3SX or other non-OEM Custom Crank Pulley vibrations vs STOCK CRANK PULLEY smooth ???

[J. Fast]

Good article... You do realize bearings and oil are secondary absorbers too right? If you take a tuning fork and smack it on a table it will ring. If you take washers composed of a softer metal material and slide them down the ends of the opposing forks and smack the fork again it will ring differently... Repeat test in water, then repeat in oil. Then do it with different weights of oil with different modifiers.

The secondary destructive order exists, but not in an RPM range anyone I know should have concern for. The way I drive, the power I'm making, and the 60K mileage on a solid pulley says different.

[ProwlerGT]

ohhhh I love it. This reminds me of the early to mid-2000's when the old 3SI was like this. Am I really that old now? lol - Its been a while since I've had a good discussion like this, because rarely people want to skip them and move on to actions without thoughts first.

J. Fast if you are making 650 HP with 60k miles (which I think is a dream to drive like that everyday) and running the solid I think I'm sold then. As most others have been saying, I should be fine in a "stock NA setup". I was mostly concerned with a lot louder engine/vibration noise and/or bolts coming loose over time.... which would suck... but crankshaft and other engine part damage would sure be a lot worse.

On a flip note - I can't believe Mitsu (or any car maker) would just literally "glue" (or mold) rubber right onto a metal ring with no other metal fasteners of any kind, given all the power transferring from that pulley? I mean with all that power transferring to the pulleys, it would seem like you'd have a solid or again a rubber molded setup with metal fasteners.... but I'm no machinist or fabricator of metals so I wouldn't know how hard that is to balance or make to begin with.

[i3igpete]

On a flip note - I can't believe Mitsu (or any car maker) would just literally "glue" (or mold) rubber right onto a metal ring with no other metal fasteners of any kind, given all the power transferring from that pulley? I mean with all that power transferring to the pulleys, it would seem like you'd have a solid or again a rubber molded setup with metal fasteners.... but I'm no machinist or fabricator of metals so I wouldn't know how hard that is to balance or make to begin with.

torsional dampers work by having the hub and ring twist against each other with a softer material in them. you bolt the inner and outer together, then you lose the ability for the hub and ring to twist.

Some might argue harmonics... mehh. It's balanced and I don't use cheap oil that breaks down and adds weight to rotating parts and throws them out of balance.

balance - whether it's internal or external - is centrifugal forces (X and Y if you look at the front of the crank). a torsional damper resists crank twist (Z rotation). they're two different things.

And for the record, bearings are very poor dampers for crank twist. They add friction across all frequencies, so you don't reduce the peaks - you just reduce the mean torque output. To prove it to you, I'll set up a simulation tomorrow for a v6 engine, and compare the torsional response for two oils: 0w20 and SAE 50. The difference may surprise you.

[J. Fast]

I get the Z direction crankwalk torsional node, is the stock pulley the answer for different weights at the crank pins? Could you run the simulation with the stock weights OEM bearings and service manual recc oils, and the change just oil weight? Then run the same simulation with a stroker kit or aftermarket kit with different rods, pistons, bearings, pins, crankshaft, and rod bolts for me Pete? If you need the weights I'm sure we could all work together and get you the info. I believe I have my rod weights, rod bolt weights, and pin weights written down in my liittle black "I did this on this date" book.

[J_Parker]

why would the mold the stock one off center?

It's not so much the "mold" being off center (This happens frequently as well though) as it is the natural breakdown of the rubber used. In my case, I will not use a stock harmonic balancer simply because my car sees months of inactivity. With the age of the rubber, and sitting there for so long the I can suspect the outer "ring" to sag over the course of time. Obviously, this is not enough that you're going to see with the naked eye, but it does happen, and it's enough to throw off the whole job it's supposed to be doing.

I say go solid, they're more durable, easier to remove, lighter, more affordable, and it's not going to throw itself off balance.

[IPD]

i've never ONCE heard of a stock damper getting out of round "because it sat". they aren't held together by chewing gum. i'll grant you cheaper, lighter and even more durable. easier to remove? how? and the stocker's durability is measured in years, not months. they should easily withstand ~10 years without difficulty. even then, you just replace it while you're doing a 60k service, no sweat. and the power gains from it being "lighter" are marginal.

if you're cheap & have n/a levels of power, then solid makes some sense. i wouldn't even call it a "mod" though.

p.s.
underdrive? lol. as old as my car is, i want my accessories running full-tilt.

[J_Parker]

i've never ONCE heard of a stock damper getting out of round "because it sat". they aren't held together by chewing gum. i'll grant you cheaper, lighter and even more durable. easier to remove? how? and the stocker's durability is measured in years, not months. they should easily withstand ~10 years without difficulty. even then, you just replace it while you're doing a 60k service, no sweat. and the power gains from it being "lighter" are marginal.

if you're cheap & have n/a levels of power, then solid makes some sense. i wouldn't even call it a "mod" though.

p.s.
underdrive? lol. as old as my car is, i want my accessories running full-tilt.

To each his own really. Those are all to me, just notable things in the reality of something held together with rubber. I just feel more comfortable knowing that a five pound ring of destruction isn't going to wreak havoc in my engine bay if it separates. Easier to remove as in; Every single time I had to remove the stock piece it was rusted solid to the crank and timing cog, even with a shot of grease between. Not once have I had this problem with the aluminum one.

[IPD]

To each his own really. Those are all to me, just notable things in the reality of something held together with rubber. I just feel more comfortable knowing that a five pound ring of destruction isn't going to wreak havoc in my engine bay if it separates. Easier to remove as in; Every single time I had to remove the stock piece it was rusted solid to the crank and timing cog, even with a shot of grease between. Not once have I had this problem with the aluminum one.

i suppose dis-similar metals can make it a bit easier to remove, but tell me, how old were the ones you pulled? separating any pieces of metal after being stuck together for a decade will be difficult. fwiw though, i never had excessive problem pulling mine. (using oohnoo tool).

[J_Parker]

i suppose dis-similar metals can make it a bit easier to remove, but tell me, how old were the ones you pulled? separating any pieces of metal after being stuck together for a decade will be difficult. fwiw though, i never had excessive problem pulling mine. (using oohnoo tool).

It may just be my climate (It's not really the easiest to live here) but I find a lot of rust on things like that. It's wet, salty, and the temperature fluctuates erratically. Like yesterday, it was +10c and now I look out the window to see -7c and six inches of new snow again. The one I had started using after worrying about the old one separating was only about a year old when I put it on.

[Intropy]

I wouldn't go back to a stock damper if you gave me a new one for free. Been running OEM-size solids for nearly a decade on everything from stock to BPU to my TD05 car.