# Flywheel Issue



## SLSTEVE (Dec 8, 2020)

Finally got the 389 back from the builder. Looks beautiful even without the intake. Long story. So I can’t wait to get this baby dressed out and installed before the painter gets the front end back on. Go to install the brand new Hays flywheel, part number 13-130. No way is this thing going on there! Tried every which way, nothing doing. At best, only three flywheel bolts will start, then the other 3 holes are way off. What gives? It is supposed to be the right flywheel for a 65 Pontiac engine. Any words of wisdom?

Thanks,
Steve


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## Old Man Taylor (May 9, 2011)

Rotate the flywheel. The holes are not evenly spaced.


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## SLSTEVE (Dec 8, 2020)

Been doing that for hours. This thing will NOT line up to bolt on. I can only get 3 of the 6 to line up and start. Did they make more than one flywheel bolt pattern?


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## Old Man Taylor (May 9, 2011)

No. Do you have it facing the right way?


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## PontiacJim (Dec 29, 2012)

The Hays number is correct. However, even though you have a 1965 engine (you are sure?), the pre-1964 engines have a different bolt pattern on the flywheel flange - from what I gathered searching on the internet. Maybe at some point in time the crank was damaged and swapped, or it is a late 1964 production engine for the 1965 model year and you go a left over 1963 crank installed from the factory.

Could also be the wrong flywheel in a mislabelled box, or poor quality control.

Read this post and see if any of it might apply.









Pontiac 389 flywheel doesnt fit


Not sure how I didn't notice before but the crankshaft hub on early 389's and 65 and later 389's are different. Any suggestions where to obtain a an adapter for the crankshaft hub or a different style flywheel. I am converting a stock roto-hydramatic to a turbo 350. The owner supplied the...




www.hotrodders.com


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## SLSTEVE (Dec 8, 2020)

After messing with this thing off and on all day, I FINALLY got it bolted on. I would try it, put a couple of bolts in, try it again, spin it to see if the bolt holes lined up, try it again. Jeez, what an ordeal. My problem being, once I got it to where I thought they all lined up, the flywheel bolts wouldn’t tighten down anymore, and I was afraid to put a wrench on it and strip the threads out. Finally got fed up and started cranking the bolts down and they all went in and torqued down so I am good to go. Now if I could just get my intake, I would be back on the road. Thanks for the encouraging posts.


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## PontiacJim (Dec 29, 2012)

SLSTEVE said:


> After messing with this thing off and on all day, I FINALLY got it bolted on. I would try it, put a couple of bolts in, try it again, spin it to see if the bolt holes lined up, try it again. Jeez, what an ordeal. My problem being, once I got it to where I thought they all lined up, the flywheel bolts wouldn’t tighten down anymore, and I was afraid to put a wrench on it and strip the threads out. Finally got fed up and started cranking the bolts down and they all went in and torqued down so I am good to go. Now if I could just get my intake, I would be back on the road. Thanks for the encouraging posts.


OK, good deal, just had to use some muscle. As OMT pointed out, you have to rotate the flywheel to find the correct alignment.

Now, I have stated this before because I use the Hays, make sure you have the correct flywheel bolts. The automatic/flexplate uses a different bolt than the flywheel. The heads of the bolts can be thicker. I ordered what was supposed to be correct new bolts and just installed them. The heads were too thick/high and the springs on the clutch disc hit the heads on the bolts. I think the automatic bolts may be shorter as well, but can't recall. Just double check this. You can set the disc on the flywheel as well and rotate it by hand before installing to make sure nothing is catching.


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## Old Man Taylor (May 9, 2011)

I had to buy the thin head bolts from Mr. Gasket to keep them from hitting the clutch springs. The ones that hit didn't do it right away. They did it after the clutch got worn.


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## Old Man Taylor (May 9, 2011)

BTW, I always run a thread chasing tap through all of the holes before I put bolts in them. Then I try the bolts, and if they are still stubborn I run a normal tap through those holes.


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## SLSTEVE (Dec 8, 2020)

I used the bolts that came in the clutch kit. There was also a bronze pilot bearing that I didn’t use because I bought one previously from OPGI, so if anyone needs it, let me know.


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## Old Man Taylor (May 9, 2011)

I strongly recommend using a pilot bearing, not a bushing.


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## Old Man Taylor (May 9, 2011)

Two points on the flywheels. 

All the bolt patterns are the same. There are differences in the crank shoulders and the ring gears.

The reason the bolt pattern is asymmetrical is so it will only go on one way. That is because the flywheel is not neutral balanced. The out of balance that I have read about is 6 inch-ounces. I have no idea why the factory did this, but I ALWAYS have mine neutral balanced.


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## Machinest-guy (Jul 19, 2019)

I'd stay away from ball or needle bearings because you don't know if the input shaft metal is compatible with the hardness of their rollers or balls. Straight up brass or bronze isn't lubricated hence inappropriate because it can gaul itself to the input shaft. The appropriate material is called Sintered oilite. This type bushing, GM p/n 3752487 or Doorman p/n 690-014 were numbers which worked well in many, now older, GM crankshafts. A sintered bushing which has been run through a hot tank or jet wash needs to be re-lubricated. This can be done by boiling in oil for several hours. In my machine shop I use a crock pot and let them run overnight. Having to draw the flywheel down with its mounting bolts indicates an improper fit to the crank hub. I'd fix that before running the flywheel. Excessive tension at the hub causes cracks to form in the bolt hole areas ruining the flywheel. These parts, when fit properly, assemble with hand pressure including running the bolts down with your fingers.

Here is a link to all you'd ever want to know about pilot bearings / bushings. Pilot bearing and bushings 

I've seen several Hays flywheels incorrectly machined in the mounting hole fillet radius area. They don't match the crank hub. When you have to force them on that mismatch is hidden - you don't feel it seat - And if you don't catch it when you do a run out measurement that flywheel will be loose in service and come apart. Scat and others - Summit Racing from China - all have those sorts of issues too. And the mounting bolt fillet radius, under the bolt head, is rarely matched with a chamfer in the mounting hole. Those need to be added before the bolt will seat on it's shoulder properly.

In OEM manufacturing moving some of the crank weight outside of the oil pan into an imbalanced damper and/or flywheel was a production driven decision, arguably not a best engineering practice. It was intended to minimize crank flex across the end main bearings so cranks can be made with less metal, hence cheaper. 

Unless you know if your flywheel was specifically made for an internal or external balance crank, the odds are very high you will not get what you need on the end of your crank with a catalog flywheel. Most crank and rod sets are very mixed up by now, and virtually all replacement pistons are not within OEM spec for weight, hence all internal assemblies need to be re-matched and re-balanced, which leads to including the flywheel and damper in that operation.

This is an area of safety concern. Be very careful to have all the fits proper and all the fasteners working well before final assembly. Best regards, Ladd


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## Jetzster (Jan 18, 2020)

Great info Ladd Thankz!😄


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## 1969 tempest custom s (Sep 9, 2020)

Machinest-guy said:


> I'd stay away from ball or needle bearings because you don't know if the input shaft metal is compatible with the hardness of their rollers or balls. Straight up brass or bronze isn't lubricated hence inappropriate because it can gaul itself to the input shaft. The appropriate material is called Sintered oilite. This type bushing, GM p/n 3752487 or Doorman p/n 690-014 were numbers which worked well in many, now older, GM crankshafts. A sintered bushing which has been run through a hot tank or jet wash needs to be re-lubricated. This can be done by boiling in oil for several hours. In my machine shop I use a crock pot and let them run overnight. Having to draw the flywheel down with its mounting bolts indicates an improper fit to the crank hub. I'd fix that before running the flywheel. Excessive tension at the hub causes cracks to form in the bolt hole areas ruining the flywheel. These parts, when fit properly, assemble with hand pressure including running the bolts down with your fingers.
> 
> Here is a link to all you'd ever want to know about pilot bearings / bushings. Pilot bearing and bushings
> 
> ...


Amen!

there are several other good reasons to use the oilite bushing. If you jam the transmission input shaft up against the bearing style when installing the transmission you could very easily damage it. then it will self destruct slinging grease and needle bearings out of the rear of the crank shaft. the grease will of course ruin your clutch disc but the needle bearings may imbed themselves in the face of the clutch disc and damage your flywheel. then with the front of the input shaft unsupported it will wobble further damaging the front bearing of the transmission and changing the contact surface of the gears when it wobbles will chew them up. You can easily destroy alot of new and expensive parts while trying to diagnose the problem. I have seen a 300 dollar clutch job end up costing almost 2700 dollars when this happened.

I have seen this happen only 3 times in my life but once is enough.

I have never seen a bushing fail. ever. they cannot fail like a bearing does. its impossible. they can take alot of abuse from clumsy installation and not fail. If you replace them, again, with another oilite bushing each time you replace the clutch it will not fail during the life of the clutch. you do want to check dimensions. a bushing cost about 4-7 bucks. a good bearing, can cost upwards of 25 bucks and there is no guarrentee it will not fail. I have used, abused and reused bushings and have never had one fail. I am older and wiser now so I only use bushings. I install things correctly and carefully and replace them when ever the transmission is separated. NEVER had a bushing fail.


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