Flywheel Question

[sturmtyger380]

I was looking for an extra flywheel to get resurfaced so when I redo my clutch I could swap it in. So a local guy that has old parts said he had a couple of Dodge engines that sill had flywheels.

So I get over there and he had been taking them apart and there were two flywheels to choose from. Now both engines look the same to me just like in my M37. One flywheel had 7 bolts going through the end of the crank and the other had 6 holes. So I get home and look at my spare engine and it has 8 holes on the crank. Well I picked the one with 6 holes to being home because it was the better one.

So I looked in the manual and it specifies 8 bolts for the flywheel. Now on the flywheel I choose it looks like in-between the 6 holes are marks for where two more bolt holes could be drilled out.

Where there different versions of flywheels? Has anyone else seen this?

Alan

[Kaegi]

on the trucks no. they all have 8 bolts. when you get into the civilian engines it all changes. I have seen only 4 bolt and 8 bolt but never 6. 6 sounds like it could be off a slant 6 or 62 and up small block/slant 6. Even the poly 318 had 8 bolt till 62. Maybe late M37 engines had 6?? check tooth count, diameter, depth, hub size, pressure plate bolt spread.

[sturmtyger380]

I wonder if it could have been from a civilian power wagon and they just did not drill out the other to bolts. Who knows what they did to those old engines 30 years ago.

[Kaegi]

I wonder if it could have been from a civilian power wagon and they just did not drill out the other to bolts. Who knows what they did to those old engines 30 years ago.

The civilian PWs had 8 bolts at least through 55. that's the latest I have worked on

[Cal_Gary]

Not so fast my friends! I run a 6 hole flywheel on my 8 hole crank. The "gov't issue" M37 flywheel is thicker in the back than the 6 hole flywheel. My civvy starter couldn't be used with the M37 flywheel-clearance issues. I don't know the origin of my 6-hole flywheel but had to have the ring gear replaced with the ring gear from my M37 flywheel-mated perfectly, and I didn't cook-off the starter after i made the change.
Gary

[sturmtyger380]

I counted the teeth - 146. I finally got some photos to upload.

[Cal_Gary]

Sturm, that looks like mine. If you take a look at the back, the civvy flywheel is about an inch thinner around the circumference toward the ring gear area as opposed to the M37 flywheel. I cooked off my starter by missing this bit of detail because the starter locked up when I engaged it with the M37 flywheel installed. I ended up having the cooked off starter rebuilt and retained the use of the civvy flywheel but it could have been disastrous if the starter had ignited the rest of the truck.
Gary

[sturmtyger380]

Gary you said -

had to have the ring gear replaced with the ring gear from my M37

So when you tried the civvy flywheel was the ring gear the 146 count one? I am still trying to figure out if I can use this one as is, (After a re-cut though), or do I need a new ring gear?

Alan

[Cal_Gary]

Yes, mine is 146 teeth, same count on either flywheel.
Gary

[Kaegi]

I would stick with the stock one. heavier and balanced for that engine. Chrysler engines were balanced really well even back in those days. usually they don't need machining anyway. just take some 60 grit sand paper on a block of wood and go to town.

[hbb]

I would stick with the stock one. heavier and balanced for that engine. Chrysler engines were balanced really well even back in those days. usually they don't need machining anyway. just take some 60 grit sand paper on a block of wood and go to town.

Yes you can go to town that way! Why not be sure you can get back home by making sure you engine is balanced , the last engine that I rebuilt ( one week ago) the machine shop tech with over forty years stated that he had never seen a crank and flywheel both so far out of balance, it in fact started to jump out of the turning cradle at initial set up. The owner was not planning to balance it and I am dam happy that I talked him into it. For what it cost to have the flywheel surfaced and balance checked it is worth not having to replace the main bearings in a few miles.Not saying that every flywheel is out of balance ,but taking a little more time to do the job right the first time is just cheep insurance and Piece of mind.

Hb

[Kaegi]

I would stick with the stock one. heavier and balanced for that engine. Chrysler engines were balanced really well even back in those days. usually they don't need machining anyway. just take some 60 grit sand paper on a block of wood and go to town.

Yes you can go to town that way! Why not be sure you can get back home by making sure you engine is balanced , the last engine that I rebuilt ( one week ago) the machine shop tech with over forty years stated that he had never seen a crank and flywheel both so far out of balance, it in fact started to jump out of the turning cradle at initial set up. The owner was not planning to balance it and I am dam happy that I talked him into it. For what it cost to have the flywheel surfaced and balance checked it is worth not having to replace the main bearings in a few miles.Not saying that every flywheel is out of balance ,but taking a little more time to do the job right the first time is just cheep insurance and Piece of mind.

Hb

what kind of engine was it? I have rebuilt quite a few flathead mopars and balanced about half. very little material was taken off of anything by the balancer. But I bet if a miss matched flywheel gets installed that could cause an issue if the factory stuff was balanced together.

[hbb]

It is a military dodge 230, I my self started slinging wrenches forty years ago and built countless engines.some I balanced most not! Back in the day we never balance engines working in the dealer ships,but now it's a whole different world.the customers expectation has gone way beyond the past and what was good enough then is crap now. How many M37's have you come across with the original engine in it? Most all were over hauled by the military and most of them have less than 30k on them.they didn't blow the bearings out by being well balanced! Heck they are governed to prevent the notheads from over revving and they still gave up the ghost.They had a short life expectancy in combat and general service so no one gave a crap about a little 230 dodge motor. Miss matched parts was a common place in the military.then they went on in the GSA and they received even less maintenance and care. Then came the general public and farmers that's when the real butchery started so to trust what should be ok is the best way to have things go backward on ya. Years will teach how not to be stupid if you pay attention and that learning thing never stops! All that we can do is share what we have learned in our travels and hope others can learn from our mistakes.

hb

[Kaegi]

It is a military dodge 230, I my self started slinging wrenches forty years ago and built countless engines.some I balanced most not! Back in the day we never balance engines working in the dealer ships,but now it's a whole different world.the customers expectation has gone way beyond the past and what was good enough then is crap now. How many M37's have you come across with the original engine in it? Most all were over hauled by the military and most of them have less than 30k on them.they didn't blow the bearings out by being well balanced! Heck they are governed to prevent the notheads from over revving and they still gave up the ghost.They had a short life expectancy in combat and general service so no one gave a crap about a little 230 dodge motor. Miss matched parts was a common place in the military.then they went on in the GSA and they received even less maintenance and care. Then came the general public and farmers that's when the real butchery started so to trust what should be ok is the best way to have things go backward on ya. Years will teach how not to be stupid if you pay attention and that learning thing never stops! All that we can do is share what we have learned in our travels and hope others can learn from our mistakes.

hb

my experience with 230s has been much different. I have probably put personally at least 200K on WCs, and PWs with 230s that were not rebuilt or I rebuilt. some balanced and some not. the bottom end as you know has the offset rod design which is a problem at high rpms but I have never thrown a rod in all the years since 1985 when I started beating the crap out of these trucks for work and play. I can see them getting over revved by military drivers. I would guess if your balancer had such a problem the crank was bent or flywheel was improperly balanced in the past. Also I have not owned many but have seen many low mile M37s and usually do not have rebuilt engines in most cases.

[sturmtyger380]

I went back to the gent that had the old engines. He still had the other flywheel. I don't think it is quite as nice as the first one. Here are some photos of what looks like the correct flywheel.

Alan





M37 on the bottom and what might be the civy one on top: