View Full Version : Lightening a Flywheel

Do It Sidewayz
03-15-2004, 02:34 AM
well...i've finally finished my Turbo Justy project (yes that is right...TURBO JUSTY!!)

anyways...at about 8 PSI of boost it slips the clutch something nasty.

I've ordered a new clutch and hope to put it in next week.

I was thinking...i am going to have it all apart, and i have a spare flywheel in the garage.. At the very least i should probably have the clutch surface resurfaced, and if i'm gonna do that, why not shave a couple pounds off the bohemoth of a Flywheel for a Justy!!! It sure would help the little 3 banger.

Anyways. anyone know where i can get it done...and how much it's gonna cost me.

I'm figuring that just about anyone with a lathe can lightening, it's just balancing it might be a trick

03-15-2004, 12:21 PM

Graeme at Canadian Cylinder Head Technologies may also be equipped to lighten and balance flywheels. His shop is in the Keele and Steeles area. His prices are excellent and so is the quality of his work in my experience.

03-15-2004, 04:46 PM
What effect will cutting down just the flywheel have on the "balance" of the engine internals?Isn't the flywheel balanced with the crank,clutch and harmonic balancer (if it has one)?

RedRabbit Racer
03-15-2004, 08:39 PM
Other reciprocating stuff like the pistons, pin, rods etc is more or less statically balanced and presumably doesn't create any significant dynamic imbalance if the crank throws are evenly spaced.

I'd say the same applies to rotating equipment like the clutch which if it is more or less statically balanced and symmetric should not create a big out of balance condition when moving. However, I'd suspect that the flywheel has the most effect on the dynamic imbalance of the engine given the location of its significant mass the greatest distance from the center of rotation. the flywheel is usually the single largest contributor to primary balance due to its inertia and thus it is the most important component to balance.

Do It Sidewayz
03-15-2004, 09:04 PM
the justy does run a balance shaft....so i don't think Balancing of the crank is a huge deal.

Just trying someplace to do this relatively cheap.

Looks like lightening the flywheel could cost me as much as my entire turbo project

RedRabbit Racer
03-15-2004, 09:47 PM
About 12 years ago in Quebec I paid $150 to lighten and balance my VW flywheel. I have used it on at least six different engines some 8v and some 16v with no problems.

03-15-2004, 10:08 PM
Most engines are internally balanced , meaning that nothing externally is used to contribute to the overall balance of the engine . Therefore the flywheel and harmonic balancer are neutrally balanced . Simply it means that the flywheel does not have a heavy side to it and it will only have small blind holes drilled into it . An example of an externally balanced engine it the 5.0 litre Ford if you look at the flywheel it has a heavy section on the engine side to it so if you pick it up through the center hole it will be heavy on one side . Kind of like if You added a lot of weights to a tire and rim to purposely unbalance it .
To the best of My knowledge fly wheels are ground on a surface grinder it is centered on a rotating table and a grinding wheel is lowered onto it . This will not affect the balance to a large degree but sometimes if they are warped excessively and then ground flat enough material is removed to cause a vibration.

03-16-2004, 10:31 AM
Originally posted by Do It Sidewayz
the justy does run a balance shaft....so i don't think Balancing of the crank is a huge deal.Balance shafts cancel secondary unbalanced forces caused by the reciprocating mass (inherent in 4 cylinder engines), not primary unbalanced forces caused by the rotating mass, like a crank that is off centre.

You might want to try Mississauga Engines as well.