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Discussion Starter #1
Guys,
Getting ready to take possession of a 4BTA w/inline pump. (Won't know CPL until I see it.) Any way, how is the 4B's balanced, internally or externally? I have read that some have a "balancing" assembly, is this via a dampener/ crank pulley or a counter-rotating set-up inside the engine? If it's a dampener/ pulley, will a viscous Dodge 5.9 "Fluidampr" work? Are they specifically designed for 4 or 6 cylinder applications? Went to their website, they list Cummins, but only 5.9's and larger.
 

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I have seen the internal balanced 4BT with a front gear driven balancing shaft. This unit rides up just above the oil pan and runs the length of the engine block. I have a fliudic balancer on the front of my 4BT . The cost of adding an internal balncer would be quite high but is supposed to handle bigger vibrations. My fluidic balancer normaly belongs on the 6BT and requires an additional spacer about 1" wide between it and the crank pulley. I posted the part numbers elsewhere at this site. I was told there is no fluidic made for the 4BT. My 6BT balancer works nicely for me but I have not run without it si I don't know. I don't have any vibrations traveling around the truck at idle.
 

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1989 Jeep Wagoneer, 360v8, 727, stock for now,
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Cummins did offer a "balancing assembly" for the 4B at one time. It attached to the bottom between the engine and the oil pan, contained two counter rotating shafts driven from the front. I've only seen one pic of it and the guys at Cummins in Avondale have never see one either. A very rare piece.
The harmonic balancer from any of the 1st and second gen Dodge 6Bs will bolt up the a 4B with the same bolts. Don't really need it but gives you a nice feeling.
 

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don't know if it helps but I pulled a pretty big balancer off the front of a '04 24 valve Dodge and it bolts up perfectly on my 1990 4BT...
 

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Discussion Starter #5
so is there a definitive answer on balancing? The 4B's I've seen have a non-dampener crank pulley and don't appear to have any weight/s on them. If the dampener is not balanced to the crank then I would assume the rotating assy. is internally balanced? Not an expert on this but do have general knowledge of engine function. The jist of this is I'd use a "Fluidampr" from a 5.9 if it didn't require any special balancing AND would actually reduce engine vibe's. Note: priced some online...$400-$450 at the few places I checked.
 

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I have the 'Before' part and seems like Driverswanted has the 'After'.

Mine vibrates some throughout the entire power band. It's most noticeable at idle of course. I'm sure I need to install softer and maybe thicker front mounts, and maybe same on rear of NV4500. Still haven't adjusted valves either which can contibute to vibration.

When DW says he doesn't have any vibrations traveling around the truck at idle that tells me a whole bunch: IT WORKS! I think I located new 6BT balancers at Rockauto.com for about $80, have to go look again. Sounds like a winner to me. Just have to wait for the blasted piggy bank to fill back up. How long does that take ha haha?
JimmieD

Yea, here it is: http://www.rockauto.com/catalog/x,carcode,1101328,parttype,5512

Napa wants $24 more [so what's new]:

http://www.napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=BK&PartNumber=6005285&Description=Harmonic+Balancer+Assy
 

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. My fluidic balancer normaly belongs on the 6BT and requires an additional spacer about 1" wide between it and the crank pulley. I posted the part numbers elsewhere at this site. I was told there is no fluidic made for the 4BT. My 6BT balancer works nicely for me but I have not run without it si I don't know. I don't have any vibrations traveling around the truck at idle.
I think DW has the fluid dampener from a 6bt. DW what engine mounts do you have?

Gaza
 

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no its a big metal one.. ther is a $60 dampener somewhere that someone posted... Probably a better deal, I think its rubber. I haven't run mine yet to see if it definetely works but a dampener is a dampener IMO, I'm sure you all have seen the 4BT flywheel correct, biggest dampener I've seen :smile:
 

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A fellow over on the engineering Forum posted that he had the 6B damper on his 4B and had no vibration problems, just like D/W.

There's a BIG difference between a Fluidamper or Fluid-type damper and an Elastometric type damper as used on 6B's. The reason the Fluid ones are so expensive is that they have a fluid [I think silicone?] sealed inside which is able to actually absorb torsional stresses and let their wave forms collapse within. The elastometric type, standard on eninges of all types, have a rubber type membrane between two separate pieces of metal. The shock loads are transferred through the inner piece, through the membrane and into the outer piece.

Unfortunately the cheapo or poorly made elastometrics can separate with catastrophic results. I don't recall it happening that often and it would probably be less frequent on a low revving engine.

The purpose of the 'harmonic damper' of either type is to cancel vibration wave forms that set up within the crankshaft. These can snap the crank in half like a pretzel and when a harmonic damper fails, especially on a cast crank, that's often the result. However the 4B forged crank is so stout that they felt it didn't even need that protection, also indicating that even with a complete failure of an add-on damper you would'nt have any problems except vibration issues coming back.

As mentioned above, there are two types beyond that: one for internally balanced engines and one for externally balanced engines.
 

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My mounts are drilled 6BT mounts. I put about fifteen 1/4" holes through each mount to soften it up slightly.
 
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