I'm not trying to teach anybody anything. I am just here to learn from the people here who are more knowledgable than me.

My bad. I didn't mean to assume that you were the reason the car failed. It just seemed from this quote that you were the one in control on the engine.

 

Sometimes, bad things happen to people who aren't Ben. Not often, though.

 

I think Savington's proof is easily enough to show they are talking crap.
However, it may be a good idea to read the product details again in the "on the topic of vibrations, harmonics and safety" section.

Do lightweight aluminum crank pulleys lead to premature engine failure?
They don't actually answer this question. They state that it still discussed because of previous engines requiring dampers.

Modern (1980s and up) Mazda and other Japanese engines are NOT equipped with external balancers.
They immediately contradict themselves with "The crank pulley found on 1990-2005 Miata engines is typically called a harmonic damper. This damper is a thin rubber band, less than (1/8 inch) 2mm, built into the crank pulley. This rubber is supposed to absorb something called NVH, noise/vibration/harshness."

These engines are internally balanced and this process has improved even further since the 90s.
ALL engines are internally balanced but the accuracy of the balance is what has changed. Engines are balanced better with modern machinery but the accuracy is no where near perfect requiring a damper.
Almost everyone has had a wheel weight come off and generally this alters the balance only fractionally and the car become a total sod.
Imagine that but being spun at several hundred times faster.
No imagine its held together by a quite floppy forged crank.
Pop goes the weasel.

Everything in building an engine is to survive. Balancing the rotating assembly will be very helpful as the will be less vibrations but you will still not want to risk the engine without a damper.

 

I wouldn't trust TDR to tune a weedwhacker let alone give me advice on it.

 

Dammit, dammit, dammit.

Here's my situation. My Kraftwerks Rotrex bracket broke, and I purchased the TDR bracket to replace it. It does appear to be a much better unit. Unfortunately, it requires a slightly longer belt, a 458 rather than the 457. The only four-rib 458 belt I could find was from Continental (Contitech) and it seems to be just a large rubber band. I never had any problems with belt slippage before using this belt. At the track the first time with the Contitech belt, I must have tightened the belt five times and still had slippage. I've used four-rib Gates and Daycos of various lengths after changing pulley sizes and when I deleted the a/c without issue. The 458 belt is readily available in the six-rib version from Gates and Dayco, so I decided to go with the TDR pulley. I'll put the OEM damper back on and run the four-rib belt.

Sav, I'll send you beer money. I'm getting the car ready for four days at VIR and you may have just saved me another motor.

Thanks!

 

Can I clear something up... Whilst a crank is balanced in terms of rotational mass and the weight hanging off the crank (rods and pistons) is symmetrical and equal, the crank still deflects under the load from the force delivered down the rod due to the explosion happening above it. Just like soldiers marching on a bridge, if those force pulses align to any of the harmonic frequencies due to the lengths of metal in the crank, then they will be additive over time and deflect the crank more and more. These pulses are less of an issue on engines that are constantly changing revs (drag cars, sort of track cars)... more so on engines that sit at static rpms (Nascar).

You don't actually need a lot of dampening to reduce additive harmonic deflection. Try bouncing on a trampoline with someone else sitting on it (they must be floppy and not rigid) and you won't be able to keep jumping higher and higher as their floppy body will absorb some energy every jump. Reduce the dampening weight and you can jump a bit higher. Remove the weight entirely and in theory you should be able to bounce infinitely high as long as there is no energy loss in the system.

- The OEM harmonic balancer uses the rubber to act like a damper to stop most of the harmonics from getting too large. The outer ring of metal is like that floppy weight on the trampoline. Rubber though can have it's own frequency but this still works fairly well, especially on street cars.
- An ATI damper is supposedly tuned to specific frequencies in the engine and it will be more effective on those, but still dampen the rest with a similar mechanism to the stock rubber damper. These work great on Nascars as the can be tuned to specifically dampen a target RPM range. They are heavy though.
- A Supermiata damper is lighter than stock, uses rubber so should act like a stock damper with more or less effectiveness. Hopefully more!
- A Fluidampr damper uses a floating fluid to reduce frequencies and supposedly works on a large range of harmonics. They used to be used in F1.
- A lightweight aluminium crank pulley does none of that. It just acts like it is part of the crank.

If the crank deflects enough a few bad things can happen. The bearing surfaces miss-align and leak oil out the sides enough so that they touch, get very hot and fuse... or the crank end where the oil pump is driven deflects enough that the oil pump gears intersect and fail.... or the crank breaks itself in two.

A couple of things to note:
1. We all typically change the rotational harmonics when we hang different rods and pistons off our cranks. This only results in minor changes to the harmonic frequencies moving them up and down the rev range. Most dampers will still work with different rods and pistons but with slightly more or less effect depending on where the harmonics fall. This is the reason why tuned dampers like the ATI damper can be less effective on highly modified engines.
2. Some of us run our engines way past stock rev ranges and that adds a whole stack of new harmonic frequencies. The higher the revs, the frequency ranges of the harmonics narrow and so tend to have less impact, but the crank is more stressed at the same time.

Some crazy people (me) have played with different mods to dampers and cranks. I run an oem stock damper with the front half cut off, spin my engine to 9k and nothing has gone boom... yet. I have also cut down a crank but have yet to spin that at speed (I have a Supermiata pulley on the shelf for that crank). Others have run the SOHC cast cranks with half the counterweights missing with success. Most of those people know what works for them, run race bearings, rebuild frequently and are willing to blow up engines to get any slight gain or for science! I don't think any serious engine builder would run an aluminium lightweight crank pulley instead of a damper.

 

Having a website doesn't make you a reputable vendor, sweetie. Neither does shipping parts on time when they're paid for. There's an inherent responsibility with developing a new part and some aren't willing to hire actual Engineers or experts or to even learn it themselves.

 

Madjak gets a
TDR gets every imagineable for selling utter dumpster fire trash to unsuspecting n00bs

 

Like me, who bought their intercooler kit that fits like ****, and when asked about it 'it's designed like that' and 'I don't know what I'm talking about'.
​​

 

Thats insane that they get away with selling this stuff and saying its perfectly safe.

 

Too Dumb to Research?

 

Thanks Madjak for amazing visual! And thanks for everyone who has contributed to this thread. At this point it seems very clear on the necessity of having those vibrations dampened.
Just playing devil's advocate here, Is it possible that the timing belt, accessory belt and water pump/ alternator belt apply a dampening effect to the vibrations on the crankshaft?

 

If they don't have dampers, then they don't damp.

 

 

Well the idea I have in my head in that timing belt has the crankshaft "fixed" from the 6 o'clock position, the accessory belt has the crankshaft "fixed" from the 8 o'clock position, and lastly the water pump belt has the crankshaft "fixed" from the 4 o'clock position. "fixed" meaning a place of contact that the crankshaft's vibrations might be able to dampen through. What do these dampers and belts have in common? Rubber.
Like I said, just playing devil's advocate and would love to hear people's opinion. By no means am I saying that this is the way it does operate, I'm just looking for thoughts on that idea.

 

My opinion is that it's a fact that if things don't have dampers, then they don't damp.

 

Empirically speaking, no. They don't damp the vibrations of the crankshaft to any meaningful degree, which is why engines with those three belts on them but no crank damper still shatter oil pump gears.

Here's a post on it the miata.net forum from 2006 (discussing events of a few years previous to that): https://forum.miata.net/vb/showthread.php?t=173225

--Ian

 

Just playing devil's advocate here, "Sure! Blow your engine up! Nobody knows you or gives a **** if it costs you $2000. Have a ******* party! Woohooooo!"

Keeping it real...

 

First, when I saw that pulley the first time I threw up in my mouth a little. I was so disappointed in TDR. I even talked with them about it, and the tone I used was "what the f are guys doing?"

I do feel somewhat obligated to say that some TDR parts are well designed and of good quality. I used the belt tensioner, and the A/C P/S delete solutions and found them to be good.

 

OP, why do you seem so intent on trying to prove that your original assertion was correct in the face of evidence. You can't just use the data and Co opt it to blame everything but the common element.

If you really want more data then you should get the pulley and run it at high rpms. Let us know how it goes!