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Interesting article on U/D Pulley "somewhut long".

1.9K views 53 replies 25 participants last post by  Ducman69  
#1 ·
Interesting article on U/D Pulley \"somewhut long\".

Bad Vibrations

I'll post a more complete rendition of this on the too site shortly, but let me begin by saying that it's good to be back and I'm only here to expressly address some questions that need some "good" answers. I am not here to provide schedules or any information regarding the blower program. The topic is that of aftermarket crank pulleys. Let me begin by saying that we have always called the pulley on the accessory drive end on the Honda cranks Harmonic Balancers. People never seemed to understand what we were talking about and so the word "pulley" was frequently used to avoid confusion. If you look carefully at a Honda "pulley", you'll find that it's not a single piece of metal. Typically, there's a nodular iron or steel hub and another "ring" of iron or steel surrounding it containing the belt grooves. The two parts are joined by a rubber layer, which is highly compressed and sandwiched between them. Why rubber? If you notice, many four cylinder engines over the years have used counter rotating shafts to help make the engine "feel" smoother. Reciprocating internal combustion engines and especially in-line four cylinder versions, all produce shock pulses, which are very apparent to the occupants of the car. Every engine produces a shock pulse each time an individual cylinder fires. So, in the case of the four cylinder variety, there are four large individual pulses for each 720 degrees of crank rotation. Each time there's a pulse, it causes the internal components to do a rapid acceleration-deceleration event. When you consider the mass of all the internal components and visualize all these parts stopping and starting during their reciprocating and rotating motions, the additional stress "spikes" tend to make it all the more reason for one to wonder how any of it can work for any length of time. The harmonic balancer is made with the rubber coupling so that, when the individual "spikes" occur, the inner portion may move with the crank, but the rubber connected outer ring's mass helps prevent the hub and crank from going as far or as fast during the spikes or pulses. Remember that the outer part had considerable mass, so it tends to want to stay in motion at the speed that it's traveling and that's why it can prevent excessive harsh motion by the crank and other internal parts. To put it simply, the harmonic balancer is a shock absorber for the engine and thus prevents the individual pulses from destroying everything in the engine. A quick bit of history; Back in the late '70's, all the Pro Stock engines had been reduced in displacement to allow the cars to weigh less. At that time the vehicle weight was based on engine "type" and total displacement. Typically, the engines were in the 330 cubic inch range and running 10,000 to 11,000 rpm was normal, especially in high gear at the traps. There began to be a lot of engines that were "exploding" their harmonic balancers on the big end. Aside from cutting the steering in half and blowing the front tires, large hunks were also finding their way into the grandstands and there were numerous injuries, many of which ended in death. NHRA immediately mandated that solid "balancers" were to be used from that point on. Keep in mind that a balancer can't be solid and function properly, but the rules were the rules. Moroso and a couple other companies who were tight with NHRA began making aluminum billet "balancers" immediately and everyone bought them so they'd be legal to race. All of a sudden, racers were getting only 10 passes from their crankshafts, which had previously lasted an entire season. Initially, most people thought the cranks were "bad", but after destroying engine after engine, a few knowledgeable engine people figured out where the problem actually was coming from and several companies that were capable of making functioning harmonic balancers sprang up over night. They are all still in the business to this day and their units are actually much better than the factory units of years before, as they are made from premium materials and optimized for high rpm applications. With this short bit of history finished, I'll begin to wind it up by stating what we do with the Honda engines. If the balancer has more belt grooves than the application needs, i.e. the power steering pulley, we machine it off. When it comes to the the pulleys that are actually a part of the outer portion of the balancer, we leave them intact. This procedure will not lighten the unbalanced hub substantialy, but the outer balancer ring will keep all its mass and function correctly. I also need to say that a large driven mass such as a blower or alternator, can have a slight dampening effect, but to actually work properly, the belt connecting the components to the crank would need to be 4" to 5" wide and the belt tension would be so great that it would wear out the number 1 main bearing as well as the bearings of the the driven parts in short order. It's especially important to keep the balancer "as is", if you're running an aluminum flywheel. The reduction in flywheel mass can also increase the pulsation shock strength and a higher level of vibration will immediately be observable. So if you lighten the flywheel,it's absolutely more necessary than ever to maintain the mass or the harmonic balancer. I realize that there's a lot of hype out there where manufacturers are promising this and that. The oversize crank pulleys can drive other geared or belted components faster due to the diameter ratio increase, but if you're deleting the balancer in the process, the short and long term side effects are going to hinge on your decisions. Larger diameter pulleys for the alternator, power steering and any other belt driven accessory are good ways to slow the speeds and drag of the those components, but when doing a large diameter crank pulley, the larger pulleys should actually be designed to fit "over" the stock balancer. Perhaps, someone will begin to make some good quality "functional" balancers some day, but until they do, you need to proceed carefully, as some good looks and minimal power gains can be off set by a ruined engine. I'm sure that there will be some fall out regarding what I'm saying here and to that effect I need to remind everyone that we do not manufacture hubs, big pulleys, or harmonic balancers for Hondas and none of what I've said is the least bit politically motivated.

And yes, any engine with a non-functional hub or balancer can ruin the crank driven oil pump and a whole lot more.

to read more about this check out www.theoldone.com


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Simply the best
www.topproducer.com
 
#3 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

I'd like to know if the Zetec is internally balanced also. I doubt that it is, since Ford did almost everything they could to save money in the car.

If they did internally balance the engine, why would they waste money and make a balancer type pully on the end of the crank.

my .02

steve...
 
#4 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

i thought everyone and their mom on FJ agreed that we have an internally balanced engine... at least, that was the general consensus when i bought my UDP
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#7 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

does this mean that some guys are replacing stock rubber dampened harmonic balancer/ drive pulleys with aftermarket solid machined underdrive pulleys (UDP's)? As RitzBitz suggests, everyone needs their stock (or equivalent) rubber dampened harmonic balancer. Doing away with that is inviting catastrophic wear and tear or worse.
 
#9 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

i was not trying to rehash the issue
i just thought this article was interesting and posed a few intersting ideas about
the crankshaft pulley. as in his description
he mentiones a crank pulley similar to ours
machined unit rubber surround the another
machined outer unit with ribs for the belt.
sorry if i opened up a can of worms.



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Simply the best
www.topproducer.com
 
#13 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

AeroChargerJim, yes they are. Every UDP out there for the ZETEC is solid.

This subject has been beat to death before. I don't believe there is a reported case of a broken crank due to an UDP and there are many cars, ZX2s included, that have 10s of thousands of miles with an UDP and no problems.

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2001 Pitch Black ZTS Leather, AdvanceTrac, Side Air Bags, Automatic
Mods: Iceman Intake, Focus Central 65mm TB, ASP Under Drive Pulley, JBA Header, Vibrant Cat Back, KW Sport Suspension Kit, 1000W 12 speaker Stereo System. See it All here: PowerFocusZTS
 
#15 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

Jim, you saw my car, it has had an Esslinger pulley on it for 50,000km so far, no problems yet.

Not conclusive in my mind until it reaches 200,000km, but so far so good.

Further, I have never seen *any* documented report of an actual failure on *any* 4 cylinder engine.

Vee engines are much more unbalanced than 4 cylinder engines, and this increases the need for a balancer.
 
#16 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

Well,

Take it as you may, but I do not belive that an "internally balenced engine" means that the use of a harmonic balencer is unnessicary. The Engine is balenced, but the harmonic balencer is not balencing the engine per say, it is acting as a damper.

I will look at my stock balencer. He has a great point though. I know first hand what a failed crank balencer will do to an engine. I always thought you guys were replacing your alternator/power steering pump pullies, not the crank balencer.
 
#17 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by FriendlyFocus:
Even so, just as he says, our stock crank pulley is designed this way. It has the ring of rubber in between the 2 pieces. Hmm. I had never looked at it that close before I read this. Why would they design it with the dampener if it didn't need it?<HR></BLOCKQUOTE>

This is exactly right, It cost more money to make a 3 piece damper, than it does a solid pully. Think about it for a min. Everything on your engine is there for a reason. Harmonic dampers are important. I had a harmonic damper fail on my Subaru, (H-4) the outer ring rotated on the rubber, within 30k miles, (I didn't notice) the main bearings and and the crank were toasted.. Hence i bought a Focus ]
Image
 
#18 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

Underdrive crank pullies are not a new thing. They have been around forever for several different makes.

Especially on an engine that is internally balanced, I'd at least like to hear of one person that has actually experienced a problem due to an aftermarket crank pulley.

Until then, I will continue to use my AFX pulley which is OBVIOUSLY much better than that Esslinger pulley. Opening up second can of worms. JK guys!
Image


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00 Ford ZX3 / 96 Ford Cobra
90 Yam FJ1200/ 85 Yam RZ350 / 84 Yam RZ350
Engine Forum Moderator -Chris-
 
#19 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

on a side note
the same author of the article
has mentioned that he is working on
various focus realted performance parts
turbo, supercharger, heads, rods etc etc
one interesting tidbit he mentioned about his involvment with foci as he is primarily
a honda builder ( he is building a great roots blower for honda engines)
he is recieveing considerable compensation
for development of focus parts.....

on another note when discussing our zetec motor, the only real issue he had with it is the "suspect" crank .... he would not go futher into it. but it is an interesting
note all the same.

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Simply the best
www.topproducer.com
 
#20 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

Could just be a NVH crap.

The car will run fine w/o a resonator (intake or exhaust). Engines not going to blow up, just be louder. Engine also wasn't designed to be used with an aftermarket exhaust, the cat removed, the airbox removed and replaced with a conical filter, and yet these are all "normal" mods that shouldn't damage your engine in the least. You can even knife edge the crank, replace the cams, put in a flywheel with 1/4th the weight of the stock flywheel that was made a specific weight for a reason.

So the argument with "well its there for a reason so don't replace it with something different" doesn't quite hold with me. That's the whole concept behind hot-rodding your engine... to replace restrictive factory components with usually more expensive and performance oriented components that place a greater emphasis on dyno numbers or high speed handling than plushness, NVH, and/or cost.
 
#21 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

The engine is internally balanced and the rubber ring is excatly as Ducman says, for NVH purposes. My friend Ed is a mechanical engineer and he says so. Why do I believe him? Because his last project was designer of the bracket and hardware to mount a supercharger to the new Yenko Corvette so he works first hand with belt systems. When it first came in, this car was throwing belts and unable to make any kind of real boost. Pictures of the car are at the link in my sig, if you don't believe me. Put this to rest, please. No accusations, but every time I hear this line of reasoning, people who sell other power adders always seem the first to chime in. A UDP works on the Focus as it does on many other cars. If you replace a fluidic damper (as fitted to the M/S 50, 52 and now 54 BMW engines for example) with a chunk of aluminium, you are asking for trouble. Replacing a quarter inch band of rubber is a different story altogether.



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Rich
teamDFL...Just Run It
www.teamdfl.com
 
#26 ·
Re: Interesting article on U/D Pulley \"somewhut long\".

or your blown motor.
Image


NVH, harmonic dampers are not there to make your ride more pleasureable.

To the guy up there who said about hot rodding engines nature to replace parts, such as exhast, air filters etc.

your comparing apples and oranges my friend. Yes you may replace you air filter with a BETTER air filer, or a WIDER exhast, or perhaps LARGER fuel injectors, or a LIGHTER flywheel, but you are replacing things with the same parts. apple for a riper apple. And not without coniqences. If you replace your Flywheel with a lighter one, you get quicker engine response, but you also kill fuel economy for example. Some things just have greater consiqences.

But with the UDP, you are not replaceing the harmonic balencer with a better harmonic balencer, your are replacing it with a hunk of metal! That is like replacing your airfilter with cheese cloth.



[This message has been edited by ZX3Rally (edited 07-11-2001).]