HELP! Re-geared to 4.56 and hear a horrible grinding noise from rear end

[David_Bricker]

Sounds like it's not your gears.. are you sure the drive shaft is short enough now with the 8.25...?

Exactly what I was thinking. that why I asked about original axle. If I recall correctly, the nose on an 8 1/4 is longer than a 35, and so the driveshaft needs to be shortened.

Do you have an SYE in the back? If so, remove the rear driveshaft, and reinstall the front. See if the sound changes. Also, make sure the rear driveshaft slip joint isn't fully compressed, or dried out. Changing the normal length of the shaft because of the different axle, could cause binding in the slip joint.

David Bricker / SYR

 

[Demonoid369]

Exactly what I was thinking. that why I asked about original axle. If I recall correctly, the nose on an 8 1/4 is longer than a 35, and so the driveshaft needs to be shortened.

Do you have an SYE in the back? If so, remove the rear driveshaft, and reinstall the front. See if the sound changes. Also, make sure the rear driveshaft slip joint isn't fully compressed, or dried out. Changing the normal length of the shaft because of the different axle, could cause binding in the slip joint.

David Bricker / SYR

Riding on that thought, do you think the drive shaft is shoving on the pinion of the axle causing the extra heat he's feeling on the diff?

 

[Digger87xj]

With an SYE I assume you have a cardan CV driveshaft. Check the CV very closely, putting particular attention to the centering ball.
If the installing shop disconnected the axle end of the shaft and let it hang off the t-case, the centering ball may have become distended and loose. This will create a thumping, helicopter-like noise on take-off and will sound like a heavy growl from there on up.

 

[831_xj]

Did the end of the ds come off and they didn't align the ujoints?

 

[David_Bricker]

Riding on that thought, do you think the drive shaft is shoving on the pinion of the axle causing the extra heat he's feeling on the diff?

Quite possibly. That extra length would have to go someplace.

David Bricker / SYR

 

[831_xj]

I'm thinking. It was on the lift and the rear had enough droop for it to fit but when on the ground it's too long.