1720 Ford starter grinding problem solved by rewireing starter functions

[90cummins]

My 1720 started having intermittent issues with grinding months ago when starting in cold weather.
I removed the starter & found no obvious problems but did notice some oil in the solenoid so I cleaned it to eliminate the possibility of that causing slow engagement, I did noticed 3 spots on the flywheel that were taking a beating but nothing serious.
I bought a new solenoid for good measure and installed it and it was fine till a couple weeks ago.
The grinding became serious requiring 2 or 3 attempts to start so I pulled the starter again which looked fine but the flywheel was worse.
I tried to dress a couple teeth but quickly gave up on that.
A new ring gear costs $300 plus 16 to 24 hours of labor so that wasn't going to happen.
Thinking about the start process I reasoned that if I allowed the starter drive to engage the flywheel before the starter motor started turning I could solve the problem.
What I did was purchase an old 70's style Ford starter solenoid to separate the 2 functions that occur automatically.
First I removed the battery cables from the starter leaving only the wire that energizes the starter from the key switch, then I spliced into that wire to supply power to a pushbutton switch only when the key was in the crank position.
I then ran another wire from the pushbutton switch to the new solenoid which would then energize the starter motor cranking the engine over.
The battery cables that were removed from starter were connected together along with a new longer battery cable which was attached to the new Ford style solenoid which was mounted on the fire wall.
A new cable from the new solenoid was directly attached to the wire that goes into the starter housing which energizes the starter motor.
A small ground wire was attached to the starter solenoid terminal that formerly had the wire which runs into the starter motor, this is a necessary ground for the solenoid on the starter to function.
This has solved the grinding by allowing the starter drive gear to engage the flywheel before spinning.
The safety interlock's intact preventing starting while in gear.
Currently when I start the engine I engage the starter gear then bump the starter button to ensure the gears are engaged.
Hopefully this will save someone the expense of replacing a flywheel or ring gear.
This should work with any vehicle that has a starter with an integrated solenoid.

Thanks
90cummins

 

[BertZegers]

My 1720 started having intermittent issues with grinding months ago when starting in cold weather.
I removed the starter & found no obvious problems but did notice some oil in the solenoid so I cleaned it to eliminate the possibility of that causing slow engagement, I did noticed 3 spots on the flywheel that were taking a beating but nothing serious.
I bought a new solenoid for good measure and installed it and it was fine till a couple weeks ago.
The grinding became serious requiring 2 or 3 attempts to start so I pulled the starter again which looked fine but the flywheel was worse.
I tried to dress a couple teeth but quickly gave up on that.
A new ring gear costs $300 plus 16 to 24 hours of labor so that wasn't going to happen.
Thinking about the start process I reasoned that if I allowed the starter drive to engage the flywheel before the starter motor started turning I could solve the problem.
What I did was purchase an old 70's style Ford starter solenoid to separate the 2 functions that occur automatically.
First I removed the battery cables from the starter leaving only the wire that energizes the starter from the key switch, then I spliced into that wire to supply power to a pushbutton switch only when the key was in the crank position.
I then ran another wire from the pushbutton switch to the new solenoid which would then energize the starter motor cranking the engine over.
The battery cables that were removed from starter were connected together along with a new longer battery cable which was attached to the new Ford style solenoid which was mounted on the fire wall.
A new cable from the new solenoid was directly attached to the wire that goes into the starter housing which energizes the starter motor.
A small ground wire was attached to the starter solenoid terminal that formerly had the wire which runs into the starter motor, this is a necessary ground for the solenoid on the starter to function.
This has solved the grinding by allowing the starter drive gear to engage the flywheel before spinning.
The safety interlock's intact preventing starting while in gear.
Currently when I start the engine I engage the starter gear then bump the starter button to ensure the gears are engaged.
Hopefully this will save someone the expense of replacing a flywheel or ring gear.
This should work with any vehicle that has a starter with an integrated solenoid.

Thanks
90cummins

I am thinking that with replacing the starter button by a small automotive relay you can make it work with the key only.



The right image shows how the big starter solenoid contact is used to switch the automotive relay to ground. The automotive relay positive would be powered from the contact switch.
If the key is turned to START, the solenoid on the starter is energized and is pulling the drive gear in the ring gear. The contact in the starter solenoid closes and the automotive relay is energized. Than the added solenoid is energized and the starter turns.

 

[90cummins]

Your drawing only adds an additional switch between the battery & key noting else.
My additional solenoid separates the 2 functions that happen simultaneously when the starter is engaged.
I bypassed the starter (motor run) contacts in the solenoid switch so the solenoid would only engage the starter drive gears.
The additional solenoid energized the motor to crank the engine.
The reason the starter was not engaging (grinding) is because the side of the gear on the flywheel where the starter gear enters is rounded over preventing the starter from properly engaging as the starter was turning.
By allowing the starter drive gear to Firmly contact the ring gear before the starter is turning the grinding is prevented.
I apologize if my explanation is confusing. I would illustrate with a drawing but I’m terrible at it.

90cummins

 

[Dataway]

I was having similar problems with my 1715, flywheel appeared fine ... looked over the starter seemed fine, bought a new one anyway ... problem solved. I put up with the intermittent grinding for two years. Found a new starter on Amazon for about $160.

 

[BertZegers]

Your drawing only adds an additional switch between the battery & key noting else.
My additional solenoid separates the 2 functions that happen simultaneously when the starter is engaged.
I bypassed the starter (motor run) contacts in the solenoid switch so the solenoid would only engage the starter drive gears.
The additional solenoid energized the motor to crank the engine.
The reason the starter was not engaging (grinding) is because the side of the gear on the flywheel where the starter gear enters is rounded over preventing the starter from properly engaging as the starter was turning.
By allowing the starter drive gear to Firmly contact the ring gear before the starter is turning the grinding is prevented.
I apologize if my explanation is confusing. I would illustrate with a drawing but I知 terrible at it.

90cummins

This does exactly the same as you are describing, but is using only the start switch to accomplish this.
I hope this diagram explains better what I suggested.
The starter wire on the starter solenoid is removed and connected to the added solenoid. Then the freed connection is connected to ground. The battery wire is removed and connected to the added solenoid. Then a standard automotive relay is added to the circuit.
Click on the picture to enlarge.


How it works; when the existing start switch is closed, the solenoid on the starter is energized and pulls the starter gear into the flywheel gear. (Or against it because it is not turning) At the same moment C1 is closed and the automotive relay is energized and C2 is closed. If C2 is closed then the added solenoid is energized and C3 is closed and the starter turns.
After releasing the start switch all contacts open and the starter gear moves back.

Only one switch, the start switch is used for starting.