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AW70 to M47 driveshaft issues - 240 edition

It's actually pretty easy to remove the yoke (or guibo flange) and then section the DS, I did mine for the V8 just recently. You do need a MIG though - cutting the shaft can be done with an angle grinder. Measure the offset from the trans output flange to the carrier bearing centerline, cut your shaft down, insert the guibo flange cut from the other DS, there's no phasing (if the splines are not keyed, that I had to consider) to check, weld it up
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PXL-20260719-203813690.jpg
 
shoestring said:
100%. Like I've said before, we've run them to nearly 7000 driveshaft rpm and never had a problem. From a production standpoint, it doesn't make sense to me that they would be balanced as assemblies. Engines aren't. Doesn't it make more sense that you would balance them as components and then put them together? Same with turbo hot and cold wheels, at least factory ones. We've just used real Mitsu parts and put them together, never worried about balance or orientation. Manufacturers are the origination of milspec: the best possible result for the least amount of money. They also have the burden of warranty repair if it's wrong.
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There are dozens of driveshaft balancing videos you can find out there where they balance them as an assembly not individually.






id trust the guy with the ISO reports over someone peddling butterscotch chips. ;)
 
Sorry butterscotch man, the greenbook agrees with brisket man. It says 240 driveshafts are balanced as a unit and must be replaced entirely.

Wouldn't stop me though, what's it gonna do, vibrate a little? I'd bet that the factory balancing tolerance is a lot tighter than any of us would notice in our clapped out junk.
 
Worst case I get them balanced. Just going to work with what I have for the time being. Given the age of these cars there is no guarantee a shaft assembly you find in a junkyard or from some parts flipper in CA are the original halves anyways.
 
Cwazywazy said:
Sorry butterscotch man, the greenbook agrees with brisket man. It says 240 driveshafts are balanced as a unit and must be replaced entirely.
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I see that. Guess I've just been lucky about a dozen times. Well, you know what they say about monkeys and typewriters and War and Peace.

Maybe it's because the front part of an M47 shaft is just a tube with no moving parts that I've been lucky with this? I don't know. I'd be worried more about an AW70 shaft where there's a universal in the front shaft, and my concern would be more that all the joints are in phase.

Well, if the book says don't do it, don't do it.

Edit: are there weights on both shafts on either side of the slip yoke? This is a real question not a ball buster one.
 
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shoestring said:
What if the butterscotch chips guy had won 3 LeMons races with mix n match shafts
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Just because it didn't catastrophically fail doesn't mean it was balanced. For an obnoxious race car, you will probably be less likely to notice something like that than a quiet daily.

Both sides get weights. The fancy machines balance the assembly and then tell you where to put the weights.
 
I already conceded this point. Better get all your reciprocating assemblies balanced also, if you change your balancer. Or your clutch. Or your flywheel.

Also our race car was refined. Vibrations and noises distract the driver. Unacceptable.
 
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