External/Internal balance Wrong flex plate?

[jblackie47803]

Long story short: I'm pretty sure I have an external balance flex plate on a '90 2.8 crank. but I'm not sure. The engine runs good but has a real slight shimmy to it. If you had mismatched the crank/flex plate would the vibration be very bad or just barely noticeable. Also the engine/'85 Blazer I have does not have the factory "pencil braces" from the tranny to the engine. Could this alone cause the shimmy? Thanks for your time.

jb

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[pocket-rocket]

I would imagine the flywheel mismatch would be a pretty bad vibration, but I've no experience with it so I can't say for sure.

I've done engine/transmission jobs and had those braces left off and didn't have a problem. The one guy is still driving the truck 2-3 years later without problems and his didn't shimmy, so I doubt that is your problem.

[ForcedFirebird]

If you are using the 85 flex-plate I would gather the issue is the crank/flex-plate mismatch. After 86 the cranks were internally balanced.

[2.8/3400 1985 Camaro]

If you are using the 85 flex-plate I would gather the issue is the crank/flex-plate mismatch. After 86 the cranks were internally balanced.

What he said.