Mongo

There's been a lot of speculation and disgruntled owners regarding the factory kickdown on 928 model Porsches. There have been kickdown switches that appear to be the cure to hold the gear the longest prior to upshift on the automatic transmission.

When I purchased my 928 in 2001, the gas pedal and lever that activates the kickdown (it makes contact with the switch on the floorboard) were about a half inch way from making this possible. I had installed a donut grommet about 1/2" thick to compensate for the distance. This had allowed me to get some sort of kickdown response, but the car would still upshift early.

When the kickdown switch is depressed all the way the motor will run until it hit's the redline RPM indicated by the DME. A signal is then made to cause the upshift. Eventually, the lever hitting the kickdown switch will distance itself from the switch causing early upshifting. This also occurs when the accelerator had been removed from the car.

Now to Correct this:

For those of you who would like to avoid using the kickdown switch but have that throttle and acceleration response from your car as it did from the showroom floor you will have to lengthen the gas pedal distance from the floor board via a ball & socket joint connect the pedal to the accelerator lever.

1. there is a clip holding the ball and socket to the accel. lever. You will need a flat head screwdriver to pry the clip away from the rounded head. BE VERY CAREFUL. I broke this clip and had to use a body clip that holds RC car bodies to a chassis. When done, remove the clip and pop the ball and socket off.

2. Pop the ball and socket off the back of the accelerator pedal. You will pull the pedal towards you. Don't pull and flex too much. ABS plastic can still bend and break on a 20+ year old car VERY EASY.

3. The diagram below represents what to expand. There is a nut you will have to back off from head of the ball and socket to keep it from screwing on more and giving the pedal less distance from the floor board, and more from the kickdown switch....yes this sounds odd, but I spent 15 minutes studying this on my pedal. When done with your adjustment, attach the ball and socket joints (install reverse removal in Haynes Manual Terms) and check and see if the lever makes contact again with the pedal. If your adjustments are right, the kickdown switch should FULLY depress and the lever making full contact.

I hope this helps you guys somewhat understand how to probably correct your kickdown problems. Also I recommend tightening the kickdown and throttle cables on the driver side of the manifold.

Diagram below. Happy motoring my fellow shark owners!

Brett Jenkins

Or you could splice in a switch to the kickdown switch and mount it somewhere so you can just toggle it off and on at will.

m21sniper

"Or you could splice in a switch to the kickdown switch and mount it somewhere so you can just toggle it off and on at will."

That's what i did.

Jager sells a shifter with a momentary switch right on the handle that i really want to get. Pricey though.

pewter82

Mine also has a toggle switch, mounted to the side of the drivers seat. It really makes for better performance. I'm not sure if there is any difference between the performance of the factory kickdown on the 94-95 then the installed versions on 93 and older cars.

jason
93GTS

Mongo

I thought of the idea of splicing a switch in too. I'm just a little weary of doing this to a car's electrical system that went bizarro on me after installing an Alpine amplifier to the same brand head unit.

I saw the Jager Engineering one too and liked their idea. It is pricey though, but I'm sure the quality and design of it are worth it.

928SS

did that fix on my old gal after new carpet was installed - worked pretty well/good write up!!

strange though, I've never had a problem downshifting at will/1st gears starts after the adjustment... w/all the extra grunt now, it's more of an issue to make sure the car is pointed straight before I "hit" it.... yeehaa!

m21sniper

The only gripe i have with my A/T is that once i shift out of first i can't get 1st back(even with the override switch engaged) unless i drop to 23mph or slower.

It's a real PITA since my car pulls hard to 54mph in first gear.

Anyone know how to adjust that?

SharkSkin

I imagine that a shop skilled in tuning MBZ valve bodies ought to be able to help you there...

m21sniper

Yeah, my trans guy said he could easily redo the valve body, but i was hoping for a quick and easy fix i could do myself without spending more $$$$$$.

I've spent a good $1500 in parts just in the last six weeks alone, i'm moving to a new apt in 2 weeks on top of it(first month, last month, security deposit), and i just donated 600 bucks to the red cross for the hurricane victoms, so i'm really stretched thin for cash, lol.

928SS

IIRC, there are a number of different valve bodies that will fit this trans... pretty easy to swap, not too expensive to get... IIRC, my shift kit was only about $75, and the different valve body was under $250.... kit was just a spring or two and a new check valve (ball bearing) and gasket... pretty easy to slap in too.... hard part is getting car up in the air w/1 hand while changing parts w/the other

might ck your cables for proper tension too... lots of threads here on adjusting them....

Thaddeus

I adjusted this by the simple expedient of slipping a small piece of rubber hose over the arm that swings down and actuates the switch. The problem with my 'fix' is that I lose a small amount of pedal travel.

I also have a manual kickdown switch on my dead pedal that I use when leaving stoplights.

So: thanks for posting this. I needed a way to get a little more out of the old girl and I'm going to do it! It would be nice to get that pedal travel back.

DonS

Great idea! Got pics?