Hard Start Relay Kits

[MNAirHead]

In the magazines they have "hard start relay kits"

Are these a waste of time?

I'm sure one of the answers is to figure out why it's hard to start...

Are these just a new relay?

[Speedy Jim]

I'll have to weigh in on this one.

The problem lies in the fact that the starter solenoid draws as much
as 35 Amps to initially pull in! It works great when
connections are new and bright AND the Ignition switch contacts
are up to the job. But after 30+ years, those assumptions aren't valid any longer.

The weakest link, historically, has been the ignition switch. If you
take a new one apart, you'll find incredibly flimsy contacts meant to
carry 35 Amps! They overheat after a short time and then the
plastic melts and the contacts only make "some of the time".

A 12V relay, on the other hand, only draws maybe 1/2 Amp to
energize its coil. So, the hard-start kits put the relay between the
ignition switch contacts and the starter solenoid.

It's a great fix, in my humble opinion, and can save you the
onerous task of replacing that ignition switch time after time after........

You don't have to buy a special kit; a common Bosch relay can be
used. Glenn has a nice diagram http://www.glenn-ring.com/temp/diagram.jpg

[MNAirHead]

Speedy.. thanks..

I haven't broken the blister pack on my original Gene Berg relay knowing there was a better solution.

T.

[2088 bob]

the only mod i make to the above drawn circuit is the wire that goes from the starter heavy power cable to pin 30 i make a 10 ga wire don't normally fuse that one and the wire that goes from pin 87 back to starter input pin i make that a 10ga as well

[ChadRat]

Is there any specific size of relay to ask for? what size wire would you use on pin 86 and 85?

[MNAirHead]

Speedy.. (or someone)

1-how much does a selenoid pull -- I've never measured it..

2-there is a difference between 12 and 6v isnt there?

[Glenn]

Actually I have a easy writeup on how to make your own.

http://www.glenn-ring.com/tech/relay_starter.htm

[Badbugtwo]

…how much does a solenoid pull -- I've never measured it.

I’ll have to measure an actual bug starter sometime, but in the electrical class that I teach, we have tested numerous starters and I believe that the highest we have seen was 80 amps! This was on a GM V-8 starter and was with both the pull-in and hold-in windings measured.

…there is a difference between 12 and 6v isn’t there?

Again, I haven’t measured it, so can only speculate, but in theory to do the same work (wattage) you would have to double the amperage if you cut the voltage in half.

…A 12V relay, on the other hand, only draws maybe 1/2 Amp to
energize its coil…

Actually it is even better! On those small ISO relays, I have measured between .15 to .18 amps to energize!

Actually I have an easy write up on how to make your own.

Good article Glenn, the only suggestion/correction that I would make is that technically the 85 terminal should receive negative voltage and the 86 terminal should be connected to positive. On many relays it wont matter, but if you get a hold of a diode suppressed one, it will destroy the diode and render the voltage spike suppression useless if not wired this way.

[sagaboy]

It took me quite a while to realize that; simply put...

The ignition key contact supply voltage to energize the relay (instead of the starter solenoid) and the relay contacts supply power to energize the starter and is the preferred round about way due to poor ignition key contacts of old age.

Therefore, the "Hard start relay" has absolutely no relationship with the: Starter, starter solenoid, the old connecting wires, the battery or its supply.