bottom pulley

kev_200uk

New Member
as title says

need a new bottom pulley asap, not one thats gonna come apart in the near future again
cheers
 

youngsyp

New Member
As a 'used' one is likely to have a limited life span, you might be better off going on eBay and sourcing one of the lightweight aluminium ones ?!
These will be 1 piece solid items so, you won't have to worry about any rubber part degrading in the future !
 

kev_200uk

New Member
thanks for the comments guys, i had a look on ebay and there was 2 types by the same seller, which one is the one i need, stupid question i know but im still all new to this
cheers
 

youngsyp

New Member
kev_200uk said:
thanks for the comments guys, i had a look on ebay and there was 2 types by the same seller, which one is the one i need, stupid question i know but im still all new to this
cheers
Afaik, the guy sells the crank pulley on its own, and as part of a set of three pulleys, that also includes the alternator and waterpump pulley. There is only one type of crank pulley although, it does come in different colours. So it all depends on what you want to spend.

From what I've read, there isn't a perceivable difference, in the way the engine behaves, between the stock and alloy pulleys so, I'd just go for the crank pulley, if the OE one needs replacing.
 

GTIR-LOZ

New Member
has anyone fitted these before as forge no longer sell their pulleys due to lack of demand are they good quality etc
 
J

jpward

Guest
There’s a very good reason why there is rubber on the pulley!

Its proper name is a harmonic damper or in short it dampens vibrations on the crank especially higher up the revs it will help look after the bearings over time!
 

GTIR-LOZ

New Member
i thought if your engine is balanced then its of no worry plenty of people seem to use the forge ones with no problem, agreed on a standard build then yes prob unwise to change it
 
J

jpward

Guest
GTIR-LOZ said:
i thought if your engine is balanced then its of no worry plenty of people seem to use the forge ones with no problem, agreed on a standard build then yes prob unwise to change it
No there are still forces acting on the crank to effectivly make it "whip" look up up on wiki explains all there ;-)
 

youngsyp

New Member
Many owners use these on numerous cars, without issue. Personally, I would use one without hesitation.

Generally engines don't have a "harmonic damper" incorporated in the crank pulley, from my knowledge and the SR20DET, isn't anything special, it works in the same way as any I/C engine.
It's just another 'safety' feature that wears out in time and in all reality, isn't missed when not there.

If you're worried about what forces are on the crank shaft, strain anw "whip" from the rest of the ancilleries attached to it via rubber belts, should be the least of your worries !
 

davey red.r

New Member
i had the full pulley kit fitted last month ,didnt realy notice any difference,least i know there on, and lighter than the standard jobbies.;-)
 

stumo

Active Member
Young, do you think Nissan would go to the expense of fitting a harmonic ballancer to the engine if it didn't need one??

JP is right, you might think a crankshaft is a solid piece of metal but when you've got a load of revs going on the thing is flexing all over the place.

Take the Rover K series for example, don't laugh, these things can put out serious HP for a naturally aspirated engine.

Racers can get hold of a very light pulley but they don't, they just use a standard one (and replace it often).

The reason they don't is because the cranks are very prone to breaking if used with a non-damped pulley.
 
J

jpward

Guest
youngsyp said:
Many owners use these on numerous cars, without issue. Personally, I would use one without hesitation.

Generally engines don't have a "harmonic damper" incorporated in the crank pulley, from my knowledge and the SR20DET, isn't anything special, it works in the same way as any I/C engine.
It's just another 'safety' feature that wears out in time and in all reality, isn't missed when not there.

If you're worried about what forces are on the crank shaft, strain anw "whip" from the rest of the ancilleries attached to it via rubber belts, should be the least of your worries !

Paul when my first gave way I went on a "Scrap heap challenge" thinking that they would not be much different car to car what I say at one yard was about 20~30 Jap engines all had a damper and only one was near to mine was a Primer which was obviously no use to me but I did buy a good condition second hander off here to replace it when I looked into getting a set of bling bling red anodised pulleys and after a good read was shocked to read these should not be replaced. ARP make after market ones but not for the SR but balance and right amount of rubbery damper was worked out by Nissan so can’t see anyone improving that.

Yes I would say you could try one and get away with it but on the other hand a solid one could fatigue the crank and other ancills quicker and you’re not going to see 10-20hp increase for the risk. :?

I would change the other pulleys to alloy ones as I will do eventually as they are only simple pulleys ;-)
 

youngsyp

New Member
stumo said:
Young, do you think Nissan would go to the expense of fitting a harmonic ballancer to the engine if it didn't need one??
It's not a balancer, it's a damper. There's a world of difference between the two things. ;-)

stumo said:
JP is right, you might think a crankshaft is a solid piece of metal but when you've got a load of revs going on the thing is flexing all over the place.
Hmmm, I highly doubt that. If that were the case, the crankshaft bearings, con rod bearings and well, all the bottom end wouldn't last very long, would it ?! :doh:
Of course it will vibrate a bit, it's not finely balanced so, that's a given !

stumo said:
Take the Rover K series for example, don't laugh, these things can put out serious HP for a naturally aspirated engine..
From what I've seen from the 1.8 non VVC and indeed VVC K series engines (other half has an S2 Elise, with the VVC engine), you can't make that much power from them. You'll struggle to get 170-180 bhp from the VVC lump, without spending a bucket load of cash on it.

stumo said:
The reason they don't is because the cranks are very prone to breaking if used with a non-damped pulley.
That's a K series engine, not an SR20DET. Again, a world of difference between the two !
 
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youngsyp

New Member
jpward said:
Paul when my first gave way I went on a "Scrap heap challenge" thinking that they would not be much different car to car what I say at one yard was about 20~30 Jap engines all had a damper and only one was near to mine was a Primer which was obviously no use to me but I did buy a good condition second hander off here to replace it when I looked into getting a set of bling bling red anodised pulleys and after a good read was shocked to read these should not be replaced. ARP make after market ones but not for the SR but balance and right amount of rubbery damper was worked out by Nissan so can’t see anyone improving that.
Maybe I underestimated it's use then but, I'm still not convinced !


jpward said:
Yes I would say you could try one and get away with it but on the other hand a solid one could fatigue the crank and other ancills quicker and you’re not going to see 10-20hp increase for the risk. :?
How will it 'fatigue' the other ancilleries quicker ? For the most part, they're attached to it by a rubber belt ?!
And I clearly said you shouldn't expect a performance gain. Not reading the posts properly again ?!

I like to hear what uses of the non damped crank pulleys experiences have been. Is there anyone who's been using the Forge item for any length of time ?

Regardless of all that, I still wouldn't buy a used one. You just don't know how long it will last.
 
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