Vibration / Shimmy at Cruising Speed

could it be an out of balance half axle? I'm still new to the Riv scene but damned near every honda I've ever had would eventually "unbalance" the half shaft on one side or another and it usually showed up under any form of acceleration.

What kind of tires, i dont know much about these vehicles but have a feeling that tire selection may be critical to ride smoothness.

Is it just very slight shimmy?
Bert

The tires are irellevant as it occured before replacement and after. New tires reduced severity significantly. It would get to 8 on a 1-10 scale before tire change. 'bout a 2 now.

It still occurs as before... normally around 70 and sometimes as low as 50. Severity flutuates but is never more than a three on my scale...with the new tires. It also happens on flat stretches on cruise control. Dosent seem acceleration related.

Never thought of the half shaft issue. I will get that checked out.

AA wrote:

I don't think the higher engine temp has anything to do with your shimmy. I used to have a vibration that came and went, but it has diminished since I started replacing shocks/struts, and other suspension parts.

If it's speed related, does it only happen on acceleration? Is is very pronounced, or only slight? Is the vibration visible in your steering wheel?

Have you replaced the rear shocks recently?

"He turned the rotors and installed monroes on the rear. I installed monroe front struts within the last 30,000 miles or two years. Front feels great. he also performed an alignment.

Shimmy was still there and seems speed related. Shifting into neutral the intensity remains steady. Intensity seems to vary and occurence isnt easy to predict. Ususally around 70 and sometimes comes and goes on cruise control. "

I've found tires to be the culprit for 100% of speed related vibrations. Did you buy good tires? Most installers take shortcuts when balancing. I have a very good friend who works at NTB and he's the only one I'll let balance my tires. No more vibrations!

Except for that one time I had a bent rim...... even he couldn't balance that out

mountainrider wrote:

The tires are irellevant as it occured before replacement and after. New tires reduced severity significantly. It would get to 8 on a 1-10 scale before tire change. 'bout a 2 now.

It still occurs as before... normally around 70 and sometimes as low as 50. Severity flutuates but is never more than a three on my scale...with the new tires. It also happens on flat stretches on cruise control. Dosent seem acceleration related.

Never thought of the half shaft issue. I will get that checked out.

What is the brand and size of your tires?
I just got my car and it had a very faint shimmy around 70mph. The first place I carried it to pulled the wheels and put them on a balancer, he came to me and said Sir, none of your wheels have any weights on them. So I asked him if he thought we should balance them, he said I would not if i were you...
I carried it to another place, the fellow put two ounces on the LF and one ounce on the other three. No shimmy.

Michelin Harmony tires
Bert

Bert

I wonder why the first guy recommended against the weights.

I was thinking the same thing.

is the vibration in the steering wheel or in the seat?
just a thought but, the original vibration could have been tires and under heavy braking it would be enough vibration to warp the rotors. turning them probably didnt help b/c they would just warp again.(and faster since they are thinner) you got new tires but still have warped rotors which could be why there is some vibration still.

Mr.Riviera wrote:

is the vibration in the steering wheel or in the seat?
just a thought but, the original vibration could have been tires and under heavy braking it would be enough vibration to warp the rotors. turning them probably didnt help b/c they would just warp again.(and faster since they are thinner) you got new tires but still have warped rotors which could be why there is some vibration still.

The tires are OE size (225/60/16) Firestone firehawk Gts. Looks as if there are no more wide ovals in my region. The shimmy is faint and manifests itself mostly in the steering. Before new tires, the seat would sometimes be active as well.

I only picked up the car two days back with freshly turned rotors. Do you think the rotors would have warped again in that period of time?

On to the high temps. I know it would be better to start a new thread, but a friend told me of a similar situation with a car he owned. His began heating up with no leaks or squeeks. it had a similar effect on vibration. He had an abrupt failure of the bearing. After replacing the pump, the vibration was gone. Wierd!

My heater has been fussy as of late and predates the vibration issue. I wonder if one of the impeller vanes came aprt and created an imbalance. Anyone ever heard of this?

I replaced the thermostat and radiator cap today at lunch. They only had a 195 t stat. It still shows about 215 and creeps toward the red at idle. I'm leaving on vacation tomorrow and will address the water pump when I return.

i would check all the motor mounts even though they might look ok,i can nudge the motor enough by hand to say to myself " wtf!" ,and also check the condition of the sway bar bushings. when i went to swap out my sway bar bushings,i could not beleive how soft the stock ones were,along with the body mounts! like sponge rubber! . also check the control arm bushings. at speed,youre more likely to have probs. im not saying that this is your prob,but the bushings can contribute to a lot of ill handling problems....... just my 1 cents worth.........

I was hopimg the group buy on poly motor and tranny mounts would take wing so that I could get them at a $75ish for the set and eliminate that potential issue. I dont know if I want to throw another $500 at this car or not. The new 135I and G8 GPX is calling me.

I'm gonna replace the water pump when I return and make the decision on cutting my losses or keeping the old gal while I'm away.

Recently I noticed a slight shimmy starting at 60 mph, peaking between 65-70 mph, then rolling off at 75 mph. At speeds higher than 75 mph it was okay. This vibration would come and go, but would always return eventually. I did not suspect the tires, as these were purchased in Nov last year, with less than 10k miles on the set.

Last weekend I replaced the front brake rotors, pads, and calipers, and also rotated tires front to back. The shimmy got noticeably worse. I knew it was either the tires or the brakes.

Took the car to Firestone, where I bought the tires. They have a new balancing machine since the tires were installed. Turns out each tire was almost 2 oz off from optimum balance. Added the needed weights, and now the problem is completely gone.

On my 98 which has new discs & rotors as well as new rear shocks. I had the tires balanced twice as when I get up to between 70mph & 80mph the car has a vibration. The steering wheel is steady but you can see it in the mirrors & feel it. When idling at a light I get a vibration either from the motor or supercharger & it seems like that at the above speeds only.

im not sure what it is but i would have it fixed very soon, call me crazy but what about loose lugs

Hey Steve: I currently have the same problem.

Unfortunately, the cause of this problem could be a few different things of things.

1. Could be your front rotors. They could be warped. You wouldn't notice it so much at lower speeds, but once it started to really get up there in RPMs, you would feel the wobble. Could be the rears, but it's most likely the front ones if this in fact is the cause of your problem.

2. You need an alignment/tire balance all the way around. The tires were unbalanced when I first got my car, which caused a vibration at the same speeds. The tire balance fixed it. Then it happened again, and it was because I hit a big bump and it threw me out of alignment. So it could be either of those things.

3. Check the lugs, like Corey said. Sometimes the most simple solution is the right one.

My advice? If you get the car balanced and aligned and it's still doing it, it's probably the front brakes (after checking the lugs, of course).

Unfortunately when people go to a place to get their rotors and pads replaced, they use those cheap Chinese-made rotors - which are SHIT. Don't let anyone tell you they are good. These are heavy cars, and the front brakes are under a decent amount of stress, so chances are you'll warp your Chinese-made fronts. Just buy a US brand, even though they cost more.

And if you're going to get it balanced and aligned? Well, it's my opinion that you don't need to balance the tires as often as you need to have the car aligned. One big pothole will send your Riv out of alignment, it's happened to me (and in Toledo, you can't avoid them).

Firestone has an UNLIMITED LIFETIME alignment available for any car you choose. It's like $120 - the cost of two alignments. After the first two you do, the rest is gravy. I've already aligned my car like 6 or 7 times. Just got back from a road trip of some kind? Align. Hit a big pothole? Align. It'll put a smile on your face for sure. I also have unlimited balance and rotation, but my mom insisted on that, and she paid for it out of her pocket, so I wasn't going to argue.

Anyway, good luck.

Unfortunately, the cause of this problem could be a few different things of things.

1. Could be your front rotors. They could be warped. You wouldn't notice it so much at lower speeds, but once it started to really get up there in RPMs, you would feel the wobble. Could be the rears, but it's most likely the front ones if this in fact is the cause of your problem.

Just got brand new rotors & pads.

2. You need an alignment/tire balance all the way around. The tires were unbalanced when I first got my car, which caused a vibration at the same speeds. The tire balance fixed it. Then it happened again, and it was because I hit a big bump and it threw me out of alignment. So it could be either of those things.

Tires were balanced twice, did not help. Alignment seems okay can take my hand off the wheel car tracks straight.


3. Check the lugs, like Corey said. Sometimes the most simple solution is the right one.

All the lugs are on tight.

If you can drive in and out of the vibration at different speeds then it's the wheel balance. You could have a bent rim. Try rotating the front to the back and see if it changes.

I think you'd only feel warped rotors when you brake.

Could be worn motor/trans mounts. I think a little vibration at idle is normal. Does it go away over 80 and under 70? at cruise or under acceleration?

Hey Steve - I have a 98 and used to have same problems. there are also more subtle possible causes.

* Worn front bearings

* Worn front struts (must use firmer aftermarket replacements such as KYB or Gabriel)

* mismount of front wheels - if you are using aftermarket wheels that require hub centering rings, you may never get them on right. Riv wheels are "hubcentric."

* tires have radial force variation issues - if this is a problem the best you can do is have the tires match-mounted at a shop that has a Hunter GSP9700 - look at Hunter web site for locations, see the site http://www.gsp9700.com/ for more - on that site you will see detailed explanatoin of this issue, and can click thru (top right tab) to a list of shops that have the machine. The Hunter will also help the tech solve 'tire pull' caused by conicity of the tires (again see the site for details). In plain English, in my experience the Hunter has given me the best tire mounts and balances I've had. You'd be shocked at the messes that the machine will help a tire tech find and fix.

On my car, at one time vibration was caused by crappedout motor and transmission mounts. If you are at or over 100,000 miles, they may be in poor shape depending on how you drive. One time it was steel wheels that had hubcenters too large, and yet another it was radial force variation. Another time it was the wheels were not bolted onto the car right, basically the tire tech used an air impact wrench and did not snug the nuts up before torquing them down.

Albertj

Update:

GM's Dealer Equipment division is now pushing (kind of) the John Bean (no Snap-On) BFH-1000. It uses computer imaging to tell the technician how to adjust the tire-wheel assembly. See http://www.snaponequipment.com/johnbean/wb.asp for more. It is easier to use and supposedly more accurate than the Hunter - which I kind of doubt because you could have a radial force problem on a tire that is consistently round... Oh well...

Albertj

My 98 has a strong vibration around 75mph. I have had the wheels balanced twice by Sears then read hear about the Hunter machine so I had it done at the dealers.Still have the vibration. Thinking back when I originally had my first Riviera a 97 brand new which I no longer have back then living in NYC did not have the chanve to do 75mph but on a trip to florida I did & it vibrated, dealer checked it out found nothing wrong but the car always did it. I wonder if something is in the harmonics of the car unibody or whatever that might cause it.

Move the wheels around and see if the vibration changes as well. I have though I had bent rims and all kinds of issues in the past, only to find out it was a bad tire shifted belt). See if you can borrow somebody else's wheels and see if the vibration is still there.

It almost always comes back to the tires.

honestly it could be anything with the suspension. from wheels and tires to the knuckels

I had the same problem and found that the boot on the right front tie rod end had split sending a large blob of grease down on the inside of the wheel where it mixed with brake dust and kind of hardened there in a thin patch about 4 inches long, 2 inches wide, and about 1/16 inch thick. I didn't find it until I relpaced my brake pads yesterday. I scraped it off and end of vibes. Now I have to replace the boot or tie rod end, though. I am hoping I can make it until next spring when I plan to rebuild the front suspension including new struts.