OEM Crank pulley and damper vs Aluminum replacement

[N/A Camry Sleeper]

OK guys - I need some scientific advice...

Since the 5S alternator pulley was a moderately challenging project, I've decided to possibly craft a 7075 Aluminum version of the OEM 5S crank pulley minus the P/S belt pulley. I know how heavy the OEM pulley is, and they rarely give out, but what gets me is the vibration damper that is built-in to this pulley. Sometimes the rubber gives out most likely due to repeated oil saturation which degrades the material over time and when it does go, engine vibrations are overwhelming.

So here's the question - Is there a way to attach that damper to an aluminum counterpart and have it still dampen engine vibrations? I have heard some people who run their pulleys without the dampers, mostly Celica and MR2 guys, and many of them say it's OK, but almost NONE of them (except maybe MrTurrari) revs past 7000 RPM. Having the engine vibration damped will be a NECESSITY with my build, since 9000 RPM will my *tentative* redline.

I need webpage links, accounts, or any other PROOF that running an aftermarket pulley without a damper will/will not harm the engine in the long run. There have been others that say running without balancer shafts will decrease bearing life, but it's only heresay - no proof has been given.

Need to separate the tall tales from the facts here and go ahead with the next phase of the build - any info is helpful! Humor never hurts either!

Thanks!

[curry.style]

I remember reading somewhere online while researching turbo 5SFE's that the damper pulley only serves to dissipate driver discomfort due to NVH in the cockpit. But that may be total bunk.

[N/A Camry Sleeper]

Was thinking of buying this one and then machining the P/S pulley completely off of the rest of it:

http://cgi.ebay.com/ebaymotors/ws/eB...category=36474

[71Corolla]

My understanding is the harmonic balancer is absolutely essential. Not only to offset vibration, but for engine life as well. You can't simply replace it with something that will perform differently and except to have no downside.

Now to get the same effect as the OE part, but also building it able to survive much higher engine speeds, that is way out of my league.

...edit, Wiki article has a brief explanation which I think is reasonable.

[lemegacool]

i installed a obx lightwheight underdrive pulley on my 1mz and i feel smoother operation with less vibrations than before! it is also much much more rev happy! no problem so far!

[Chris Crash]

I think if you remove balance shafts (anyone doing a build should), you're already going to have vibrations and a modded pulley will not create more. I felt no difference with my unorthodox pulley, except free'r revs.

Then again, this is the info you don't want -- heresy, nothing empirical. Just things I've experienced. Mostly opinion I would suppose...

[N/A Camry Sleeper]

How many miles have you put on your 1MZ since the build?

I'm thinking that the 1MZ is internally balanced while the 5SFE is both internally (balance shafts) and externally (harmonic damper) balanced. Removing both items from the engine may be detrimental - but I just might have to do it and see, just like all my other mods!

[Chris Crash]

No I've got the balance shafts and unorthodox pulley on the 5SFE. Still working on the 1MZ!

The 5SFE has just rolled over to 17,000 miles with no balance shafts and the pulley with no damper.

[RichieRichJP]

Originally Posted by N/A Camry Sleeper

I need webpage links, accounts, or any other PROOF that running an aftermarket pulley without a damper will/will not harm the engine in the long run. There have been others that say running without balancer shafts will decrease bearing life, but it's only heresay - no proof has been given.

Need to separate the tall tales from the facts here and go ahead with the next phase of the build - any info is helpful! Humor never hurts either!

Thanks!

You won't get proof because this has been a long debated topic.
The OEM pulleys come with a rubber insulator for a reason. If you made an aluminum pulley, I would try to take it off the design of the OEM one. Then again, I don't know how you'd be able to sandwich rubber between two aluminum bits and not cause any short term or instant failure.
There are already some crank pulleys out there so it's kind of a waste of a project.

[curry.style]

So Chris, if I understand correctly you have nothing balancing your motor?

[Chris Crash]

Correct. There is slight vibration at idle, but that's about it. The balance shafts used in the 5SFE engines are prone to catastrophic failure.

[N/A Camry Sleeper]

OK - I've read some links and articles discussing the subject and have decided to go with this item - only thing is they make it for a 3SGE which I'm not sure if it fits.

http://rossperformanceparts.com/mj_r...cers.html#race

Anyone confirm interchange between these two motors?

[RichieRichJP]

That may be incorrect info. The 3SGE is not 2.2L.
No, the 3S and 5S pulleys are different.

[BMR]

DIY'ing a harmonic balancer would be a crap shoot. As that Wiki article 71corolla posted, its job is to damp out torsional vibrations, particularly at the resonant frequency of the crank. So it is tuned; which means the mass of the outer sleeve (pulley) and the torsional stiffness of the elastomer are designed so that they have a resonant frequency that matches the crank's first resonant frequency. The equation below (ripped off from wiki) shows the relationship between frequency (fn), stiffness (k) and mass (m). If mass is decreased, to maintain the same resonant frequency, stiffness would have to decrease to keep the k/m ratio the same. Good luck widdat!!!



With all that said, what happens without one?... it depends on a lot of things. At what RPM does the crank hit its resonant frequency?... and how much time does it spend there? What's the maximum stress that occurs each time the crank is twisted by one vibration cycle?

The failure mode here will be fatigue. Which is failure that occurs due to repeated stress below the tensile strength of the material (think of bending a paper clip back and forth until it snaps). Eventually, the crank will develop fatigue cracks, and ultimately, fail in torsion. Might take a few months, might take a long, long time. Might get away with it in one application, and have a catastrophic crank failure in another.

/geek-engineer-speak

[N/A Camry Sleeper]

^OK - Good info there. I should most likely shy away from building one and just purchase a racing version. I talked to Ross - they are located in Australia - they suggested I send them a 5SFE OEM crank pulley so they can manufacture one with the right diameter, stiffness, etc.

At $550 though, I may just go with the Heavy duty 5SFE version rather than have a custom one made. I don't want to leave anything to chance with this build - and BMR's statements about fatigue and creep are real issues when talking about a crankshaft's torsional loads. I plan to engine this vehicle for years to come, I'm in my second year of rebuilding the entire car's systems and trying out new stuff as well. Might as well build it right...

And fatigue failures will happen at the worst times...

@ Rich

Could you elaborate? Are a they different diameter, thickness, etc? If the inside hole is larger on a 5SFE that's an easy mod - simply bore out the hole and redo the Woodruff key - no sweat. But if the offsets are different...yeah - I'm just going to have Ross fab a custom one and say hell with it...At 9000 RPM one needs to have all the bases covered...