I think I understand this but the reason for a solenoid is so you can send a relatively low voltage to it so it can then complete the circuit for the heavy voltage requirements of kicking over a starter from the battery

that said, if you had a heavy duty starter button and just ran from the battery to the button then to the starter, you wouldn't need a solenoid

Is there something I am missing in this that would potentially damage the starter?

and yes, I'm from the old school of jumping the solenoid with a screwdriver.

Not voltage, it’s Amps. Is your button designed to take 100-150 amps?

I had an old Suzuki Samurai with a bypassed ignition switch and a button directly to the starter for years, and never had any starter problems.

The short version....don't try that.
DC current is highly prone to arching, DC switches are fast acting, very solid, locking throws for preventing DC arch.

A momentary, push button such as you describe is anything but what is required in DC switching.

It's theoretically possible, but the solenoid approach is better.

A cranking engine draws 200 amps or so. So short, heavy wiring is required.

At 200 amps, a 1/100th of an ohm of resistance will drop 2 volts. 1 meter of 15 AWG wire has that much resistance.

If you tried the "heavy duty" starter button thing, you'd better make sure it can handle 700-1000 amps. The solenoid has 2 functions on a modern starter. It engages the Bendix at the same time as it closes the contacts from battery to starter motor. The solenoid signal is not low voltage, it is battery voltage, but needs only a few amps to activate it. The starter will draw anywhere from 500 to 100 amps depending on engine size and ambient temperature. Wiring directly through any type of switch will be short lived. You would have to have battery very heavy (4 guage) wiring to attempt that.

That is, if I understand your question properly. If you are still using the battery cable to drive the starter motor itself and use the button to energize the solenoid only, then that's not a problem.

You wouldn't damage the starter, but that would need to be one heavy duty switch. Solenoids are pretty cheap and easy to replace. IMHO.

True kwfa, many vehicles back in the day skipped the whole solenoid thing ....generally with something that looked like a dimmer switch, but in fact was a high amperage momentary push button switch...usually foot operated. NAPA for one, still sells them, tractor starter switch sold under the Balkamp name, I paid abot 25 bucks for one last year.

“Ford style” solenoids are dirt cheap (less than $20) and work well enough that there’s no need to go jury-rigging something.

https://www.jegs.com/i/JEGS+Perform...V-Ovr9wIVSP7jBx0bkwW_EAQYAyABEgJg7_D_BwE

If you feed a motor proper voltage but skinny on the amperage supply you will damage most motors, lack of proper amperage will melt windings.

ok, good to know

this is for a smaller motor - 300cc or so

I just replaced the solenoid on it and it appears the switch is the culprit. I was hoping to just bypass it.

I found a 50A switch laying around but it sounds like that wouldn't be enough from the responses here. I'll try just bypassing the OEM switch using the new starter button and going straight to the solenoid. Just as easy and I don't need heavy duty cable.

The switch in a solenoid arrangement doesn’t handle much, most likely a 10 amp switch. The solenoid is just like a relay, the switch pulls in the coil( low amperage) engaging the contacts (high amperage) to the starter. Release switch coil opens and contacts open disengages starter. If bypassing the switch but keeping solenoid your switch is more than adequate.

Millions of Chevy six cylinder engines had a foot operated starter switch for about 40 years- - - -no solenoid. So did Ford Model A's and a bunch of other cars and trucks from the 1930's and 40's. Then the "engineers" got involved and tried to make things "simple" and "idiot proof". Pushing the foot pedal would spin the engine with the ignition switch on or off.

Sounds like a wheeler or motorcycle? If you put a push button on it to start you're bypassing the key and anyone could take it for a ride but if you want to use a push button see what amp rating your bad switch is and find a push button that's rated the same.

Interesting thread - appears here while I have a Delco Remy starter/solenoid combo completely apart on the bench. Removed it from the 1970 GMC 3500 with camper because the starter no longer will spin properly once it gets heated up from proximal exhaust connector - still spins fine cold. Am thinking it has never been off the engine in 52 years and 150k miles. Probably a better setup than the direct engagement pedal on the floorboard of my first car way back when.

I did not expect it to be a solenoid problem - and it isn't. It has been doing an OK job of switching high amps to the starter and engaging the Bendix drive. I will simply clean up the internal contact components, reset contacts as needed, and put the solenoid back together. As suspected, the starter brushes are worn to a nub and the bushings at both ends of the rotor are badly worn - so is turning sloppily and adding to the drain, especially when hot.

Installed new brushes (ouch - that is some tricky finger work for an old guy), recut and cleaned up the commutator, and replaced the brass bushing at the drive end. BUT, the supposedly correct bushing for the commutator end will not slip over the shaft and also will not go into its housing in the end cap - so the ID is too small and the OD is too big. Grrrr.

Now, unless I want to drive an hour to a bearing shop or good parts store in the "city", I'm going to have to deal with the computer-dependent low experience clowns at O'Reilly's in search one tiny component of the correct dimensions. With that bushing installed and all back together, will have the fun of trying to hold that load (for me) way up near the mounting site and re-installing all of the wiring before bolting it all back in. Actually, once I get it up to the area, will use heavy wire to hang it from the frame until time to bolt it in.

Just happened to be one of today's tasks. Yes, whomever said it, the Ford type solenoid itself is much simpler.

If the switch is bad...replace the switch. Momentary switch will be easy to find and keep all of the high amp protections working.

With a drill press and some careful file work you can make that bushing OD fit the end frame by using a bolt and a nut to hold the bushing in the chuck.. Then chuck the bushing (gently) in the press and use a piece of sandpaper and a dowel rod to open up the ID. Taking material off is easy- - - -putting it back on can be a challenge! No drill press? just bungee a hand drill motor down to the top of the workbench.

A 1/4" roll pin and a length of emery paper doubled over makes a pseudo flap wheel which will work to gain your clearance.

Many of the springs for the brushes can be used to hold the brushes in the over expanded position by side loading them.

Thanks - this is good - have done this routine in the past when confronted with other such bushing issues - set the drill press to run very low speed. In this case, just talked with a local mobile NAPA guy and he says he is going into Tucson and can have the one for this DelcoRemy by AM for less than $3. I will take the shaft and end plate over there in the morning - maybe got lucky - less tedious.

Found this informative. Puts it all together.

Very good overview video.

Solenoid is one of the strangest of words.

5sdad, i agree with you - and, actually thought the same when first I heard my Dad use the term back in the 50s or early 60s. I remember asking him what it meant and his explaining the device and how it worked (I was "helping" him diagnose someone's vehicle problem) and, as normal, I bugged him a bit (just one more time) by, once again, asking where that word came from. He said he didn't know which language, but it sounded like a Frog word - and then told me it had to do with a coil of wire shaped like a pipe - or cylinder. That's about all I've ever known about the term.

Think the screwdriver trick....
Why run a high amp (low gauge) wire on a round trip past all those gas transfer lines to an interrupt switch when a short run offers so much less resistance?

Especially since everyone pronounces it "sell - a - noyd".

No.

It's sole.

If your switch is going to be working with that current/load,
You need wires to carry it.

The solenoid allows much lighter weight/cheaper systems.
Plus as the heavy cables get longer, they need to be even heavier.