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Old 11-26-2018, 12:56 PM   #1
esmth
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Default Drive shaft differences & u-joints

I have 2 driveshafts: one is the original 1991 aw70 shaft and the other is a 1986 m46 shaft (dl wagon if it matters). Right now I am using the front part of the m46 shaft and the rear of the aw70 shaft as the m46 rear shaft has a blown rear u-joint. The m46 one seems to be much thicker because it has some sort of internal damper, I read.

After a week of driving on the aw70 one, I seem to like it better. I think it drives more 'firm' and has less rotating mass, but i'm not sure if its just placebo because I was used to a bad u-joint which mucked the old m46 one up. Has anyone else noticed a difference?

so: should I replace the u-joints in the m46 one and put it back in, or should I do the u-joints in the aw70 one and keep using it. Will using the non-dampened aw70 one mess with the overdrive or something over time? Why did they stop using the dampener later on in the m47/aw70 ?

Also, does anyone know off the top of their head what u-joints I need to buy to replace them in either drive shaft? Where do I measure on the joint to get ie 2 5/8", 3" or 3 3/16" ?

Thanks for any input
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1991 244 LH2.4 m46 293k miles with B cam advanced 4*, 935 fuel & 146 ezk, pink injectors, 2.5" exhaust w/ magnaflow straight-through & some kaplhenke suspension goodies
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Old 11-26-2018, 01:01 PM   #2
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Cup to cup.
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Folks on here don't know a good deal when they see it.
how psi stock cna support?

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Old 11-26-2018, 01:07 PM   #3
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Cup to cup.
So I need to remove the joint to measure it? or some spacer to subtract that allows me to measure it with a caliper as they're recessed in the yolk? My micrometer is not large enough

i answered my own question, ty.
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Old 11-26-2018, 01:14 PM   #4
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Or put the caliper on a couple nuts zero it out, then arrainge them on the cups and open it up to the new measurement.
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Old 11-26-2018, 01:59 PM   #5
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Measured the two joints on the rear part of the 1986 M46 shaft.
front ujoint: 2.951" 2.942"
rear ujoint: 2.940" 2.945"
I'm assuming it needs the 3" u-joints? Volvo part #3520997

Last edited by esmth; 11-26-2018 at 02:57 PM..
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Old 11-26-2018, 02:34 PM   #6
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I would put u joints in the shaft that's out then throw it on the shelf for a spare
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Old 11-26-2018, 11:01 PM   #7
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I am surprised how well the car drove tbh. this was the rearmost joint in the m46 d-shaft.
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Old 11-27-2018, 01:34 AM   #8
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Nice catch!
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Old 12-02-2018, 01:26 AM   #9
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just finished the job. replaced all 3 u-joints in my 86 m46 driveshaft with the 3" version. First time doing u-joints myself and it was pretty easy as long as a needle bearing doesn't fall over. Only happened on 1 of 12 cups though. The other u-joints were fine but weren't grease-able so I replaced them. The last one pictured above was the only bad one.

But, I ran into a slight issue. I also attempted to replace the carrier bearing. I used a socket extension inside the splined section of the shaft and used a gear puller to (try to) pull the bearing off. I forgot the driveshaft is hollow so what ended up happening is I pushed out the circle of metal welded internally that keeps the grease in the splines INTO the hollow driveshaft. I gave up pulling the bearing as it was actually fine so I just re-packed it. When I drive, at low speeds, I can hear the metal disc bouncing around in the shaft. It quiets down at ~10mph. How can I get this disc out?? Should I ask a machine shop?
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Old 12-02-2018, 02:15 AM   #10
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You're supposed to get in just behind the thin dust flange with a drift or large flat screwdriver at an angle and knock the center support bearing off by chasing it around 90º at a time.

Chasing it back on in a similar fashion you'll need to stay on the inner race or you'll ruin the bearing runs if you strike the outer race.

Also make sure the cups are knocked back against the circlips by striking the yokes and or tubes with a dead blow or block of wood and hammer to assure proper articulation.
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Old 12-02-2018, 02:46 AM   #11
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Quote:
Originally Posted by Redwood Chair View Post
You're supposed to get in just behind the thin dust flange with a drift or large flat screwdriver at an angle and knock the center support bearing off by chasing it around 90º at a time.

Chasing it back on in a similar fashion you'll need to stay on the inner race or you'll ruin the bearing runs if you strike the outer race.
I was just trying to pull the bearing off to replace it, so damaging it wasn't an issue

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Also make sure the cups are knocked back against the circlips by striking the yokes and or tubes with a dead blow or block of wood and hammer to assure proper articulation.
I watched a couple youtube videos for doing u-joints and was told to do this. It's crazy how much it loosens up the stiff joint right after the install. I'll probably give them a couple more taps and a another chooch of the grease gun when I pull the shaft again to get the dang disc out.
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Old 12-02-2018, 11:46 AM   #12
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Quote:
Originally Posted by esmth View Post
I was just trying to pull the bearing off to replace it, so damaging it wasn't an issue


Well if you damaged it side loading it it's gonna be an issue soon.

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I watched a couple youtube videos for doing u-joints and was told to do this. It's crazy how much it loosens up the stiff joint right after the install. I'll probably give them a couple more taps and a another chooch of the grease gun when I pull the shaft again to get the dang disc out.
If it flops around completely freely manipulating it by hand it's good to go.
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Old 12-02-2018, 11:52 PM   #13
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Quote:
Originally Posted by esmth View Post
The last one pictured above was the only bad one.
Just out of curiosity, which one was it? IIRC, it's the rearmost u-joint that fails more frequently.


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Originally Posted by esmth View Post
But, I ran into a slight issue. I also attempted to replace the carrier bearing. I used a socket extension inside the splined section of the shaft and used a gear puller to (try to) pull the bearing off. I forgot the driveshaft is hollow so what ended up happening is I pushed out the circle of metal welded internally that keeps the grease in the splines INTO the hollow driveshaft. I gave up pulling the bearing as it was actually fine so I just re-packed it. When I drive, at low speeds, I can hear the metal disc bouncing around in the shaft. It quiets down at ~10mph. How can I get this disc out?? Should I ask a machine shop?
I don't think that disk is welded in there; it's a press fit. Sorry that it became dislodged. Probably the only way to remove it now is to cut open the driveshaft, remove it, and reweld the driveshaft together. Wait-- doesn't it have like a 3mm hole in the middle of it (like a fender washer)? Might get lucky with getting a long screw into that center hole and pulling it out, like a slide hammer dent puller.
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Old 12-03-2018, 02:43 PM   #14
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Quote:
Originally Posted by Redwood Chair View Post

Well if you damaged it side loading it it's gonna be an issue soon.
The shaft is coming back out next weekend to go to the machine shop. i'll just have them swap the bearing as well.
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If it flops around completely freely manipulating it by hand it's good to go.
They seemed a-ok to me

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Originally Posted by tintintin View Post
Just out of curiosity, which one was it? IIRC, it's the rearmost u-joint that fails more frequently.
Yes, it was the rearmost one. All the others were perfectly fine, just sealed so I couldn't grease them without pulling them apart so I replaced them all with GKN ones with zerk fittings.
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Originally Posted by tintintin View Post
I don't think that disk is welded in there; it's a press fit. Sorry that it became dislodged. Probably the only way to remove it now is to cut open the driveshaft, remove it, and reweld the driveshaft together. Wait-- doesn't it have like a 3mm hole in the middle of it (like a fender washer)? Might get lucky with getting a long screw into that center hole and pulling it out, like a slide hammer dent puller.
It was my fault it became dislodged. I should have known the shaft was hollow and doing what I did was stupid. I may try to find a long screw and try what you described. I noticed the hole in it you speak of
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