Switching from a harmonic balancer to an all-metal crankshaft pulley

[inquirer]

I was wondering how crucial is the rubber ring crankshaft pulleys have?

The rubber supposedly dampens the crankshaft's vibrations.

But for some car's that are equipped with an OE pulley that has a rubber ring, there are lightweight versions of the crankshaft pulley that are all-metal. Do they have any disadvantages or any side effects?

 

[bdcardinal]

Some engines, like the SBF, will have an imbalance built into the crank which has to be accounted for with the harmonic balancer and flywheel.

 

[inquirer]

Some engines, like the SBF, will have an imbalance built into the crank which has to be accounted for with the harmonic balancer and flywheel.

Machine shops can easily create a lightweight pulley for any car. In that case it wouldn't be a good idea to do it, if you don't know the specifics of the car's engine, right?

 

[Exhaustgases]

If its a lawn mower engine you will be fine. If the manufacture installed one like most all cars and trucks have, if you change it to a non damper then you are running a test to see how long things last before something breaks. Just keep us all posted on what happens with this test.
Oh and usually any light weight pulleys are made to bolt on to the damper to crank inner flange/ hub itself not meant to replace it.

 

[bdcardinal]

Machine shops can easily create a lightweight pulley for any car. In that case it wouldn't be a good idea to do it, if you don't know the specifics of the car's engine, right?

Absolutely. They need to be designed to match the engine. That is actually sometimes an issue when doing stroker engines, you have to make sure you buy the proper balancer that matches the crankshaft. Engine Masters had a video on it and they used basically a sprint car front pulley and flywheel and the gains were noticeable on the engine they used due to the lower rotating mass.

 

[Cujet]

It really depends on the engine. My Jaguar's AJ126 V6 does very well when removing the harmonic balancer and installing an aluminum supercharger pulley. As the crankshaft is very robust, and has the same 5 main bearings as the V8 version.

Some engines that have an oil pump directly on the crankshaft will not survive for long with the removal of the harmonic balancer. This is due to vibrations/crankshaft twisting causing oil pump failure. The early Miata's and some American V8's are good examples of this.

 

[inquirer]

If its a lawn mower engine you will be fine. If the manufacture installed one like most all cars and trucks have, if you change it to a non damper then you are running a test to see how long things last before something breaks. Just keep us all posted on what happens with this test.
Oh and usually any light weight pulleys are made to bolt on to the damper to crank inner flange/ hub itself not meant to replace it.

Here is the OE pulley for the 4A9 Mitsubishi engine:

As you can see there is an EPDM rubber ring, between its inner and outer part.

Here is an aftermarket all-metal one made by 7075 T6 aluminum alloy:

Is it really incompatible then?

Absolutely. They need to be designed to match the engine. That is actually sometimes an issue when doing stroker engines, you have to make sure you buy the proper balancer that matches the crankshaft. Engine Masters had a video on it and they used basically a sprint car front pulley and flywheel and the gains were noticeable on the engine they used due to the lower rotating mass.

A balancer? Is that a separate part? Or are we still talking about pulleys with rubber?

 

[inquirer]

It really depends on the engine. My Jaguar's AJ126 V6 does very well when removing the harmonic balancer and installing an aluminum supercharger pulley. As the crankshaft is very robust, and has the same 5 main bearings as the V8 version.

Some engines that have an oil pump directly on the crankshaft will not survive for long with the removal of the harmonic balancer. This is due to vibrations/crankshaft twisting causing oil pump failure. The early Miata's and some American V8's are good examples of this.

OK! Then this upgrade requires deeper research!

 

[Exhaustgases]

Just my opinion. I find those balancers that use the weight to drive accessories a bad idea. Every time a varied load like an AC compressor is applied, the tuning has to be affected some how. Its the weight and the isolator that determine the dampen frequency.

 

[inquirer]

Just my opinion. I find those balancers that use the weight to drive accessories a bad idea. Every time a varied load like an AC compressor is applied, the tuning has to be affected some how. Its the weight and the isolator that determine the dampen frequency.

Yes, you have a point. Also I guess that the engine harmonics change at different RPM.

 

[Bottom_Feeder]

What are you trying to fix/improve by changing this?

 

[inquirer]

What are you trying to fix/improve by changing this?

What else? Less weight means better efficiency. It won't make a huge difference of course, but it is a cheap upgrade.

 

[ctechbob]

Old school BP Mazda engines will eventually shatter their oil pump gears without a damped balancer. In that case, the benefit is outweighed by grenaded hard parts.

 

[Trav]

I wouldn't call the good possibility of taking out the engine main bearing and oil pump out much of an upgrade. These are made for engines that have been internally balanced, they are called a harmonic balancer for a reason. One common alternative to original is a Fluidampr that they claim are better than stock at controlling the engine harmonics.

https://fluidampr.com/

https://eaglerod.com/balancing

 

[inquirer]

Old school BP Mazda engines will eventually shatter their oil pump gears without a damped balancer. In that case, the benefit is outweighed by grenaded hard parts.

I get that the effects vary widely for different engines.

I wouldn't call the good possibility of taking out the engine main bearing and oil pump out much of an upgrade. These are made for engines that have been internally balanced, they are called a harmonic balancer for a reason. One common alternative to original is a Fluidampr that they claim are better than stock at controlling the engine harmonics.

https://fluidampr.com/

https://eaglerod.com/balancing

Yet you can find readily available all-metal pulleys for many cars, especially for sport cars.

I wonder if it is that difficult for the manufacturers to use a similar design and produce a divided pulley by a rubber ring, of course with the use of a lightweight alloy.

I also wonder if a rubber of very specific stiffness should be used in order to achieve the required dampening effects.

 

[ctechbob]

I get that the effects vary widely for different engines.



Yet you can find readily available all-metal pulleys for many cars, especially for sport cars.

I wonder if it is that difficult for the manufacturers to use a similar design and produce a divided pulley by a rubber ring, of course with the use of a lightweight alloy.

I also wonder if a rubber of very specific stiffness should be used in order to achieve the required dampening effects.

They're available because people buy them, not that they're necessarily in the best interest of the engine.

 

[inquirer]

They're available because people buy them, not that they're necessarily in the best interest of the engine.

No doubt that there are people who are interested in buying them.

Still, I would say that the manufacturer has the responsibility to engineer their products in a way that makes them meet specific standards.

 

[RooflessVW]

No doubt that there are people who are interested in buying them.

Still, I would say that the manufacturer has the responsibility to engineer their products in a way that makes them meet specific standards.

It sounds like you've made up your mind.

So what are you hoping for here?

 

[inquirer]

It sounds like you've made up your mind.

So what are you hoping for here?

I actually recently changed the pulley with an OE one, because I thought that the rubber had developed several cracks on its surface. That's also what a mechanic who checked the pulley said.

After it was uninstalled and I took it in my own hands, it turned out that the rubber was covered with paint that had cracked all over the place. The only thing (that I guess it's not a serious problem) is that the rubber ring of the old pulley has become more stiff, not much, but enough to feel that there is definitely a difference.

I'm asking about lightweight pulleys, because it happened to learn from a machine shop that they can make one for a very good price, compared to the OE. So I'm asking for possible future use.

 

[barbersurgeon]

It really depends on the engine. My Jaguar's AJ126 V6 does very well when removing the harmonic balancer and installing an aluminum supercharger pulley. As the crankshaft is very robust, and has the same 5 main bearings as the V8 version.

Some engines that have an oil pump directly on the crankshaft will not survive for long with the removal of the harmonic balancer. This is due to vibrations/crankshaft twisting causing oil pump failure. The early Miata's and some American V8's are good examples of this.

That SC belt is what replaces the dampener.

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In general,

A torque converter also acts as a dampener to some effect. There are lots of variables, factory built engine vs true balanced rotating assembly for one. Belt driven water pump? Belt for AC compressor. Timing belt(s) vs chain. Having good primary and secondary balance by engine design, straight six or V12 ideally, or flat six.

If your engine came with a dampener, it should probably have one. If you feel the need to upgrade this then spend up for an ATI or Fluidampr. Or run a lightweight pulley set with the factory dampener and find a lighter tire/wheel combo.