SOLVED PAGE 5: Shudder/shake/vibration when hitting bumps at highway speeds

[bill1013]

When my 1999 Tahoe (4X4) had the same problem it was the front sway bar bushing was deteriorated. Slipped a new one one a it stopped.

 

[Fless]

We both have G65, not G69, and I sure as shit have Nivomats on my Tahoe. If you remember, were the rears you pulled off much, much thicker than the fronts? If so, those are likely Nivomats and will need new springs if going with a traditional shock.

Same with mine. ZW7, G65 = Nivomats on the rear.

 

[clandr1]

We both have G65, not G69, and I sure as shit have Nivomats on my Tahoe. If you remember, were the rears you pulled off much, much thicker than the fronts? If so, those are likely Nivomats and will need new springs if going with a traditional shock.

Here is a pic. Do the black ones look like nivomats?

 

[swathdiver]

View attachment 251920 Here is a pic. Do the black ones look like nivomats?

Yes, they are bigger.

 

[clandr1]

Yes, they are bigger.

Thanks for confirming these are Nivomats. I'm assuming my next step is to buy this MOOG spring set, and four of these MOOG coil spring insulators. Installing these should make my rear suspension more stable, yes?

If anyone disagrees with installing the MOOG springs, please let me know.

 

[swathdiver]

Thanks for confirming these are Nivomats. I'm assuming my next step is to buy this MOOG spring set, and four of these MOOG coil spring insulators. Installing these should make my rear suspension more stable, yes?

If anyone disagrees with installing the MOOG springs, please let me know.

Well, they look right, certainly larger than those other two. I think the Nivomats are larger in diameter than standard rear shocks. Do you know their diameter?

 

[Fless]

They do look like the Nivomats. On my '04 they're all black, the top shell is plastic (about 3-1/8" diameter, hard to measure because it's a bit flexible), and the solid bottom tube measures about 2-3/4" or 2-7/8".

 

[clandr1]

Well, they look right, certainly larger than those other two. I think the Nivomats are larger in diameter than standard rear shocks. Do you know their diameter?

Unfortunately not - the picture I posted was taken around 3 years ago when I changed them out - they've long since been disposed of. I can tell you that, looking at the picture, the rears seem substantially larger in diameter compared to the Bilsteins that replaced them. I think, for $65, I should buy the MOOG springs and install them. I can't imagine what else would be causing my issue since the front end seems to be tight, and the shocks are all (relatively) new. I got 12 years out of the factory shocks, the Bilsteins have only been on for 3...

 

[clandr1]

After sleeping on it, I've ordered two MOOG rear springs (PN 81071), and four MOOG spring insulators (PN 160072). They'll be here next week. I'll update this thread when I've replaced them.

If anyone else has any suggestions, please feel free to post up in the meantime.

 

[clandr1]

I installed the new MOOG springs and insulators last night. Today I drove ~75 miles, most of it highway. Unfortunately the problem still persists.

At this point I think I'm going to start refreshing my steering/front suspension components one at a time, starting with the least expensive item first, and working my way up from there. If I didn't know any better, I would guess I needed new shocks because the vibration seems like bouncing, for lack of a better term.

What front end item should I try replacing next? The idler arm? The sway bar bushings? UCA? LCA?