TMitchell

I had read on this forum where someone had problems with their tires slipping on the stock chrome wheels. I haven't had any problems yet, but I think I will use a magic marker on the inside of the tire/wheel to mark where the tires are in relation to the wheels. It will be interesting to see if the tires do move on the wheel.

nanotech

iTrader: (2)

I have a vibration problem between 65 and 85 mph...slower than 65mph is fine, and faster than 85mph is fine too.

I have the stock 17" chromes on my 99 GS400 and Bridgestone S-02 Pole Position tires. The guy says the brakes are fine and the pads are like-new.

I got the tires balanced, but it didn't fix it....do you guys think that the Hunter machine will fix this problem? The service manager at the Nissan place is a friend of mine, and I found out that he has that machine (checked on Hunter's website)....do you guys think after alignment with that machine vibration will be gone?

I have heard aftermarket rims may be a problem, mine are stock...and I have heard bent rims may be a problem too, but the car only vibrates between 65 - 85...so, what I figure...its alignment, maybe?

Any input will be greatly appreciated!

RON430

I hope you mean balance. Alignment might cause a speed related vibration problem but it would take a combination of circumstances. Invariably, speed related vibrations relate to balance or trueness of something. In the good old days, we had stamped steel A arms (probably 35lbs each) and what we called pivots were bolts through rubber bushings. Stabilizer bar links were connected about the same way. The weight of the components and the friction of all the pivot points added up to a considerable amount to move so we were proportionately less sensitive to balance (tires were also quite a bit smaller and lighter). Today, suspension engineers are far more sophisticated with light weight forged suspension struts and proper pivot points with ball joints. Now, the suspension is far more refined but more susceptible to out of balance forces, similar to how a race car driver can so easily pick up a vibration. We have reduced the weight and friction in the suspension but we still have disk rotors (probably larger than ever), bigger rims and heavier tires, and they all rotate at quite a few rpm. There is no suspension design flaw, most modern suspensions are far more susceptible to out of balance conditions and the more weight (and potential out of balance or out of round) you put farther out from the center of rotation (in the tire), the more susceptible it is. Someone with the Hunter machine should be able to do a good job and be knowledgeable enough to sort this out. Hope no one here takes this the wrong way but most of the more advanced cars on the road today with agressive wheel/tire setups get this problem whether they are Lexus or BMW or Audi or whatever. If the guy is good I would do at least one thing - don't ask for an alignment or a balance. Tell him what the problem is - the vibration - and then see what he recommends to solve it. I have had BMWs where the tires had to be trued to make things tolerable. As I have posted before, bad news is, it comes back. The tires are always wearing unevenly and we tend to be bouncing off of things that make the fix only hold for so long. Anyone think flat spotting just happens in Nascar? The vibration can be gotten rid of but there seem to be a lot of alignment/balancing shops that either don't have the equipment or expertise to deal with it. Chances are, not 100% but probably close, that the guys who know what they are doing will not be the cheapest guys around, but they will be worth it. Just my two cents.

D-MAN63

Ron, you made some interesting points. I'm heading to my brother's bmw shop today to see whats the problem. The thing that still boggles my mind is the day that I drove to the shop to get my suspension installed, I drove like 80 MPH on the H-way and it was smooth sailing. No vibration BEFORE lowering at any MPH. Then a few hours later after the H&R's and bilstein was installed I get back on the H-WAY and the vibration starts around 50 MPH and ends around 60 MPH. So I am thinking it cannot possibly be a weight falling off my rims or me bending a rim because just a few hours before the installation everything was fine.

I am thinking it cannot be a balancing problem because I would have experienced that before the installation. It must be some other factor, like warped rotors, maybe still the cambers and toes are a little off because I did the alignment manually.

I'll let you guys know what happens today.

D-MAN63

Just wanted to let you guys know what happened at my brother's shop with my problem.

Well first off, I found out when I got there, that his machine can't take off the tire because my rims are too big . He did a manually check of all 4 wheels and everything seems to be fine, no bend, no missing weights, no bubbles etc.. He is stumped on the problem . I guess I have no choice but to look for the Hunter Balancer.

nanotech

iTrader: (2)

what about this:

"but if it only vibrates from about 55 to 65 you might want to look into Technical Service Bulletin:

ST003R-98 JUN 98 Steering - Vibration/Flutter"

It was posted earlier...can I just take it to the dealer with that TSB?

Steegull

regarding the TSB for the steering flutter, i had the same problem with my car at 60 MPH.
their is a TSB for that but the GS4 has specific VIN numbers that the TSB qualifies for. Mine missed out by a few numbers but was dead on with the rest.

Oh well, oddly enough though, the last 4k miles, the flutter has gone away and i cant fugure out why.

i have pirelli p700 super sports and the dealer said they are not good for the Gs4.
get the piolts xgt vrs and they will fix the vibration/flutter problem.
sd the pirellis are the cause of my flutter....

hope that helps.

RON430

DIESELMAN63 - First BMWs I had 15 years ago introduced me to this vibration. The speed of rotation will create harmonics that vary with speed that I think is why it comes and goes. Funny how regardless of the car, it is right around 55 to 65. Something going on that some computer simulation would be great to do. Not sure I really know what the cure was but you quickly get into discussions of tires (some run truer than others), rims (likewise, some run truer than others), mounting, and balancing. When it was really bad, aligning and balancing wouldn't do it, the tires had to be trued to run round. You could still get some strange physics with a rotor not running true or having some damaged or strangely worn part causing it to not stay in plane as it rotates but the physics stays the same. The mass of the rotor is always going to be closer to the center of rotation of the axle than the majority of the weight of the rim and, especially, the tire. The rotating mass will always be more sensitive to out of balance conditions farther out. I am not saying that under some circumstance it could not be the rotor but if it is similar to what I have enjoyed for over 15 years on cars, it is not the rotor. In the early days of radials, it was tough to get tires that didn't have problems. Not trying to hype Michelins but they were the tires that you had the best chance of getting a true running set. At the other extremes, some tires just couldn't get you very many true running tires in a set (none for some brands). I am not sure if it still applies but you used to be able to have rims marked for the heavy spot and the same for tires. You set them up to be 180 degree apart and then balance. I think one of the things to watch out for is the amount of weight it takes to balance. Not sure where the break is but if I were getting several ounces on a tire/rim to balance, I would look at it pretty strongly as a candidate for either tire or rim (or both) replacement.

D-MAN63

Ron, as always you post some very valid points and solutions. I was too thinking that my rotors may be warped or got warped faster since I got my 20's. I took a look at my front rotors and they are not in the best of shape to say the least. Though, first I want to explore all possible options of fixing this little annoying problem before I attempted to get the supra brake upgrade. The last option that I can think of is to try the Hunter machine and hope that will do the trick.

RON430

DIESELMAN63 - Any pulsing in the brake pedal when you apply it? One of the other signs of our times is the warping of rotor phenomenon. Whenever I have had it, you can definitely feel that pulsing in the brake pedal. I have had warped rotors and the famous 55 shimmy and I have had the warping without the shimmy so I can't vouch for any connection. There was an argument made some time ago that using air wrenches to tighten lug nuts instead of torquing them was the cause. I am sure that it can warp them but it just seems to get the modern brake performance, this is just another one of those things. I was sort of interested by your comment though. Is their something specific in your 20s that you think might contribute to warping rotors? Hard to imagine but just trying to keep learning.

D-MAN63

Ron, from my experience and from seeing warped rotors at my brother's bmw shop, large wheels tend to wear out the rotors quickly. In my situation, I don't have 'light' 20" rims. For my car to stop, my brakes work extra hard and upon examining my rotors, I could see slight 'bending' of the rotors, not a smooth flat circle anymore. I would say my stopping power decreased noticabely but not depleted far enough where it would be a hazard. One of my brother's biggest complaint by customers at his shop is warped rotors as a matter of fact. Mostly due to large wheels (20's).

I am still debating if I should just change my 2 front rotors and leave my back ones alone. I don't know the adverse effect of doing that, I don't want to change the chemistry of the brakes by adding different components in the front and leaving the back the same.

Also, I do not get any pulsating effect like you mentioned. If it is my warped rotors, I don't feel anything different in terms of feeling something strange when braking.

RON430

DIESELMAN63 - Well isn't that interesting. Wonder why it is exactly? You have 4000 lb car (more or less) and most of the heat generated is due to the friction required to stop that weight from whatever speed you are travelling. I wouldn't figure the weight of the wheels have a lot to do with it but it certainly has an effect. I have always assumed that the rotor warping is from either mechanical (like the impact wrench lug tightening) or thermal. If you do something that gets the rotors hot and then doesn't let them cool uniformly, it is a prescription for warping. Once clobbered a whole set of rotors with a poorly placed puddle after getting off course. If I understand what you wrote, and I do misunderstand a lot of things, that image of the rotor no longer being a "smooth flat circle" is a little disconcerting. Almost sounds like calipers/pistons not floating or getting hung up and pulling the rotor - very strange. Any "clicking" when you just hit the pedal? That is usually what I get when a caliper is a long way off from where it should be and pulls in. As I am sure you know, the fronts do most of the work so it is not too bad a situation changing out the fronts and leaving the backs alone for a while. If you get the real bug and go get a book or two on racing car chassis dynamics, front and rear braking are definitely separate issues. As long as the rear rotors and pads are OK, shouldn't be any problem leaving them alone. I have this feeling that a lot of brake problems are from bedding the pads to the rotors (either new or turned). I think pad glazing is much easier to have happen than anyone really wants to admit. I also have this feeling, about the original topic, that tread wear is no longer a great indicator of when to replace tires. Seems like modern tires have really high levels of grip but when they get worn, even with a fair amount of tread left, they just get a lot noisier and a lot more prone to the shimmies. Nothing we can't cure by just throwing dollars at it.

D-MAN63

Ron, I had a problem like a year ago where my front left brake would not release completely after I let go of the brake. I was getting deep vibrations from the car at 20-30 MPH and then clearing after that. I didn't know what it was and after weeks of searching I found out that one of the 'pistons' or 'screws' that clamps the pads on the rotors were rusted and when it was time to release the brakes, one of them would not 'spring' back. I found this out when I lifted up my car and put my car in neutral, when I tried to turn my left front wheel, it was VERY hard to budge, then I knew right away that particular brake was still pressing against my rotor. I think that also contributed of warping my rotors faster. As far as 'clicking' noises, I haven't experienced any, only the occassion 'thumping' when accelerating which many GS owners here faces unfortunately .

Also, I read on here that I would probably need to get Lexus's exact alignment specs for my car. When I did the alignment I didn't have the specs, maybe thats the answer to my problems. Hey who knows...

RON430

DIESELMAN63 - Sorry to hear about the brake problem. Then again, glad to hear some history and possibly be on the trail of a problem. I hate superstitions and mysteries - problems that are atributed to the wrong thing but some fix makes them go away. Cars are subject to a surprisingly large amount of these sort of problems but I always feel better finding out, if possible, what it is that is going wrong and what it is that fixes it. Personal opinion, an alignment shop who doesn't know what I am talking about when I talk about the vibration at 55 to 65 is not where I want to be. Just look through the various boards, not only here but bmw, audi, mercedes, and you will inevitably find references to this problem. Like I said, I first experienced it in the mid 80s so it shouldn't be a big surprise to anyone. My guess is that bigger rims and lower profile tires concentrate even more mass farther out and make things even more sensitive to balance. My additional guess is that if you don't get it corrected, it will not only increase wear on suspension compnents but makes the tires wear unevenly, not across the tread but makes the tire get out of round. Just part of life. Hope the brake upgrade gets you a more reliable setup.

nanotech

iTrader: (2)

This vibration problem is called a 55 to 65mph vibration...but my gs4 vibrates from 65 to 85...