So I had the stock (Ford I think) viscous damper. What I recall is a puck and 4 hard to find bolts that I bought at Cummins. Do you happen to have the version that uses a crank pin along with the 4 bolts?

 

Are you talking about the center dowel? My 3925233 had the center dowel hole in the damper, and a protrusion from the spacer to transfer the crank's dowel to the damper. If you're talking about a dowel in the bolt pattern, then my engine, nor my OEM damper setup, had that. See below, this is what's on my engine.

 

My exact set too

 

My setup is the same as above. But as you can see the back of my spacer/adapter thing is drilled half way through to run a dowel in the crank.

The fluid damper already has the additional holes (see pic)

so just wondering if I should drill my balancer out and run the dowel through all of them, or just dowel under the spacer/adapter.

 

I do recall reading that the additional pins were to help prevent the twist that occurs with just the bolts. I don't have issue but in my head the pin or pins should be drilled out and used.

 

If I recall 3000rpm and up is when it’s recommended to use the pins. I have 4K springs, but it will just be a daily driver, so just wanting to see what the thoughts are.

 

What you have is an aftermarket dampener, not the OEM Cummins. Although those are essentially the same design, that pin you mention was an addition. I assume your adapter piece was custom made as there's no dowel on the crankshaft end to fit that hole. That part was a racing only item and didn't use any belt pulley. Fluidampr has one like that as well. You'd have to modify the crank to accommodate that pin. 3000 RPM was the normal limit on the factory units since they were mostly on the marine engines and they maxed out around that speed.

 

Char, I just posted a picture of the Fluidampr brand balancer to show the additional holes for the dowel I’m talking about.

I have the exact Cummins harmonic balancer (3925233) shown above by Johnny and Jeep, along with the adapter to go with it (3968954) also shown in the picture by Johnny and Jeep, along with the million dolllar bolts (3924584) lol. My crank IS drilled to accept a dowel.

This picture is of the backside of my spacer adapter puck thing (3968954) and as you can see is drilled half way through. I don’t know if your guys came like that, but mine did as I did not drill anything.

So, back to the top question. Should I just pin the adapter to the crank and not drill anything? I’m leaning towards this option.

Or drill it all the way through the adapter and drill the balancer to run a pin through all of them?

 

The balancer is a cummins part that was used by Ford I believe. And the million dollar bolts are unobtanium!

My adapter did not have the pin holes. But my question to you, which is what I am using to give you my opinion, is how much of the crank has been final drilled? To me it seems like the best approach is to find out what fluidamper is doing. I would guess putting the pin through all 3 pieces but I'm not sure.

 

I'm somewhat curious about that small hole in the back of the adapter. You said your crank is drilled for that pin? None of my Cummins parts manuals show any hole other than the 4 bolt holes. Would leave one wondering what's the part # for the pin. Can you take a photo of the end of the crank? Maybe the hole was added in later models to insure the spacer doesn't move and put undue stress on the bolts. One member had his bolts snap. Torque on those is pretty high. All the photos of the adapter I've seen had no extra holes. The original part # for the spacer was 3924579. That was later changed to 3968954. Maybe that's when the hole was added. Here's a photo of the back side of an original. Those hard to find bolts sort of depends on where you get them. I've found them in the $7 range and also more than twice that. That size bolt was also used on a Porsche brake system and you can get those for about $50 each. LOL.

 

Don't quote me but I remember getting them from cummins for so much more than $7 or $14 each. Heck I dont consider that expensive for a cummins related thing! I used to have an old porsche so I do believe you must have been shopping on a discount site if you saw bolts for only $50 LOL

 

I got my parts from mamau diesel and the bolts were $8 each. Can’t remember exact number, but up here in the land of tax and being bent over on everything, Cummins wanted like $25 per bolt.

Char, I will snap a pic of my crank on Monday, but it was drilled by buddy who built my motor.

Fluidampr recommends using their drill/pin kit on the 5.9/6.7 above 3500rpm.

 

You said your crank is already drilled for that small dowel? The adapter is drilled in the exact same way, and it is a cummins adapter, but your balancer is not? That is strange.

Pin the adapter to the crank, and torque the bolts properly. I've got no pins in mine, and run it above 3000rpm pretty regularly. No issues in the past 4.5 years.

 

Here's a listing for those OEM bolts for $7.33 each. https://shop.moderngroup.com/3924584-screw-hex-flange-head-c/ Sort of strange that Cummins dealer price has gone up so. The last time I checked the local dealer was in the $6-7 range. Maybe they had to have some more made and the cost went up. A Cummins marine dealer would be a likely source but probably wouldn't be any cheaper.

 

As Johnny said, I’m just going to pin the adapter to the crank and leave the balancer alone. Thanks guys.

 

That is really strange. I believe that's the first crank I've seen with that pin hole. Big question would be what's the part # for that pin. None of my ESN's on Quick Serve or any of my parts manuals show a crank with that hole. Might be a marine item since the factory dampener was on all the marine engines. Also came on some industrial generators. Would have to be a later model because none of the early parts were bored.