7.3L Flywheel Indexing = Vibration?

Bull Gear

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So... what's the deal with flywheel balancing on a 1999 7.3L? Is that a internal or external balance motor? Is flywheel indexing critical?
I'm replacing a reman ZF6 after about 50K mis. The trans was in the truck when I bought it. Apparently, the pilot bearing failed and took out the input shaft bearings. When I pulled the flywheel to replace the pilot bearing, I noticed that the flywheel was not indexed correctly (alignment dowel holes 180 deg off, and obviously no dowel). The flywheel is an aftermarket Perfection brand and it looked fine, as did the clutch so I reused it all. When I re-installed the flywheel, I aligned the locating holes but did not realize there was supposed to be a dowel so I did not put one in there. I bolted my "new" trans back in, but left off the transfer case so I could run the trans through the gears. I test ran it on the lift and felt a noticeable vibration just above idle that I never noticed before. It happened in all gears, clutch in or out. I didn't run it long enough to really warm up the motor because I was kinda freaked out at this point.
Could I have screwed up the balance somehow? ...or am I just being paranoid? I've never done a power balance on this motor, so now I'm thinking maybe it's just in the motor since I didn't warm it up properly.
 

Magnum PD

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Don’t make sense. The fly wheel should be balanced.

You do have the harmonic balancer on right?
 

Bull Gear

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Balancer was never touched.

I tried it again today after I warmed up the engine and it produced the same paint shaker effect from idle to about 1200rpm and then again above 2500rpm.

I looked at another 7.3 balancer and flywheel and they both have counterweights. I assume this means that motor is in fact EXTERNALLY balanced. That being the case, I suspect that I have not indexed the flywheel correctly.
HOORAY, I get to pull the tranny again!!!

Problem is, the more I research this, the more confused I get.
I now realize that there is a spacer on the back of the crankshaft. All of the pics I find show this spacer as having just one hole, so no confusion there.
HOWEVER, I have found pics of 7.3 crank flanges that have either 1 or 2 holes for alignment dowels (see pics). What's up with that!?

I'm starting to wonder if the reman motor that was installed before I got the truck might have one of those "2 hole" cranks in it and the spacer was put on 180 deg out of phase. If so, when I aligned the flywheel with the spacer hole it threw the balance way off. That might explain why I originally found the flywheel oriented with the alignment hole 180 deg away from the spacer hole. I was thinking the fella before me didn't know what he was doing. I'm starting to think maybe he DID know and that I'm the idiot!

At any rate, it's all coming apart again. I said "f--- it" and bought a new LUK Repset to eliminate any doubt about the old flywheel and clutch parts. I suppose I can determine the proper flywheel orientation by looking at the location of the counterweight on the balancer. If the spacer does appear to be improperly indexed I'll pull it and try to make it right.
 

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Bull Gear

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I think I answered my own question... the crank with the 2 hole flange seems to be for a 95-97 that is an entirely different animal with hollow rod journals.
 

Bull Gear

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all of a sudden I can't edit my previous posts...
Today, I compared my flywheel indexing to another motor I recently pulled from a parts truck. On that motor the counterweights on the flywheel and balancer are opposed (180 deg apart). On my motor, I installed the flywheel with the counterweight aligned with the balancer counterweight. So this seems to conform everything I had feared.
I sure wish someone that knew the real deal would verify this, though.
 

Bull Gear

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Alright... I'll answer my own questions, then. No help to me, but maybe it will help some struggling soul in the future.
- The crankshaft spacer is only used with auto trans flexplates, so not a factor here.
- I found a couple more pics of '99-up crankshafts that have 2 holes in the flange. The 2nd hole, opposite the dowel, appears to be smaller diameter.
- There should be a 3/8 x 2-1/4 roll pin in the alignment hole, Ford part #20640-R1
I'll need to confirm all this and I'm still at a loss to explain how I got my flywheel 180 out. I'll find out when I pull this trans out again.
 

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