ATKM5

My car has the same issue. It short shifted from 1 to 2 at around 5500 rpm. I'm glad that procedure worked for you! As soon as I get my car back, I will do the same. Its getting a manifold fixed...

alx, juicee got a sub 1.5 sec 60", I'm pretty sure that this translates to a sub 4 sec 0-60...

Juicee! Thanks for your help!

juicee63

Sorry but this is absolutely not the case. Cars that shift at 6800-7200 are faster than cars (63's) shifting 5200-6000, That short shift will be difficult to make up in the 1/4 mile and most certainly will kill you 0-60mph.

As far as 0-60mph , I would bet a billion dollars and a dozen donuts the car shifting at 6800 beats the car shifting at 5800. The 63 shifts at 40-42 mph from 1st to 2nd when the transmission is at the top of its game

fixinbones

Playing around some more with the tranny. M mode definitely sucks. Its very easy to over rev the car because of the delay in shifting and finding the right time to hit the up shift paddle. I can see M mode working much better in the SL63, and new E63 with the 7MCT tranny which has much quicker shifts.
I can see how the car wants to short shift now occasionally with loss of traction in first gear. Im wondering if Juicee could comment on the best technique to either launch the car from a stand still or kick it down to first at say 15-20mph and maintain traction thus improving acceleration and avoiding that occasional short shift when traction is hampered.

juicee63

Yes M mode with this trans is difficult to master. I do not even try although I do know of a car that has pretty good success in M mode. The delay to shift is to hard to anticipate causing limiter bumps and nasty bog.

The best acceleration in this car is attained by learning to apply throttle after traction is maximized. Rather than crush the accelerator let the car roll and depress the pedal in a fluid motion. Rather than hit the kickdown plate simply downshift prior to hitting the pedal on a rolling start. Light to light or 1/4 mile launching is quite an art. It is hard to slow your motions and not hammer throttle but 99% of the time the wheels will spin then bite unless you are on a well prepped 1/4 mile strip. Go to a parking lot or empty road test your car by applying pressure to the brake and accelerator. Mark down the rpm at which the tires slip on each surface. Keep in mind if you surpass this level initially you are going to spin and absent lsd one side will break lose and the car will pull power from that wheel.

My car slips on most surface streets around 1400 rpm. Take the slack out of the drivetrain put your suspension lose so weight wilkl transfer over your rear wheels and test the car, if she slipos try a less aggressive throttle application and find a balance minimizing spin and maximizing straight line accel.

I have never seen a CL 63 on the drag strip, you should take her out. I would imagine the CL 63 is slightly different and while heavier perhaps this could help off the line. I agree with you the newer transmissions are better suited but since very few attend track events it is really hard to say.


Ultimately seat time in your own car will be the best teacher and you have begun the journey.

My times were all achieved on a well prepped track but I have seen other cars do sub 4 second 0-60 times in stock form and weighing in at 4250 lbs.

The CL is likely a few hundred pounds more so this is another factor you must account for.

Good luck, have fun and that downshift application is your friend.

alx

true when you have traction. you maximize tq to the ground and when you upshift the rpms drop back in the sweet spot. no question.

what i am trying to say is that in sports mode if you have traction, the car will upshift at redline.

if there is no traction and abs is pulsing the rear brakes on non-lsd car and tq mgmt is actively retarding timing and throttle control - the car will elect to shortshift as "forecast" is that this unproductive behavior will continue for the rest of 1st gear. as mentioned before it is important to note that the driver might or might not be aware of this intervention as the yellow triangle might or might not flash depending on many things.

what you are doing by "teaching" the car to shift at redline in first gear when there is limited traction is "skewing" the adaptive algorithms.

alex

juicee63

I definately agree the real problem is not a problem at all , the cars electronics at times do prevent maximum acceleration to keep the occupants safe.

Very good observation alx

fixinbones

[quote=alx;3788306]true when you have traction. you maximize tq to the ground and when you upshift the rpms drop back in the sweet spot. no question.

what i am trying to say is that in sports mode if you have traction, the car will upshift at redline.

if there is no traction and abs is pulsing the rear brakes on non-lsd car and tq mgmt is actively retarding timing and throttle control - the car will elect to shortshift as "forecast" is that this unproductive behavior will continue for the rest of 1st gear. as mentioned before it is important to note that the driver might or might not be aware of this intervention as the yellow triangle might or might not flash depending on many things.

what you are doing by "teaching" the car to shift at redline in first gear when there is limited traction is "skewing" the adaptive algorith

I understand your explanation, but during short shifts its not like the tires are breaking loose that much there is minimal wheel spin. You would think that a hi perf amg car's computer would be able to realize the difference between slight wheel spin which is not hampering acceleration and continue to accelerate the car in the current gear under WOT