Please post a picture.

 

Bill,

Thanks for the report, I also drive mine like a stick and have been doing that from day one and after your finding's I'll keep doing it. Only time my car hits D is when were rolling on to the Highway. I do my own shifting all through town and it has become second nature like I was shifting my 951. Thanks for trying it out.

Cliff 87 $ 4 Murf # 44

 

One thing that might stop many people from doing this is the stock "T" shift handle. It's a bit cumbersome in the hand. I have a Jager shift handle, and find it makes rowing the autobox more comfortable.

 

I disagree with you Bill. You cannot manually shift as well as the tranny will automatically if set properly. And it is not for only if you leave the lever in "D". You can set your cable tension and shift points on the tranny to shift at redline if you like. It takes some trial and error adjusting, but the final result is seamless and leaves both hands on the wheel. Anything but first will allow you to drop down a gear by the press of a momentary switch which will immediately drop a gear and rev out to the proper shift point you have set. No fumbling around (no matter how good you think you are) with buttons or making sure you don't shift too far up....or even into neutral or beyond. It takes a bit of thought to manually shift properly. No thought with hands on the wheel and concentration straight ahead of you with the momentary by-pass. Remember, this is a "kick-down" not a "kick up". The beauty as well, is even if you DO leave the lever in "D", you can still KD in any present gear to a lower one by just a toe tip...meaning if you are in "D" and the car is pulling in second, you can knock it down to first. I have seen the autos smoke the tires with a KD while cruising on the street. The KD comes in very useful when going straight, but really shows it's potential in the twisties. JMHO...strongly recommended

 

This was pretty much my experience with the S4 auto as well. Regardless of the bypass mod, fine tuning of the cables at the quadrant made a world of difference .... even though it is a bit time consuming. ( I set up one '88 for a guy that had never seen north of 4800 rpm - netting 6K shift points ).
With a switched bypass in place, one is not obliged to use it; however, when switched in, the more lively downshifting is the most obvious feature .... but the upshift can equally be prompted by a slight lift of the throttle.
Also, with the bypass switch engaged, I recall retaining full 'manual' control with the shifter .... specifically snicking down a gear in the braking zone and enjoying full engine braking identical to as if the switch was off.

Alas, now that the magnificant auto of the S4 is gone, I must row the 6-sp of the 4S .... ... so I trust these recollections are not favourably amplified by nostalgia.

 

Looking at the circuit, the KD switch applies battery volts to the terminals of the kick down relay. So this will not result in any current drain until the KD relay is triggered by rpm. I don't know what that rpm trigger point is.

So the gearbox solenoid will not be continously powered by having a permanent link.

Personally I think a foot operated momentary or on/off KD switch is the best option.

 

John - I recently learned more about the kick down relay operation (even though I don't have one). It is not intuitive.

The relay is not activated by the switch (or a bypass installed instead). Instead it is activated variously over the years by engine RPM, throttle position, speed, dynamic throttle inputs).

The relay terminals are normally closed and the solenoid is activated directly by the kick down switch (or bypass) though these normally closed contacts. When the solenoid is activated the AT control pressure is lowered & the shift point speeds are raised.

The kick down relay is activated primarily by an engine RPM signal (at high RPM points - from dash) which causes the relay to turn off the solenoid - this is what causes the shift to happen - which itself causes the RPM to drop and reengages the solenoid to hold the next gear until it gets to high RPM again...

So bottom line is you will engage the solenoid almost full-time if your kick down is always activated/bypassed. It does not seem to be a major reliability factor since I haven't seen reports of solenoid failure and as far as I can see its just operating a pressure relief valve so is probably quite low power...

So in summary:

The kick down switch causes the trans to hold in gear to higher RPM/speed.

The relay momentarily breaking the connection causes the high RPM shifts to happen.


I do also think a (left) foot operated momentary switch is probably the best option to control this.

Alan

 

Hello Alan
I didn't realise that the relay has normally closed contacts. What I said earlier should have more correctly stated "Looking at the circuit, the KD switch applies battery volts to the 12v side of the CONTACTS of the kick down relay".

So as I understand it, the KD relay may be opening its contacts at some predetermined rpm but until the KD switch is bypassed or normally activated then the KD relay can't activate the gearbox solenoid because there are no volts available to energise it (and then allow the relay to break those supply volts)

Do you agree ?

 

Yes - the KD relay is actually more of an "anti K-D" relay in most versions. Its job is only to disable the kick-down when the trans should shift or before a min speed has been reached. This is what is not intuitive at all about it - it works quite opposite to the switch.

Only in the GTS dynamic kick-down can the relay actually activate the solenoid itself. In that case it still retains the disable function - its just as if there is now also a parallel kick-down switch inside the relay. The schematics for the later relay do not show this extra contact set - but they must be there.

Alan

 

Talking about my '89 S4 here...

I can induce first-gear starts with the lever in drive, by taking a quick stab at the pedal on launch. This can be really quick stab to 1/4 throttle then back off to normal launch pressure. That's with the TV cable three turns tight from original, so that there is virtually no slack in that cable. The shifting was a bit too lively for my LA in-town in-traffic driving conditions, so I gradually set that cable looser until I could navigate in the 20-60 range without the annoying downshifts. That's three turns loose from original position, and that's where the TV cable is set now. I'd rather just let the engine torque move me through traffic at that point. Downside is that one must use the gear lever to get reasonable performance in the twisties. So the goal for a KDB for me is to give me two completely separate personalities for the car. I'm not sure a simple switch will do the job. For me, the dream shift controller would look at throttle position, manifold pressure, current speed, and current engine RPM's, and from those make a decision on whether it wants to pick a lower gear. I'd have a simple selector that would give me the current three-turns-loose grandpa mode option, the sport mode based on inputs listed, or the full-on aggressive mode with the pedal switch jumpered full-time. Ideally that selection would be made at a three-position slider switch embedded in the front of a Jager-style gear selector ****, maybe with a push-button added for instant solenoid action on demand. The switches/button need to be down far enough on the shifter that they don't get disturbed accidentally, yet high enough to be engaged easily without hunting for them.

I also want to mention that unanticipated shifts in the middle of a corner can easily upset the car's handling. One of the reasons I like the current grandpa mode is that I can select a gear with the lever and be fairly sure that the car won't accidentally downshift in a corner unless I demand it with the lever.


I've been gathering bits for the prototype controller when I see them. I need to find a throttle position sensor that gives a variable resistance as the pedal moves. There are plenty that mount on 'murican car throttle bodies; I'd like one that just has a link to the pedal linkage under the dash, out of harm's way and easily accessible. I have a MAP sensor, and the tach and speedo signals are handy in the dash already.

 

Dr Bob - why not go with the GTS Dynamic Kickdown - did you dismiss this option?

That TPS includes an angular velocity sensor - so it can detect the quick throttle stab you mention...

It does not have continuously variable throttle data but it seems to work very well - you can of course still combine it with a KD override since the basic KD mode still works the same.

Seems it would meet much of your desired operation.

Alan

 

Yep, we definitely disagree. I find manually shifting the autobox to provide much more control, including any gear at any throttle opening and engine braking that won't happen with the bypass.

 

Alan--

I do get the stab-to-kickdown action I want from a standing start, with what's in there now. How hard is it to get the GTS dynamic kickdown in my S4? I have been under the impression that this requires a valve-body change. Is there a simple fix?

 

Dr Bob - new TPS & New KD relay and a bit of additional wiring - 1 new wire between the new TPS & the relay should get you exact GTS 94+ behaviour. Actually not that hard to do electrically (but you have to pull the intake to swap the TPS. Its a little more complex on 88 and older...

See https://rennlist.com/forums/928-forum/245964-dynamic-kickdown-conversion-and-powdercoating-project-finished.html

Alan

 

You won't get any argument from me there. I may not have stated it, but I was not saying KD by-pass over manual shifting. I was just directing my thought to KD vs no KD. Using both manual shifting and the momentary switch really does allow for less need to sling the shifter up and down. When used in coordination with each other, there is less work and more/faster action.