crank pulley answers

[slider85]

Hey, i thought I would post this. I emailed Unorthodox Racing about losing the harmonic balancer on the stock crank and replacing it with a solid aluminum pulley. This is what they said:
"I believe that what you are hearing is a misconception about how people perceive the pulleys. People are confusing the pulley for a torsional damper found and needed on most V8 applications. On most of the newer imports there is a rubber elastomer sandwiched into the pulley that looks similar to what you would find on a damper but is there for noise suppression from the groan of the alternator and p/s pump and when the a/c compressor kicks on and off. We have a number of original pulley samples without any rubber in them. A damper is used to control twisting motion, every throw of the piston & rod twists the crank journal and when it rebounds in sync with other deflections at certain frequencies can cause a crack in the crank, it's not there to protect bearings. While these forces are present in all engines they are not detrimental in small displacement short crank shaft lighter rotating assembly engines especially 4 cyl engines because they have an opposing stroke to cancel out the harmful frequencies. We have had nothing but success for 7 years with pulleys on all the applications we offer from daily drivers to heavily modified cars."

Is this true? What do you guys think?

 

[4GSixty3]

I have always heard that any aftermarket pully that does not have a damper is bad for our cars in the long run.

 

[dave99gst]

I have always heard that any aftermarket pully that does not have a damper is bad for our cars in the long run.

me to - bushur makes a dampend one.

 

[FireyIce01]

subscribing, interested in the results of this discussion

 

[krisj144]

funny how that statement is coming from the maker of an undampened pulley....

If you read closely, you'll see how they make a distinction between the elastomer style and the fluid dampeners. But I don't agree with how it is presented. I think they both accomplish similar goals though with varying success. Both reduce the transferrence of noise (though this is a secondary concern) and both help balance the reciprocating mass.

This is obviously a bigger concern on engines where the balance shafts are already removed. True, our 4 cyl engines are well balanced from the factory, but if you go around removing the balance shafts, installing stiff motor mounts, and throwing on a cheap umdamped underdrive pulley for a whopping gain of 5 hp or so you're probably going to be sorry.

Both 1g 7bolts I've seen crankwalk has underdrive pulleys on them, and coincidentally, they are also the only 1g's I've seen that had underdrive pulleys. I'm not making a concrete statement here that all cars with an aftermarket pulley will crankwalk, but I don't think it helps.

Bushur's fluid-damped pulley is very high quality, and also, very expensive. If my crank pulley went out, I'd stick to OEM without hesitation.

 

[LaserDad91]

I just went through this and after checking out costs and possible side effects, decided to stay stock. Reference this link by Mach V Motorsports.

http://store.yahoo.com/machv/tip11cranpul.html


I thought it was great information for someone like me with a daily driver. I do not see spending $350 for the Buschur dampened underdrive pulley, not enough of a gain for the buck. You could almost get a nitrous kit for that much cash.

I decided if I use underdrive pulleys, I will just install them on the accessories themselves. Personally, I would rather spend the money on a header, cams, and/or a locking differential, than pulleys, but that is just me. But, once the alternator on my car dies, I will upgrade to a higher output and then install the pulleys, as they do look nice!

 

[djsven]

Hi,

2 years ago in the summer my oem crank pulley broke. The car is a 95 gsx. I had the car only for a few thousand miles. Total miles was less then 70k. What happened was the crank pully came apart were the rubber damper holds the 2 metal pieces together. It damaged my front case, crank sensor with the blade, snapped some belts, .... Very costly.
I searched around for some aftermarket ones. Mainly the one from unorthodox. I talked to some experienced racers and they told me that there is 2 problems with them. 1) they don't have the damper and 2) the aren't balanced to our specs. These factors are a risk for damaging our engines. So eventely, I decided to go with an oem pulley. I didn't want to risk the change of failing again.

Sven

 

[KingAWD]

I agree. I had the same situtation with my car. I had lost the crank pulley and all of my belts fell off. I stuck with the original from the dealer, which only cost me $130 bucks. Not bad. Haven't had any problems since.

 

[LaserDad91]

I agree. I had the same situtation with my car. I had lost the crank pulley and all of my belts fell off. I stuck with the original from the dealer, which only cost me $130 bucks. Not bad. Haven't had any problems since.

I agree. I have had no issues with belt squeal, Alt. belt flying off, etc. since I had the pulley replaced. I am glad I did it before it flew apart!

Here is a funny twist to all of this, not related at all to our cars. I was changing the oil on my 96 Dodge Caravan and noticed there is no harmonic balancer or dampened pulley on the crank, unless they overcome this some other way, I thought it was kind of weird. But van is OEM, so be it!!

 

[slider85]

is there anyone out there with something positive to say about crank pulleys?

 

[skinnypimp]

is there anyone out there with something positive to say about crank pulleys?

sorry to go against everyone's theories, but i had machv set when they first came out on my 98 gst. had it on my car for two years, 35k miles had no problems. every car is different so maybe i got lucky. ta lon

 

[90GSTman]

is there anyone out there with something positive to say about crank pulleys?

I've had an aluminum underdrive pully on for the last few years and have not had a problem.

 

[Boiler2]

I did a lot of research on this a little over a year ago and decided to try the UR underdrive pulley set. I have had it on for ~15,000 miles with no crank issues. The car really has run smoother. If I had to do it over again, I would get the Buschur one because I run the supra fuel pump which draws a lot of amps and at idle. With the lights on, my battery voltage drops to 12.0 over time at idle with a few dips into the upper 11's.

I also emailed UR about the damper and they gave me a similar response stating there was no evidence and it is a myth. I will try to find the email and post.

 

[doug]

I've been running a lightweight aluminum one-piece pulley for over two years with no problems. My main concern is the stock pulley separation-- I don't care about a 3-4 HP difference. To me, HP gain is not the reason to use a one-piece pulley-- having your two-piece stocker come apart and cause damage is.

 

[slider85]

thanks guys, so far I don't believe I have heard from anyone who has actually experienced crank failure due to an aluminum one-piece pulley. It seems that every story starts with, "A friend of mine did this..." and " I heard someone did that...". I am curious as to how many of you with the bad stories have actually had crank failure because of this product.

 

[boostcreep]

thanks guys, so far I don't believe I have heard from anyone who has actually experienced crank failure due to an aluminum one-piece pulley. It seems that every story starts with, "A friend of mine did this..." and " I heard someone did that...". I am curious as to how many of you with the bad stories have actually had crank failure because of this product.

Unfortunately, I had a link to a site but lost it when my system crashed. I too had the same burning question, as to what damage can or may occur due to one piece pulleys. What I did find states that engines tend to have a specific vibration, and the amount tends to increase and cause oscillation or, twisting of crank the further down the crank (one end to the other). The rubber mounts tend to eliminate this vibration. The site was BMW based and not only described it in detail but gave visual CG graphics. I found it when DSMTALK was still around. I'll do what I can to dig it up again.

 

[boostcreep]

ENJOY:

Torsional Vibration (Natural Frequency)

Every time a cylinder fires, the force twists the crankshaft. When the cylinder stops firing the force ceases to act and the crankshaft starts to return to the untwisted position. However, the crankshaft will overshoot and begin to twist in the opposite direction, and then back again. Though this back-and-forth twisting motion decays over a number of repetitions due to internal friction, the frequency of vibration remains unique to the particular crankshaft.

This motion is complicated in the case of a crankshaft because the amplitude of the vibration varies along the shaft. The crankshaft will experience torsional vibrations of the greatest amplitude at the point furthest from the flywheel or load (i.e. pulley location)This information was supplied by Steve Dinan (BMW GURU). Although it's not a DSM it's still universal.

 

[slider85]

ENJOY:

Torsional Vibration (Natural Frequency)

Every time a cylinder fires, the force twists the crankshaft. When the cylinder stops firing the force ceases to act and the crankshaft starts to return to the untwisted position. However, the crankshaft will overshoot and begin to twist in the opposite direction, and then back again. Though this back-and-forth twisting motion decays over a number of repetitions due to internal friction, the frequency of vibration remains unique to the particular crankshaft.

This motion is complicated in the case of a crankshaft because the amplitude of the vibration varies along the shaft. The crankshaft will experience torsional vibrations of the greatest amplitude at the point furthest from the flywheel or load (i.e. pulley location)This information was supplied by Steve Dinan (BMW GURU). Although it's not a DSM it's still universal.

i've read that before, but thanks. I still want to know who has FIRST-HAND knowledge of damperless pulleys causing damage.

 

[boostcreep]

Why jack around with something when you dont have to. If your like me you want your car running on the edge whenever possible. You invest countless hours and tons of money (especially if it's a daily driver). Play it safe, you cant go wrong. I sold my pulley while doing my swap after reading that post. Just wasnt worth it to me.

 

[silkcity100]

my rod bearings went approx 5000 miles after installing a lightweight pulley,only had 52,xxx miles on at time

 

[out there]

5xxx miles and they failed? more info?

 

[Defiant]

i've read that before, but thanks. I still want to know who has FIRST-HAND knowledge of damperless pulleys causing damage.

You started the thread by asking us what we think. I think it's odd that if Mitsubishi -and, all other 4-cylinder engine manufacturers- could skip the cost of a harmonic balancer, they would. But, they don't. I also think Unorthodox's story is a sales pitch.
There are a couple of threads here about both a snapped crank, and one of wiped bearings- both of which were running un-damped cranks. Whether it was causal or coincident I'd not guess.
Many people are running undamped cranks, and there's less fright about their breaking than there is of crankwalk.

Pretty much your call.

 

[Raph]

Got to get you here man.. modst 4cyls dont have a harmonic balancer.. on many opels,VWs,Audis..ive noticed some do,many dont.. only have seen two separate.. one on a ecotec,another on a 3.0 turbo diesel... most ecotecs dont have a harmonicdampner because it insnt necessary(instead,they have an extremly lightweight pulley on the crank..ive weighed them,they weigh LESS than my Aluminium crank did..)

 

[turbohounds]

I would be skeptical of any of the propaganda from Buschur or Unorthodox - both are trying to sell you something. I've chatted with the guy from the BMW site, and you have to realize the design and length of the crankshaft in the BMW relies critically on the dampener. To use an undampened pulley would be a very bad idea on a 6 cyl BMW.

I had posted some pictures of all my bearings after 50K miles of use of an UR pulley on my '92 6 bolt. The end result was no significant wear that could be attributed to the pulley. I drove my car hard, autocrossing and running 13.2s in the 1/4. My car is an auto, so it also has the torque converter wieght to help dampen vibrations. IMO, the chance of problems are less with a solid pulley vs. a two-piece stock, and no more than adding more boost or other performance mods.

Of course, I'm pretty sure solid pulleys are responsible for the war in Iraq

 

[skinnypimp]

hondas don't have dampeners either, i guess that's why they last so long