Concerns about pulley's

[Black_griffin6]

Hey guys,

I've recently been doing a lot of research about the lightweight pulley's NST offers and how they might affect my Yaris. From what I can tell, they replace the OEM pulley's with a strong lightweight pulley that reduces weight and allows the car to rev better.

Sounds great...right?
Well from i've also read is that the stock pulley's are weighted a certain way to balance the engine, and by replacing them you're running the risk of greatly reducing you're engine's life.
I believe that has to do with a Harmonic Balencer? (Correct me if i'm wrong.)
I've also seen a few threads about the water pump dying shortly after installing these pulley's, though i'm not sure if that's related because I hear about water pumps going bad all the time.
Anyway, I would like to eventually get some of these lightweight pulley's, I mean they sound really great and i'd love to reduce some weight and free up my engine...But not at the risk of doing some harm to it.

So basically, i'm concerned. Some people say it's fine, some say don't do it, and since i'm not a mechanic by any means...i'm stuck.

What's your thoughts/opinions?


EDIT: I just did some more reading, and i'm reading that accessory pulleys (AC, alternator, ect) are fine to use just not the crank pulley.
Not sure if that's true or not either. XD

[CrankyOldMan]

My take on it is this: the mass of the original crank pulley (NOT a harmonic damper/balancer) is intended to maintain the rotational inertia of the crankshaft, and therefore smoother operation of the engine and accessories when releasing the throttle or decelerating. Same goes for the flywheel. As a passenger vehicle, the engineering focus is on operator comfort and smoothness of operation. When making performance mods to a vehicle, you (generally) have to sacrifice said comfort to improve performance.

I've had mine on for a few weeks now and I'm enjoying it. I'm also looking forward to improving the flywheel/clutch/transmission in the near future. All of this of course comes with the implied "cost" of reduced comfort and even longevity. I'm modifying my vehicle so that it's more able to respond to aggressive operation. Any vehicle--modified or not-- will have reduced life expectancy when operated aggressively, and I'm OK with that. I bought my car for $9k cash, and I plan on driving it till the wheels fall off. If that happens to only take 10 years instead of 15, or hell, even 5, then so be it.

[johnny_vitz]

There is nothing wrong with using lightweight pulleys (Crank, Alt, Water pump) they will not hurt your engine in any way. Like said above, the increase in aggressive driving habits is the only thing that will wear your engine out faster. It is definitely a worthwhile upgrade for the money spent. Just make sure the pulleys are installed properly and everything is torqued to spec. I've had a lightweight crank on for almost two years now (light flywheel as well) with NO issues. Just buy a quality brand piece like NST and you'll be fine.

[Black_griffin6]

Cool, thanks guys!

I do a lot of research before I even consider buying an aftermarket part for my car. I want to be sure it's good quality and won't ruin my car shortly after I put it on. So when I heard a bunch of people saying that lightweight pulley's hurt your car, I got a bit worried.

[tk-421]

I've been running the entire NST pulley kit for years (even upgraded to the CR Lite version as well) with no problems whatsoever. The harmonic balancer topic has been discussed for a long time around these parts (just give that term a search and you'll see what I mean), and the conclusion is that these pulleys were designed in such a way that a harmonic balancer is not required for smooth engine operation.

[Viperoni]

Even from my Saturn S-series days, the DOHC motors had a harmonic dampener and the SOHC's didn't - the SOHC's never had any issues with bearings wearing prematurely or anything like that. The bottom end on the DOHC's and SOHC's was more or less the same too.

On the topic, todays haromic dampeners aren't nearly as big as V8's had back in the day too... don't know why this is, but it's something I've noticed.

I'm eyeballign a NST underdrive pulley myself, not worried for a second about it hurting the motor.

[jekqmb]

Do it and dont worry about it, with each mod comes more stress on the drivetrain! If you want to mod a motor dont worry about problems that come with that mod your doing!

[bzinn 1]

I couple of years back I called NST......I don't remember who it was I talked to but he fully understood my concerns....he did not try at all to sell me on his product but instead explained the hows and whys of failures....what the crank experiances using the product vs stock pully with the rubber bushing that dampens harmonics....

I already understood from years of building V8 motors that less moving mass meant less power needed to turn said mass,which in turn allows that power to goto making motion quicker.....faster I can rev to shift point the faster I get down the 1/4.

The 1.5 is a fairly well made motor,short of some narrow oil passages that can clog(but so does every motor)....being an I4 motor the stresses on the crank are not as bad as on a conventional V motor where the motor is not internally balanced and needs a balancer to keep it from doing a jig.

the crank is sturdy,the bearings are also a good product,the block is built well enough to withstand a lot before failure.

I have seen pullys used over the years on a lot of cars and no problems.....I also have seen stock motors go boom from something as simple as running a quart low all the time on oil.

Our cars were meant to be economy,generic consumer products....as such they idiot proof them,over build for longevity.....the pullys dont add power they free up the power that you already generate by reducing mass.

Could they cause a problem.....so as explained to me by NST has not had any product failures,or proven motor failures from their product....they are on just about every forum,make and model,and they openly will discuss any concerns with any consumer.

Now for my opinion,from what I have seen first hand.....the waterpump on the 2.4 and the 1.5 suck.....are prone to failure on stock motors....jsut the luck of the draw.

Never seen a spun bearing or broken crank that the owner either did not maintain or trashed the hell out of it.

Toyota motors such as the 1.5 and the 2.4 have owners who have ran them problem free for as much at last count 75000 miles.

Remember it is a car,a machine,keep it clean,new fluids,dont trash on it like a teenager....mine has seen some pounding in the 60000 miles since new and it still runs like day one.

Would I trust to use a pully.....yeah,once you understand the machine you see it has to be something that can improve how the motor operates.....walk around all day with 5lb weights in your pocket....takes more energy to do so....same in example with a motor.

Could they be a contributing factor to engine failure....sure....but so could not changing oil,other fluids....bat belt.....dirty air filter.....

I plan on finally installing a full set on my car this winter mainly for the look over the function,I like to change out everything on a car....been that way since my first car 25 years ago...

Give them a call.....ask them about your concerns....they are pretty good at explaining it.....and they dont shy away from any questions...at least in my case and those of many others who also have called......sorry I just finished my evening coffee....lol

[Black_griffin6]

^ Next time have a spot of tea instead.
I kid.


Well thanks guys for all your replies!
I think I understand a bit more about it now.
As i'm sure most of the people here understand, I like to do mods on my car and make potential upgrades, but I want to be sure I won't hurt my car. I take good care of it, take it in for a service when it needs it, I check all the fluids and filters on a regular basis...heck I even check the tire pressure at least once a week.


I think I'll give these pulley's a chance sometime in the near future, I feel a lot more comfortable with it now.

[cali yaris]

CrankyOldMan post #2 is a really great answer.

[yaris4062007]

Nice!!

[cali yaris]

Awesome bump. Micro Image pulleys will be in stock this week!

Improvements over previous designs: 1. Beefed up center thickness 2. OEM size with 10% underdrive weight. Best of both worlds.

[Altitude]

Those look real nice Garm.

[Black_griffin6]

Can't wait for those! I'll be waiting on the site hitting the F5 key repeatedly in anticipation. XD
I know i've asked this before but...do you have any plans for accessory pulley's? I know you weren't sure before.

[cali yaris]

^ Same answer, this will depend on sales of the crank pulley. Need the capital to make the accessory pulleys.

Unless maybe.... a paid-up Group Buy? Those haven't gone that well on YW, I'm afraid.

[1NZYaris1]

I have had my NST pulley on my car gor 90,000KM's now with no issues what so ever.
Oh Garm those new 1's looks so sweet

[goliath1812]

Any NST trade-in value?

[cali yaris]

^ That has come up. I'll make a decision about it soon. It's a little sticky, since I believe I now have a better product.