Carrier Bearing and U Joints Replaced Driveshaft Needs to be Balanced

[Mitchell]

Hi,

 

I have a 79 620 long bed and recently had the 3 U Joints (SKF) and Carrier Bearing (Timpkin) replaced. There's a vibration now that reminds me of when a carrier bearing is worn. I think they didn't orient the driveshaft correctly. Will a driveshaft specialist be able to re clock it correctly?

Edited January 13, 2023 by Mitchell
extra wording

[Stoffregen Motorsports]

Three piece driveshafts need to be phased properly, like in the pic below.

[Mitchell]

Thank you, I checked this out and the U Joint nearest to the transmission is out of phase with the other 2 U Joints located at center and differential. But only about 15 degrees. Not sure if rotating in 90 degree increments will help this since there's only 4-bolts?

[Crashtd420]

Is this driveshaft the same as a 521 with a slip joint between the carrier and the differential?

 

If it wasn't balanced after the work was done and they didn't pay attention to how it was originally oriented you could have an issue... 

 

I almost made the mistake leaving the driveshaft shop... I slide the 2 halves apart as I was leaving, it is splined so It could be off a spline or 2 or more. they promptly told me to come back and not to do that.... my shop aligns the 3 u joints by the zerk fittings before they balanced it so for me they gave me an easy way to be sure it the same orientation from when it was balanced....

[thisismatt]

Need to clock the slip joint like above

[Mitchell]

Well thanks you guys much appreciated, it sounds like if the shaft is splined it just needs alignment. I didn't do the repair so I'm not sure if it's splined, do any of you know for sure if the 79 620 driveshafts are splined? 

[datzenmike]

The 620 does not have a slip joint on the dear drive shaft, only the 521 has this, the transmission end is splined for any front back movement.

 

There's no way the U joints can be  out of phase let alone 15 degrees. The yokes are fixed and welded into place and only the U joints can be removed. So I don't know where that is coming from. If the guy who did the U joint replacement told you this he's full of it. If it is out then the drive shaft has hit something and is damaged.

 

The 620 two part driveshaft is balanced as an assembly so it's possible the front and rear were not marked and were put back together 180 out. Probably the same guy who told you it's out 15 degrees. You can uncouple the front from the back and turn 180 and bolt it back together to see if the vibration is fixed.

 

 

[Mitchell]

Thank you very much, I'll try that. Will I need to remove the driveshaft or can it be rotated while on the vehicle in place?

[datzenmike]

Just raise one rear wheel and you can disconnect the back driveshaft at the carrier bearing and just twist it.

[Mitchell]

Okay Great, I'll be able to do that, Thanks

[Stoffregen Motorsports]

2 hours ago, datzenmike said:

The 620 does not have a slip joint on the dear drive shaft, only the 521 has this, the transmission end is splined for any front back movement.

 

There's no way the U joints can be  out of phase let alone 15 degrees. The yokes are fixed and welded into place and only the U joints can be removed. So I don't know where that is coming from. If the guy who did the U joint replacement told you this he's full of it. If it is out then the drive shaft has hit something and is damaged.

 

The 620 two part driveshaft is balanced as an assembly so it's possible the front and rear were not marked and were put back together 180 out. Probably the same guy who told you it's out 15 degrees. You can uncouple the front from the back and turn 180 and bolt it back together to see if the vibration is fixed.

 

 

Isn't there a splined flange on the middle of the two piece shaft near the carrier bearing? If so, it could have been installed wrong.

[thisismatt]

20 minutes ago, Stoffregen Motorsports said:

Isn't there a splined flange on the middle of the two piece shaft near the carrier bearing? If so, it could have been installed wrong.

This was my thought as well. It must have a spline shaft after the carrier bearing otherwise it would force the carrier bearing with suspension travel.

 

Edit: looking at pictures I guess it doesn't. I suppose it just pushes the carrier bearing forward a little in its bushing

Edited January 13, 2023 by thisismatt

[datzenmike]

25 minutes ago, Stoffregen Motorsports said:

Isn't there a splined flange on the middle of the two piece shaft near the carrier bearing? If so, it could have been installed wrong.

 

No. The two driveshafts are joined by the middle U joint.

[Mitchell]

Just to finish up, Mike you were right again. Rotating the rear portion of the driveshaft 180 degrees corrected the 35-45 mile per hour vibration. The driveshaft connection behind the carrier was not splined but was easier to rotate by disconnecting at the carrier and from the diff,. I did notice the transmission shop replaced my driveshaft bolts and they aren't matched, some are 1/2" head and others are 13mm head and longer in length does anyone know the correct size / pitch of the driveshaft bolts and best place to get them? Thanks everyone for your comments.

[Mitchell]

The driveshaft bolts are Nissan Part Number BOLT-HEX M8X1.25 x 25mm length  08120-82510

Edited January 17, 2023 by Mitchell
Additional Information

[Stoffregen Motorsports]

I used to swap to 280zx bolts. They have a nice shank and a taller head so they don't eound as easily. They also have a built in flange and a torx drive built into the head.

 

Funny, just poking around the web, I can't find anything even close to the drawer full I have of those 280zx bolts.