911Jetta

We're not talking high speeds.

Instead, just reducing the incessant up - down motion in town and at sub highway speeds.
I don't feel like I'm living on the edge by changing the spoiler activation from 50 to 75 MPH? Or even 100 for that matter.
My stock 4X4 height 964 feels pretty rock solid at 75 without the spoiler raising.

It seems pretty silly for it to cycle up and down 5 times on my way to work...

Porsche964FP

I understand the logic... personal preference as always. Would be good to have a switch that reverts back to normal for driving in anger though.

jody stowitts

GeorgeK: Sounds like perfect rationale to do the RUF idea. Or the cheap one the "savants" are proposing that lets you program in your own up and down values with no need for a manual "in cabin" control. These guys must be pretty sharp, and probably wont be long before its available.

Esel Mann Jr.

Hi All,

I'm going to make a couple of posts to break up the details. Note that all this information will eventually find it's way into a document, but I wanted to post it to get it out there.

I found the location of the spoiler control unit in my 1993. Essentially, locate the glove box ****, and follow down from there towards underneath the dash. Once underneath you will find a module attached to a bracket with a single screw. That's the spoiler control unit. Removal of the single screw permits the module to be removed from the mounting bracket. Note that there is a plastic alignment pin on the module which goes into a hole on the bracket. Once removed from the bracket the harness connector comes off easy enough.

If you do decide to remove yours, please take the time to disconnect the battery cable from the battery and wait several minutes to permit any capacitors associated with live electronics to properly discharge.

While this location and these details appear to apply to a 1993 non-turbo model year 964, past experience with Porsche leads me to be cautious about inferring it is the same for all model years (eg. 911Jetta's is located underneath the passenger seat).

So we now have information on the location for the 90 and 93 model years. If folks would be so kind as to chime in as to the location for the other model years, please do so. Pictures are great if you have them. My guess is that 89-90 is underneath the passenger side seat and 91-94 is underneath the dash at the glove box. However I would like to validate to ensure misinformation doesn't get out there.

Attached (I hope) are the pictures. Note if they don't make it into the post I'll try to figure out some other means.

Esel Mann Jr.

Hi All,

Ok with the spoiler control unit removed from my 1993, it's time for what's in the box???

Firstly, the part number of this module (as shown in one of the attached pictures) is 964.618.212.00. The name Sitronic is etched in copper on the top side. I would venture a guess that this is the company who either did the circuit board layout, or the company who did the entire design of the module. It is definitely a micro-controller (aka uC) based design.

The uC in question is a 4-bit NEC uPD75402AC. 1920 Bytes of programmed at the factory ROM and 64 nibbles of RAM. So, reprogramming the program area of the uC resident in the spoiler control module is not a reasonable approach. Because I haven't traced out the circuit, I can't be 100% certain, however after a quick perusal of the uC datasheet and user manual, it is unlikely that the settings (aside from selecting kph or mph) are made external and as inputs to the uC. My reason for not being more certain about the setability as an external input to the uC is because it's pretty balsy to design a masked ROM uC. Reason being once the program is in there, there's no changing it. With the way the automotive industry is constantly tweaking, I would expect the design to have a means to tweak it.

So, I've attached pictures for everyone's viewing pleasure of the module's innards. The next step for me is tracing out the circuit.

jody stowitts

Having done this alteration just yesterday (about 60-90 minutes because I proceed with more caution now that I'm no longer a youth), be apprised of a couple of details from my experience. This appertains to the "under dash" situation (91 Cab). 1) use a medium size phillips to remove screw while reaching up above the unit and use a downward counter-force to combat the considerable upward force needed to retract the screw from the plastic casing; too small a phillips will just roll-over the slots. 2) Unplug the black terminal from the gray box by lifting up the tangs on the side(s). 3)Note the numbered pattern of the wires 8 and 12 on the plug, remembering that you'll be working in reverse (mirror image) from the opposite side for pulling them away from their respective holes 4) Considerable jimmying is needed to prise off the plastic cover over the end of the terminal plug. 5)You now have access to the terminals*****BE CAREFUL NOW because the whole lot of them can slide out of their respective holes and can be a min-bitch to re-orient them back into position (ask me how I know) in this awkward position under dash.. Rest of procedure is in earlier section of this thread and reinstall is usual reverse procedure. *****snapping end cap back on needs considerable force!

jody stowitts

Addendum to previous post: To ascertain that indeed my unit was the "under dash unit", after removal from its bracket and unplugging the wire harness, I turned on ignition and used manual spoiler control on console----dead!----hence proving that indeed this was it.

jody stowitts

Having done this alteration just yesterday (about 60-90 minutes because I proceed with more caution now that I'm no longer a youth), be apprised of a couple of details from my experience. This appertains to the "under dash" situation (91 Cab). 1) use a medium size phillips to remove screw while reaching up above the unit and use a downward counter-force to combat the considerable upward force needed to retract the screw from the plastic casing; too small a phillips will just roll-over the slots. 2) Unplug the black terminal from the gray box by lifting up the tangs on the side(s). 3)Note the numbered pattern of the wires 8 and 12 on the plug, remembering that you'll be working in reverse (mirror image) from the opposite side for pulling them away from their respective holes 4) Considerable jimmying is needed to prise off the plastic cover over the end of the terminal plug. 5)You now have access to the terminals*****BE CAREFUL NOW because the whole lot of them can slide out of their respective holes and can be a min-bitch to re-orient them back into position (ask me how I know) in this awkward position under dash.. Rest of procedure is in earlier section of this thread and reinstall is usual reverse procedure. *****snapping end cap back on needs considerable force!

jody stowitts

Please excuse double entry!

mojorizing

Esel,

Here's a link to Cowtown's effort to produce a new module for the his 993

https://rennlist.com/forums/993-foru...ghlight=module

and

https://rennlist.com/forums/993-foru...ghlight=module


He used a PIC16FXXX if I recall.

From your pics of the board, is that the 18 DIP 600 mil version of the micro?
What is the value of the xtal?

It be nice to swap out the old 4 bit processor with a pin compatible 8 bit PIC of recent vintage.

Cowtown posted his asm of his project, but he pulled it from the mighty interwebs, and he hasn't posted in years.

FYI, the early years of the 964 had an auxiliary module also.... I'll post the schematics of the external
wiring/connections.

Here's a post listing the connects to the module
https://rennlist.com/forums/964-foru...r-spoiler.html

Kevin

mojorizing

My '91 has module number 911 618 112 00
Identical to this pic below

alexjc4

Looks a bit more old school. The la6324 chip is just an op-amp what's the number on the other one?

I've been thinking on this, and it would be cool to do something a little more advanced than was readily available in 1989, I'm thinking you could take inputs from the existing speedo input add and air intake temp sensor ($10), 2d accelerometer ($10) and plug these into an arduino and write a little code to intelligently raise and lower the spoiler depending on:

Driving style, say raise the spoiler if lat/long Gs are above a x or speed goes over y mph (ie you're giving it some beans) and keep it aised until say 90 secs after the Gs subside and speed goes below z mph.
AND
Independently, the spoiler could go up if the IAT goes above a certain value and stay up until it drops below a second lower value, regardless of speed or Gs.

On the issue of safety, I suspect the factory up and down values chosen are a little abitrary, based on local speed limits rather than aerodynamics (many cars active aero elements that are only really effective over ~70mph - below that they're just adding dag, but they have to come up earlier so you aren't just waving a flag to the fuzz to pull you over). The safety concern I'd have would be if the spoiler was setup such that it might lower in the middle of a medium speed sweeping bend, which might get a bit tricky. But the with the G based system you wouldn't have that problem so much, so I would probably set mine to 60mph and to lower and 40mph - leaving all other variables to one side - that would be a good balance for UK speed limits, allowing some posing around town with the spoiler down without it popping up at the first sign of dual carriage way.

Silvertarga

"FYI, the early years of the 964 had an auxiliary module also.."

That "auxilary module" is a relay Part No. 96461814200

koenig_roland

When i drove top-speed with my car for the first time three years ago, i realized afterwards that my spoiler was not working and i drove fifth gear in the reds without spoiler support from munich to nuernberg here in germany whenever it was allowed to drive "flat out".

There was no problem with stability or other side effects. Also oil temperature was "ok".

regards

Lorenfb

"With the way the automotive industry is constantly tweaking, I would expect the design to have a means to tweak it."

Not really. The up/down speeds are determined digitally in the microprocessor version
and are set in the microcode. There was no need to later change the settings once
Porsche determined what they wanted. It's not like there were some unknown outcomes.
The early analog version uses simple frequency to voltage conversion. That one can be
modified basically to any up/down settings. It's been done a number of times.