Thumping noise from the rear

[The General]

Just replaced the tailshaft with a rebuilt one, new LSD, and drive shafts. It is a IRS setup.

All the break in procedures were carried out to the letter, and the correct oil in the diff.

It has been driven for 600klm's over the last few weeks without problems.

Took it for a longer drive today, and a thumping noise, when turning or steering to the right.

Driving at 100km on the freeway, no noise or thump.

What could be causing the problem?

Thanks, John & Michael.

 

[EYY]

Did you use proper LSD oil? They require special oil so that they can slip. If they can't slip, the axles bind and then the lsd chatters or clunks around corners. Even sometimes with proper oil, tight LSD's will chirp and hop a little around car parks. In my experience, it's more pronounced when trying to reverse park.

 

[try_again]

Thumping noise from the back??? It's the hitch-hiker you shoved in the boot - they're trying to get out!

 

[The General]

It is the correct oil, and it's a sound that was not there before. It sounds like the drive shaft has been flogged out, but as I said, they are brand new.

try_again, I let the hitch hiker out last week. Boot is empty.:rofl2:

 

[Jxfwsf]

Nah it's the other dead hitch hiker, their back pack must be on the drivers side muffling the thud of the body on left hand turns.... easy to forget about these things before the hotter days kick in and it starts stinking up the place.

I mean, have you gotten back under and made sure everything is still done up and nothing has shifted/loosened?

 

[The General]

Back under this morning to see what the problem is......:bang:

 

[The General]

It was just a tight LSD. Even thought the oil recommended had additives in it, it was recommended to put in another 150ml. The diff is now working properly with only the very occasional chatter.:beer chug:

 

[Wild bill]

Just replaced the tailshaft with a rebuilt one, new LSD, and drive shafts. It is a IRS setup.

All the break in procedures were carried out to the letter, and the correct oil in the diff.

It has been driven for 600klm's over the last few weeks without problems.

Took it for a longer drive today, and a thumping noise, when turning or steering to the right.

Driving at 100km on the freeway, no noise or thump.

What could be causing the problem?

Thanks, John & Michael.

 

[losh1971]

?????

 

[Wild bill]

thumping sound is coming from the end float of your two axle drive flanges. The design is that the Axle and CV joint holds the drive flange in place by its length, nothing else. At slow speeds or starting off the flange is floating on splines from the axle gear (both sides) as torque increase s the flange is thrust back against the side of the axle gear within the diff housing creating the thump. The GM fix sent out to dealerships was to "loctite"(retaining compound) the flange to the spline. It does work. There is nothing wrong with your diff.