: Harmonic Balancers



char1355
11-01-2012, 08:41 AM
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.

GLTHFJ60
11-01-2012, 09:31 AM
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.

Truckman
11-01-2012, 11:38 AM
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.

Lonno
11-01-2012, 11:40 AM
Fluid Dampner sells both.

char1355
11-01-2012, 06:15 PM
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.

chickenlights
11-02-2012, 05:05 AM
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?

GLTHFJ60
11-02-2012, 10:50 AM
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.

Machman
11-02-2012, 12:22 PM
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.

Drifter
11-02-2012, 01:06 PM
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!

viking427
11-02-2012, 04:17 PM
Here's Cummin's version of their viscous (fluid filled) dampner, as they use in Marine applications;

http://www.ebay.com/itm/271074017446?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

http://www.ebay.com/itm/180813483408?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Drifter
11-02-2012, 06:55 PM
R those good? Has anybody noticed a big difference in a rubber vs the fluid or even these viscous? How much difference is there?

Mark Nixon
11-02-2012, 06:59 PM
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.

Drifter
11-02-2012, 07:13 PM
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.

WHITExGUY
11-02-2012, 07:21 PM
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.

Mark Nixon
11-02-2012, 07:27 PM
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.

Mark.

Drifter
11-02-2012, 07:27 PM
I'm thinking of running my engine at times around 3500 that's why I'm curious, plus protection, and drivablity.

Lonno
11-02-2012, 07:41 PM
I'll let you all know. I ordered one.
Dave

Drifter
11-02-2012, 07:53 PM
Sweet, wish I had the $$$.

char1355
11-03-2012, 08:43 AM
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.

GLTHFJ60
11-03-2012, 11:04 AM
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:
http://www.forengine.com/img/IMS/769120323049143.jpg

char1355
11-03-2012, 05:18 PM
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.

Drifter
11-03-2012, 06:59 PM
Sounds like might have to do so measurements and go to a machine shop and bolt store.

char1355
11-04-2012, 07:14 AM
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.

Drifter
11-04-2012, 07:34 AM
Have u found a price on those part #s yet.

char1355
11-04-2012, 08:47 AM
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.

GLTHFJ60
11-04-2012, 08:15 PM
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!

SauceBoss
11-04-2012, 09:04 PM
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?:dustin:

GLTHFJ60
11-05-2012, 06:36 AM
The question will be will they make enough difference for it to be worth the dough?:dustin:

Exactly. Answers hopefully soon!

char1355
11-05-2012, 06:51 AM
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.

char1355
11-05-2012, 07:23 AM
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.

GLTHFJ60
11-05-2012, 08:23 AM
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.

That was quick! Shipping shouldn't be too bad from Cummins Atlantic either. Thanks for doing the leg work man!

As for machining the spacer, we already have the dowel diameter and depth as well as the bolt diameter and spacing, just really need the thickness.

Lastly, where did you get the part numbers from? Do you have a Cummins part reference that you can share?

char1355
11-05-2012, 09:49 AM
Johnny, that original part # came from a thread right here on the forum from about 4 years ago. Someone was putting one of these on an engine. The revised part # came from Cummins when I called them.

studedude
11-05-2012, 09:52 AM
I think that bolt size is the same as at least one of the crankshaft bolt sizes,I am sure about the thread and pitch ( M12 X 1.25) and the length should be about right.Crankshaft flywheel bolts should be strong enough.
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.

WHITExGUY
11-05-2012, 10:10 AM
A decent machine shop that deals with companies who use all metric parts should have m12x1.25 in stock even if the length is wrong they can be shortened. I dont know off hand how much they cost but i know we use that size bolt often for factories that wont convert there machines to standard.

Also all you would need from the spacer is the thickness and use the bolt pattern on the crank or balancer. We made alum spacers to replace the old rubber ones in the steering shaft of a nissan 240sx, looks about same OD as that cummins pulley spacer and .5 thick, we were able to blast a few out and sell them at 10$ a piece, so im sure a reasonable machine shop could pop one of those spacers out of steel quick for cheap. Just my .02

char1355
11-05-2012, 03:40 PM
On these bolts, the Cummins price of $6.77 is right on the mark. I just got a wholesale price for a M12x1.25x60 cap screw in grade 12.9. They are $6.30 ea wholesale. Flange heads will cost as much as cap screws if not more. Porche gets $25 each for them. As for that spacer, you are correct that thing could be made for $10, even less if you have your own lathe. Just got to have an original to get the measurements.

khaoskustoms
11-05-2012, 04:08 PM
I have an ATI Super Damper for my 4BT. It's quite a bit larger then the old 1st gen cummins one I had before.

char1355
11-05-2012, 08:11 PM
Khaos, I wouldn't have thought that from the photos of the 1st gen Dodge. The ATI unit is 8.07" and I would have bet the Dodge was at least that big. Of course photos can be deceiving.

Mark Nixon
11-05-2012, 08:19 PM
The 2nd gen 12 valve damper is substantially larger in diameter than either the 1st gen Dodge, or the 24 valve versions are.
I'll get pics of a '95 version and a 24 valve one for you to look at.

Mark.

khaoskustoms
11-05-2012, 09:53 PM
I think i have a stock commonrail damper at work, ill get a pic if it next to my ati tomorrow.

khaoskustoms
11-07-2012, 12:02 PM
Pics of a super damper. I couldnt find my stock damper for comparison.

15263

15264

GLTHFJ60
11-17-2012, 11:12 PM
Just picked up a Cummins fluid dampener, spacer and bolt set off eBay for $125 shipped. Pretty excited! bounce

I won't have a before / after comparison, but this should make the motor smoother once I get it installed.

https://lh4.googleusercontent.com/-9kxdxrU_roQ/UKh5p1FY_jI/AAAAAAAARIE/hsjRk4IhgG8/s640/IMG_20121118_005936.jpg

Looks brand new:

https://lh5.googleusercontent.com/-E84fmkwm5xQ/UKh5wzqFBoI/AAAAAAAARIE/oPXTYcy_rI0/s640/IMG_20121118_005950.jpg

char1355
11-18-2012, 05:43 AM
Johnny, that thing does weigh a pound or two doesn't it. Think it's about 21 but haven't put mine on the scales. If that one has been used any at all it sure was take good care of. Great deal. All I have to do is round up the spacer and bolts for mine.

GLTHFJ60
11-18-2012, 09:39 AM
Johnny, that thing does weigh a pound or two doesn't it. Think it's about 21 but haven't put mine on the scales. If that one has been used any at all it sure was take good care of. Great deal. All I have to do is round up the spacer and bolts for mine.

Or you could machine your own!

https://lh6.googleusercontent.com/-TJKm6_0OMJM/UKkIpp4OBrI/AAAAAAAARLI/ZzdOYslWHyc/s640/IMG_20121118_110935.jpg

https://lh4.googleusercontent.com/-Ox9UGTz01j8/UKkIxYXZ5tI/AAAAAAAARLI/EwzDHDrQH2o/s640/IMG_20121118_110949.jpg

https://lh4.googleusercontent.com/-jiIyMRZ-Eis/UKkI3xwbpWI/AAAAAAAARLI/kYxYNhXPcjI/s640/IMG_20121118_110956.jpg

https://lh6.googleusercontent.com/-tW86RovRJK8/UKkJPBLIFMI/AAAAAAAARLI/PVocqNN83Rg/s640/IMG_20121118_111244.jpg

https://lh6.googleusercontent.com/-eVZwUZSrmKc/UKkJzOwATmI/AAAAAAAARLI/8M_xEEBEr5s/s640/IMG_20121118_111336.jpg

https://lh4.googleusercontent.com/--sHEFjzQqok/UKkJ5xt7IUI/AAAAAAAARLI/jAB_0FPenyU/s640/IMG_20121118_111402.jpg

Drifter
11-18-2012, 10:19 AM
Super cool man, thanks for the dimensions.

GLTHFJ60
11-18-2012, 12:31 PM
Super cool man, thanks for the dimensions.

No problem!

GLTHFJ60
11-19-2012, 08:52 AM
Here's what it looks like installed, right over the stock pulley:

https://lh5.googleusercontent.com/-oxP-1ebD9nI/UKlibBrv-BI/AAAAAAAARNc/P-3pstawSUg/s720/IMG_20121118_172700.jpg

https://lh5.googleusercontent.com/-tara5dAV8qE/UKliv8DEKrI/AAAAAAAARNc/XCFR8WpRpn8/s720/IMG_20121118_172705.jpg

char1355
11-19-2012, 03:15 PM
Looks great and you didn't even have to paint it. By the way, how deep is that recess in the back side where it fits against the pulley.

GLTHFJ60
11-19-2012, 09:19 PM
Looks great and you didn't even have to paint it. By the way, how deep is that recess in the back side where it fits against the pulley.

****, I didn't measure that.

It should be the same depth as the length of the towel on the front of the crank. The pulley is inbetween, so right there would be a bit of space for fitment.

Andrewscag
12-28-2012, 08:54 PM
Interesting thread. Anybody have before and after comments yet?

W.R.Buchanan
12-30-2012, 03:01 PM
I got a Fluid Damper given to me by them.

Problems: First you have to drill the crank for a dowel pin. It needs the pin to lock it in position in rotation, the screws just hold it on the crank and are not designed to prevent rotation.

This is not hard to do if you have good access to the front of the engine, but it is hard unless the engine is on a stand or the front is open. If you don't have a good strait shot at the front then you need to make it that way.

Second: In my case the unit is too big to clear the overlay pulley for the high mount A/C drive. So I can't use it.

Fluid Damper uses the same unit for 4BT's and 6BT'. They said they had produced units for Cummins at one time.

What this thing will do for you is smooth out the idle speed range of the engine. As soon as the engine is above 900 rpms it will smooth out any way.

Randy

char1355
12-30-2012, 03:47 PM
Randy, I think you'll find the drilling and dowel pinning of the Fluidampr is only for engines turning over 3500 rpm on very high performance diesels. The boring kit is an option. The Cummins unit has not provision for extra holes because it's max speed is 3000 rpm. As far as I know the Cummins unit will clear any accessory drives on a 4bt which it was designed for. That's probably the reason it has a spacer between the crank pulley and damper.

viking427
12-30-2012, 04:00 PM
...First you have to drill the crank for a dowel pin. It needs the pin to lock it in position in rotation, the screws just hold it on the crank and are not designed to prevent rotation. ...Fluid Damper uses the same unit for 4BT's and 6BT'. They said they had produced units for Cummins at one time.
Randy


I suspected as much, that Fluiddampr built the Cummins factory ones shown above. Everything about them looked identical right down to the two small plain head rivets on the face. Funny Cummins doesn't mention the need to drill the crank for their factory version though - probably why Cummins put a 3000 rpm limit warning on theirs while Fluiddampr doesn't, knowing they'll find their way on to some pretty high revving sled pullers.