lol. the dealership's mechanics should know how to do it. a few of the MB motors had a harmonic balancer recall, so the procedure should be covered in their technical reference guides.

good luck...

 

Thanks for that helpful tidbit. There’s no denying your superior intellect.

No disrespect intended toward hooleyboy or his stout C55, of course.

Worthwhile thread for those contemplating an undampened, lightweight crank pulley:
http://www.benzworld.org/forums/abed...guarantee.html

Omey Homey, Dr. C36, and E55 PWR are some of the SN’s AMS has masqueraded under on our forum.

 

I've posted extensively to that thread, and unfortunately it has gotten long and is turning silly. This single post there pretty much sums-up my case for why it is a big mistake to purchase an AMS pulley: http://www.benzworld.org/forums/abed...ml#post3049268.

 

youve cracked the case! where have you been all this time, none of us knew about the multiple aliases and the incredulous claims regarding the CP's.. please enlighten us!

we all know about omey and his CP's, what are you trying to get at making sarcastic remarks? i was trying to help someone who already had the CP try to get it installed. and seeing as though MB already had to swap out a bunch of CP's due to faulty harmonic dampeners, then there must be thousands of mechanics who know about the 6 ft breaker bar... good luck with your investigation sherlock. dr c36 hasnt posted for a while, maybe after all this excitement he'll come out of the woodwork and continue making large hp gain claims...

 

Personally I find it hilarious when he (omeyhomey) starts to talk to himself using his various aliases to bolster his overstated performance claims.

FYI I have absolutely no problem with someone not associated with the vendor posting product reviews - providing they're accurate and objective.

On the other hand when a company stoops to using false ID's and shills, then they deserve everything they get !

Maybe that's why AMS et al have been banned from MBworld ?

 

If that was the case of talking to yourself with muliti user names thats strait up funny! I dont even know what his claims are for this CP but i was able to get some power out of it. My product reviews are very objective. I think the pulley works and makes some power. However i did get private messages form "E55 PWR" asking be to repost my dyno results as i took them down to free up for webspace. So "E55 PWR" and "Dr. c36" (sorry if i got those SN's wrong) are the same person? IDK, I like the pulley, but those kind of tactics if they are true are FUNNY! Anyway we should let this post get back to what its about and thats installing

 

E55 PWR+Dr. c36=omeyhomey

 

and those are just the ones we know about for sure - there's also several others which look very dubious in terms of posting style, timing and content.

Here's a link to a suspect thread started by Greg, C36ickness (Omeyhomey?) where he replies to himself as DR.C36 - the thread got closed, no prizes for guessing why :-)

https://mbworld.org/forums/showthrea...&highlight=ams

These sorts of tactics while off topic imho certainly don't lend credibility to the AMS operation as a whole.

I'm not saying that AMS may not eventually offer a credible performance modification, in fact I'd go so far as to say I'd be the first to praise Omey when (or if) AMS does.

It's just to date these wild claims of HP, mpg improvements etc are just that, wild claims with little more than suspect dyno pulls and 'shills' to back them up.

This is not to mention the outright lies he's told as to where they're actually manufactured and how the 'harmonic damping' of the pulley itself has no effect on the torsional damping of the crank.

 

tim, being an ex race engineer, do you think that these pulleys would be a worthwhile upgrade? given the claims that they weigh 2lbs vs 6lbs for the stock one.

 

as I know some people on this forum will disagree with me and apologies for the length of this post...

Short answer: no significant gain for 2lbs versus 6lbs weight reduction on the CP.

Long answer:

Based on my first hand experience (edit: of testing engines on real dyno's), calculations and (edit: engineering ) commonsense I can say without doubt (and stake my reputation on it) that the gains will be minimal and not measurable on a typical dyno of any kind. Certainly less than 1HP at best and even then I'm being generous.

What a light weight rotating 'anything' does is to allow the engine to rev up faster thus hitting it's power band and peak power that much sooner. Hence the effect of enhanced mid range punch in certain cases.

This is effect is most noticeable in smaller capacity high revving engines in light weight vehicles - such as motor bikes and race cars etc.

The well published claim that "1LB less weight = 2.7HP" is barely applicable to a 600LB 180HP super bike revving to 14,000rpm much less a road going car.

In a 3500LB sedan where the rate of change of rpm is more modest the gain is minimal.

Several others have independently performed calculations and come to the same answer <1HP.

As I've posted elsewhere, on one occasion we ran a F1 V10 on an engine dyno with and without pulleys or accessories to determine parasitic losses - the best we could determine was about 2HP gain and that was revving to over 19,000 rpm. Even then this result was difficult to repeat consistently.

Bottom line the gains of 10 - 20HP, 2-3MPG improvement are simply bogus and don't even get me started on the importance of a correctly damped crankshaft - I've seen first hand what happens when one let's go due to inadequate torsional resonance damping, bits of engine embedded in the test cell brick walls !

Edit: a few dyno charts from a 'shop dyno' prove absolutely nothing, as any race engineer worth his salt would tell you.

 

Me along with some other members have these pulleys and they are working well for us and our set ups.

Your first had experance with these pulleys is Zero, I think that is fair to say. Maybe you have had some with other pulleys but not this one.
If you stake your reputation on there are no gains on a dyno than you just lost it. I have posted all my dyno runs from a stock dyno run and dynos after every mod worth dynoing. I was able t gain power on a Dyno-dynamics dyno and have the dyno to prove it. Onther members on here who have some killer AMGs and have this pulley will tell you the same. What I dont get is why someone would say there are no gains to be had and my dyno run is wrong. When in fact my My dyno run just shows that your mathmatical calculation in wrong. Why tell someone it does not make power when you base it on "commonsense" and what you think is "correct math"



here is the proof that my CP made power. and there goes your reputation you staked on it.

 

You win :-)

Clearly your dyno chart, vast experience, undying faith in AMS, butt dyno etc trumps my education, training, knowledge, practical experience and proves that all that matters is youthful enthusiasm and a willingness to believe in what you think the truth / facts are - based on suspect dyno pulls and what the manufacturer tells you.

(But didn't bobterry just debunk your dyno chart on the other forum and you are now considering re-running ?)

In any event clearly my 30 years of engineering experience is no match for such a belief system ;-)

However I'll leave others to decide the facts here.

In the meantime enjoy your 'special pulley' which must somehow behave much differently to the others I've seen working and tested on a REAL ENGINE DYNO.

If you should hear or feel any odd vibrations between 4k and 5.5k RPM, I'd suggest backing off.

PS - are you sure you're not related to Omeyhomey ?

 

Butt dyno??? Thats a deal dyno on (IMO) the most truthful dyno you can put a car on. your 30 plus years of engineering experience still adds up to zero when it comes to this pulley. No one debunked my dyno chart and i did offer to re-run a dyno to show that this did make power. To even call a dyno-dynamics dyno into question would be foolish, Unless the operator some how messes up it would be the only way for the dyno to be void. I do believe that who ever is over at AMS does have some trick tactics to promote his products and thats rather funny on its own. I have no affiliation with AMS other than emailing him about some pulleys and a few replies I would be more than happy to share those with you all. I will take into advice if i feel a vibration in the upper RPMs. That is a good piece on knowledge. I think the question should be Has anyone had any problems with an AMS pulley? like say engine failure. If so I would like to know about it. as soon as some one does I will be the first to take this pulley off. Dont get me wrong i think that you are a honest, knowledgeable guy. What i do know though is this pulley makes power somehow. All I know is I dyno'ed it. it made power and I've had no problems with it as of yet.

 

if the pulley was outright a bad upgrade, you would realize immediately. however, if theres a slight margin of error, you wont know the damage until its too late and 30k miles later you need some serious repairs to replace some hard-to-reach components

 

A dyno is merely a comparitive tuning tool, no more, no less.
Gains within 3% are considered within reporting tolerance.

The only way to truly prove and confirm increased performance beyond your "seat of the pants" feeling is for a time measured run pre and post modification.

Quarter mile is a great proof as are results from an in car 3 axis accelerometer like a G-tech.

Other then that your dyno run is just a piece of paper that some feel give them "bragging rights"

Big difference on the rollers versus rubber on the tarmac !!!!

 

I find this interesting, maybe these members are related but as long as this pulley does not damage my engine I don't mind. I would think the lighter the crank the less strain, but I understand if this pulley is not balanced perfectly it would cause problems. (It is very well made and the and looks like it’s been made with care and accuracy)

My car has the original pulley still fitted, the recent posts here seem to be varied and sharing knowledge and facts is great, but..................

Should I not fit this now due to speculation that it may damage the engine?

Should I get it balanced checked or was that already done by AMS?

Should I expect no positive benefits and just accept this as a precaution pulley change as my car did not have any recall carried out, my car has a 10 year old 100,000 mile pulley and this will still be cheaper than going to an MB main dealer and buying an original.

Or is this just down to theorised comments and assumptions being made with no actual proof?

I trust who ever engineered this pulley to be competent and capable of producing something that does not have a negative affect on the engine.

Thanks

 

Putting aside any power gains for a moment..

The pulley (in fact practically any pulley) is rotationally balanced and the AMS part is clearly well made, but to prevent crankshaft damage caused by crank torsional resonance the pulley assembly has to absorb the impulse energy from the crank.

This is done by having a two piece pulley with damping rubber between them and a critical mass to dampen the oscillations at a specific RPM.

Torsional resonance is not too much of a problem on short 4 cylinder cranks but for 6 and 8 cylinders it's critical.

The pulley in question has not been designed with crank shaft torsional resonance in mind - thus the longevity of the crank must be in question.

On the AMS website there is a .wav file which demonstrates how well damped the pulley is - which in of itself, it is. The problem is that it's not tuned or matched to the crank resonance. There is a good reason why MB has designed 7lbs or so of rotational mass hanging off the front of the crank.

Some people here may disagree with the following link - but it in fact it's totally accurate from a purely engineering aspect:

http://www.dinancars.com/bmw/technia...armonic-damper

FYI - Benz_addict for one has removed his pulley for this reason (amongst others) and is now offering it for sale second hand.

Bottom line - there is a finite possibility that long term (or not so long term if you're unlucky) that this pulley without an adequate integrated damper of the correct mass will damage the crank when attached to 6 or 8 cylinder engines.

If your existing pulley is not showing signs of wear and tear (bulging rubber), then it's likely ok - none the less I'd keep an eye on it.

But if for peace of mind you decide to change it, I would stick with the OEM part for the above reasons.

 

I find it ironic that most of the younger posters don't remember that the correct name for the "pulley" mounted to the front of the crank is a "vibration damper" or "harmonic balancer".

Both very descriptive names !!!

Why????? .... because it is not a straight pully design as are the true pulleys used on the driven accessories

If you don't believe Timdf , then here is some engineering design text book stuff

Vibration Damper
The power impulses of an engine result in torsional vibration in the crankshaft. A vibration damper mounted on the front of the crankshaft controls this vibration (fig. 12-21). If this torsional vibration were not controlled, the crankshaft might actually break at certain speeds. Most types of vibration dampers resemble a miniature clutch. A friction facing is mounted between the hub face and a small damper flywheel. The damper flywheel is mounted on the hub face with bolts that go through rubber cones in the flywheel. These cones permit limited circumferential movement between the crankshaft and damper flywheel. That reduces the effects of the torsional vibration in the crankshaft. Several other types of vibration dampers are used; however, they all operate in essentially the same way.

A picture is worth a thousand words !

 

I am afraid it all makes sense and it does raise concerns.

now I really am completely in two minds,

does the OEM harmonic balancer really need to be weighted as much as it is,
if it does not have the correct weight ratio required to satify the resonace of the crank then my understanding is that it won't do its job properly.

doesn't it just need to be balanced in the normal way a wheel and tyre is.

As long as the AMS harmonic balancer absorbs the vibration and is balanced is that not enough? (I can confirm that my AMS pulley does have rubber pressed into the construction, i.e its not a solid metal piece pulley)


This tech info link below talks about replacing the harmonic dampener with 'a lightweight alloy assembly' AMS state that its an alloy harmonic dampener pulley which they produce?




http://www.dinancars.com/bmw/technia...armonic-damper

 

The AMS is not a harmonic balancer its just a pulley.
Hence no vibration dampening or harmonic cancellation.
That's the problem.

Just apply common sense....is a gain that is within tolerance of a dyno reading of 3% worth having a future problem.

Ask AMS who is the manufacturer how much product liability insurance they carry and if they can show you a current insurance policy then go for it.
Any damage caused to your engine or you then would be actionable against the manufacturers product liability.

I go back to the sixties and have owned many vehicles with performance levels higher then most modded AMG's...
Never even considered doing anything to the front balancer.
Lightweight flywheel yes...balancer no.

There are teams of engineers and banks of computers at AMG that somehow calculate what the proper weight and design the front balancer should be.

You're in the UK...are you familar with the NHRA ( National Hot Road Association ) ?

Below are "Top Dragster" rules for cars that run a 1/4 mile in under 6 seconds....much faster then even the fastest Black Series AMG


Top Dragster Rules

--------------------------------------------------------------------------------
Wednesday, January 30, 2008

TOP DRAGSTER

Class is for dragster and open bodied altered-type vehicles only. Altereds must have open front wheels; no full fender and/or running board equipped street roadsters or funny car bodies permitted. Qualified fields with competition conducted in a dial-in E.T. format.

Designation

TD followed by car number. Numbers must be at least four inches high.

Weight Breaks: *

Supercharged or turbocharged big-block altered: 2,000 pounds

Naturally aspirated big-block altered: 1,800 pounds

Supercharged or turbocharged big-block dragster: 1,800 pounds

NOS big-block dragster: 1,700 pounds

Naturally aspirated big-block dragster 1,600 pounds

Supercharged or turbocharged small-block altered: 1,700 pounds
Supercharged or turbocharged small-block dragster: 1,650 pounds
NOS small-block: 1,550 pounds
Naturally-aspirated small-block: 1,500 pounds

Naturally-aspirated 4 or 6 cylinder: 1,400 pounds

* Divisions 6 and 7 minimum weight for all entries 1350 pounds.

Refer to the current NHRA Rulebook and/or rules revisions for additional vehicle/driver requirements, specifications, and general regulations. Any cars running quicker than 6.00 seconds must meet all comparable requirements for TAD or TAFC.

REQUIREMENTS AND SPECIFICATIONS

ENGINE:1
Induction
Carburetors, fuel injection or electronic fuel injection permitted. Two return springs mandatory. Throttle stops prohibited.

Engine
Any internal combustion reciprocating automotive engine permitted; any modification to engine acceptable. Four-valves per cylinder maximum. Engine may be in any location in dragster; front engine only in altered. Harmonic balancer meeting SFI Spec 18.1 mandatory.

Here is a link that better explains SFI Spec 18.1

http://www.pro-race.com/faq.htm

Soooo why do you think real high performance race cars need a harmonic balancer...and why do they add weight to obtain a dynamic balance ????

Break a crank at speed and it can be life or death because everything comes to an abrupt stop and hot oil, gas, and flames tend to spew all over the place

 

Do not confuse rotational balance or inherent mechanical resonance of the pulley with the need to dampen the torsional twist of the crank.

The mass on the other side of the rubber damper is critical to the damping / absorbing effect, as is the stiffness of the rubber.

The dampener mass needs to be considered as part of a complete system comprising flywheel, crank and dampener.

I'm sure MB could have made the crank pulley lighter, but chose not to as they calculated how much mass is required to dampen the cranks natural resonant frequency at a given RPM.

It's actually quite a difficult calculation and not something I'd mess with.

Crankshafts are actually a very complex piece of engineering and are affected by what's attached at each end.

Hope this helps.

Tim

edit just read this link http://www.pro-race.com/faq.htm posted by RBYCC above and it really is informative as to why damper mass is required and the dangers of reducing it.

 

THANK YOU FOR THE INFORMATION GUYS.

YES AND IT IS FACTUAL, so I am thinking it would not be wise to not pay attention to it.

I am obviously not an exspert engine builder, but I would have exspected after reading this information that the AMS pulley was bench tested first in some way and the physics and calculations carried out properly?

Please AMS could you confirm that this process took place in the production stages. It may be completely fine and there are no issues.

As I am now stuck between a hard place and a rock and amazed that no one picked up on this earlier before I purchased it.

 

Here is AMS response when I asked him that exact question - ie how were the damper co-efficients calculated to make sure they were still within tolerance

to which I replied
To which I got no reply, see post #63 on this thread

http://www.benzworld.org/forums/abed...arantee-7.html

From this I conclude mass was simply removed with no regards to the damping properties required by the crank.

As for your next steps, you could

1. Install and test it, if you're satisfied - keep it and report your success.
2. If after installing it you're not satisfied - Return it for a refund, ie test the guarantee.
3. Sell it on as second hand and put it down to experience.

Personally I go for #3 - which is what benz_addict has decided to do, see link below. Also note E55 PWR (AMS / Omeyhomey posting as a shill).

https://mbworld.org/forums/showthrea...844&highlight=

As for nobody picking up on this before - actually they did last year on the other MB forum, it was quite brutal. This thread is worth a read if you've got the time. It's really very entertaining :-)

http://www.benzworld.org/forums/g-cl...nk-pulley.html

 

I must say that once the this thread went past the arguing phase it has become very informative. I was curious if M-B actually designed the hub/integrated pulley to function as a vibration damper because the design is very different from their past practice. Thanks timdf.

Also, I would be suspect of anyone (Dr. C36) that quotes the incorrect torque. Fortunately, splinter corrected this rather serious mistake in post #20. The torque spec of 200 Nm + 90 degrees angle of rotation is fairly common knowledge. Lots of folks were discussing this back when the early vibration dampers were failing and it is also specified on the factory C-Ds, on www.startekinfo, etc..

 

It's helpful to know that AMS is a.k.a. C36ickness, omeyhomey, Dr.C36, E55PWR. He is a recent graduate of the University of Arizona with a degree in marketing. He has no background at all in engineering or physics. He claims to have performed calculations for his pulley but refuses to show them even when offered money. On his website and in his business plan he cites Newton's Second Law of Motion, but with respect to a rotating pulley he gives the wrong formula. It's obvious no calculations were done.

The pulley he sold you will add about 1/2 HP to the rear wheels when accelerating in first gear and less HP in other gears. That is a scientific fact that any high school physics student can verify. It's probably not worth risking the reliability of your engine for so little gain.