Drive Train

[maxed_out]

Hi Guys, hope everyone is having a nice summer. Was tracking down a thump-thump-thump from the front wheels which looks like it was just air low pressure. The new Z rated tires call for 44psi, they were at 25.

Anyway, jacked the car (91LS-118k) off on all 4 wheels and spun them looking for flat spots. Saw some minor up and down variation but nothing to get excited about. I'm pretty sure balances are ok.

So since I had it up in the air (Safety blocks deployed of course) I ran her in gear-up to about 70mph and noticed considerable noise and vibration coming from the drive train at about 40mph plus. Sound/vibration seem to be coming from the tranny back to the rear only at the higher mph. NO I didnt get underneath to do more recon. Just from inside.

Thought I'd ask you gurus what you would consider replacing. Drive line bushings? Hanger bearing? other stuff???

Any reccomendations appreciated.

maxed

[maxed_out]

just bumping...some of you must have an opionion. I just bought a spare drive shaft at my local yard. Going to change the hanger, bushings and u joints.

[maxed_out]

I know you are all following this post on the edge of your chairs..... Had some time tonight and jacked her up to get under. Getting the driveshaft out without taking off some the exhaust will be tricky but I'm going to try.

Took off the rear trans support bushings and they are shot. Maybe thats the source of the vibration? Will get new ones and advise before messing any more with the drive shaft. For everybodys info, that drive shaft is 2 pieces and there is a hanger bearing.

maxed

[blessed]

Hey Maxed,

So did you change your drive shaft or the hanger bearing? I'm beginning to encounter some "clicking" noise when I let off the gas peddle. I don't think the LS has CV Joints so I'm my bet is on the drive shaft, u joints or the hanger bearing.

Let me know how tough of a job it was if you did change the ds.

Blessed

I know you are all following this post on the edge of your chairs.....  Had some time tonight and jacked her up to get under.  Getting the driveshaft out without taking off some the exhaust will be tricky but I'm going to try. 

Took off the rear trans support bushings and they are shot.  Maybe thats the source of the vibration?  Will get new ones and advise before messing any more with the drive shaft.  For everybodys info, that drive shaft is 2 pieces and there is a hanger bearing. 

maxed

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[huckleberry]

:)

[maxed_out]

Glad to update...I bought a used drive shaft and changed it. Very easy, just make sure you mark the center connections...it can be separated into 2 pieces...again I'm told these things are balanced so if you can mark it prior to install it would help. In the end I suspect it was part of the problem but not all.

The driveshaft has u joints which felt tight and the hanger seemed ok so I'm not convinced it was the drive shaft. I guess they could click if they are wore out. Mine was not clicking...it was kinda rumbling and making vibration.

My 91 has CV joints in the rear and I changed the drivers side too which seemed to help. Changing the CV is a bigger job but doable.

The rear diff has 3 rubber busings that support it that were also changed. They were getting pretty bad. Another pretty big job since the rear has to come out and I had to make a special tool to press out the bushings. I'm told the bushings are made to handle the harmonics of the drive train. The left bushing looks different from the right one.

In the end I'm now satisfied,but, like I said I can't say it was all driveshaft.