All to familiar grrr on decel... (1 Viewer)

[ARB777]

I just spent 2 years chasing mine with new u-joints (2x, once by me, then once at pro shop), balanced drive shaft, adjustable arms, etc etc. Just installed a DC rear shaft 2 or 3 weeks ago and finally vibe free.

I would hate to keep on troubleshooting the oem shaft just to end up with a dc shaft anyway. Sucks cause i just replaced the u joints. My problems started after i regeared to 4.88 with 33 inch tires. Maybe because its spinning faster now. I just pulled the rear shaft and the grrr is gone. I may just follow your lead. Thanks.

 

[ARB777]

I ran a double cardan rear shaft with about 5" of lift, 25 5/8" rear fender to hub, and never had any noise.

I went back to a stock shaft with oem joints when I came down to 24 3/4" but picked up the highway speed de-acceleration growl with slight vibration. I have adjustable upper arms to match pinion and t-case angles. I began to suspect worn pinion bearings since I had the pinion pointed towards the t-case for 8 years with the double cardan shaft.

However just for grins I installed the rear shaft with the slip yoke at the diff and I swear the noise is now reduced by 50%. If this keeps up, I suspect a new slip yoke is in order. Anyone else care to try swapping their rear shaft around and reporting back?

Why not go back to dc rear shaft?

 

[Bear80]

Why not go back to dc rear shaft?

The rear springs have to bow quit a bit more than I would prefer. No rear springs that I know of are designed for that. It reduces the springs load carrying abilities and increases fatigue -- but everyone's first hand results may vary.

The pinion also needs to be pointed upwards to 11* from 3*. I never was thrilled with the idea that the outer pinion bearing may not be oiling sufficiently.

 

[baldilocks]

The rear springs have to bow quit a bit more than I would prefer. No rear springs that I know of are designed for that. It reduces the springs load carrying abilities and increases fatigue -- but everyone's first hand results may vary.

The pinion also needs to be pointed upwards to 11* from 3*. I never was thrilled with the idea that the outer pinion bearing may not be oiling sufficiently.

I’ve been running a rear DC shaft for three years now on Slee rear coils. I removed the springs recenlyt for something I was doing and they stood up perfectly strait on the shop floor showing no sign of permanent deformation and they carry a load like they always did. These are heavy springs mind you.

As for pinion lubrication, I park my 80 nose down a fairly steep decline in my drive way and pump extra oil into the housing. Many miles with no problems yet. I’m one of many people out there doing this.

 

[Bear80]

"Everyone's first hand results may vary." I suppose it was overlooked that I used a double cardan rear shaft for well over 8 years with no issues...yeah yeah slee 6" rear springs etc. The springs are in the for sale section, no bow no visible issues. I merely answered the question posed why I personally chose to discontinue the use of a double cardan shaft.

Now, is anyone else willing to swap around their rear shaft to corroborate my experience?

 

[bajaphile]

I rotated the pinion up a bit, but not so that it is pointing directly at the transfer case output. The guys I talked to at the driveshaft shop said it didn't matter. As long as the U-joint at diff side wasn't at an extreme angle, it would be OK. They said most people don't even mess around with the pinion angle.

From the best measurements I could do with my digital angle finder, I am running the rear U-joint at about 3deg. This allows for no vibration and minimal bow to the springs. I've only got 500 miles on it so far, so we'll see how it goes.

For what its worth, the front DC shafts everyone uses do not employ the golden rule of rotating the pinion up to the xfer case, as you don't really have the adjustability like the rear. I've been running a DC front shaft with 4" of lift since 2012 and not had any vibes or issues.

 

[ARB777]

The rear springs have to bow quit a bit more than I would prefer. No rear springs that I know of are designed for that. It reduces the springs load carrying abilities and increases fatigue -- but everyone's first hand results may vary.

The pinion also needs to be pointed upwards to 11* from 3*. I never was thrilled with the idea that the outer pinion bearing may not be oiling sufficiently.

Sorry but I don’t follow. What do you meant by the rear springs have to BOW?