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Flywheel balancing

s2willdo

Donation Time
I'm rebuilding my clutch, pressure plate, flywheel.

My starter gear ring on the flywheel is not "fully seated" all the way around the flywheel. I can fit a penny in the gap on one side. Do I need to worry about this being out of balance? Rick at SS said no. He thought more damage could be done by heating the ring up to remove/replace it.
 

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DanR

Diamond Level Sponsor
HOLD IT!! The teeth on the ring gear look to me as being very badly chewed up where the starter engages.....

I believe you need a new starter ring gear!

I surely would get it replaced before I would install the engine and then find a problem!
 

beamdream

Gold Level Sponsor
I`m with Dan, there`s no way I would be putting that ring gear on my car. I f it hasn't already done significant damage, I would also be looking closely at the starter pinion gear.
 

loose_electron

Donation Time
Somebody has tried to spin the starter while the engine was running. Pinion on the starter probably has similar damage.
 

jumpinjan

Bronze Level Sponsor
The flywheel teeth are okay. They may look they are "mashed" over but they aren't. The factory cuts a chamfer on one side.
Jan
 

DanR

Diamond Level Sponsor
JAn, You are correct on the factory cuts, just in the pictures they sure look chewed up inplaces....

I;m not jhome at the moment or I would pull out a new starter ring and take some PIC's for comparsion.
 

jumpinjan

Bronze Level Sponsor
Yep, pretty much correct. I have installed new ring gears and one can see the chamfer they put on. Now, if you have a 1725, for some reason the 1725 seems to stop at about the same crank position every time. I don't know why. But the 1725 ring gears I have replaced are worn in one location. Some of them have only 1/2 of the tooth width left...and it's just in one spot from the starter engaging it. Doug Jennings also mention this observation to me too.
Jan
 

DanR

Diamond Level Sponsor
I've noticed that on several auto's including the 1725. Just removed and shifted the ring gear on a couple (only if the treeth are in decent shape otherwise).
 

DanR

Diamond Level Sponsor
Jan, I thought about the flywheel stopping in the near same spot most times and wondering if maybe the "balance" of the engine would have an effect on where the engine stops most frequently?

Could or does that make sense?

Have you ever moved the teeth (position) of a ring gear to a different position?
 

Bill Blue

Platinum Level Sponsor
Dan, the ring gear gets the odd wear pattern because it stops at the same locations due to compression.

Bill
 

loose_electron

Donation Time
Dan, the ring gear gets the odd wear pattern because it stops at the same locations due to compression.

Bill

That was my initial thought too, but with a 4 cylinder engine, I would think that there would be 4 spots that the engine would halt at, namely coming up to TDC on the compression stroke for each cylinder.

No?
 

Bill Blue

Platinum Level Sponsor
No, only two. #1 comes up on compression and fires at crankshaft TDC. 360 degrees later, #4 compresses and fires. Same with 2 and 3, only it happens at crankshaft BDC. All that banging (and compressing) happens at only two crankshaft locations.

Bill
 

loose_electron

Donation Time
No, only two. #1 comes up on compression and fires at crankshaft TDC. 360 degrees later, #4 compresses and fires. Same with 2 and 3, only it happens at crankshaft BDC. All that banging (and compressing) happens at only two crankshaft locations.

Bill
Interesting. If I understand this correctly -

So two revolutions of the crankshaft completes the full cycle of the engine?
That makes sense since TDC gets used for both compression to power cycle and exhaust to intake cycle.

If that's the case, then the distributor rotates 360 degrees for 720 degrees revolution of the crankshaft.

As well, there's a 2:1 rotation ratio between the crankshaft and the camshaft. Which makes sense when you look at a timing chain setup and the relative gearing sizes.

Funny never really thought that one out very much, and I've changed a fair number of timing chains in my younger years.
 

Gordon Holsinger

Diamond Level Sponsor
I'm rebuilding my clutch, pressure plate, flywheel.

My starter gear ring on the flywheel is not "fully seated" all the way around the flywheel. I can fit a penny in the gap on one side. Do I need to worry about this being out of balance? Rick at SS said no. He thought more damage could be done by heating the ring up to remove/replace it.
Replace the ring gear and starter pinion. You won’t have any worries if you replace it.
 

Hotrodhillman

Donation Time
I put a new starter ring gear on the flywheel of the 1275 A Series BMC engine I put in my Traveller. It cooled before I got it tight. There was perhaps a 0.025 inch gap around 1/3 of the circle. It works fine.
 
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