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So, my earlier life in analog/digital circuits says nearly $300 for a 86.5 kickdown relay is somehow avoidable.
Is anyone in the community repairing these mid-20’th century electro-mechanical devices?
These prices suggest there’s lots of margin for labor profit.
That Kick-down relay is pricey as it has an additional circuit that kills the Injection Pulse if the engine is Starting and not already running.
So it has two functions, normal mode is a Kick-down when at speed, the second mode is to clear a Flooded engine by holding down the accelerator peddle while cranking.
Wondering if a simpler relay could be used w/o the extra feature (just a Kick-down).
Wondering if a simpler relay could be used w/o the extra feature (just a Kick-down).
Dave K
Good question. I am not e-v-e-r spending $300 on that relay. At present there’s a jumper in place. And no, not a great idea but it works in the way I use it. Accel pedal kickdown isn’t used. A dead pedal button is blipped for passing. When it is sold, a good used or repaired unit will be inserted. In general the car is driven a bit more like it is 37 years old
The complicated relays are becoming more expensive but more cheaply made. Several of my customers send their 911 overrun relays for repair because the new ones just don't work as well. They are hand tuned for correct operation and hysteresis and in some cases this has to be done, in others generally dry joints are the culprit Also see 928 headlight relays. The modern replacements (I have not seen one yet) are 120GBP and use solid state switching according to one customer. He had an odd fault where the headlights would go out above 3000 rpm that went away with an original relay.
Edit. The new headlight relays use mini relays but they are failing due to poor component selection that overheat.
The complicated relays are becoming more expensive but more cheaply made. Several of my customers send their 911 overrun relays for repair because the new ones just don't work as well. They are hand tuned for correct operation and hysteresis and in some cases this has to be done, in others generally dry joints are the culprit Also see 928 headlight relays. The modern replacements (I have not seen one yet) are 120GBP and use solid state switching according to one customer. He had an odd fault where the headlights would go out above 3000 rpm that went away with an original relay.
Edit. The new headlight relays use mini relays but they are failing due to poor component selection that overheat.
Whats overheating, the coil or the load component?
Whats overheating, the coil or the load component?
I don't know the specifics but I imagine load as it's worse when high beam is used for a while. One of the UK owners studied the design and submitted a paper report to Porsche UK last year. Hasn't heard anything in reply so far unfortunately.
Unfortunately Porsche added lots of logic into their 'special relays' along with the actual electromechanical relay itself (sometimes multiple relays).This is usually just extra input diodes, logical functions or tachymetric sensors. These features might have been better just separated into a single or a few self contained modules that update as needed by model year (features) - while keeping the actual relay switching functions separate and standardized. Generally this part of the circuit should be very reliable especially when not heat cycled inside the relay can. The relay contacts do suffer from long term degradation especially on high loads and sometimes the coils can fail - but simple generic relays are cheap!
But too late for that now!
However some 'unavailable relay' features can still be recreated outside the relay allowing a standard relay to be used instead (but this needs to be documented somehow for future reference). The necessary external circuitry could be added on the back of the CE panel (e.g. input Diodes) or perhaps in another repurposed relay can for more complex functions - then wired into the circuit as needed via the CE panel.
I have some other ideas on this topic too but they are on the back burner for now. I did once build a tachymetric fuel pump relay from scratch in a repurposed relay can - so this is certainly doable for someone able/willing to get into circuit design and soldering - but again it's a one off thing every time - not really scalable (and not cheap or easy).
I don't know the specifics but I imagine load as it's worse when high beam is used for a while. One of the UK owners studied the design and submitted a paper report to Porsche UK last year. Hasn't heard anything in reply so far unfortunately.
Yes, I'm running their solid state DME Relay in my 911.
I've salvaged a failed headlight relay, by replacing one of the internal relays with a scavenged relay from another source. at the time I found what I thought would be a readily available replacement for the internal relays, but that was years ago and I'd need to go back and see if I could find the info. As I remember there were two configurations of internal relays in the headlight relay assembly and i only found one of the styles, and even at that it would be tedious as the trigger coil pins weren't aligned and would need to be de-soldered and relocated directly to the board.
luckily still had the old email from 2014.
Copy and pasted below:
"Finally got a chance to sit down and investigate the failed headlight relay from last month’s breakfast. There are 3 relays internal to the relay housing. #1 - controls the headlight motor, #2 - switches between high and low beam and #3 - supplies power to the headlights. Relay #1 and #2 appear to be specialty relays designed specifically for the headlight system; however #3 fortunately is a standard PCB mount relay.
I do not know which of the relays most commonly fails, but if the one I have is the common failure mode (headlights raise and lower, but do not turn on), then they can be fixed by replacing relay #3.
The "direct" replacement is relay part number V23133-A1001-A133. I also found another relay which looked promising (V23071-A1009-A132), but would require slightly more modification.
Both relays have the coil wires soldered to pins which are in the wrong place for installing into our combo relay, so the extremely thin coil wires need to be de-soldered from the pins and the pins need to be removed to mount the relay. V23133 is a SPDT (single pole double throw) relay which therefore has 2 sets of contacts, one for when the coil is energized and one for when it isn't. The V23071 relay is SPST (single pole single throw), only has a set of contact for when the coil is energized and is completely open when the coil isn't energized. Conveniently the installation in the combo relay only uses the one set of contacts which would allow the use of the V23071 if desired. Due to the SPST design of the V23071 one of the PCB mounting pins is located in a slightly different position; however this pin is not necessary and could be ground off.
The extra work of the V23071 may be worth it for 2 reasons.
1. from what I could find the V23133 cost about $12 ea. The V23071 cost about $6.
2. The V23133 is rated at 30A. The V23071 is rated at 70A so would potentially last longer.
For the combo relay, I took home, I conveniently scavenged a V23133 out of a defunct seat memory unit from my range rover, which I had laying around. After replacing the relay I tested it in my car and it seemed to work fine. Haven’t done any kind of a long term test though.
I would also like to try one of the V23071 relays but didn't have one available and the place I found to get them had a $30 min order so I would have had to get 6 to meet the order. Not that $30 is all that much to run an experiment, but I already had the V23133 available so tried it first. If you can come up with another relay to try to fix, I'd probably consider getting a few of the V23071s to try.
Lisa and I will be out of town this weekend, so won't make the breakfast/drive/lunch. Wish Laura happy birthday for us. I'll have to get the relay back to you at a later date, or could mail it to you if you like.
So, my earlier life in analog/digital circuits says nearly $300 for a 86.5 kickdown relay is somehow avoidable.
Is anyone in the community repairing these mid-20’th century electro-mechanical devices?
These prices suggest there’s lots of margin for labor profit.
Loren at Systems Consulting.....Genius at repairing old circuits/solving problems/inventing new circuits.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
07-06-2023, 10:58 AM
Is no one rebuilding/refreshing relays?
