After reading numerous posts for and against lightened pulleys, flywheels, and the potential problems vs benefits, my question for the forum is this:

If we have an engine shop balance our cranks to the lightened underdrive pulley, and the lightened flywheel, wouldn't this negate much of the potential for damage while yielding the HP/Tq benefits we all seek? Especially if we throw in some stronger crank and rod bearings while we are at it?

Considering the potential for gains involved, it seems like solving this problem would rank high on the order of we who wish to increase performance (especially n/a)

Thx

 

My initial thoughts are that the cost of balancing a crankshaft and replacing the bearings you mentioned would far outpace the benefits seen. Labor alone would be ridiculous unless you have the capacity to DIY which I would guess the majority of the forum doesn't.

 

A stock, normal weight flywheel on our cars doesn't accomplish the task of making the motor vibes go away by being unevenly balanced to account for certain areas where the motor is not smooth... it accomplishes it by having mass to it which continues to spin in the same direction as the crank with more inertia than a lighter flywheel, so that when a vibe does happen, you don't feel it as much since the flywheel's mass will continue to spin and absorb some/most of that vibe.

I don't think the vibes in these cars come from imbalanced motor internals anyways. It's more likely the result of the combustion sequence and momentary lapses in timing of each power pulse. If we had straight-6's instead of V-6's, then we'd have a motor that would be more naturally smooth and probably not so much of a noticeable phenomenon.

 

Thank you both for the replies...

@ Blue Dream - I agree about cost. Moreso something that would be done during a build/rebuild.

@ Partyman66 - I agree with your comments about the vibes and understand that much of our vibes also come from our tranny and shitty driveshaft?

The question I have is really about streamlining the entire drivetrain from the UD pulley all the way back through the diffs without spinning bearings and trashing our motors? I am in my G for the long-haul and am looking to remove inefficiencies and weak spots throughout the car as I go.

 

I don't know where you heard that about the vibes supposedly coming from the driveshaft and tranny. They aren't from the driveshaft, that's for sure. If they were, it would do it all the time, even when in neutral or with the clutch in since the flywheel is disengaged from the rear half of the drivetrain while coasting in neutral. The same is true of the transmission... or at least everything on the rear 2/3's of it.

 

Apologies... Vibration from driveshaft only occuring when carrier is wearing.

One issue we see come up alot on the boards is vibration during deceleration on the 5mt/6mt. It is often attributed to motor or tranny vibes being transfered up through the stick shift, due to normal firing or rotating parts.

So back to the main issue... Many in the forum warn against using the lightened pulley in place of the OEM with the balancer, and likewise warn against the lightened flywheel. The argument is that they run out of balance with one another and can damage the motor train.

So why not just balance the 3 pieces to one another (the lightened pulley, to the crank, to the lightened flywheel)?