Harmonic Balancers
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    Default Harmonic Balancers

    It is interesting to note the both Fluidampr and ATI list the 4bt in their diesel dampers. They are the same part numbers as the 6bt but they have added the 4bt to the list of applications. Both companies make similar performance claims. The Fluidampr unit is 9.75" in diameter and weighes about 23 lbs where the ATI unit is just a fraction over 8" in diameter and only weighes 11 lbs. I know several members have used the fluid type and found it does help. Curious if anyone has used one of the ATI units.

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    I have not used either, but I am also in the market for a harmonic balancer.

    **noob questions**
    The balancer that these companies sell is a complete replacement for the stock crank pulley, correct?
    Is the harmonic balancer pulley the same diameter as stock?
    **end noob questions**

    I would think that the heavier dampener has a better dampening effect.
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    Quote Originally Posted by GLTHFJ60 View Post
    I have not used either, but I am also in the market for a harmonic balancer.

    **noob questions**
    The balancer that these companies sell is a complete replacement for the stock crank pulley, correct?
    Is the harmonic balancer pulley the same diameter as stock?
    **end noob questions**

    I would think that the heavier dampener has a better dampening effect.
    Actually, the balancer/dampener bolts to the front of the pulley. Simply remove the four bolts, install dampener, replace and tighten four bolts.
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    Fluid Dampner sells both.
    1970 F250 Crewcab SB. VE 4bt. M5R2, Hx30/Hx35 Twins, 40hp stix, DennyT stage 2 pin, Intercooled, 3200 gov spring, Starwheel cranked, smoke screw screwed, M&H dynamic timing advance, Hydroboosted.http://www.dieselpowermag.com/featur...ins/index.html
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    From what I have read, a stock Cummins damper is pretty much a waste of time on a 4bt. The Cummins add on fluid type is good but has a limitted rpm range and is the most expensive of all. The Fluidampr unit is the second most expensive but has a good reputation and no rpm limit. The ATI unit has peaked my interest because it is designed for NASCAR engines. It is smaller, lighter, cheaper and uses a different technology than the fluid units. It is also rebuildable, but rebuilds are recommended every 10 years. I figure either one will make some noticable improvements. Just have to decide to shell out $400-500.

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    i know its supposed to reduce vibration and harmonics in the engine but is this thing actualy worth $500? what driveability improvements would you see?
    2000 quad cab dakota 4x4 4bt cummins, hx30/35 compounds, 30% over injectors (6X9.5) nv4500 trans, np231 t-case Pump maxed out, M&H M2 fuel pin, two turns UP on the star wheel. Dodge 9.25 rear LSD with 3.55 gears 275/75/R16 Hankook RF-10s

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    Quote Originally Posted by chickenlights View Post
    i know its supposed to reduce vibration and harmonics in the engine but is this thing actualy worth $500? what driveability improvements would you see?
    From what I've read, it helps the most when in the higher RPM ranges. It increases the destructive resonance RPM of the motor, allowing you to more safely hit 3800-4000 RPM. It should make for a smoother running motor and increase longevity by decreasing main / rod bearing wear.

    As I said, this is what I've read, not what I've seen.
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    I'll throw my $.02 in..

    I've got the rubber ring type off a 1st gen 6.9 on my 4BT. (Stock pulley was eat up with rust, had the harmonic dampener laying around, so...) It did smooth out things at idle a bit, and it seems smoother revving up.

    Better performance? No. Actually, you're cutting your performance a slight bit by having more mass to spin. But, as previously said, the offset is normally that you can then go make more power without busting things up, or at least not quite so quickly.
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    Quote Originally Posted by BobS View Post
    You need to first confirm the problem BEFORE you start buying and replacing parts.

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    Char1350
    I'm so glad u started this thread, I've had questions and thoughts running through my mind about this.

    Machman
    Thanks on the input on the rubber dampner, I was wondering if anybody noticed a difference.

    Love this site!

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    Here's Cummin's version of their viscous (fluid filled) dampner, as they use in Marine applications;

    http://www.ebay.com/itm/271074017446...84.m1438.l2649

    http://www.ebay.com/itm/180813483408...84.m1438.l2649

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    R those good? Has anybody noticed a big difference in a rubber vs the fluid or even these viscous? How much difference is there?

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    CMIIW, but wouldn't getting the rotating assembly balanced at a machine shop also make the engine smoother and more responsive, even with the stock un-dampened front pulley gigamjig?
    In my mind (sometimes feeble, I admit) a nice balance job and an isolated damper would alleviate the potential for both crank wear and breakage, as well as smooth things out some.

    I've been witness to a damper from a 1st gen Dodge and a 2nd gen 12 valve (2nd gen 12 valve is larger in diameter) actually taming some of the vibration at idle, so I wouldn't necessarily call that "no difference".

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    So there was a noticable difference with the 2nd gen? I have a 3rd gen I think, it doesn't have a notch for rpm senser. R the cummins viscous even better? It might be worth 85-150 to get better vibration damping. I have rebuilt mine already so balancing is out until next time.

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    As far as balancing a crank, yes it helps some but with a half counterweighted crank like that of a 4bt youll have vibrations in higher rpm no matter how balanced you make it. With a 6bt you dont have this issue as the crank is somewhat self balancing to a point.

    Ive used ati before and will be using it on my race built 4bt. Also i have numerous friends with engines ranging from small displacement 4 cyl up to big v8's that all swear by ati with there engines.

    Sadly i have no comparison of engine wear before and after the damper.

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    A pal of mine had a mid-'90s Crown Vic with a 4bt and put a damper from a 1st gen Dodge 5.9 on it and the difference was definitely noticeable.
    I would imagine that the 2nd gen Dodge 5.9 one, again, a larger diameter version, would also be noticeable.

    I don't have any experience with a Cummins viscous damper, short of a 6.7 one from the Dodge trucks, and IIRC, it may not clear the pan on a 4bt.
    The only dampers with the notches are 1990-1993 VE trucks and all 1994-1998 12 valve inline pumped Dodge trucks, all others had no notches for the crank sensor.

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    I'm thinking of running my engine at times around 3500 that's why I'm curious, plus protection, and drivablity.

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    I'll let you all know. I ordered one.
    Dave
    1970 F250 Crewcab SB. VE 4bt. M5R2, Hx30/Hx35 Twins, 40hp stix, DennyT stage 2 pin, Intercooled, 3200 gov spring, Starwheel cranked, smoke screw screwed, M&H dynamic timing advance, Hydroboosted.http://www.dieselpowermag.com/featur...ins/index.html
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    Sweet, wish I had the $$$.

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    I just ordered one too off ebay. For $85.21 for a brand new 3925233 which is the Cummins marine unit. Those are about $600 from Cummins. Heck, I've pissed away a lot more money than that on other stuff. Now all I need is that mounting spacer and the bolts which I am sure are Cummins only parts. This unit is good to at least 2500 rpm continuous and I'll never run that high. Don't need high rpms when you got torque.

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    Quote Originally Posted by char1355 View Post
    I just ordered one too off ebay. For $85.21 for a brand new 3925233 which is the Cummins marine unit. Those are about $600 from Cummins. Heck, I've pissed away a lot more money than that on other stuff. Now all I need is that mounting spacer and the bolts which I am sure are Cummins only parts. This unit is good to at least 2500 rpm continuous and I'll never run that high. Don't need high rpms when you got torque.
    Well I just impulse bought the other one that the seller had, so I've got one as well.

    Do you have the part numbers for the bolts and spacers?
    Do we have any more info on the specs / RPM range of this dampener?

    EDIT:

    Assembly diagram:
    Last edited by GLTHFJ60; 11-03-2012 at 11:11 AM.
    Johnny C - KK4HAN - TLCA# 17825
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    I haven't found the part #'s for the spacer and the bolts yet. Found a listing for the spacer but the part # was wrong. May have to get with a Cummins marine dealer on those. Don't know the exact engine speed rating but I would feel is a bit above 2500 rpm. Cummins marine 4bts go a couple hundred above that. Like I said, I don't rev very high. Just let the torque do the work. I bet when we find the other parts they may cost more than we paid for the damper. If I had a ESN for a marine engine I'd plug it into Quickserve.

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    Sounds like might have to do so measurements and go to a machine shop and bolt store.

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    I found the part #'s for the spacer and bolts in an old thread on the forum. Spacer 3924579 and bolts 3924584 (M12x1.25x60 flange head). RPM limit on this damper is 3000. That sounds about right because is was used on the 250hp 4bt marine engine which was set up to rev higher that standard 2500 rpm. Interesting to note I found a second diagram of this damper installed differently. It is mounted behind the crank pulley. Don't see how it could work since the belt would be out of alignment with the other accessories. Would require a special water pump and fan pulley set up.
    Attached Images Attached Images

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    Have u found a price on those part #s yet.

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    No prices yet. Most Cummins places aren't open on Sunday. I did find a price on the bolts at Costal Marine Supply $8.25 ea. That price doesn't surprise me since those are very special bolt. I'm not even sure they can be reused once they are torqued down. Maybe do some shopping tomorrow. Hey, maybe CrewCab59 can get us the prices. He's a Cummins dealer.

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    RPM limit is listed as 3000, eh? We'll have to test that.

    Good find on the parts number and thank you for posting the bolt dimensions. I can go source those bolts locally for a bit cheaper than $8+ a piece I hope.

    Based on the pictures of the dampener, spacer and pulley, it looks like they will stack up either balancer or pulley closer to the timing cover. Good thing I have my engine on the stand so I can do some easy test fitting!
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    Quote Originally Posted by Dougal
    I'm an engineer, I find solutions that work and really hate marketing dribble.

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    Quote Originally Posted by Mark Nixon View Post
    CMIIW, but wouldn't getting the rotating assembly balanced at a machine shop also make the engine smoother and more responsive, even with the stock un-dampened front pulley gigamjig?
    In my mind (sometimes feeble, I admit) a nice balance job and an isolated damper would alleviate the potential for both crank wear and breakage, as well as smooth things out some.

    I've been witness to a damper from a 1st gen Dodge and a 2nd gen 12 valve (2nd gen 12 valve is larger in diameter) actually taming some of the vibration at idle, so I wouldn't necessarily call that "no difference".

    Mark.
    Balancing the lower end will most certainly help with vibrations, however, even with a 'perfectly' balanced lower end, you will still have vibration on an engine, which is due to the to the impact of the actual combustion process taking place itself. This is why most engines have a 'counterbalancing' system on them of some sort. The most common method in the automotive industry is what we are discussing here, the harmonic balancer, where as in the aircraft industry, crankshaft mounted counterweights are the choice, for a better, if you will balance, but this system has lots of drawbacks.

    I'm really curious as to how well the ATI damper will work on the 4BT, because I want one on my build, just haven't decided if I have the funds for it yet.

    I'm fairly certain all of these dampers will make some noticeable difference at some range. The question will be will they make enough difference for it to be worth the dough?

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    Quote Originally Posted by SauceBoss View Post
    The question will be will they make enough difference for it to be worth the dough?
    Exactly. Answers hopefully soon!
    Johnny C - KK4HAN - TLCA# 17825
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    Land Cruiser adventures, documented through YouTube

    Quote Originally Posted by Dougal
    I'm an engineer, I find solutions that work and really hate marketing dribble.

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    Johnny C don't expect to find those bolts at any bolt store. They are special. I've only found one other source and that was a Porche racing supplier. You don't want to know how much those were. The main porblem is the 1.25 thread pitch and I believe they are grade 12.9 or higher. Haven't called Cummins Atlantic yet. Found a Cummins generator supplier in Florida that list them for $6.50 ea. They are probably too specialized for a regular bolt company to have.

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    Update. Called Cummins Atlantic. Part 3924579 has changed to Part 3968954, price $59.66 and Part 3924584 is $6.77 ea. Not exactly sticker shock. If we had one of those crank spacers for a pattern, a good machine shop could probably make one for $20. There isn't much to it. Just need the dimensions and we would already have the bolt spacing.

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