harmonic damper?

[warpspeed]

Right guys/girls,

The outer pulley on my crank pulley has seperated from the inside, i will replace it with a standard one for now but i want to fit something a bit lighter in the future.
Does anyone know of an uprated/lighter replacement pulley/harmonic balancer that's available?
I would buy an alloy one that i could modify to fit a damper but would prefer an off the shelf option if available.
I know it's not good to use an alloy crank pulley without a damper but has anybody ACTUALLY come across any problems with one fitted? what is the maximum power anybody has run with an alloy pulley with/without problems?
I am thinking that if their are no aftermarket options available i would start looking into something for myself, with a view to selling some, anybody interested?

 

[johnsy]

i may have a hold of the wrong end ofthe stick so to speak, but i believe there are light weight pulleys available on ebay scott, i think the crank pulley one is £99.99

 

[warpspeed]

yeah Dan, there is ones on ebay but they are just plain alloy and quite expensive for just one pulley.
The standard pulley has the alternator pulley bonded onto the hub and the bonding material absorbs torsional vibrations in the crank to avoid stress cracks

 

[Animaldaz]

think its CDF racing that make alloy pullies, i dont think thier crank pulley has the damper in it though.

 

[warpspeed]

no it doesn't but thanks anyway

 

[eastwood]

I have a CDF set which I havnt fitted yet (no damper) It all depends why the original damper was fitted by Nissan I doubt it was for some internal engine vibration so as to help balance the engine, its more likley there to smooth out any NVH (noise vibration and harshness) issues heard by the customers something which has already been ruined if you have a full set of polly bushes coil overs or any other chassis mods LOL.

 

[warpspeed]

yeah, i have a feeling that your right and it's probably ok to use the alloy pulley, i just want to do some research to see if anybody has actually had any probs of if it's all just chinese whispers (you know what the internet can be like! :roll::lol

 

[PobodY]

Hasn't Boby had problems with the alloy pulleys destroying the seals on his oil pump? - I thought that's what it was there for.

 

[red reading]

The dampar pulley's are fitted to reduced harmonic's (crank whip for a loose term)

Harmonic's are the tuning fork effect,everything has a natural frequency at which it vibrates (or rpm for this instance), and when a crank does it it flex's and knocks out the bearings (on our engine's?!) or snaps the crank .

I personally would use the standard pulley as i understand harmonic effect's,no amount of lightening and balancing will change that harmonic's do happen, F1 deliberatley dont use there engine's at set rpm (say 21000rpm) because it literally destroys itself from the vibration of the tuning fork effect. You can't erradicate it but you can change at what rpm it happen's at.

 

[red reading]

ps. food for thought, when my pulley broke up the vibration distroyed no1 main bearing on my old engine but no other bearings had any sign of wear (i got the crank checked and it was fine ,not a mark on it and am still using it now with no machining work done to this day), that wasn't really a harmonic effect but it show's that vibration will distroy things if you dont catch it in time.

 

[pulsarboby]

Hasn't Boby had problems with the alloy pulleys destroying the seals on his oil pump? - I thought that's what it was there for.

ive never used one and wouldnt.
not because of what ive read or what people said on internet but through my own findings of cars weve worked on....ive seen two that have destroyed front crank oil seals (more than once) but soon as a proper pulley is fitted then no more probs!

bit like the arp head studs thing lol
people carry on using them but i wont touch them through what ive seen happen with them time and time again.
only way youll find out for sure is buy one fit it and see for yourself, like andy on here yours maybe fine

 

[warpspeed]

cheers for that boby.
Have you considered that the reason alloy pulleys destroy seals is that they expand more than steel and then reduce the clearance?
I would be planning on use the steel centre and machining it so the alloy part located on it (would be an interferance fit)

 

[pulsarboby]

its a possibility scott, i just dont know if im honest with you!
i would have thought the pulley would not have got hot enough to expand so i put it down to the lack of damping and maybe balancing and poor machining.
if you get one machined youll soon find out for yourself whether it works or not.
i would say if the pulley is finely balanced and machining is good then theres no real reason why it wouldnt work

 

[vss irvine]

its because theyre alloy, they wear quicker and reduce the seal,

the new cdf pulleys have a sacrificial brass collar on them, but im still not sure this is enough

g spec performance and jim wolf do puilleys aswell which are made from better grade alloy and resist wear alot longer.

the damper is there to allow a slight amount of give when your loading up the pulley, ie turning on the aircon at high rpm.

its not for engine balance.

 

[eastwood]

the damper is there to allow a slight amount of give when your loading up the pulley, ie turning on the aircon at high rpm.

its not for engine balance.[/QUOTE]

That makes sense otherwise you would also see issues with the crank when fitting differant rods or flywheels of differant materials/wheight as they would change any frequences on the engine/crank by having less recipericating mass.

Looks like the oil seal is a problem Im going to take a view on wether its worth fitting mine.

 

[warpspeed]

Makes sense as the damper is only on the outer pulley for the a/c and alternator.

I didn't think they were for balance but wanted to find out some facts first.

So if i machined the steel hub to accept an alloy pulley look like it would work fine

Got any alloy pulleys for sale then Martyn?

its because theyre alloy, they wear quicker and reduce the seal,

the new cdf pulleys have a sacrificial brass collar on them, but im still not sure this is enough

g spec performance and jim wolf do puilleys aswell which are made from better grade alloy and resist wear alot longer.

the damper is there to allow a slight amount of give when your loading up the pulley, ie turning on the aircon at high rpm.

its not for engine balance.

 

[vss irvine]

no alloy pulleys for sale as we're using those, but you'll need to check with my dad direct for the steel one, ive asked him twice already but no joy so far...

 

[eastwood]

Ive just checked mine the crank pulley has a steel sleeve fitted.

 

[vss irvine]

must have been the early ones he used brass on.

 

[warpspeed]

no alloy pulleys for sale as we're using those, but you'll need to check with my dad direct for the steel one, ive asked him twice already but no joy so far...

ok, im away tomorrow to the alix so i'll just give you a shout in 2 weeks or so.