Dynamic dampening front pulley

[nkaminar]

Has anyone tried installing a dynamic dampening front pulley. I am trying to reduce torsional vibrations under certain conditions for my engine. A dynamic dampening pulley is used on modern engines. It has a viscus or rubber coupling to a heavy pulley that absorbs torsional vibrations. They were first used on straight 6 and 8 cylinder engines to eliminate broken cranks.

I have located a dynamic dampening pulley from a company in New Zealand, photo below. I am trying to decide whether to buy it or not.

[nkaminar]

I should add that it is a direct replacement for the standard pulley without modification to the engine.

[Synchro909]

I have fitted one on an engine I haven't driven without the Dynamic Balancer so comparison is a little difficult. I have, however driven many other Model As over the years for comparison. I believe it has made a difference - this is my smoothest running (of 4) engines. Would I do it again? Yes!
BTW, the pullies come with an option. For those with the original ripe style front seal, there is a reverse scroll machined into the pulley available to help reduce leakage. For those with the modern style seal, the pulley is plain for the seal to seat against.
The only negative I can give is they are a little closer to the front cross member which means fitting a fan belt will take a little fudging.

[AL in NY]

I agree with Synchro909, the pulley did make a difference on my engine which had harmonic vibrations at 1500 and 2200 RPMs before I installed the pulley. Like Synchno909 said, installing a fan belt becomes a bit of a chore.

[Y-Blockhead]

There are a couple of threads on 'Harmonic Balancers' or 'Vibration Dampers'. I have one on my Town Sedan. I believe it works well for what it is designed for but if you have an engine that is out of balance the Harmonic Balancer is not going to cure your vibrations.

I use a segmented belt with my HB so I can get it off or on while on the road. The segmented belt also seems to help some with vibrations.

[Jack Shaft]

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Murray Horn.. email [email protected]..

A nice balancer, quality unit and a good man to do business with.. torsional vibration has a 'tuning fork' effect. Herm Kohnke felt that the torsional vibration caused a .001 deviation at center main at 2400rpm.I figure the pain of belt replacement a small price for extended bearing life.

[1931 flamingo]

How often are you going to change the belt??
Paul in CT

[nkaminar]

Thank you all for you comments. Based on what people have said, I am going to order the pulley. I will report the results to the forum with I have it installed in a few weeks.

[Y-Blockhead]

Originally Posted by 1931 flamingo

How often are you going to change the belt??
Paul in CT

Only takes once...

[Pete]

That pulley may help a very small amount. It is no where near heavy enough to really do any good though. In theory the front pulley needs to be as close to the flywheel/clutch weight as possible for maximum torsional vibration dampening. This is not possible in the real world but in some cases of race engines it can be close and definitely helps.
The heavier the damper, the better.
Here is a pic of a 12 lb. big block Chev one adapted to a B circle track engine.

[shew01]

Originally Posted by Y-Blockhead

There are a couple of threads on 'Harmonic Balancers' or 'Vibration Dampers'. I have one on my Town Sedan. I believe it works well for what it is designed for but if you have an engine that is out of balance the Harmonic Balancer is not going to cure your vibrations.

I use a segmented belt with my HB so I can get it off or on while on the road. The segmented belt also seems to help some with vibrations.

I’m curious. Where did you purchase your segmented fan belt? I looked online and didn’t see any obvious site offering them. That would be handy to keep in the car.


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[Pete]

Originally Posted by shew01

I’m curious. Where did you purchase your segmented fan belt? I looked online and didn’t see any obvious site offering them. That would be handy to keep in the car.


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Here is one.
https://www.fennerdrives.com/powertwist-drive/

Sent from my Western Electric crank phone on my kitchen wall using Crankatalk.

[Y-Blockhead]

Originally Posted by shew01

I’m curious. Where did you purchase your segmented fan belt? I looked online and didn’t see any obvious site offering them. That would be handy to keep in the car.


Sent from my iPhone using Tapatalk

Try Restoration Supply Co. https://restorationstuff.com/shop/#fb0=61

Fennerdrives.com only has red and blue ones (unless you want a red fan belt).

[shew01]

Originally Posted by Pete

Here is one.
https://www.fennerdrives.com/powertwist-drive/

Sent from my Western Electric crank phone on my kitchen wall using Crankatalk.

Wow. I wasn’t expecting 14 “flavors.” Is there where you purchased yours? Which one did you order?


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[Pete]

Many flavors except licorice. Harbor Freight has lime.


Sent from my Western Electric crank phone on my kitchen wall using Crankatalk.

[shew01]

Originally Posted by Pete

Many flavors except licorice. Harbor Freight has lime.


Sent from my Western Electric crank phone on my kitchen wall using Crankatalk.

Lol. That other site was like Baskin Robbins.

I found a link. Lime will probably work.

https://www.harborfreight.com/vibrat...elt-43771.html


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[Y-Blockhead]

Originally Posted by shew01

Lol. That other site was like Baskin Robbins.

I found a link. Lime will probably work.

https://www.harborfreight.com/vibrat...elt-43771.html


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Wrong size. You need a ⅝" belt not ½".

[shew01]

Originally Posted by Y-Blockhead

Wrong size. You need a ⅝" belt not ½".

Thanks.


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[Flathead]

Use a standard black fan belt and keep a rainbow belt under the seat for emergency to get home. If you have the extra belt with you Murphy says you will never need it!

[Jack Shaft]

It takes a little persuasion but I was able to work a B belt under the balancer., to me its a small price if the balancer saves bearings.

[Dave in MN]

Changing the belt: While on a long road trip and about 2,400 miles before I made it home, I started to hear a “chirp” every time the alternator started to charge. The belt had worn narrow and would no longer engage with the sides of the pulley on the alternator. Tried my best to get the spare belt past the cross member and u-bolts, the dampener pulley was just too close. I removed the front u-bolt nuts, raised the bolts to allow them to tip sideways from the crank guide. This allowed me to slightly raise the crank guide and push it forward slightly giving me the clearance I needed to get the belt in place. With the weight of the car on the front spring, nothing moved out of position and reassembly was quick.

Vibration: When I installed the dampener pulley, I estimate the rpm range of the felt vibration narrowed to about half but it did not totally eliminate it.

[wensum]

This is my favourite theme, and I can only reiterate that Murray Horne's harmonic dampener worked miracles on our modified engine which had been scrupulously balanced, eliminating a loud timing gear rattle and the vibration periods of the motor.
It made the biggest single improvement to the driveability to our car.
Most modern cars have similar devices of a similar size

[Synchro909]

I also have wrangled a notched B section belt under the pulley. It's not an issue in my mind.

[SAJ]

I agree with Wensum and Dave in MN. Much of the clatter in my aluminium timing gear was reduced. But not all. As Pete says the balancer could do with being heavier but there is not much room.
In our 31Tudor a belt could possibly be finagled though the gap, but no way would one fit through on our 30 roadster. So I carry a segmented spare belt on this one.
The Tudor had almost subliminal crank torsional wind-up noises to my old ears. Almost gone with the harmonic balancer pulley. Passengers cannot hear anything but years of driving Model A's let me sense the crankshaft vibes as they come and go through certain rev ranges. Or maybe the tinnitus and crickets in my ears is fooling me!!
SAJ in NZ

[old31]

With the engine and radiator in place, and using a front float a motor, are you able to take the old pulley out and replace it with a Murry?

I might have just found my answer from Patrick, YUCK.

"Changing the crank gear in the vehicle can be done with some difficulty. The front of the engine needs to be jacked quite high. The radiator needs to come out, the rear motor mounts need to be loose and the one mount bolt on each side should be removed. The gear is really on the crank and usually takes serious heat and a real puller to get off. When putting the new gear on, do not beat/pound the gear on. Press it on. I use a length of turned pipe closed and drilled at one end so a bolt the same thread size as the crank can be used to press/push the heated gear on."

[Y-Blockhead]

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Old31, As you can see in my picture there is not enough room to get the stock pulley off and especially not enough room to install the Murray Pulley.

I had to jack up the engine plus I removed the front spring ubolts to give me more room. I also replaced the broken hand crank guide a this time.

[duke36]

Pulley cost?

[Y-Blockhead]

Originally Posted by duke36

Pulley cost?

I believe I paid ~$300 including shipping from New Zealand. That was a couple of yeas ago.

One of the features I really like is the reverse scroll on the snout that stops the front seal from weeping oil.

[Jack Shaft]

Be very careful installing any crankshaft pulley or balancer on an engine with a babbit thrust bearing.

[old31]

Jack, how would you know if you had a babbit thrust bearing and the type of front seal that you have?

The bottom line is I blew it, I should have installed the balancer when I installed the engine.

[jack wingard]

I checked with Murray Horn. With shpg to US $336

[The Master Cylinder]

Originally Posted by Jack Shaft

Be very careful installing any crankshaft pulley or balancer on an engine with a babbit thrust bearing.

Never heard of this before. Please explain.

[Pete]

Originally Posted by The Master Cylinder

Never heard of this before. Please explain.

He is referring to hammering a pulley or damper on instead of using the proper
"puller".

[nkaminar]

Well, the dampening pulley finally came and I installed it a few weeks go. I am going to report on the results in three posts. The first post will be some background theory that I uncovered while waiting for the dampener. The second post will explain how I installed the new pulley, and the last post will be the results.



So here is the first post: Warning: Technical discussion following.



The crankshaft experiences torsional vibration AT ALL ENGINE SPEEDS and the vibration can be several different modes at the same time. At certain rpm’s the vibration can be more extreme due to the exciting pulses matching a resonate frequency of the crankshaft. The resulting torque on the crankshaft can be 6 to 10 times the amount of torque going out the end of the engine to drive the car. For the Model A, the natural resonance of the crankshaft can be within the operating engine rpm depending on how fast the engine is revved, but there is always torsional vibration present.



The flywheel rotates at a more or less constant speed while the front end of the crankshaft can be torqued 1 degree or more. The torsional vibration can lead to a broken crank and can reduce the life of bearings, camshaft gear, cam bearings, and variation in ignition timing. The maximum torque on the crankshaft due to torsional vibration is at the rear bearing.



The stock flywheel rotates as a very constant speed because the node point (where there is no torsional movement of the crank) is right at the flywheel. For a lightened flywheel the node point moves forward so the flywheel now experiences some torsional vibration. A counterbalanced crankshaft will lower the natural frequencies somewhat but will add to the overall torsional deflection at the front of the crankshaft.



The dynamic dampener pulley consists of three parts: The hub which is pressed onto the end of the crankshaft, the inertia disk which is a heavy disk mounted to the outside diameter of the hub, and the rubber that connects the two. The dynamic dampener has its own natural frequency, the rubber acting like a spring. The natural frequency of the dynamic dampener is designed to counteract the natural frequency of the crankshaft. It applies a counter torque at the end of the crankshaft that dampens the crankshaft. There is some energy absorbed by the rubber but the main action is a counter torque due to the resonance of the dampener. The dampener has to be designed to fit the engine. It does not have to be especially large but it does have to have the proper natural resonance. Computer modeling and vibration testing is used to design the dynamic dampener. This is not something that an average Model A owner can do.



The hub of the dynamic dampener has to be a press fit on the end of the crankshaft so that the hub and the end of the crankshaft work in unison. The rubber is molded between the hub and the inertia disk and has to be the right durometer, compound, and configuration. There is a lot of science built into each dynamic dampener. The rubber compound will determine the life of the dampener and is a closely guarded secrete held by the manufacturer.



Most of this information came from an article in the “Vintage Speed & Sport Secrets Magazine”, volume 23, number 4, April 2014, which in turn is referencing a white paper by William C. Sisco for BHJ Dynamics. (Note: when I tried to visit their website I got a security risk notice.)

[nkaminar]

Installing the dynamic dampener was fairly straight forward. I had to jack up the front of the engine after removing the radiator using a floor jack and a block of wood. I removed the two main bolts from the rear Float-A-Motor mounts and removed the two bolts supporting the front of the engine on the stock front engine mount. I used a puller to pull off the old front pulley after removing the crank nut. I used the correct socket wrench with a breaker bar and put the car in high gear with the overdrive in high. I put the parking brake on and blocked the rear tires.

The dynamic dampener is larger than the old front pulley, see the first picture. This will increase the rpm of the generator or alternator and water pump/fan. I put the fan belt on before lowering the engine. I have not tried to replace the fan belt but it looks like it will be impossible without jacking up the front of the engine.



It is important not to hammer on the dynamic dampener as this will damage the thrust bearing for the crankshaft. I used a series of bolts that fit the thread of the crankshaft (5/8-18), each 1 inch shorter than the last, to push the dynamic dampener onto the crankshaft, see second photo. I carefully lined up the notch in the dynamic dampener with the key on the shaft nose and used a roller bearing underneath the bolts to keep the dampener from turning on the crankshaft and getting out of alignment. I used one then two roller bearings before switching to the shorter bolt.

The dampener went on fairly easily. It is important to have a press fit for the dampener and to tighten the crank nut securely. After getting the dampener on I lowered the engine and put the bolts in for the mounts. The bolts for the Float-A-Motor are just snugged up, not very tight.

[alexiskai]

Originally Posted by nkaminar

which in turn is referencing a white paper by William C. Sisco for BHJ Dynamics. (Note: when I tried to visit their website I got a security risk notice.)

I think this is the white paper in question.
BHJDynamics_Damper_Info.pdf

[nkaminar]

It took me a couple weeks before I could test the dynamic dampener as I has some other issues with the car and had to wait for parts.

Before the dampener I had a torsional vibration issue at about 2,400 rpm. Since installing the dampener I have run the engine up to 3,000 rpm with no torsional vibration issues. I feel that this was a good investment for my engine. It runs nice a smooth now. I have a counterbalanced crankshaft and insert bearings with a high volume oil pump.

If you are running a stock Model A at 45 to 50 mph, you may not feel the need for a dynamic dampener. If you are running a higher performance engine and drive at 60 or so you will definitely want a dynamic dampener. Even the stock engine could benefit from one as the crankshaft has torsional vibration at all engine speeds, even if you don’t feel the vibration. Although stock engines have run for 90 years without a dampener so the choice is yours. The major drawback is the difficulty in changing the fan belt.

[nkaminar]

Alex, Thanks, yeah that is it.

[alexiskai]

Originally Posted by nkaminar

I have not tried to replace the fan belt but it looks like it will be impossible without jacking up the front of the engine.

A lot of folks who use these dampers switch to link belts for this reason.

[Y-Blockhead]

Originally Posted by alexiskai

A lot of folks who use these dampers switch to link belts for this reason.

[Pete]

Here is some more info on dampers. These are very good units. I have one on my Bonnevillle engine and had one on my 4 banger circle track engine. I use the 8 inch ones.
For a stock frame you may have to trim the front cross member.

https://www.enginelabs.com/engine-te...our-questions/

[old31]

Isn't the real cost of the pulley $476.21?

When you send Murray a paypal payment of $330 doesn't PayPal convert the currency and deduct $476.21 from your account?

[Y-Blockhead]

Originally Posted by old31

Isn't the real cost of the pulley $476.21?

When you send Murray a paypal payment of $330 doesn't PayPal convert the currency and deduct $476.21 from your account?

I paid $300 total for mine a couple of years ago. Murray has one on eBay for $270 + shipping. Paypal doesn't add to the total price. I assume Murray has included the Paypal fee in his price? Certainly not #146.21?


If you are concerned about PayPal, pay him with a Credit Card.

[CarlG]

I paid US$300 + $30 for freight 2 months ago. Don't know what the net to Murray in NZ$.

[old31]

Carl, what belt are you using? And are you using a gen or alt?

[AL in NY]

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You don't have to change belts using the Murray Horn Dampener. Your standard wide/length belt will work. You will need to carry a jog belt while you are traveling because you can't get a standard belt between the front cross member and the dampener.

[CarlG]

Originally Posted by old31

Carl, what belt are you using? And are you using a gen or alt?

1) I don't have mine all back together yet, so things might change.
2) I have an alternator, but I also have A/C, so the belt I had is NAPA 25-22495
3) I bought a new one and it fits just fine with the engine in place
4) Based on what Y Block has said, I ordered the link belt from Restoration Supply. It will also go on assembled.
5) I will probably stick with the link belt, but carry the new NAPA belt as a spare, along with extra links if the need arises.

[CarlG]

. . .

[CarlG]

Originally Posted by AL in NY

... you can't get a standard belt between the front cross member and the dampener.

I had no problem getting mine to go on.

[old31]

Carl, that's funny. You are from Alaska and have AC.

To me that would be like the guy installing a heater that drives in death valley.

[old31]

I didn't need to worry about the Paypal $476.21 charge for the balancer. My price on the invoice for the balancer was $330, and that included shipping.

The balancer fit great.

A standard NAPA B41, 44" x 21/32 belt was installed. It was not easy. I had to grease the front shackles and beat the belt under the balancer.

I am using a Powermaster 6 volt alternator, that is why I need a 44" belt.

[katy]

Originally Posted by old31

I did not need to worry about the price.

Lucky you, It would be nice if'n I had that sort of problems

[CarlG]

Originally Posted by old31

Carl, that's funny. You are from Alaska and have AC.

To me that would be like the guy installing a heater that drives in death valley.

All of our modern cars have A/C, so why not our A's? Actually there are 2 pickups in our club that have A/C.

[GeneBob]

Originally Posted by Pete

Here is some more info on dampers. These are very good units. I have one on my Bonnevillle engine and had one on my 4 banger circle track engine. I use the 8 inch ones.
For a stock frame you may have to trim the front cross member.

https://www.enginelabs.com/engine-te...our-questions/

I don't see a Fuidampr for the Model A engine. Any further information?
Thanks

[Y-Blockhead]

Originally Posted by GeneBob

I don't see a Fuidampr for the Model A engine. Any further information?
Thanks

I think Pete mentioned he uses a BBC damper on his race engines. Fluiddamper does not offer a damper for the Model A.

The only person that makes a Harmonic Balancer for the Model A is Murray Horn (as far as I know??)

Originally Posted by old31

Carl, that's funny. You are from Alaska and have AC.

A/C is useful for more than cooling, It helps keep dust and diesel fumes out of the cab of my F-150 also. Keeps the co-pilot happy.

[Gene F]

OK, so if I want to use one of these I need to cut the crossmember, or not? Forget about the belt, I can buy either one I need. I want to know about the crossmember frame.

[AL in NY]

You don't touch the crossmember. You can use the same belt you used with the standard pully. The clearance between the installed pulley and the crossmember is tight and it's nearly impossible to install the standard belt without raising the engine. That's why you need to carry a link belt when you travel.

[Y-Blockhead]

Originally Posted by AL in NY

You don't touch the crossmember. You can use the same belt you used with the standard pully. The clearance between the installed pulley and the crossmember is tight and it's nearly impossible to install the standard belt without raising the engine. That's why you need to carry a link belt when you travel.

2X what AL in NY said...

No frame cutting, link belt optional.

[nomadpsd]

I had Murray make mine for a serpentine belt. Belt just slips past pulley.
IMG_0033 by nomadpsd, on Flickr

[old31]

Originally Posted by katy

Lucky you, It would be nice if'n I had that sort of problems

Let me rephrase that. I always have to worry about price.

I only said i didn't need to worry about the $330 price because I thought after my PayPal transaction to Murray that they charged me $476.21 for the pulley and I was worried about that transaction.

[Big hammer]

Originally Posted by Y-Blockhead

2X what AL in NY said...

No frame cutting, link belt optional.

Is the link belt directional ? looking at the inter part of the belt those angled flap pieces thanks