I have a vibration issue that is driving me nuts! Its been going on for about a year now. It happened when i swapped to a 383 and a t56.. I put in a new spec 2+ clutch with a resurfaced flywheel, with grade 8 bolts (didnt have stock pp bolts). It has an ebay harmonic balancer on it.

I just bought a new flywheel, thinking that was it...Nope. I just had the reverse gear fixed in my trans, and the guy checked the rest out when he was working on it...The only thing left that i can think of is the harmonic balancer, or those grade 8 bolts that dont have the long shoulder.

The vibration starts to get really bad around 3000 rpm....driving, stopped, in neutral; it doesnt matter.

Any help Would be appreciated!!

 

What's your driveline angle? may need to raise/lower the trans mount. (I put washers in my IROC in between the trans crossmember and the floor and it fixed a similar problem)

 

Was your engine balanced?

 

I just got a new transmission mount and put that on because the other one had a tear in it. i think it is a little bit of a different height, nothing too crucial.

As for the engine, it was balanced the same as a stock lt1....Neutral at the front, external at the back...As far as i know from the engine builder.

 

bump...car is now for sale.

http://vancouver.en.craigslist.ca/rd...472705240.html

 

Did you balance the clutch and flywheel together? If this was not done it could easily be the reason that you are seeing vibration. The stock flywheel is not "0"-balanced from the factory. It is mounted with the clutch and balanced as an assembly. For this reason it is imperative that it be balanced with any new clutch that you purhcase.

 

the clutch and flywheel were not spun up together on a balancer....my 383 is apparently balanced the same as stock which is neutral at the front harmonic balancer and external at the back with a weight on the flywheel. but the clutch and pp should be neutral as well...i should maybe have that checked..

 

It's just better to be safe than sorry when you are using a clutch and flywheel that were not originally assembled together. Also, issues with motormounts, transmission mounts, driveshaft, fuel, spark, timing, etc...can also lead to vibration. If the you see variance in the amount ot vibration relative to RPM then it is likely relative to part of the rotating assembly. At this point all you can really do is start checking things and moving to the next potential cause. Keep me posted and let me know if you have any further questions.

 

you note the vibration is there even "stopped or in neutral". This suggests the balance problem is your motor 9or FW/clutch bolted to it), not driveline.

If I understand you swapped a 383 AND a T56 into what was a Auto car...

typically 383 motors are built "internal" aka "neutral" balance. A stock FW is weighted for "external" aka "stock" motors. You note your builder said they built it as external balance...really confirm wtf it is.

It could be it is an internal balance motor and you need a "neutral" balanced FW and have the PP also neutral balanced to it. You can either have a OEM FW neutral balanced or but an aftermarket "zero" balance FW (and have it checked by machine shop to confirm)

a internal balanced motor using an external balanced FW will shake like a dog shiating razor blades. at any RPM. You note your vibration is worse at 3k rpm, does it vibrate al all RPM's?

you should also confirm you have no grounding issues going on (motor mounts lose, exhaust hitting frame or x-member). Assume you have checked the front damper as it should be neutral but if it has worn (rubber) it could be now not neutral and induceing vibration.

I bet you will be hard pressed to sell the car with this vibration...unless cheap. Motor vibration like this will kill bearings and it appears motor source since it happens when not driving