Bad Vibration from Rear End after replacing pinon seal

[FastGT94]

Greetings,

I was going to replace the pinon seal on the rear end while doing my clutch install so I marked the driveshaft and took off the pinon nut (without checking preload or backlash ). Wound up not replacing the seal since I saw no leaks and put it back together.

The books I have say 140 ft lbs minimum but the nut was so loose when I took it off I figured that 105 would be fine. The resistance to turn the pinon (wheels on) was about 12 inch pounds and I didn't measure the backlash since I didn't know I have to. When I put it back together and went for a drive I now have this bad vibration at 40 mph that isn't related to engine RPM's. So I figure that I did something wrong with that Pinon Nut.

Can anyone help me out here? What I figure on doing is to check the backlash with a dial indicator and shoot for the specs that the book says. I'm hoping that I'm above the desired backlash since that would mean I didn't torque it enough instead of torquing it too much. If anyone else can shed some light on this, I'd appreciate the help. As long as I'm going back in there I'm going to replace the seal anyways since I don't want to go through this again soon...

Can you tell I'm a rookie at working on the good ol 8.8?

Thanks!

 

[k12]

I'm sure you've checked but is the D shaft installed the same way it came out? I'd double check, and even try to switch it before going on.

 

[Rick 91GT]

If you didn't torque it back to where it is was the crush sleeve could be torqued less or more (too much)....major issue.

 

[FastGT94]

So if all my manuals say minimum 140 ft lbs, I (most likely) need to go back and torque it more then right? I'll probably check the backlash first and see if I need to go tighter or if I went too far. And I did mark the DS before removing it with some red paint so I know that's ok.

 

[HardmanGT]

any time that you remove that nut you should replace the crush sleeve and re torque. It take s a lot of pressure to crush the sleeve and get your preload. Once the sleeve is crushed you have to check your preload. I'm sure the vibration is caused from this and has zero to do with your driveshaft.

 

[FastGT94]

Can I get away with using the old crush sleeve or do I need a new one? Is it right that the backlash will get smaller as I tighten it? Ex from .012" to .006"?

 

[rd]

make sure the driveshaft is reinstalled the same way and tight.

Then, I would as a minimum, torque the old crush sleeve to the spec, in several increments, checking the pinion turning torque as you go.

When you get to the spec number, drive it.

If that does not fix it, install a new crush sleeve.

The crush sleeve should not have any effect on backlash, unless it is grossly too loose.

 

[Rick 91GT]

make sure the driveshaft is reinstalled the same way and tight.

Then, I would as a minimum, torque the old crush sleeve to the spec, in several increments, checking the pinion turning torque as you go.

When you get to the spec number, drive it.

If that does not fix it, install a new crush sleeve.

The crush sleeve should not have any effect on backlash, unless it is grossly too loose.

 

[FastGT94]

So torquing it to 140 ft lbs (spec) won't crush it further?

Is the turning resistance done with the wheels on or off?

Backlash is the amount that the driveshaft twists before the gears start turning correct?

Seriously talk to me like I'm two here, I have no idea what I'm doing. lol

Thanks!

 

[FastGT94]

Oh yeah, and I'm doing all this with the differential cover on (never took it off to do the seal) so everything is currently installed in the diff.

 

[FastGT94]

Checked the driveshaft to see if it was installed wrong

Well, I checked the driveshaft (4 different ways) and that's not the problem and I was thinking about this and want to see what you think.

There's some twisting play (gaps between teeth) between the pinion and the ring, but the pinion does not move front to back (laterally). Also, there's a decent amount of resistance to turning it (wheels off, brakes installed and rear end all installed) and I'm thinking that the gap between the teeth (turning the pinion) will only get larger as I tighten the pinion nut further. Am I right here?

I've ordered an inch pound torque wrench and am going to check the rolling resistance but I'm not sure if the brakes and all that need to be taken apart. Can I check this with the differential still installed? Or will this affect the resistance? I'd really like to keep everything installed until I determine that I do need to replace the crush sleeve.

If it turns out that I have too much rolling resistance and need to replace the crush sleeve, do I have to take everything apart to get at it? (wheel bearings, axles, differential)???

Finally, am I ok re-using the pinion nut, or do I need to get a new one?

Thanks!