headlight relay question

John Barbieri

True Classic
exactly what type of relay should I be looking to source? I got a pair of 12v 30a relays from Partsource that have plastic bodies and the mounting ears are plastic as well. The wiki instructions for performing the headlight relay state that the relays must be well grounded to the body, this is not possible to do as the body of these relays are plastic. Also, the wiki instructions state that the relays must have their leads mark with L, S and B. These relays have one lead marked with numbers 86,85, 30 and two of them 87. There are 5 leads. Do I have the incorrect type of relay? I asked for 30a relays and they told me this is all they have. TIA
 
Those relays are correct.

Ground 85 OR 86 on each relay. (choose one)
You don't need to ground the case.
 
This might help.
A relay is just another switch you add so the device (headlights) can get more direct power instead of that power running through other circuits and switches, like your headlight switch and all that. You use the stock switch (light switch in this case) to trigger the relay and the relay allows the current to go to the headlights directly, avoiding loading down the original switch and all those old tired connections. I added two (one for high beam, one for low) right in the rat's nest above the fuse box. When it says to "ground the relay" it means the wire from the relay that goes to ground (usually pin 85) has a nice solid clean connection to a good grounding point.
 
Sounds about right

From your description, sounds like you need (and have) a bosch-style relay.

Lots of recommendation from folks here about the best sources.
Lots of options on ebay, the auto parts store, etc.

I purchased these: http://www.ebay.com/itm/5-12V-12-Vo...024?pt=LH_DefaultDomain_0&hash=item3f240211b0

Seem to be well built. Very solid/heavy with good specs including air/water tightness. However I'm a noob and haven't any significant long-term experience with what I've purchased.
 
You wrote, ..."two of them 87..."

****EDIT: See Greg Smith's (budgetzagato) post for more comprehensive info.

Actually, one is 87 the other is 87a.

On a 5-pin standard Bosch type relay, when the relay energizing circuit (85-->86) is not powered, pin 30 connects to and powers pin 87a and pin 87 is "dead." When the energizing circuit is powered, that flips: pin 87 gets the power from pin 30 and pin 87a is now "dead."

When using the five pin relays, the safety point is to know that even though the relay is not energized, that unused 87a pin is live so best to cover with heat shrink or a spare insulated spade connector.
 
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I too get them in bulk off ebay with the harnesses. I've got 'em all over my car. 5 I think, 2 headlight, 2 wiper, 1 solenoid
 
Not necessarily Dan...

Some 5-tab relays have two (87) tabs (Single Pole Single Throw or SPST), some have an (87) and an (87a) (Single Pole Double Throw or SPDT). The ones that have 2 (87) tabs are what I use in my Spider relay kits, since each of the (87) tabs can power a light. These are also called "normal" and "switching" relays respectively, and the Bosch ones in our cars are either unmarked (SPST) or marked with a red stripe (SPDT).

Here's the similar but different SPST relay:
IMG_9103.jpg


Here's a pic of the pin-out diagram on a SPDT relay:
IMG_9102.jpg
 
Some 5-tab relays have two (87) tabs (Single Pole Single Throw or SPST), some have an (87) and an (87a) (Single Pole Double Throw or SPDT). The ones that have 2 (87) tabs are what I use in my Spider relay kits, since each of the (87) tabs can power a light. These are also called "normal" and "switching" relays respectively, and the Bosch ones in our cars are either unmarked (SPST) or marked with a red stripe (SPDT).

Here's the similar but different SPST relay:
IMG_9103.jpg


Here's a pic of the pin-out diagram on a SPDT relay:
IMG_9102.jpg

yep, that's what I got. Can someone translate the numbers to the instructions for the wiki headlight relay mod? TIA

also if someone can also translate for the wiper relay mod, I'd really appreciate it. Thanks.

what else can I put a relay on? Fan blower motor? Turn signals? both of these drain the electrics. eventually I'd like to eliminate all drains with relays.
 
Easy...

It's easy enough; 30 is power in from battery or fuse panel, 87 is output to light(s), 86 is signal power from original light power wire, 85 is ground. You can swap 86 and 85 if you want, but 85 as ground follows the DIN standard.
 
Here's an attempt to share a diagram of how I did mine. Not the "best" way but pretty easy way and sure did help.
headlightrelays_zpsb48bc6b7.jpg
 
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Believe it or not Dan,

You have more with the 87/87 relays in your X than the 87/87a type. :)
 
Indeed, most 30A relays today are plastic with...

a ground lead necessary to one of its terminals.

In the OLD DAYS... they were INTERNALLY grounded to the STEEL casing so you would need to be sure they were mounted to a good ground source, usually the chassis or a part thereof.
 
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