drnick

john,

i have a switch wired in parrallel to the kickdown and when the tranny is warm it operates to shift back to first approaching car park and sharp turn speed. very usefull!

Ed Taylor

Mine is an early 87 as well, but will not upshift when starting with shifter in 2. I also have a kickdown switch wired which does facilitate kickdown as desired, however the upshift is unaffected by it's position.

SteveM928

There has to be somebody somewhere that knows how to modify the transmission to do the downshift to first like that. Adding the parallel kickdown switch that some install does NOT do this.

Jim Nowak

Try www.bergwerks.com. I have one of their first gear start modules on my Mercedes 560 SEC. Since Mercedes makes these trannys, it will probably work.

Mark

My '85 does the 'start in 1st - shift to 2nd at redline" with shifter in '2',

What is FUN (takes a little practice) - downshifting to 2 from 3.

Drop shifter from 3 to 2...blip throttle just the right amount at same time...it is like heel toe downshift in a manual.
In fact - at the last DE - another driver asked me to help him with heel-toe, because, as he listened to me going into a turn - he thought I was heel-toeing better then anyone he'd seen/heard!
Imagine his expression when I said "SURE!" and showed him the 'stick'!!

John Speake

Hmmm,
There's an rpm feed to the kick down relay, I wonder if that has something to do with the reluctance to kick down from 2nd to 1st at any sensible speed ?

Some investigating to do !

Mark

John - I would LOVE if you could figure out a way for a "reasonable" downshift from 2-to-1.

EVERY owner with the AUTO I know would KILL to be able to get her to downshift to 1st if you WOT @ around 25mph!

Tony

to what Mark said.

25 mph, foot to the floor and going now where fast really SUCKS in the 4spd Auto. It has to be the biggest performance down fall IMHO.!

It will have to take some awareness on the drivers behalf though. You dont want the rear wheels perhaps locking up on you on the down shift on an every day drive in "D" when you dont expect it. A sort of "SPORT" swicth tapped to the assoc chips..wiring..voodoo in the LH would be the trick.

Investigate you should John!

heinrich

There is an aftermarket co that does Mercedes trannies that listed "coming soon" an auto Porsche 928 module ... maybe the same co as listed by Jim above ... John Speake - here's your chance :-) Wizz kid!

Jim Nowak

"EVERY owner with the AUTO I know would KILL to be able to get her to downshift to 1st if you WOT @ around 25mph!"


Mark,

That's how I have my SEC set-up. You can program the downshift and upshift points with their module.

dr bob

The BergWerks module works by operating the kickdown relay, at speeds that are programmed into the module. The module reads speedo pulses to do its magic.

But... it won't work on your car if the kickdown solenoid doesn't force first gear. It doesn't work on my '89, and there is good info pointing to maybe '87 as the last year when it would.

If you want to do the first test, try shorting the two wires at the kickdown switch, the one under the skinny pedal. With those ywo wires tied together, does the car start off in first gear? If so, the BergWerks module may be right for you. If having that switch shorted/bypassed like this doesn't make for first gear starts and early downshifts while the car is still in Drive, don't buy a module. If your car shifts to first with the wires tied together while still rolling and no manual gear action, get one of the programable BergWerks modules.

John Speake

Thanks all for the feedback. My car is an '86, so it does always start off in 1st gear.

Dr Bob, you are quite right about the changes to the 'box vlave body which gives 2 gear starts. The Tech Info for MY 88 says "Changes on Upshift and Downshift program - introduced in Spring of 1987"

The reason given is that the box gave a jerk as the box re-selected 1st when rolling to a stop.

So it appears that those later boxes require a change to the valve body.

It also make sense that a programmable module works on road speed.

I assume at present that the rpm feed into the kickdown relay is a safety, to prevent kick down at too high rpm ?

When I can make the day 30 hours long, I will have a look !

dr bob

Hi John--

The discussions with BergWerks points to the need for a valve body change as you suggest. Drivers of '89+ cars with the higher (numerical) axle ratios may want to look carefully at how they program the module once the valve body is changed. First gear on my '89 is relatively brutal, at least in my opinion. I'd be looking for a module "kickdown" setting of almost a dead stop before engaging first gear again. That would cure the problem that Porsche points out as a reason for the valve body mod thay started in '87.

Perhaps the next course of action is to examine the pre-'87 valve body and compare it with the later one. It may be that a spring change would do the deed for us, but I'm never that lucky. After that we look for a pre-'87 body to just swap in for the revised shifting.

For almost all the driving I do, the factory shift map is just fine. Stop-and-go traffic is a one or two-gear operation. Once I'm on a clear road, there's no lower-gear operation anyway. Unless I need to get out of the way of a school bus or something as I pull away from a stop light or something, I never really need first gear at all. With the shift cable snugged up, it grabs first from a stop with just a quick stab at the pedal anyway.


If one was handy with a little analog electronics, a pair of 556 IC timers and a few discrete components would make a handy shift-management module similar in functin to the ones that BergWerks is selling. On the other hand, the one they sell is a nice, easily-programmable piece that pretty much plugs in, except that you need to do some splicing at the speedo sensor wires.


HTH!

John Speake

Hi Dr Bob,
Just had a look at the BergWerks website (thanks for the link Jim).

Interesting.......

I appreciate your comments about first gear on the later cars. I am pretty happy with the 'box on my car, especially when accelerating. Great fun selecting 2 at the lights, and letting it red line in first before it changes up......

The problem is at 30mph around town. I usually drive in 3 around here, it's slowish traffic. But if I enter an island slowly, and the exit is clear, and I'm doing 30mph or so, the 'box won't kick down lower than second gear, which is 3000rpm - no really "on the cam" of my Euro. If it would drop to 2nd on the kickdown switch, then I would have 4000rrpm, much more useful !

It appears that the later cars had a lower 1st gear ratio, and made the gap between 2nd and 3rd smaller. The latter is quite wide on my car.

It would be great to know what the differences are in those valve bodies,,,,,the electronics would be easy, especially when linked into the kickdown system, so you wouldn't have problems with it engaginging first at too high a speed when you are on light throttle, slowing down. But it would when at kick down.

SteveM928

The RPM signal to the lickdown relay is to more precisely control full throttle upshifts. Under normal driving the kickdown relay is closed. Full throttle closes the kickdown switch under the gas pedal, causing the transmission to shift into or stay in a lower gear. When the set RPM is reached at full throttle, the kickdown relay opens in response. That causes the transmission to upshift, just as if you would have lifted off the gas pedal to open the kickdown switch under it. This electronically controlled full throttle upshift method is used because it's much more precise and consistent than if the upshifts were controlled by something like vacuum or hydraulic pressure. No problems with varying full throttle upshift points, or hitting the rev limiter when you're allowing the transmission to automatically upshift.

Personally I don't care if there's any frst gear part throttle start. If somebody does figure out the higher road speed downshift to first gear issue, I definitely want that!