Starter/Flywheel grinding

[Ryan_M]

I installed the MB motor in the red 3A over the weekend. I have much to say about the entire process but this post will focus only on the starter issues.

For the swap I installed an MB motor with original flywheel and a NEW 124 tooth ring gear on it (NOS from QTM parts). I used the same 3A bellhousing.

When I depress the foot pedal to start the jeep the starter grinds on the ring gear. The Jeep will start but something is not right. I checked the old 3A motor to confirm that flywheel also has a 124 tooth ring gear - it does. Not sure if maybe the starter is spinning before it meshes with the ring gear?

I found and adjusted the starter button in and out but it makes no difference in the grinding. The sound does not transfer nearly as well as I had hoped in this video but I'm posting it anyways. When then starter is turning it doesn't grind but makes a much raspier and metallic sound than normal. The second the engine starts to fire the starter grinds no matter how fast I take my foot of the plunger. It's much more pronounced in person.

[media]https://youtu.be/PpS8EDyyJfc[/media]

Just for kicks I measured the distance from the face of the starter to the face for the ring gear teeth on the installed set-up - roughly .0942". Measuring the old motor now sitting on the floor it was .0977". Pretty close.

I'd love to know if I'd still have this same grinding if I swapped the old ring gear and flywheel onto this MB motor. Not too thrilled about having to pull the motor again to do it though. I removed the starter and reinstalled. No difference. Anybody see anything alarming?





And no matter what I do to this pic it still shows up here upside down....


As you can see the new ring gear teeth are not at all beveled. The ring gear teeth on the old 3A motor are very slightly beveled...the first noticeable difference between old and new. I need to research some more but I've found other references online to 3A ring gears not always being beveled.

When I have more time this week I'll see if I can swap the starter from my gray 3A just to try and pinpoint the exact culprit. Any suggestions? Anyone else have a 3A ring gear without beveled teeth?

[athawk11]

This is puzzling.  New ring gear.

Just a thought...Did you get it fully seated on the flywheel?

Tim

[Ryan_M]

This is puzzling.� New ring gear.

Just a thought...Did you get it fully seated on the flywheel?

Tim

I am certain the ring gear is seated all the way. This morning I swapped starters with the gray 3A and have ruled out the starter as the problem. No matter which starter is where the gray 3A starts fine and the red one grinds.

I also noticed the gray 3A does not have beveled ring gear teeth either. They are worn a bit but appear to have been straight cut when new. Really puzzled here.

[athawk11]

Okay,
How about the rear engine plate?� 3A or MB?� And are they the same thickness?� Just throwing ideas.

Tim

Edit: The reason I wondered if the flywheel wasn't seated...I can see a small silver band on the flywheel.� A ghost of the previous ring gear?

[Ryan_M]

Okay,
How about the rear engine plate?� 3A or MB?� And are they the same thickness?� Just throwing ideas.

Tim

Edit: The reason I wondered if the flywheel wasn't seated...I can see a small silver band on the flywheel.� A ghost of the previous ring gear?

Good eyes Tim and you did make my stomach jump into my throat when I looked at that pic again. However, the ring gear seats up against that lip on the clutch side of the flywheel and it is seated all the way back. The "ghost ring" is where the MB ring gear was seated so either that one wasn't pushed in all the way or - more likely- was slightly thicker. Confused yet?

Yesterday I measured the distance from the face of the starter to the face for the ring gear teeth -roughly .0942". Measuring the old motor now sitting on the floor it was .0977". Pretty close. I am using the MB rear plate.

I don't have the clutch cable hooked up yet (waiting for parts) but I can't imagine that would make any difference either way. I'm not shifting - just starting in neutral.

[athawk11]

I am following you on this.  Here is a photo of my flywheel.  I removed the gear and flipped it over so the starter would engage fresh teeth. (I'm cheap)  You can do this with some non-tapered ring gears.



But it still may be why the starter gear isn't engaging quite as well.  If the new ring gear isn't as thick, it would be further from the starter gear.  So, could the mesh up not be as solid?  It may not be significant enough to make a difference, but the only new addition to the equation is the ring gear.

Tim

[Ryan_M]

Tim do you know if there is any adjustment on the starter to make the gear engage further?

Worst comes to worst I pull the motor and install the flywheel/ring gear from the old motor. I'd just really like to not do that if I can help it.....

[aboyandhisdog]

Hi Ryan,  you said you messed with the starter button on the starter.  Screwing it in all the way will allow the lever to throw out the pinion as far as possible before the electrons hit the starter motor, so screwing it in is the way to go.  I had a very similar (maybe identical issue) with mine last summer.  I installed a new ring gear - no change.  Rebuilt the motor - no change.  Installed three different starter drives for different motors - no change.  Finally...screw it...I put in a new one of those little 12v racing gear reduction starters and have never had an issue since.   

Important to note that my old starter had just gotten worse over a few years time.  It had worked flawlessly once, but deteriorated over time.  Got worse and worse until it would only engage the ring gear about half the time.  I can't explain it...must have been something wrong that the  starter rebuilder didn't pick up on.  I know this is of little help to you.  But I did find that screwing in the button was the only thing that was of any help at all.

[athawk11]

Ryan,
I think Tom's input is more helpful than mine would be.� I don't have a 3A starter on any of my Willys.� I had to go mess with my spare 3A starter just to understand what Tom was talking about.� :-?

I did measure the throw on this starter.� The adjusting screw is about 3/16" from being driven all the way home.� When I push the lever, the drive gear moves 5/16" before it touches the start button.� When I push the start button all the way home, the drive gear moves an additional 1/4".� So, a total of 9/16" throw when fully pushed.�

None of this is probably helpful to your predicament.� I'm pretty sure you've eliminated the starter as the issue.� I don't even know if this starter works.

Were you able to check the thickness of the rear plates?� Any difference?

Tim

Edit...Please note: My 3A starter is the later version.  Yours is the earlier version...which makes my input even more useless

[garage gnome]

I wish I had my engine back together so I could measure for you

[Ryan_M]

I appreciate all the input. Even if it's just random thoughts one of them is bound to be the culprit. I have both early and late 3A starters that I have tried and the result is the same with both, even after adjusting the button.

Engine plate thickness on the gray 3A, the old red 3A motor, and the new MB motor are all the same: 0.102"

The new ring gear teeth themselves are slightly smaller in front to back depth. The new teeth on the MB flywheel are 0.34" and the gray 3A and old red 3A teeth measure 0.378".

I am out of time this morning but I have a couple other things I want to rule out. I'd like to see what is happening at the starter when I push the starter pedal. Since I only have one set of eyes I will set up a camera to do this. Is there a chance the starter pushrod is fetching up on something? The bottom of the coil maybe? That might be limiting the distance of the throw. Hopefully I get home early enough tonight to mess around some more.

[athawk11]

So a smidgen over 1/32" difference in ring gear thickness.  I can't see that being a factor.

Looking forward to the culprit.

Tim 

[aboyandhisdog]

Ryan, you make a good point about that push rod.  I had one on mine that had been mostly straightened out as I recall, with only a small 90 degree bend at the end.  I bought a new one from Walcks with all of the different bends in it and it really did make a difference.  I believe the angle at which it hits the button is more straight on.

[Ryan_M]

Still running in circles. I confirmed that the starter push rod pedal is not binding on anything. Next, I swapped push rod pedals with the gray 3A. There's no doubt the bend in the pedal and adjustment of the starter button are important but no matter what I did I couldn't get it to solve my problem. I even swapped batteries just to rule that out.

Below are pics of the gray 3A starter that I tried on the red one. This starter was just overhauled a couple weeks ago and has started the gray 3A maybe three times since then. The teeth were dressed smooth during the overhaul. You can see where they've been chewed on, presumably now from the red 3A test.







The "grinding" still seems to be the worst when the engine starts to fire - as if the starter drive doesn't disengage as fast as it should.

Either way, I'm not in any big hurry to pull the motor and change flywheels especially since I do not know for certain that would even solve the problem (although I think it would...). I might as well just run it. Worst case is I destroy the ring gear that I was going to have to change anyways and beat up the old starter which is probably already due for an overhaul. Best case is the gears wear just a bit and learn to mesh a little more quietly.

Besides, I have a rebuilt trans and TC installed that I haven't even tested yet. No sense in pulling the motor until I know whether or not the rest of the drivetrain needs to come back out. New and much needed clutch cable arriving later this week so we should be mobile again. Nothing like a full first-time test drive to discover more catasrophes....

[athawk11]

I don't know enough about these starters, but I thought I'd offer an observation you've probably already noticed.  The chipping is on the top of the gear teeth.  Would this mean the gear isn't fully engaged on the ring gear when it starts to spin?   Almost as if it's clipping the forward face of the ring gear, prior to it slipping into position.

Tim