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.
SOLVED PAGE 5: Shudder/shake/vibration when hitting bumps at highway speeds
- Thread starter clandr1
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Same with mine. ZW7, G65 = Nivomats on the rear.
OP
OP
clandr1
Full Access Member
Last edited:
swathdiver
Full Access Member
Yes, they are bigger.
OP
OP
clandr1
Full Access Member
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
Full Access Member
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?
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".
OP
OP
clandr1
Full Access Member
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...
OP
OP
clandr1
Full Access Member
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.
If anyone else has any suggestions, please feel free to post up in the meantime.
OP
OP
clandr1
Full Access Member
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?
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?
96-2D-Hoe
Full Access Member
- Joined
- Feb 14, 2019
- Posts
- 529
- Reaction score
- 409
Could this be the culprit? Might want to start with that.
My old 96 truck has always shuddered when I hit a bump, but mine seems to travel from the back to the front. I always blamed it on the cranked up torsion bars but I don't know that's really why it does it. Worse when I have rear tire pressure high.
Replaced all my steering components last year including the steering box. I did not want to revisit it any time soon and the parts were not too expensive. Literally did everything apart from the LCA bushings and lower ball joint as that's not really something I can do in my apartment parking spot.
Last edited:
OP
OP
clandr1
Full Access Member
Symptoms of a bad idler arm are wandering or loose steering which I don’t have, so I’m not sure it’s related. Probably a good idea to do it anyway regardless, though.
96-2D-Hoe
Full Access Member
- Joined
- Feb 14, 2019
- Posts
- 529
- Reaction score
- 409
It's definitely done a few miles. I guess it all depends where your shudder is, in the steering or the suspension/body. Best of luck.
OP
OP
clandr1
Full Access Member
Does anyone else have any suggestions/ideas on what I should do next?
Do a 2 man inspection of front and rear suspension.Also check body mounts. Long pry bar, one wheel at a time jacked a little. then front end jacked hanging at stops, rear jacked hanging at stops. Pay close attention to control arm bushings front and rear. Look for any movement outside of normal plane of movement. Such as when a tie rod wears, it will lift or shift instead of travel in normal direction. Pittmann arm/Idler arm Known trouble spots on these trucks, some people never see the wear/movement. When a problem child is in the shop, get a second set of eyes on it, along with a thorough test at various positions (turning left/turning right/ full turn on stops.)Touch and wiggle everything.A 1/8 inch movement in steering suspension is alot. Post if you have questions on your findings.
OP
OP
clandr1
Full Access Member
Thanks, I'll see about having a friend over to help me one of these weekends. In the meantime, I decided that @96-2D-Hoe is right - I've ordered an AC Delco Professional idler arm assembly and will replace that as a next step. It needs to be done, and I'll do it first to see if it has any impact on my issue.
OP
OP
clandr1
Full Access Member
Update: I replaced the idler arm assembly yesterday morning with no change. It needed to be done anyway since it was the factory original.
I just finished replacing the sway bar bushings/links in the front but won't hit the highway until later this afternoon. I'll see if this offers any improvement, but I'm not hopeful. I had them on hand and figured the originals probably needed to be replaced anyhow.
While the wheels were off today I grabbed a pry bar and inspected the passenger side upper ball joint since the vibration seems to be worse on that side, and it does appear there is a little movement between the upper control arm and the steering knuckle. The tie rods are solid, and difficult to move so they seem to be in good shape.
Here is where I need some input. The way I see it, I have three options on what to do next:
1. replace complete upper and lower control arm assemblies on the front
Pros: should result in a completely tight front end suspension that should be worry free for another 5-10 years
Cons: most labor intensive and expensive option
2. replace upper control arm, and lower ball joint
Pros: likely will solve my problem and is a mid point solution from a cost/labor perspective
Cons: if lower control arm bushings that attach to the frame are worn, I may still have a little slop in the suspension
3. replace upper and lower ball joints only
Pros: lowest priced option
Cons: only an interim solution if the control arm bushings are worn, could be a huge pain in the ass to get the ball joints replaced
Bear in mind I plan on doing this work myself, and cost really isn't an issue - I'd rather do it right/do it once and have it fixed for the long term.
I appreciate anyone's input/insight who has been through this before.
I just finished replacing the sway bar bushings/links in the front but won't hit the highway until later this afternoon. I'll see if this offers any improvement, but I'm not hopeful. I had them on hand and figured the originals probably needed to be replaced anyhow.
While the wheels were off today I grabbed a pry bar and inspected the passenger side upper ball joint since the vibration seems to be worse on that side, and it does appear there is a little movement between the upper control arm and the steering knuckle. The tie rods are solid, and difficult to move so they seem to be in good shape.
Here is where I need some input. The way I see it, I have three options on what to do next:
1. replace complete upper and lower control arm assemblies on the front
Pros: should result in a completely tight front end suspension that should be worry free for another 5-10 years
Cons: most labor intensive and expensive option
2. replace upper control arm, and lower ball joint
Pros: likely will solve my problem and is a mid point solution from a cost/labor perspective
Cons: if lower control arm bushings that attach to the frame are worn, I may still have a little slop in the suspension
3. replace upper and lower ball joints only
Pros: lowest priced option
Cons: only an interim solution if the control arm bushings are worn, could be a huge pain in the ass to get the ball joints replaced
Bear in mind I plan on doing this work myself, and cost really isn't an issue - I'd rather do it right/do it once and have it fixed for the long term.
I appreciate anyone's input/insight who has been through this before.
I would replace the whole arm assemblies. Might be less labor intensive that pressing the old ball joints out and pressing new ones in. No matter which route you take, you’ll need to get it aligned. With new arms, you have new bushings and new ball joints.
OP
OP
clandr1
Full Access Member
OEM upper and lower control arms are showing $902 on GM Parts Direct. I went to Amazon and looked at the AC Delco Advantage, AC Delco Professional, and MOOG replacement control arms, but the reviews have me scared that they aren't built very well.
As much as I hate to let go of $1,000, if it means it'll be done right with quality parts that will last for years, I'm willing to pony up the cash.
As much as I hate to let go of $1,000, if it means it'll be done right with quality parts that will last for years, I'm willing to pony up the cash.
Stay away from AC Delco Advantage and Professional lines. They are crap. AC Delco OEM is good.
Moog Problem Solver lone has been good to me. Others may have other thoughts.
Similar threads
