Harmonic Balancer. Can't they be rebuilt?

Judging by a Google search of "harmonic balancer rebuild," I'd say yes.

 

Not well using eBay sleeves.
This might be real?
http://www.car-truck-parts.com/car-detail/crankshafts-parts/Ferrari-Harmonic-Balancer-for-308-325-Mondial_201284359537.html

 

Not for the Concours guy, but Nick's forza makes a (pricey) lightweight replacement that adds ~10hp in performance. Also, unless I'm mistaken, since our cranks are substantially similar in design and dimension to everything up through the 360, would it not be possible to widen one's eBay search to a 328/348/355/360 balancer (cue someone more knowledgeable than myself to chime in...)?

 

Send it to Damper Doctor.

Good service and good work.


Don't buy some snake oil or use one from another model.

 

I dont understand how you can have a lightweight version. The weight of the damper is critical to its operation.

 

Beats the hell out of me. Just thought it worth mentioning as an option. Maybe SMG2 here can chime in? Doesn't he work with Nick on engine builds?

 

I'm a dummy.

What does that HUGE chunk of heavy, dense rubber really do?

 

Tuned mass damper - Wikipedia, the free encyclopedia

 

The rubber is quite small, the inertia ring is big.

It dampens torsional vibrations in the crankshaft. Has differing degrees of importance in different motors and types of cranks.

 

"Nick's forza makes a (pricey) lightweight replacement that adds ~10hp in performance."

10 HP by changing a damper?

Right...

And I've got a perpetual motion machine I'm selling cheap...

 

Gee, how much is it mister?

 

I am not sure about the 10 horsepower gain........think i will buy a lottery ticket instead as better odds of success....otherwise every manufacturer of cars would be doing this simple item for significant cost effective gains.
A generic h balancer adjusts for the normal 50 hz vibrations of a typical vehicle. The change in frequency only occurs in higher performance modified vehicles, typically race oriented vehicles, which produce different frequencies. So unless you are heavily modifying the driveline, such as valves, pistons, crank, rods, driveshaft(s)...which produce a different frequency due to the different stresses, putting a racing lightweight balancer (even a fluid damper) is a waste of money, will not add horsepower and would most likely be counterproductive as the race version is set up for higher frequencies not the typical 50 hz. I would have no issues if you can provide documented proof that changing the mass and frequency = increased horsepower without long term stress of the driveline components.
I will not get into the (il)legalities of this modification on racing.

 

+1 for damper doctor. They work in seasons though so make sure they are around.

 

Some dynos measure how mast an engine can accelerate a known mass and figure out horsepower. So the faster the engine can accelerate (spin up) the more power the dyno calculates it has. Less rotational mass means faster spin up. So it might look like more horsepower on those dynos. And it might even give you real-world better acceleration with less mass to spin up.

But it's not actually more horsepower. Those dynos infer how much horsepower and engine has rather than measure it.

 

the downside is that rotational mass decreases faster on deceleration, because a higher mass has greater inertia to keep it spinning longer which means less abrupt rpm variance (slowing or accelerating). where one believes you have a bit more horsepower accelerating, translates into more work for the engine in reaccelerating as the rpm drops faster (with a lower mass wheel). any changes, one needs to balance at the rear of the engine as well with the flywheel (usually) or other internal balancing. there is about a 2 degree twist with each power cycle per cylinder. without a proper balancer, this twisting force sets up stress which damages the engine. i will try to find it when i have time, years ago GM's racing department did a great technical writeup on modifications of damper/crank pulley. In conclusion, I do not care what any performance shop says, short of a properly rebuilt engine designed for racing, do not use lightweight crankshaft pulleys, especially if you want your engine to last. Years ago, when racing forums went to solid lightweight pulleys (to avoid parts blown up pulleys being thrown into the engine area/drivers/other vehicles/spectators), engines started to last a few races only instead of entire seasons. just my 1.5 cents (reduced from 2 cents for the inertia of the mass of the American economy) worth.

 

Guys,

Thanx.

Learned something today.

 

Will this give the same effect with lightened flywheel? I would think so

 

Your first part is mostly wrong. The second part is close. The polar moment of inertia of the harmonic balancer is insignificant when compared to the polar moment of inertia of the other rotating parts, especially the flywheel. Take the engine off the test stand and put it in the car and now the polar moments of all the drive train and the wheels make any changes to the balancer super insignificant. The balancer is there to dampen the dynamic torsional inputs from the pistons firing. It is a tuned system and should not be f'd with in my opinion.

 

when i used to quarter mile race in my much younger days, we always tried to balance the input to the transmission to the crank pulley, taking into account the drag of the pulleys running of the crank pulley (alternator, supercharger (if applicable), PS (if applicable), AC (if applicable). lightening one side only placed undue stress on the opposite end and the internal journals, and the uneven twisting force was magnified. if you can increase the rpm in a calculated manner, ie. lightening the flywheel and modifying the final drive ratio, effectively you can increase the horsepower of the engine by moving more air/fuel in a fixed period of time, which is the same thing as increasing the displacement of the engine.

 

You are probably right for drag racing and such. I thought we were talking about 308s where all discussions on HP and Torque you deemed to be frivolous.

 

Their site says they do motor mounts too. May be worth an RFQ.

 

Yes they do but I don't believe it would include 308 type mounts.

No harm in asking but I think it is limited to the more classic rubber between 2 steel plates type of thing.