Solid crank pulley

[clubagreenie]

If necessary we might be able to run if through a flow meter (I'll bring one home from work( to check flows and pressures, ave tap in at different points)

[Billzilla]

er bill, the volume of the scavenge vs pressure (ratio) is determined by the size of the pump stage, not the rpm. that ratio should be fixed independent of rpm

Better have another read of what I wrote.

[andrew_mx83]

bill when you say pressure pump are you referring to the internal oil pump and just using the external as a scavenge?

i am as yet undecided to whether i will retain the internal one or just use the external for everything.


but enough about dry sumps


any ideas roughly how much ill pay to get a dampened custom balancer made up?

and if it is dynamically balanced will this get rid of the nasty crank-destroying harmonics which would be present in a standard motor and be the main reason not to run a solid pulley?

[clubagreenie]

Static Balance can be measured by a static balancing machine where the tire is placed in its vertical axis on a non-rotating spindle tool. The spot on the tire where the mass is greatest is acted on by gravity to deflect the tooling downward. The amount of deflection indicates the magnitude of the unbalance. The angle of the deflection indicates the angular location of the unbalance. In tire manufacturing factories static balancers operate by use of sensors mounted to the spindle assembly. In tire retail shops static balancers are most usually non-rotating bubble balancers, where the magnitude and angle of the unbalance is observed by looking at the center bubble in an oil-filled glass sighting gauge.
Dynamic balance

Dynamic balance describes the forces generated by asymmetric mass distribution when the tire is rotated, usually at a high speed. In the tire manufacturing factory the tire is mounted on a balancing machine test wheel, the assembly is accelerated up to a speed of 300 RPM or higher, and sensors measure the forces of unbalance as the tire rotates. These forces are resolved into static and couple values for the inner and outer planes of the wheel, and compared to the unbalance tolerance (the maximum allowable manufacturing limits). In tire retail shops tire/wheel assemblies are checked on a spin-balancer, which determines the amount and angle of unbalance. Balance weights are then fitted to the outer and inner flanges of the wheel. Dynamic balance is better (it is more comprehensive) than static balance alone, because both couple and static forces are measured and corrected.

I used to static balance wheels at home, just using a hub assy welded to a plate mounted very accurately vertically in both directions.

[Billzilla]

bill when you say pressure pump are you referring to the internal oil pump and just using the external as a scavenge?

i am as yet undecided to whether i will retain the internal one or just use the external for everything.

Yeah the internal one is just fine 99% of the time. It's much cheaper and easier to use it as well.

[oldeskewltoy]

Not 6 cyl, but 4AGE again....


Too many horror stories for me.... I bought an OEM rwd crank pulley and had it customized to my needs.........

[oldcorollas]

do the cars with damped flywheels also have damped pulleys? or solid?

[petergoudie]

Quote from wikpedia:

"A harmonic balancer (also called crank pulley damper, crankshaft damper, torsional damper, or vibration damper) is a device connected to the crankshaft of an engine to reduce torsional vibration and serves as a pulley for drive belts.[1][2]

Every time the cylinders fire, torque is imparted to the crankshaft. The crankshaft deflects under this torque, which sets up vibrations when the torque is released. At certain engine speeds the torques imparted by the cylinders are in synch with the vibrations in the crankshaft, which results in a phenomenon called resonance. This resonance causes stress beyond what the crankshaft can withstand, resulting in crankshaft failure.

To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft. The damper is composed of two elements: a mass and an energy dissipating element. The mass resists the acceleration of the vibration and the energy dissipating (rubber/clutch/fluid) element absorbs the vibrations.

Additionally the energy transferred from the piston to the crankshaft can induce as much as 2 degrees of twist in the crankshaft, which has many follow-on effects on all engine elements that require adequate timing such as valve opening, cam timing, ignition timing etc.

Over time, the energy dissipating (rubber/clutch/fluid) element can deteriorate from age, heat, cold, or exposure to oil or chemicals. Unless rebuilt or replaced, this can cause the crankshaft to develop cracks, resulting in crankshaft failure.

Performance enthusiasts have been known to remove harmonic balancers, usually when the balancer is attached to the crank pulley, deciding that they aren't necessary and their mass reduces the performance of the engine. However, this is unproven and potentially very risky because the danger of damage to the engine from the vibrations the damper is intended to prevent is too high.[citation needed]

Certain cars, however, do not come equipped with an external balancer on the crank pulley, and as such, can have the pulley replaced with a performance oriented product which counter-act these resonance frequencies."

Also from me:

The straight 8 Duesenburg of the 1930s had a hollow counterweight on the crank and it had mercury in it to absob the vibrations.

[petergoudie]

Here's another explanation from the net and it references the 7MGTE:

After the last round of ur pulleys and removal of the stock harmonic
balancer, I completed additional research, including a note to
Fluidampr, the manufacturer of fluid type dampeners. Basically, this
is what I learned:

As to its primary purpose, a "harmonic balancer" should, more aptly,
be called a "torsional dampener," since a crankshafts actually twist a
small amount every time a cylinder has a power stroke. Thus, the
HARMONIC portion of the name is that a harmonic balancer
attempts to "cancel out" or disrupt those rhythmic (harmonic)
vibrations. These vibrations consists of fundamental and
HARMONIC frequencies. It cancels out the vibrations by flexing a
heavy metal ring, mounted/vulcanized on rubber every time the
crank twists; it is a simple spring (rubber) - mass (metal from the
rubber outward) unit tuned to a narrow band of vibrations. - it is
designed for the specific range of "vibrations" that a specific engine
produces - hence, just not any harmonic balancer will do. Elastomer
dampers, such as the one on the 7M-GTE, are, actually, a tuned
absorber.

Technically, the primary purpose of a harmonic balancer is to cancel
out third harmonic distortion by using intermodulation between the
second harmonic and the fundamental in the space charge regions
of the triodes Doesn't everyone just love engineers when they make
such statements :-)

Without such a dampener, the ultimate problem could be that certain
vibrations could occur at a frequency (rhythm) that happens to be
the "critical" vibration point of the material the crankshaft is made
of.

In addition, per a response email from Fluidampr, the harmonic
balancer has a secondary purpose. The BALANCER part stems
from external balance engines' requirements for enough weight
to allow the engine to run smoothly. The manufactures add weight
to the damper and/or flywheel to make up for weight that can not be
placed in the counterweights that connect the main bearing journals
to the rod journals.

Hence, putting the Harmonic ( frequency dampener) and the
Balancer (add weight for smooth engine operation), we arrive at the
name of HARMONIC BALANCER.

Bottomline, replace the Harmonic Balancer at your own risk.

Just my thoughts and research.

Arlene Lanman
88T automatic

- BTW: Fluidampr and Streetdampr substitute high viscosity
silicone fluid to do the job of the rubber in the factory damper. The
silicone allows the fluid type dampers to be true torsional vibration
dampers. They work at any engine speed/load combination.
Fluidampr is, currently, looking into making a damper for Toyota
Supra (they were not specific but, probably, meant for the MarkIV).
++

[AdrianS]

How many 4 cyl cars in the last 15-20 years have come out with anything else but a cranshaft pulley.

My 4AGE 20v (1999 blacktop) has a harmonic damped crank pulley, and I'm keeping it on, despite the knock-on effects with belts/ancilleries.
Harmonic torque fluctuations can be staggeringly destructive - during engine dyno development we had 4 cyl engines break input shafts that were fine with big v8s. The failures were fatigue related, not torque overload, and occurred after some tens of hours of running.
We tracked the problem down to speed fluctuations : the whole crankshaft / flywheel assembly speeds up and slows down marginally every stroke of every piston, and the drive coupling was trying to accelerate/decelerate the dyno accordingly. The problem was eventually cured by improving / tuning the damped input shaft coupling.
What was fascinating was how hot our damped coupling got in operation : it was clearly absorbing / dissipating a fair bit of energy.

[Sam_Q]

A friend of mine, Hen from these forums, was running his 4AGZE in RWD form with a "12 PSI" equivalent solid aluminium crank pulley on it for at least 2-3 yrs of hard hard driving bouncing off the limiter and participating in drifting, autocross etc and he eventually had a fail just driving down the freeway to Wilson's Prom. The front snout of the crank where timing gear and crank pulley mounts snapped clean off and we supsected it was due to the harmonics generated but not eliminated combined with the stresses of the larger diameter pulley. Just an example for you.

right near the oil pump right? Of reports I have heard every failed 4age crank breaking so far has been in that particular spot. I won't even machine the front section off my pulley in-case I change the harmonics of it.

[PlacentaJuan]

this keeps coming up and no one really has a definitive answer,

i installed an alloy undamped crank pulley about 3-4 years ago on the 2jz (my factory let go in melbourne and i had no cash and a lightweight alloy one at home that was a fraction of the price to post) however i still havnt replaced it with a proper harmonic balancer which i was going to do asap.

so far i have had no problems but everytime i hear a funny noise or see an oil leak it makes me wish i have changed the bloody thing already.

it was an underdrive pulley also and i have not noticed any power increase, but i have noticed less alternator power, power steering pressure, and air con performance at low speeds and idle which is really gay.

i will replace it with a factory harmonic balancer asap

[andrew_mx83]

some good info guys keep it coming!


i think the next step is to speak to an engine balancer and ask if the dynamic balance will get rid of these crank breaking harmonics. from what i have read this seems to be the #1 issue with an undampened pullley

[Supra967]

how do they load the crank in a balance? Do they try and simulate the power stroke?

[Sam_Q]

this keeps coming up and no one really has a definitive answer,

thats because we can't see it or usually feel it. Ontop of that some people have put them on their 4age race cars without an issue but others have had the snout of their crank break off. Confusing eh?

for me its along the lines of the risk is so high compared to some trivial gains so why bother