Hi...


Will downshifting the autostick to slow the car instead of using the brakes cause any harm / excessive wear ? I.E. doing this on a regular basis...

...or is is better to just use the brakes ?


Thanks...


Dave...

 

Dave.... Everything I've read (mostly on the "BenzWorld" forum) and my experience so far says no you won't hurt anything. This is a "Smart" tranny... It won't let you put it into a gear that will damage it. I use mine all the time for downshifting and it works great. I figure that if I use that feature a bunch now, while I'm still under warranty, and it breaks... They will fix it. But the SLK folks haven't had any problems with the 5 speed. So my guess is this is one very tuff tranny.

 

Thanks...

Tranny must be well built... it's used in 1-ton trucks... but this application causes tranny problems...


Dave...

 

If you go to the Mercedes sites you will find that everyone really praises this tranny as being virtually bullet proof. Another good indicator is that the SRT6 will only be offered with the 5 speed autostick. If it can take what that car can dish out, I doubt we will have any problems.

 

We'll on everyhtnt gyou guys were saying I dont know how bulletproof they are because I already had mine replaced with only 2000 on the car, and to boot i didnt beat on it hard for anyhting to happen. Maby it was just a lemon trans.

 

What was wrong with it??? Yours is the only one, including on the MB forum that I've heard of having problems.

 

Lemons happen. I'm sure the one they put in will be problem free.

BTW what kind of issues were you having?

 

Is it the same exact tranny with all the same internals? If so, it doesn't seem like a very financially smart decision on DCX's behalf to use the "overbuilt" tranny in the base crossfire/slk.

 

I really think the downshifting idea is a legacy from the days when brakes weren't worth a damn-both ineffective and short-lived. We're decades past that now. This car has really nice brakes (made even better by the large contact patches the tires give us). Why use an extremely complex and expensive transmission to do what the brakes do better and more cheaply? I'd rather replace pads then planetary gears.

 

Heb80.... A friend of mine has a 2003 SLK 320 5 speed and they look identical. They operate exactly the same way and the owner's manuals for both cars have the exact same transmission info. My guess (and it's just a guess) is that it is the exact same. I do know that the engine and electronics are exactly the same as the SLK 320. The Brakes and suspension are all from the SLK too. Just makes sense that the tranny is to.

 

I know the base SLK320 and the base Crossfire share the same drivetrain. What I was asking is if you are sure that the Crossfire SRT-6 and the AMG SLK shared the same transmission as the base Crossfire and SLK320.

 

I'm not positive that they are the same as the AMG or the SRT. I will do some research and see if I can find out.

 

Here's a link to AMG... It says that the Transmission, suspension and brakes have been "refined" for the added performance of the AMG engine. I couldn't find anything to tell me exactly what the they did to "refine" it. It could be as little as changing the line pressures and shift points... Your guess is as good as mine. :?. My guess is the SRT will have the AMG tranny.

http://www.mbusa.com/amg/model-inc.j...delsection=SLK

 

Just a thought on wear-

The act of slowing a car is simple- you convert inertia into heat energy. The brakes do this through friction and dissipate the energy through the rotors/pads.

Downshifting causes the engines compression to slow the vehicle. The act of downshifting does put a load on the transmission (which it is designed to do) which is transferred through various wet clutches to hold various portions of the planetaries. This does cause wear on the clutches- as this is how a transmission is designed to operate.

SO- would you rather use the cheap brake pads to slow the car- or the expensive transmission/engine to slow the car?

Both are designed to do this- but one's sole function on this planet is to slow your vehicle- the others is a little more complicated and expensive. Now if you are autocrossing- you are not worried about the minor wear on the trans/engine- you are worried about performance. But I assume none of you were autocrosing to and from work. So either will work, its up to you to decide how to drive your vehicle.

 

Excellent point, Jamikest..... Brake pads are much easier and cheaper.

 

Hi...


So... brakes it is... thanks for your replies...


Dave...

 

The only Autostick I've ever driven was a Chrysler 300 Special. I had it for a few days while my crossfire was in the shop. The way that thing downshifted it didn't seem too healthy for it... it did alot of whining.

I downshift, but of course I have the Manual Tranny. I don't like brakes... they make my wheels dirty. :lol: Once you get the heal-toe shifting down, its alot of fun too.

Brakes are for wusses anyway... but then so are autostix :P

 

You heel and toe in order to AVOID overrevving the engine by stressing the drivetrain when you engage the next gear. However, if you don't stress the drivetrain you are not slowing the wheels/braking with the transmission. The Heel and Toe is especially designed to let you dedicate an entire foot to the brakes. Also especially useful for keeping the engine in the powerband so that you can best accelerate back out of the corner.

(Now chicken, but fondly remembering pre-marital G-Production)

P.S. Jamikest: nowhere near your credentials, but thought I said that :)
"Why use an extremely complex and expensive transmission to do what the brakes do better and more cheaply? "

 

You want to be at the correct RPM before you shift into a lower gear or else you'll be riding the clutch or bucking thru the corner. Once you are in that lower gear you let off the gas to allow the engine braking to take over.

 

"Once you are in that lower gear you let off the gas to allow the engine braking to take over."

...which stresses the drivetrain, 'cause that's what connects the engine to the wheels.

BTW, I'm not proud of my autostick, generally agree with you they are for weanies. 3 years of DC traffic wore me down, though. Shame! :cry: