Another Super High End U20 Part

[Datsunparts.comInc]

3 dozen sold - 12 sold in our full engine kits. No Harmonic Balancer or front damper gets anywhere near the quality and performance of this part. We spent the money to make it. No need to send a deposit. We have the wherewithal to make this and to keep it in stock for you and not use our customers to fund projects. Read the details at the link. We like it, you will too!

https://datsunparts.com/products/datsun ... f434&_ss=r

https://datsunparts.com/pages/uhqp

[tjp]

No rubber to cancel harmonics?

[23yrRebuild]

I was wondering about that, too.
Mike

[Datsunparts.comInc]

Yes rubber/elastomer. This was deeper down in the text referencing the parts construction. "Most engine designers prefer elastomer-type dampers because of their durability, superior high-frequency damping qualities, and ability to dampen all types of vibrations: torsional, axial and radial."

D-

[Solex68]

I like this part but I would have requested the pully be made for one belt, not two. Not Dean's fault but the manufacture who makes them. How many 311s run two belts today?

[Gregs672000]

I like this part but I would have requested the pully be made for one belt, not two. Not Dean's fault but the manufacture who makes them. How many 311s run two belts today?

I think he said the second groove is for balancing as he mentions using the v-groove for the belt. If I were in the process of converting to a crank-fired system I'd buy this one.

[david premo]

In fact it cannot be a harmonic balancer as it lacks the means to absorb and dissipate vibrations. Harmonic balancers are built in 2 types that I’m currently aware of. The first type uses an inner hub fixed to an outer dampening weight that is attached via a vulcanization process. The second type came out in the late 70 or early 80 and used a fluid chamber that encapsulates a steel ring that would absorb vibration energy. In essence the new product shown here, I would classify as a pulley. As a pulley of substantial weight it would have some benefits for the flexing of the crankshaft but could do little to eliminate 3rd harmonic vibrations that could cause cracking in the crankshaft.
Dave

[Solex68]

In fact it cannot be a harmonic balancer as it lacks the means to absorb and dissipate vibrations. Harmonic balancers are built in 2 types that I’m currently aware of. The first type uses an inner hub fixed to an outer dampening weight that is attached via a vulcanization process. The second type came out in the late 70 or early 80 and used a fluid chamber that encapsulates a steel ring that would absorb vibration energy. In essence the new product shown here, I would classify as a pulley. As a pulley of substantial weight it would have some benefits for the flexing of the crankshaft but could do little to eliminate 3rd harmonic vibrations that could cause cracking in the crankshaft.
Dave

I think it does have the dissipate material, it's just not easy to see in the image. It is very thin.

The company who makes them, if I'm not incorrect, makes them for many cars and pretty well known and makes them for many brands, American cars, Jags, Porsche and Toyotas to name a few,

[Datsunparts.comInc]

HARMONIC.PNG

Greg,

The red arrows in the half section profile point to the space where the elastomer fits inside the two piece part. While Dave's reporting off history may be correct, he is incorrect in his conclusions about this part. BHJ products is a very, very respectable company. They are not selling out of their garage. Many other highly reputable companies sell their race oriented harmonic balancer products.
This U20 design is indeed a harmonic balancer and were contracted specifically with this in mind when I ordered them. They do not make ANY pullies that slide directly onto crankshaft snout.
This style has been used on many race cars.
As far as the thinness of dampening material, that is a bit of guessing don't you think? I can not share the blue print, but I can tell you that what you see in the photo for gap between the outer ring and the inner ring is not indicative of what the material thickness is inside.
Here is the link to their web-site: The Roadster one is not listed there because it is a proprietary part that only I have access to.

https://harmonicdampers.com/index.php?m ... Path=74_10

Dean

[Gregs672000]

I see they offer a 36/1 toothed wheel for L-series for crank-fired ignition systems... nice that someone is making these. Probably not enough demand for U/R motors, but they would certainly have experience that would transfer.

[Datsunparts.comInc]

Yes, Chris at BHJ would be more inclined to do special products for such a low production vehicle as the Roadster. But we have to be careful in how we support these legitimate companies, respect their efforts and don't do things to offend their efforts. Positive questions and inquiries to gain more information are welcome. Criticism and guess work, erroneous information and stuff designed to offend.... Well they will just say no to the community of Datsun Roadster owners. My understanding is that already 2 companies are now black listed and can not buy from them for spurious on line claims.

Dean