Well, it’s been about a year since I finished my 914 restoration, you can read all about it

HERE.

Everything works perfect except for the electrical problems I’ve been having with the relay board. I spent lots of hours trouble shooting electrical issues with the fuel pump. It turs out that my relay board had some bad connections for the fuel pump relay. After searching this site I discovered that the relay board is truly the weakest link in the 914. I tried to remove the epoxy bedding underneath the board and resolder the connections. This worked for a while but the fuel pump would sometimes stop and kill the engine. I finally figured out that the contacts for the fuel pump relay to the board were causing the problem. This seems like a never ending problem. I could buy another 40 year old used board and have the same problems.
So, to make a long story short, I decided to design a new relay board from scratch. I replaced the original electromechanical relays with industrial solid state relays. They have the same connection labels as the stock relays: 85 & 86 for the coil and 30 & 87 for the switch. The relays are available at most electrical parts dealers like Mouser or Digi-Key if one ever needs to be replace. They also use a lot less power than the original 914 relays. Also, since they are solid state and don’t have any moving parts they will last a lot longer and are more reliable. I also replaced the old ceramic fuse with a modern ATC style fuse and added an LED that illuminates when the fuel pump has power. This is great for trouble shooting fuel pump issues. It comes on for a few seconds after the key is turned on and stays on when the engine is running. Also, I removed the connections and plug for the rear window defroster. I used wires soldered to the connectors eliminating all of the riveted connections. All connections are soldered. To make the board I CNC machined the board out of high density polyethylene plastic.
I built a few extra boards to offset some of the development costs. They are quite labor extensive to build so I don’t plan to mass produce them. PM me if you want one. I would like to get $500.00 each. That includes the board with the solid stare relays. It does not include the voltage regulator. I used a solid state one from Pelican Parts. Both the stock and solid state voltage regulators will work.

Wow...

Very nice!

Just a FYI, i was able to buy a brand new relay board from Porsche not too long ago.

Thanks for posting; I saw your car at the PCA Concours in Dan Point and was impressed with your relay board.....very clean looking. Is this going to be a one-off or are your going to produce them ? Even a kit would be very cool

Really cool!

What's the back look like? Did you make the pins as well? I'm working on a similar project, but will be severely modifying the layout to better suit my car.

Very impressive. You have some skills there.

David

I like it!

I'm running solid state relays on my car too. They work great and trigger as low as 3VDC.

Holy crap that is cool!

Wish I had the cash as that is likely one of the best changes you could make in a 40 year electrical system.

Very nice work. Not in my budget right now, but perhaps in the future...

Very impressive - nice work!

Thanks,
The back is filled with epoxy to seal in all of the wires. I found a supplier for the pins. Are you using solid state relays?

Am I missing it or is there no plug for the heated back window? Very upscale replacement.

Damn...that is a nice assembly....Tormach mill?

I take my hat off, sir! Amazing stuff!

Menno

Doesn't this belong in the Sandbox?

...because that is pure 914 porn!

There was only room on the board for 3 solid state relays - Power, Fuel Pump and Heater.
Also, my car doesn't have a heated back window.

Wasn't planning on it. I'm a bit of a nut about emulating originality, so I'm debating between original round relays and more modern Bosch square relays. But I still totally appreciate the upgrade to solid state. If I could find a solid state that looked exactly like an original round relay, I'll buy 100 right now.

What is the diameter of the stock round units? There are mini-ISO relays that are ≈25mm square, maybe remove round covers and put these over? There are smaller ones but then you get into thru hole mount or surface mount assembly and your costs are really going to go up.

+1
First Class product

I'm gonna sound redundant but...that's some damned impressive work. Well done. Wish I had five Benjamins laying around just so I could display that in my engine compartment.

That is some very nice work there.

Question for you Looks like they are. Are the Solid State Relays are serviceable ?? And is there a warranty?

Very cool. Nice work. I assume it won't work on a six?

No affiliation with OP and hope not to step on ones toes....

SSRs are not serviceable, there are 0 moving parts inside, the plus to this is no mechanical wear or pitting. The downside is no way "activate" the relay without the power signal unless you use 12vdc jumpers which isn't difficult since you have a 12vdc power source (your battery)

Another downside is that while most of the time mechanical relays fail in the "off" position, SSRs have a tendency to fail in the "on" position when they fail which is not too often, we use and others use SSRs on million dollar equipment all the time so I really wouldn't worry about them failing (I wouldn't buy an SSR from some Chinese reseller like banggood for my car or equipment at home!) Stick with name brands and you should be fine, the SSRs should last as long as you own your vehicle.

Nice blend of modern technology !

Mueller is correct, these are not serviceable. Not many digital electrical components are. I'm not sure if the stock 914 ones are. However they are, on this board, easily replaceable. Also, these are not Chinese.

I like this a lot. Did you do your own pcb, or how did you connect all the components together on the backside of the board?

Impressive, got to be in the hundreds of hours in development.

In 10 years of industrial experience, we had hundred of SSR in our industrial ovens and had less than 1/2% fail after 3-5 years of 80% duty cycle at 70% load rating.


In my opinion, those relays will last a very long time

As long as you don't dead short them....

That is a work of art worthy of being framed and hung on a wall!!!

That would be awesome ..

I used wires to make all of the connections. After it was all soldered and tested I filled the back with electrical epoxy potting compound like the original board.

Hi Steve, my apologies if I made it sound like you are using Chinese components!

And thanks for not getting too upset with me replying to your thread!

No problem. I never thought you were implying they are Chinese and you brought up a good point.

This will go very well with my 160 amp alt kit. It is a single wire so no need for regulator. Does it come complete with all relays and does it have a cover? Can u give me a price shipped to san jose, ca 95124

It comes with all of the relays and no cover. I'll pay for the shipping.

Steve

I would like to get with on the relay board. Wes

I wish you made one of those boards for the Sixes. I definitely would buy one.

Hello Steve,

Do you have any left, and has the price point come down ?

I live in so cal so shipping should not be a big deal

Yep, I still have some left and, sorry, the price has not come down.

BTW, I'll pay for the shipping.

Steve

These are beautiful! Worth every cent.

Click to view attachment

Drooling over this, I have some observations and questions:

* This board would not work for 914s with a rear window defroster
* This board would not work for the 1972-only 914s that use pin 3 of the 12-pin connector for an oil temp sender circuit (to the dash gauge)
* Why the difference in the slotted/Phillips screws on the corners of each relay? Are those screws are ready power sources in the engine bay?
* Would you consider making a kit with just the base and parts list/instructions available?

Hi Jeff,
* This board would not work for 914s with a rear window defroster .Yep, there was only enough room for 3 solid state relays. I read somewhere that only about 5% of 914 have a rear window defroster. Is this true?

* This board would not work for the 1972-only 914s that use pin 3 of the 12-pin connector for an oil temp sender circuit (to the dash gauge)
Good point. My car is a 1973 and I didn't notice that there is a difference. Are there any other differences between years for the relay boards?

* Why the difference in the slotted/Phillips screws on the corners of each relay? Are those screws are ready power sources in the engine bay? . No reason. one of the relays I got had different fasteners.

* Would you consider making a kit with just the base and parts list/instructions available?
Maybe in the future. Right now I am working on another project.

Your work is commendable Steve, I hope you can find a way to make these available to the masses. I understand that the 914 was one of the first if not the first vehicle to use a configured board like this and a modern replacement using current technology would be welcomed. If a kit was available, there are enough DIY types here that mounting the relays and wiring it up would be one way to minimize the investment. Maybe a group buy in quantity as well. Mark Whitesell may be interested in producing them with your assistance, especially if they can be molded or done in a production mode. "Mikey914"

The 914/4 boards were all the same, but the three harnesses that plug into them were different. The 1972-only ignition harness is the only one that uses pin 3 of the 12-pin, I don't recall if the chassis harnesses interface with the board differently, would need to research it. The /6 guys need their version just as much as the /4 guys do.

Thanks Jeff.
I already spoke to mark about these. Unfortunately, when I designed this board I was not thinking about mass producing them. I have a good day job. I really just planned to make one and a couple extra to sell to help pay for some of the tools I needed. The board itself is machined from plastic using a CNC mill that uses 10 different tools (end mills and drills) and takes 3 hours to machine. My mill does not have an automatic tool changer so I need to be near the mill for the 3 hours. Also, the relays are industrial quality that are used in robots and medical equipment so they're not cheep.

However, I think it could be redesigned to be machined on a CNC router with one tool and use automotive solid state relays. Right now I just have too much on my plate.

Small hijack (the relay board is AWESOME BTW)...do you know of a source for automotive SSRs? Hella and Delphi are supposed to make some but I've never actually been able to find any to purchase.

Rallylights sells one:

http://www.rallylights.com/hella-hl87251-m...ay-12v-20a.html

Click to view attachment we use these at work...

Any good relay boards for sale?

I am asking since driving around the neighborhood for 15 mins then smell old glue smoke. Not sure if the relay board as also, feel less power after the smell.

History behind it is a local Porsche mechanic re-started the engine by tinkering with the relay board and finally unplugging one of the relays (the bottom left hand).

Don't know much about the electronics but need some assistance if need a new relay board.

Any guidance?