Flywheel help....

[434nova]

I finally took the flywheel out of my car that was broken. When I went to put the a used stock flywheel in i noticed it had what look to be 3 dime size weights and there weren't as many holes drilled in it. Motor was rebuilt in the past I'm not sure if it's internally balanced now. Cause stock is external right ? Does this look to be a stock flywheel for a 87 lc2 engine. Don't want to put the flywheel back in and find out that it's vibrating, etc. Here are the pics.
The one on the right is the one i just took out the car and the one on the left is what I am replacing it with. The one on the left even has a extra hole at 6 o'clock. Thanks in advance.

 

[434nova]

Oops on my phone the hole was at 6 o'clock and now it's at 3 o'clock on the computer.

 

[434nova]

Bump..

 

[fastblackracing]

The flywheel you took out still looks to be externally balanced...but balanced to your engine now.
The internally balanced wheels will be much more uniform in appearance..like either a mostly solid plate or it will have 6 big holes and some much smaller balance holes.
I remember the stock turbo flywheels having that D shaped hole from the factory and as much drilling as was done on your bad flywheel to bring it in to balance you may very well have issues with your replacement wheel causing some balance issues.

 

[434nova]

Do you think if I can get the new flywheel to way the same as the old one I would be ok or does where the holes on the flywheel are matter ? Thanks

 

[No disintegrations]

Thinking outside the box; if you could prop up one side and put the other on a very accurate scale record the weight. Do it at 12, 3, 6 and 9 o 'clock positions. Then drill the balance holes to match original weight at each position.

 

[No disintegrations]

Thinking outside the box; if you could prop up one side and put the other on a very accurate scale record the weight. Do it at 12, 3, 6 and 9 o 'clock positions. Then drill the balance holes to match original weights at those clock positions.

 

[434nova]

Would anyone know what the flywheel without the D shape in it came out of ? Would it be a 3.8 n/a motor or a 4.1? If I can find that flywheel I would just use my old one as a template and drill the holes but I need the one without the d shape in it.

 

[David Husek]

The builder balanced that Flex Plate to your engine, according to all the extra holes drilled. It should have been done internally. You cannot install a stock flex plate without being out of balance on your engine. I have spun up multiple stock flex plates and none were the same even though they look the same.. Each flex plate is balanced at the factory for the engine it is installed on. Ever notice the weight plug in the outer part of the balancer and the random holes drilled/weights added to the flex plate. See picture. This was the final balance for each engine. Find a good machine shop and see if they can copy it..

 

[434nova]

Dave would happen to have a idea of what engine the flywheel I have would have came from originally? It's the one that doesn't have the d shape in it. If I can find that flywheel I can take it to a shop and let them replicate the holes and make sure both flywheels weight the same. Thanks

 

[David Husek]

You cannot copy the holes. It needs to be balanced to a crank to be copied. If you cannot get this done locally, get in touch with me.

 

[No disintegrations]

How about my idea in post 6? Anyone?

 

[Wahoo]

So does this mean that if you have a bad flywheel(cracked), you cant just replace the flywheel?

Have to have the new flywheel balanced/matched to the old one, or have to have the rotating assembly balanced to the flywheel?

 

[TexasT]

Depends how deep your pockets are and how out of balance the replacement piece is. I replaced a cracked one on my car decades ago and it is still running. Is it balanced? I guess not but it does run and get 19-20 mpg driving it to and from work.