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1972 F250 4x4, 78 d44, 3.55, np205, 200hp 4bt nv4500 in progress
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Discussion Starter · #1 ·
There’s some severe runout:

Aircraft Airplane Propeller Composite material Engineering


I filed away at the previous owner Dowel pin jimmy-rig:

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is it worth it to try to fix this?

95 Dodge 5.9L adapter/bh
 

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In the first pic is the bore even round? Just looking at the #'s you swept it looks off.
If it's round and flat it could be worth your time to do a pair of over size dowel pins, I'd likely do so but I have all the time in the world as well as like the process of saving parts.
On a side note I have 75,000 + miles on a front hub that I bored and sleeved the outer bearing race bore on. ;)
 

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Steve, I'd be curious just how accurately centered the big hole was to begin with. You notice that at the top you start at zero and as you go to the bottom the variance just keeps getting greater. Is that truly an accurate measurement? The center point for the hole would be based on the center of the crank. Is that gauge mounted on a shaft that is dead center in the crank? I'm not sure how well centered the input shaft of manual transmissions are or the bearing retainer that fits into that big hole.
 

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looking at the numbers it looks like the block was line honed and the crank center line has moved up. that or it took a hit or got dropped. only question i have is on the direction of the numbers. when you say plus is the plunger in the indicator getting longer or shorter.
 

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Remove the dowels and see if it will line up.
If so redrill the dowel holes and fit larger dowels.
Used to be a common problem with IH trucks here in Aus.
Cheers Steve
 
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1972 F250 4x4, 78 d44, 3.55, np205, 200hp 4bt nv4500 in progress
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Discussion Starter · #6 ·
Thanks all for your input. Like egg man I too like the idea of making old ‘good’ parts work. I’ll remeasure to triple check then I’m expecting a fight to get the pins out.

Blackduck, since the variance has to be .005 max, I’m not confident of my skill at marking and drilling blind holes after aligning. I can think only to get it bolted in spec then drill through both housings at the same time.

This video got me thinking about the importance of this alignment.

 

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Yep you do not drill individually, you drill right through both while clamped in position.
May actually then need to ream the holes to get a good finish to suit the dowels.
We had bits and reamers to suit the oversize dowels when I worked for IH.
In your case even some good spring steel roll pins would hold the alignment if the housing bolts loosened off or you need to remove the housing again. Just need enough metal to drill through both flanges.
The bolts do the clamping work, the dowels are just for alignment.
Cheers Steve
 
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Looks like you go north with bellhousing .030 you might come up with good numbers. Ive used the lakewood offset dowel pins with success.
 

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1972 F250 4x4, 78 d44, 3.55, np205, 200hp 4bt nv4500 in progress
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Discussion Starter · #10 ·
looking at the numbers it looks like the block was line honed and the crank center line has moved up. that or it took a hit or got dropped. only question i have is on the direction of the numbers. when you say plus is the plunger in the indicator getting longer or shorter.
redark, the plunger is getting longer on + readings. Line honed sounds scary. the mains appeared to not have been messed with. Thanks for your input!
 

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How is the indicator mounted? First and foremost make sure gravity is not effecting your indicator. You need a very stiff/solid mount to minimize gravity on an indicator hanging out 6".

Line honing cannot possibly account for an error of that magnitude. The gears would be bound up if you moved the crank up .005"

What I would do is establish if the trans bore is round. If it is I would run a weld bead inside the dowel sleeve bores. Then I'd set the bellhousing up with a couple gage pins in bolt holes and using a straight edge against those pins sweep it in square with the machine travels. Then I'd clamp it somewhere were I had uninterrupted access to the trans bore. Then sweep the bore, make it my origin and re-machine the dowel holes to factory specs followed by a light dusting of the flange face to remove any warp from welding heat.

A decent shop should be able to tackle that job for around $250. If you don't want to pay for that then I would agree with the poster above who suggested lining it up, drilling in place and using a couple 3/16" spring pins for alignment. The righter way to do it would be to use a drill, then a taper reamer, then install a taper pull pin, but a cheap old spring pin will probably do just fine for what it is.
 
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