Hey all,

In the Porsche 928 world a common mod to the auto transmission is a parallel kickdown switch. Check out this link:

http://members.rennlist.com/v1uhoh/kickdown.htm

Is this something anybody has done to their MB, specifically an E500/500E? BTW, as most of you know the 928 auto tranny is sourced from MB.

Thanks for any info.

Randy
'94 E500
'93 928GTS 5-speed

For those interested in the 1st gear start modification for the 722.3 transmission for V8 cars utilizing the "B" switch in the shift console to activate 1st gear, we have perfected an ELECTRONIC method of applying first gear at idle, then normal shifting afterwards. Also, since this mod IS electronic, it may be disabled for 2nd gear start. And NO, simply hooking up a switch to jump the kickdown is NOT the answer, this involves driver intervention to activate the switch everytime one comes to a stop. Also, leaving the switch engaged causes unpredictable kickdowns as well as causes the car to hold the gears all the way till redline....in a nutshell...bye bye K2 band and clutches.

The proper way is to use the VDO control unit which takes the speed reading off of the speedo head, when under 10km/h, 12VDC+ is applied to the "B" switch (and kickdown which is in parallel) and therefore, the kickdown solenoid. 1st gear is obtained. Then, when speeds pass 10km/h (6mph), 12VDC+ is released from the kickdown solenoid and hydraulic pressure plus throttle position determine the shift points.

It's just that simple and effective. This is NOT some whacko modification. MB used this on all 1984-1985 500SELs/500SECs. The 12VDC+ to the control module was supplied via the neutral safety switch.

Basically, to those who are interested, please contact me directly at: admin@mbcoupes.com

I don't want to bore the list with more fine detail.

Regards,

Satish

Would this mod be possible on the 4 speed auto on a 1981 380SL? -Jim380

Does your transmission have a "B" switch that must be clicked on to obtain 1st gear in the shifter console? Check it out...

I don't believe so. I've seen the switch under the accellerator pedal and the wires connecting to it. I've also heard of post-1981 transmission upgrades/adjustments that MB did to offer better performance. For right now I have to shift down to D1 to get a decent start. If there is a way to upgrade my tranny I would LOVE to do it! Thanks, Jim380.

Randy,

I just ran across this thread, and I have had experience with the modification you were asking about. As a matter of fact I thought I had invented it until I read your message!

I have a 1996 C36 with 4-speed transmission, the same as the E500, I believe. I was always disappointed in the passing performance of the car because it resisted kicking down in the highway passing range. I had my mechanic bypass the kickdown switch and wire the bypass into the little child-proof door lock switch on my console. The good news is that it works great when you want it, giving a full kickdown as soon as the accelerator gets to about 2/3 throttle. The bad news is that it's too sensitive when driving around town. A little too much gas and you're catapulted into the SUV in front of you! In retrospect, my choice of that tiny switch on the console wasn't very smart. It's too small to find easily while you're trying to accelerate past a semi. Otherwise, I'm real happy with the mod.

In the near future, I'm planning my Mark II mod in which I'll have the bypass triggered by a switch which will be closed when the shift lever is moved back to the third gear position. That way as long as I'm in Drive the sensitive kickdown won't be enabled, but when I pull the lever back to 3 I'll be "good to go!"

That is absolutely the worst mod one could make. Jumping the kickdown enables the solenoid always active...ie, very unpredictable downshifts, often 2 gear downshifts when making right turns at low speeds, etc. Also, erratic 1-2 and high rpm 2-3, 3-4 shifts. I know this mod well and its a bad one. Keep that flared 1-2 shifts and bye bye K2 band and clutch.

Of course your C36 drives erratically and overly sensitive. The transmission is fighting itself electrically from the solenoid and hydraulically via the throttle valve cable.

A proper electronic unit OR valve body modification is the only proper way to acheive true 1st gear startoffs without damaging effects and erratic driving characteristics. A true 1st gear mod renders the car just like any other car that starts in 1st gear. It acts like it was built from the factory that way.

Satish

Wait, im not exactly understanding what your guys are trying to do here. On my 92 300E, I have that factory switch under the pedal, and if I floor it to the switch while accelerating... it automatically kicks down a gear or two. When im starting from a standstill, and I mash the throttle, the car automatically kicks down to 1st, and the car takes off. Now, is the post 92 300E the only car with this feature? Or are you guys trying to do something entirely different?

They are trying to acheive a first gear start without having to floor the throttle or activate the B switch. A first gear start gives a signifigant acceleration advantage without having to floor the throttle over a second gear start.

Cheers
Matt.

Oh ok, gotcha But seriosly, if your gonna first gear start your car, wouldn't you want full throttle to accompany that? I mean, isn't kicking down gears and then laying off the throttle a little counterproductive?

Badinfo,

With a proper first gear start mod, you are already in first gear even before the gas pedal is all the way down. It also allows you to modulate the throttle so it's not an all or nothing deal...which should be a ton of help when you're trying to avoid excessive wheelspin which in turn should keep ASR from being such a killjoy!

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Hehehe, thats right! With your 500, the possiblity exists to actually get wheelspin The thought of peeling out in a benz never even crossed my mind... you can tell I have only 177 horsepower to lay down on the road...

Actually, I'm not trying to get first gear start because my C36 already has it. What I'm trying to do is get easier kickdown at highway passing speeds. I've been driving for over 50 years and slamming the accelerator pedal down against the floorboard isn't a knack I've ever developed and, as Rainmaker says, I'd rather be able to modulate the throttle.

I share Satish's concern about damaging the transmission and that's why I think a switch to turn the bypass on temporarily is so important, but my little switch on the console doesn't do the job because I have to look down at the console to find it, and also because it's not spring loaded to the off position.

As I said above, I've considered having the bypass triggered by a manual shift to the 3 position. Another idea I've been considering is a button on the shift knob or steering wheel. I might even use the horn buttons, then figure out an alternative for blowing the horn. I've even seen wireless buttons which strap on to the steering wheel rim. I think they are designed to activate a nitrous system.

If all else fails, I can always trade up to a 1997 C36 with 5-speed or a C43, but this is a fun project that doesn't cost very much. Anyone have any good ideas?

At the risk of stating the obvious, why don't you just shift the car? That's what the shifter's for! This option also has the added bonus of being the least cost option...you can't beat free!

The idea of connecting the kickdown to the "3" position in your gear selector sounds like a winner...just make sure you get some sort of an electronic switch that acts like a spring loaded one otherwise you run in to the aforementioned problems. This works for any and all speeds (except those which exceed the max speed for 3rd gear).

Come to think of it, if you really need it for highway passing as you mentioned, shifting the tranny back down to 3 actually downshifts the car! No need for the kickdown!

A springloaded switch mounted in a place convenient for you should also work.



Have fun drivin'

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Hey Rainmaker,

What's the point of an automatic if I have to manually shift!!??:p Actually, I do that, but manual downshifts are fairly leisurely while kickdowns are RIGHT NOW! In addition, depending on my road speed, I can often get a kickdown from drive directly to second. If I had the big torque of your E500 I wouldn't have to worry about this stuff, but my little 3.6 litre needs all the help it can get.

Thanks for the input,