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M47 Driveshaft Refresh with Fresh Vibrations

blkaplan

50 shades of beige
300+ Club
Joined
Jul 30, 2002
Location
Rockville, MD
I decided to do some PM on my 92 245 w/ m47 and replace the Guibo Flex Disc, both the U joints and the Carrier Bearing. Now I have a vibration around 65-70 mph when I didn't have one before.

I did try and mark the DS assembly to maintain the correct phasing front to rear but there is a possibility that it did not get reassembled correctly as the marks were a little far apart with the carrier bearing and slip joint in the way.

The new Ujoints are Moog brand w/ zerk fittings. Is it possible that the new u-joints with zerk fittings are different enough in weight that its throwing the balance of the shaft off?

Does phasing of the front and rear half of the DS matter that much with the guibo up front? I know its critical w/ the m46 u joint connection.


Is it SOP to have it re balanced after installing new U joints? I wouldn't think it would be that critical...
 
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I did try and mark the DS assembly to maintain the correct phasing front to rear but there is a possibility that it did not get reassembled correctly as the marks were a little far apart with the carrier bearing and slip joint in the way.

The yokes should be in the same plane when the marks are aligned. If the shafts are one spline off, it should be enough to see.

There are arrows engraved on the shaft ends underneath the crud and undercoating.
 
I looked closely for the arrows, I didn't see them. I have seen them on m46 drive shafts. This style driveshaft only has yokes on the rear portion. There are no yokes up front.
 
I looked closely for the arrows, I didn't see them. I have seen them on m46 drive shafts. This style driveshaft only has yokes on the rear portion. There are no yokes up front.

Ah yeah, both yokes on the back shaft, my apologies. I have an M47 shaft in the hoard, but haven't had one on a car.

I would expect that shaft to be less sensitive to misalignment, but probably still enough to matter.
 
I just replaced the rear U-Joint on my M47 240 with a GMB joint that has a zerk fitting. All went well and there is no new vibration.

The alignment marks are incredibly crude. Here are some pictures of mine. I added the white-out to make them easier to see.

h712OE3.jpg


4HSzKhy.jpg
 
It is definitely critical to get the front and back halves aligned correctly. Worst case though, if you think it's 180* out, it's easy enough to flip one end or the other around.

If you think it's a balance issue, a quick way to play with it is to put a hose clamp around the shaft, see if it changes. If no, move it around 90*, drive, another 90*, drive, etc. and see if it's better in one position or another. If so, yeah, balance issue. If not, something else.

Any of the joints feel tight after you got them in?

As for the weight on the zerk's causing an issue, not likely to add enough to be an issue, plus the cross-shaft will be drilled anyway so there's less weight there, partially replaced by the weight of the hollow zerk.

Now, one other issue. What's the runout on the carrier bearing? Had a new SKF swapped onto mine, turns out the bearing had .020" runout. Grabbed one from the dealer, .005" runout. Didn't fix the issue since it was a tubing issue the local shop couldn't understand, but swapping from the new SKF to the new blue box SKF did lessen the vibration I was trying to track down.
 
I cant imagine with the 240 style center support bushing that a .020" TIR bearing would cause a vibration, probably a 740 style support would cause that.

I looked very carefully and didn't see any alignment markings, i checked other m46 and aw70 DS's here and they all had them but this one doesn't
 
I did realize i dont have one of these,,, which could allow the shaft to not be centered...

tranny_flange.jpg


Anyone got a spare they wanna sell me?
 
On getting the driveshaft balanced, I tried this once and could not find a shop that has volvo specific fixtures for the balancing machine so that may be a no-go for you.
I also have the same issues with my m47 driveshaft, and I have just gotten used to the vibration. It's been with the car to one degree or an other since I bought it, and that was years ago and it has not exploded yet. :)
 
I've taken a bunch of front and back halves apart and swapped them even and never marked them or tried or cared to put them back as it don't matter. What does matter is that centering thingy and you gotta put the bolts and nuts on the quibo the right way... that is critical..
 
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