bmukkamala

Hi there. i have acquired an 88 s4 that i believe based on my reading here starts in second gear. i will be counting shift points today.

i also have an 89 mercedes 560sec and i believe the transmission is the same or similar as they were both manufactured by MB.

in my 560sec i have installed a module that activates the kickdown solenoid below a set speed to allow 1st gear starts from a stop.

this module is now available with a few neat options from a company in cali.

http://bergwerks.com/control_module.jsp

i am curious as to wether anyone here can provide insight on if this will work in the 88 s4.

thanks
bobby

Garth S

Interresting find!
Yes, a 'normal' S4 start is in 2nd. First can be selected at low speed/stop by shifting to second (flooring the throttle seems to work also - haha).
Reading the link, Bergwerks claim to have a 928 module "comming soon": to persue adaptability, a call/email to them come Monday is sure to give the best response.
Like the 'Benz - but sure to like your 928 better!

Ispeed

I know what you're talking about, but if your car starts off in 2nd, there's something wrong. The thing going on is the '88 has a 2.20 rear end (the '89 auto has a 2.54 and it makes a difference) and the car shifts to 2nd at 4500 rpm. This is so that there is less stress on the driveshaft than if it went to redline in 1st. The end result (if starting in first) is that it is not that fast off the line. It's something you may have to accept.

I installed a parallel kickdown switch and that is pretty cool to switch ON because under throttle, the car downshifts and runs like it's in a big hurry. It doesn't make the car run out longer in first, though.

Carl.

hacker-pschorr

Welcome to the list. Awesome Mercedes. I have a 380 SEC under construction. I'm trying to find a 500 Euro motor to drop in.

bmukkamala

About the euro motor for the sec, you should check out a website called mbcoupes.com to see what others have done to their cars.

dr bob

I spent a bit of time with BergWerks trying their module. We discovered that the "kickdown" solenoid does NOT force a first gear start on my '89.

Their module is a cute little thing that reads car speed from the speedo pulse sensor, and makes decisions on when to engage that kickdown solenoid for you. But it does no good if your trans isn't forced to first on solenoid activation.

First test for your car then would be to see if the module will do any good once installed. To do that, make a jumper that you can use to plug in the two leads under the loud pedal, and connect the two together. Drive the car... Does it start out in first gear every time? If so, you are a candidate for their module. If yours is like mine, having the solenoid engaged will let you select first with a brisk push on that same pedal, but less brisk that you need without the jumper.

More than a few folks have used those same leads to wire a push-buton or switch in parallel with the switch under the pedal. Lets you decide how you want the car to shift.


All that said, I'm not sure that I'd like to have my 2.54-geared car starting off in first all the time. It runs through first a lot faster than the 2.20-geared cars, so second-gear starts are better for me and the way I drive most of the time. With the bowden cable (the one to the trans...) adjusted a litle snug, it pulls to first nicely on launch with just a firm, -quick- stab at the pedal. Before you go out and spend $$ on a gadget, try the paralle switch trick first, and make sure your cables are adjusted just right.

Steve Cattaneo

To command a 1st gear start in a 928s as will as Mercedes Benz that do not have a B,W and S mode on the shift lever, the kick down solenoid has to be activated in conjunction with a certain amount of travel of the Throttle valve. This is why you can only command a 1st gear start in these cars at WOT, Assuming no modifications have been done or it is designed to start in 1st. By activating the kick down solenoid alone, will not command 1st gear. The only cars that will start in1st by activating the KD solenoid are those that have the B mode- engine braking, W mode – winter driving, and S- mode sport mode. In these transmissions the valve bodies are calibrated different. That control module will not work and can not work in a 928.

Brent 89-GT

I thought I was reading some bad info in Pano this month. Charlesworth was also saying that the S4 autos shifted into second at 4500 rpm. He said that he had broken two driveshafts running to rediline in first. How can this be? Is the driveshaft on the auto that much weaker than the one in the manuals? I run my GT to redline in first all the time and haven't broken a driveshaft. I would have to think that an agressive shift in a manual car would be far more stressful than a torque convertor dampened one in an auto car. I even took my car to a drag strip last summer and ran it hard all night. It made three track weekends after that, and thousands of miles on the road. It doesn't seem any the worse for wear. It just boggles my mind that a Porsche would have to be short shifted to keep it together. Is this what you guys with auto's have to live with?

Drewster67

In all honesty and thanks to the PO (Dont know exactly what he did but my KD switch has been passed permantly), my 84 S2 starts in 1st gear ALL the time. Even at a slow start - Insight anyone??

TIA

bmukkamala

Ok let me assimilate. jumping the kickdown switch leads may result in a first gear start on my 88 s4. if not, the car will start in first if i depress the throttle some.

here is my thought, perhaps the reason some cars start in first just with the jumper and others only with the jumper and throttle depression could be the extra play in the throttle linkage?

i think i will try jumping the leads AND eliminating the excess play in the throttle linkage and see what happens.

dr bob

Steve-- I know you are a trans guru. Seems that my S4 is much more sensitive to the --speed-- that my foot moves down on the pedal than how far down it goes. I can easily force a first-gear start by pressing quickly to 1/2 pedal, then quickly let off and it stays in first 'til I hit a normal shift point. If I let off real quickly, there's a harsh shift to second.

BergWerks guys spent time looking at the balve body numbers, and seem to think the auto trans in my S4 is more closely related to the one in some six cylinder M-B cars than to the big V-8 models that most seem to think of as the donor cars for the 928 auto boxes. Have any insight to share on this?

If my diff was out on the floor and I had a choice, I'd seriously consider putting 2.20's in there instead of the 2.54's to get some more miles-per-revolution on the engine. I don't drag race or anything, first gear never gets used anyway. Maybe what we need is a way to put a late M-B 5sp auto box into the 928 housing, with some overdrive in that top gear, and have a real lockup converter to cut losses and heat some.

Nicole

Worldwide, all 928s from 88 on started in second gear. I think that this was implemented in 1987 for the US. That's why earlier 928s start in first gear.

Steve Cattaneo

Two broken driving drive shafts that says lot to the strength of the automatics, I am not surprise.

brent,
You are right the autos can handle more torque then the manuals. The torque converter absorbs and uses the engines torque, until it has reached it torque capacity at that point its slips/ stall speed.

Drew,

Not all Mercedes transmissions start in 2nd gear. Your euro starts in 1st without the KD solenoid activated.

Bobby

If you pull the shift lever down to manual 2nd the Trans will start in 1st.

Drewster67

Thanks Steve!

Steve Cattaneo

DR Bob,

Have you try adjusting the TV cable that’s were I would start, loosen the cable until you have early shifts then tighten it one turn and go for a road test repeat the procedure until the overall shifting pattern feel right. The TV cable is very sensitive to adjustment.

The valve body may need rebuilding or yes it is the wrong one for the car. At your next transmission filter change send me the ink and casting numbers on the valve body I can tell you if it is the right one.

If you what you can borrow one of my1st gear start valve body. Try it in you car and see how you like it. I can not send it until late spring; I have a lot going on. You can send me the casting numbers at.

Email

928euro@mastertechtrans.com