Lucien911

Hi all. I have what will probably be a not so common problem. Please take the time to read. All details are important...

So yesterday I installed my spacers, and now I'm getting a vibration from the rear of my car that gets worse as I approach and pass 70 mph. At about 80-90 mph, the vibration is bad enough to where I don't want to go any faster.

The very important background to mention on this is that when I lowered the IS a few months ago, I suddenly started feeling a very slight vibration @ 80mph or so from the rear only. At first I thought maybe it was just a combination of the roads I was driving on and the stiffer suspension that I wasn't used to, but the vibration came back @ 80mph no matter how smooth the road was. Actually, I barely felt a thing on rough roads because there's more interference as far as small bumps are concerned, so any small vibration will "blend in" with the rough road..

Then I thought it was because my rear tires needed to be rebalanced, but even after getting them rebalanced, the vibration continued. Puzzled me a bit, and made me think axles..

And now that my spacers are on, the vibration that I've noticed since my car has been lowered is amplified and even worse than before. What used to be a barely noticeable vibration at 80mph is now quite a heavy vibration even at 70mph.

I have to take the IS to Lexus for an oil change and alignment in the next couple weeks, but being the DIY'er that I am, I'd like to track down this vibration problem BEFORE I take the car to the shop so I can have more insight and decide what I'd like to do once I see what the stealership says.

Anyone on this board experience this before? I'm looking to promote dialogue here, so please, any relevant suggestions or ideas are welcome.

Thanks much!

FiveOhNine

Sounds similar to what happened with my car (not lowered). The wheels had been balanced twice, 3-4 alignments and still had a high speed vibration.

Road force balance on a hunter gsp 9700 fixed the problem. Almost all Lexus dealerships have this machine I believe.

tfz_hebe89

iTrader: (1)

what are you lowered on? maybe be bad springs/coilovers

Lucien911

Lowered on Eibachs. I thought bad springs but wouldn't that happen at more speeds than just 70+? It seems like a rotational vibration of such..

kikaida

I dont think it is the spring. I think the only reason why your feeling more of the vibration is due to the increase stiffness of your new spring. Well that's what i think...

Have you check the weights used to balance your rear wheels? If there is a lot of weights (meaning a lot when you can use the weights and make a nice bracelet around your wrist) you might want to have them rebalance but tell the wheel guy to break the bead of the tire and rotate the tire and the wheel 180 degrees from where the weight originally was placed and rebalance it. Hopefully less weight will be used.

If you still have vibration or there is still lots of weights, then your wheel might be warped. Hope this helps.

lobuxracer

iTrader: (2)

First question - is the wheel still round to within 0.25mm? If it is not round, it will vibrate no matter how well balanced the wheel is.

Second question - if you had an unsolved vibration before the spacers, why did you exacerbate the problem with spacers? Solving the vibration should be the first order of the day. Putting spacers on a wheel only adds to the stress the wheel bearing must tolerate since the centerline of the wheel is no longer on the centerline of the wheel bearing. Any vibration experienced with the wheel and bearing in line will only be amplified by putting the wheel off the center of the bearing. (BTW, all you guys running spacers should know you'll need to replace your wheel bearings more often...)

Third question - are you certain the shock is not leaking; that all the bolts holding the subframe on the car and the suspension pieces on the subframe have been properly torqued? If anything is loose or not properly tightened it will contribute to vibration in the chassis. Remember the units of measure for suspension components - it is tonnes because it is entirely possible to put the majority of the car's weight on any of the four corners, and given the leverage factors, the forces on the bushings, bearings, shocks, and springs are very large compared to anything else on the car. Ensuring everything is properly tightened to spec will eliminate these elements from suspicion and leave you with bad tires as your culprit.

Lucien911

This turned out to be a bad tire on the rear of the car. (Thankfully...kind of.)

Just wanted to update!

tfz_hebe89

iTrader: (1)

glad that you got it solved.. what do you mean by bad tire? can you elaborate?

Lucien911

Bad tire as in defective from the factory. It was a problem from the time I put them on the car but since I had so many different things done to the car that day, I looked elsewhere and didn't think of the tire thing..

I'll have to make a warranty claim, I presume.

Car is rolling much better now, and that slightly nervous feeling I had is finally gone now that I know it's not shaking itself to death anymore..

Laters!!

Lucien911

Just saw this. Good advice for sure so thank you. The reason why I put the spacers on the car "anyway" (so-to-speak), is because the vibration that I had before the spacers were installed was so very slight that I actually thought it was just a rough road. (Even smooth roads are rough here in NJ). It was only after installing the spacers that I actually noticed the vibration pattern enough to observe that it was irregular and just an amplified version of the 'original' vibration that I thought I was just dreaming about. The spacers actually helped me diagnose the problem faster because I probably still would have never taken it in for the vibration if it had stayed how it was initially and I'd still have the bad tire on my car which obviously isn't safe. Sometimes things just need to be amplified to be noticed--in electronics as well as cars.

I'm not saying I planned it, but that's what happened! I would apply that same logic again.