Starter Relays, I recommend them on all cars now Options

[McMark]

I've been meaning to post this for awhile and Andyrew's recent starter thread inspired me. I used to recommend against a relay at the starter because it was always known as a 'hot start' relay, and hot start issues can be a sign of a wearing starter. So I considered the relay to be a baind-aid to avoid have to really fix the problem - a bad starter.

Jamie (JRust) was having some ignition switch issues and I started to rethink my position on the starter relay. I realized that the crappy reproduction ignition switches that are available now are prone to failure from having too much current pushed through them. They simply aren't built with enough focus on quality to stand up to the way Porsche/VW designed the starting system.

So now I recommend a starter relay on all cars in order to avoid undue stress on either old, tired factory ignition switches or crappy reproduction switches. This can be any 30A or larger relay and Bosch sells a starer relay kit, but I didn't like some of the choices they made, especially because it's sold as a universal kit, which means it doesn't fit nicely on anything. So I put together my own kit designed specifically for our cars. I also found a relay that has a fuse built in, rather than a separate unit.

A starter relay can be made with pieces available from your FLAPS, but for those of you who don't feel like going that route, I've made a few of my setup available for sale. This thread is more about sharing information though, so I'll exclude the details here.

[Spoke]

I like your re-fit. I want one. Looks very clean.

It is '70s technology to run the solenoid of the starter through the ignition switch. Powering an inductor like the solenoid is just bad for the switch. When turning off the solenoid, there is likely an arc across the ignition switch which can lead to premature failure. This isn't done at all today. Most motors, contactors, lighting, solenoids are likely controlled by relays or MOSFET or NPN solid state switches.

Would you please explain what is in your kit and show a schematic of the circuit? I'm curious of the fuse shown in the pic.

[jvmarino]

I added one to my car a few years back. I still have issues every now and then, but I believe it is due to poor electrical contact of the blade fuse, as fiddling with the fuse holder usually solves the problem when it does happen. It beats crawling under rear tire to jump the started solenoid with a screwdriver (especially if you are on a date (IMG:style_emoticons/default/smile.gif).

Your design looks nicely packaged, but one concern I would have with the installation location is the relay/fuse will be exposed to the elements (as well as the heat from the exhaust system). Mine is mounted on the rear wall of the engine compartment, and the fuse holder is a rubber capped unit. I am sure mounting it inside the trunk would be even better, I used my location for ease of wiring the retrofit, as well as easy fuse access.

Jim

[Mike Bellis]

(IMG:style_emoticons/default/agree.gif)
100%

All new cars have a starter relay. The ignition switch should never transfer that much current. Carbon builds up over time and will render the switch useless...

[jimkelly]

after getting my v8 engine connected to fuel and what not, and running it a little bit in my garage, several times the starter and ring gear did not fully engage. I do not know if my switch is faulty or not. BUT I've been thinking full power (consistently) may not be making it thru and have been thinking about this very thing. thanks to mark for always giving full thought to 914 issues. jim

I stumbled upon these pics I saved to my computer

[shuie]

Awesome. I have one in my cart to order. Why is it charging me CA sales tax in the shopping cart?

[Mark Henry]

Been doing this for 25 years. (IMG:style_emoticons/default/smile.gif)

[ConeDodger]

Yes please. (IMG:style_emoticons/default/biggrin.gif)

[Mike Bellis]

Awesome. I have one in my cart to order. Why is it charging me CA sales tax in the shopping cart?

California charges tax on all online purchases now.

[r_towle]

Why a fuse?

[Spoke]

Why a fuse?

I was wondering this too. The only thing I could think of is the red wire comes directly from the heavy starter wire from the battery. When active, the relay connects the yellow wire to the red wire (12V) with no fusing. The fuse must be to protect the relay and wiring from shorts.

[76-914]

Exactly. Nice install. I went the Ford route. +1

[Tom]

Mark, you are right on with this modification! The contacts in the ignition switch are not designed to handle the arc from the initial closing contact or the arc produced by the break of contact in ignition switches. Relay contacts , however, are engineered to suppress the damage by the arcing so they last longer. The engineers at VM/Porsche did a good job with what they had at the time, but there are much better solutions available now. I already modified my electrical system years ago to take advantage of newer technology or I would be following your advise.
Tom

[jimkelly]

I assume the high current circuit is grounded thru the starter.

how is the low current circuit grounded? is the another wire I am not seeing?

jim

[Spoke]

I assume the high current circuit is grounded thru the starter.

how is the low current circuit grounded? is the another wiring I am not seeing?

jim

Good catch. There should be 4 connections: 2 for coil and 2 for contacts. Maybe the case is grounded?

[jimkelly]

I do see a small wire loop underneath but can't see where it comes from or goes, but this must be it?

[Elliot Cannon]

So, where to I hook up the big assed wire that comes from my battery? I want one of these but it better come with instructions. (IMG:style_emoticons/default/laugh.gif)

[jimkelly]

I think the big assed wire from battery goes to same stud on starter as the red wire pictured above, thus it is where the red wire pictured above gets its power from.

[Mark Henry]

I think the big assed wire from battery goes to same stub on starter as the red wire pictured above, thus it is where the red wire pictured above gets its power from.

Yep

[jim_hoyland]

Is that a 3 PIN relay ? Is the clamp The ground ?