35 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVibration above 68mph
Leading reported evidence
Clean insides out
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Performed · outcome unconfirmed · Original poster
So I rebalanced the wheels a third time, this time doing it myself -- removed tires, cleaned the insides out, replaced and finely balanced again (the nearby Naval Base has a dynamic balancer that we can use).
Leading evidence: 'Clean insides out' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'still present' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Adjust air psi' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
It is a habit with me before I use an air gun to add air to a tire I give the air gun a try and often the initial blast of air contains water, sometimes a considerable amount.
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Suggestion
Reseat the beads & adjust air psi to what you use driving.
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Suggestion
Paying for a roadforce balance in no way insures the "tech" will operate it properly or take the time to adjust tire position on the wheel.
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Discussions that suspect a cause
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Suspected cause
Since the issue was still present with a new set of tires, evaluating non-balance-related items - like bearings - might also be prudent.
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Suggestion · Original poster
I think the first thing I better do is put the car up on blocks, remove the wheels, take off the tires, strip off the chrome myself, then check the trueness of the wheels.
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Performed · outcome unconfirmed · Original poster
So I rebalanced the wheels a third time, this time doing it myself -- removed tires, cleaned the insides out, replaced and finely balanced again (the nearby Naval Base has a dynamic balancer that we can use).
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Suggestion
At this point you should know if you want to rebalance the rear wheels & tires, replace the front wheels & or start inspecting/replaceing suspension components that have undoubtably deteriated from the high mileage.
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Suggestion
At this point you should know if you want to rebalance the rear wheels & tires, replace the front wheels & or start inspecting/replaceing suspension components that have undoubtably deteriated from the high mileage.
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35 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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4 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
The vibration SLIGHTLY improves when I get above 80mph; no change at 100+mph -- the vibration just gets finer.
2002 996 Targa, 168K miles, Tiptronic.
I got the car with about 165,000 miles on it about 2 years ago. From day-one of ownership, I've been having a noticeable (but not speed limiting) vibration when I get above 65mph or so.
The vibration SLIGHTLY improves when I get above 80mph; no change at 100+mph -- the vibration just gets finer.
So I put on new tires and had them balanced.
Result: still a vibration, but not as bad -- but undeniably present.
So I brought the car back to a different tire store and had them balance them again.
Result: no change in vibration. Still present.
Then I had the local Porsche Indie check out the car's suspension up on the rack and by driving it.
Result: suspension all ok (although he said that the right rear shock might need replacing in the future sometime); he stated the problem had to be the balancing of the wheels/tires.
So I rebalanced the wheels a third time, this time doing it myself -- removed tires, cleaned the insides out, replaced and finely balanced again (the nearby Naval Base has a dynamic balancer that we can use).
Result: same problem, same vibration.
One more note: these are the chromed Porsche twists, and the chrome is peeling off in several places on at least 3 of the wheels (in a few places, up to 4" spots).
SO, ANY SUGGESTIONS WHERE TO LOOK NEXT BESIDES THE WHEELS/TIRES?
Can the vibration be due to the peeled chrome? Is it possible that a few ounces of chrome actually can cause this high-speed vibration?
Thanks for any suggestions.
I have chased this around a few times in various cars. I have to have perfectly balanced tires or it bugs me.
If I were you, I would put a different set of wheels/tires from another car on and see if the situation changes. This is the fastest way to rule out your set of wheels/tires.
If it goes away, you probably have a bad tire. I had one bad DWS when I bought a set last year and went through the same rebalancing act as you. As soon as I switched that one tire, all was well.
Of course you could have a bent rim but the tire mounters should have seen that.
If you switch wheels/tires and it stays the same, something has some play allowing the vibe. This is sometimes tricky to find as 986/996 suspension seems tight when testing statically but has enough looseness to be a problem.
This is what I have found anyway.
Couple of things...
Be sure tire pressures are correct. Overinflation of at least the front tires can produce vibration that is indistinguishable from tire/wheel imbalance.
Regarding tire inflation be sure one or more tires doesn't have a load of water in it. It is a habit with me before I use an air gun to add air to a tire I give the air gun a try and often the initial blast of air contains water, sometimes a considerable amount.
Be sure you balance all 4 wheels/tires. As these tires wear they can go out of balance. More often than not I'm finding I'm having to have the front tires/wheels rebalanced after about 20K miles -- when I have the car in to replace the worn out rear tires -- as the front tires have gone out of balance. Sometimes the rear tires need rebalancing too, as they wear.
If the balance problem persists suspect the wheels are not centering properly on the hubs. Even a perfectly balanced wheel/tire combination will deliver a less than smooth ride if the wheel is not perfectly centered.
Feel the tread faces of all 4 tires for any signs of feathering, or scrubbing, that can arise if the alignment is off.
I had a similar problem with mine...after 2 different wheel balances and one alignment I found the issue was within my suspension changed out the lca and ball joints and never had an issue since.
Excellent replies and suggestions so far -- thanks. See my comments below IN CAPS (sorry).
GOOD IDEA. DON'T KNOW IF/WHEN MOUNTS CHANGED. NO VIBRATION AT IDLE; NO WIGGLE ON PASSENGER SEAT, ALTHOUGH I WILL CHECK WITH A HIGHER LEVEL OF SUSPICION.
WHEELS DO NOT APPEAR TO BE OUT OF ROUND -- PER OBSERVATION WHILE SPINNING ON THE BALANCER.
REF LOWER CONTROL ARMS -- MIGHT BE; PORSCHE INDIE DID NOT SEE A PROBLEM WITH THEM -- BUT BEARS BETTER CHECKING.
I DON'T HAVE ACCESS TO ANOTHER SET OF WHEELS/TIRES, ALTHOUGH I HAVE BEEN TOYING WITH THE IDEA, IF FOR NOTHING ELSE, TO GET RID OF THE PEELING CHROME ON MY WHEELS.
THIS VIBRATION WAS PRESENT WITH THE FIRST SET OF TIRES, AND IT'S WHY I CHANGED TO NEW TIRES. VIBRATION STILL PRESENT.
DUNNO. THESE ARE NEW TIRES, AND ALL 4 WHEELS HAVE BEEN BALANCED 3 TIMES SINCE MOUNTING. PLUS, VIBRATION WAS PRESENT WITH THE OLD TIRES.
HAVE ADJUST TIRE PRESSURE SEVERAL TIMES, ALTHOUGH I WILL PAY MUCH CLOSER ATTENTION.
FUNNY YOU MENTION ABOUT THE WATER IN THE TIRE! THE LAST TIME THAT I BALANCED THESE TIRES, I REMOVED ABOUT 50CC OF WATER FROM ONE. HOWEVER, IT MADE NO DIFFERENCE IN THE VIBRATION.
RE. CENTERING ON THE HUB... HOW WOULD I CHECK THIS?? IS THIS SOMETHING THAT I CAN SEE AND CORRECT, OR WOULD THIS BE AN INHERENT WHEEL DEFECT THAT CAN ONLY BE CORRECTED WITH A NEW WHEEL?
THIS MIGHT ALL BE LEADING TO A PROBLEM WITH ONE OF MY WHEELS, WHICH IS NOT IMMEDIATELY VISIBLE. I MIGHT BE HEADING TOWARD A DIFFERENT SET OF WHEELS.
WITH OVER 165k ON THE ODOMETER, YOU MIGHT BE CORRECT. I AM TRYING TO GET THE COMPLETE SERVICE RECORDS FROM THE DEALER/MECHANIC IN CA WHO PERFORMED allllll OF THE SERVICE ON THIS CAR PRIOR TO MY OWNERSHIP.
WHAT IS A "ROAD FORCE" BALANCE, AND HOW CAN I DO IT, OR WHERE DO I HAVE IT DONE?
Thanks again for all the inputs.
Motor mounts are easy to do and not expensive. Whether this is the cause I don't know but if say they're in the "worth doing" category.
A good alignment shop will have a road force balancer (see
http://www.motorweek.org/features/go...orce_balancing
) but more importantly lots of experience
A decent if not long winded explanation of road force balancing. Machine made by Hunter. They have a locator application on their website.
http://www.tirerack.com/tires/tirete....jsp?techid=40
That is going to be the ticket. A Road Force balance will tell you if it is your wheel or your tire and give the tech enough info to balance it properly. Find a shop that has it.
+1 on Road Force balance
It can detect and help correct out of round wheels and tires as well as run out on the wheel
I had a slight vibration at hwy sped after a regular balance. Took the car to a place that does RoadForce balance and now it is perfect. Best e$30 I have ever spent
I found my place on Tirerack under installation
You can also go to the Hunter search page
http://www.gsp9700.com/search/findgsp9700.cfm
Negative on that! You have access to a capable wheel balancer & you are the individual most highly motivated to solve Your problem. Remove your front wheels & dismount the tires. Remove any loose chrome. Mount the bare wheel on the spin balancer & spin it up. Lower your head so your eyes are level with the top edge of the rim. If the edge of the rim has up & down movement it will duplicate this movement on the car. Eyeball the side to side movement of the wheel by watching it spin from the front. No wheel or tire is perfect but if you see a "hopping" motion you need to replace the wheel.
If it is ok or marginal, mount the tire &
Dynamic
balance it using weight on the outer & inner "backside" edges of the wheel. If it calls for more than 2oz of weight at either of the 2 edges, DO NOT install the weights! Deflate the tire & spin it 180degrees with respect to it's orientation on the wheel. Reseat the beads & adjust air psi to what you use driving. Repeat the balance procedure & if you get acceptable weight requirement, install weights & retest balance while observing "hop". Now deceide if you want to spin the tire 90 degrees to try for a better balance. Repeat for other front wheel. Undoubtably the vibration will have diminished. At this point you should know if you want to rebalance the rear wheels & tires, replace the front wheels & or start inspecting/replaceing suspension components that have undoubtably deteriated from the high mileage. If the wheels are true & you have bought "cheap" tires &/or the vibration is at 80+ mph you may need a high speed wheels "on the car balance.
Really????
spend an hour per wheel using a trial and error method that may or may not give you the result you want or pay someone around $15-$20 per wheel and have them done perfectly in less than 30 min
The road force system calculates if the tire needs to be rotated on the wheel and then exactly where it should be for best result
Not sure how safe it would be to put your head close to a spinning wheel on a balancer. "Eyeballing" slight variations in the wheel is not a very accurate method.
Of course all of it could be a moot point if the tires are cheap POS
This entire procedure will take about an hour for 4 wheels & tires for an experienced tech, IF there are problems that require rotating the tire on the wheel. Paying for a roadforce balance in no way insures the "tech" will operate it properly or take the time to adjust tire position on the wheel. Also won't insure they are able to observe the spinning tire safely. If your eyes are are inadequate for seeing variations in a fast spinning round object you can lightly touch the edge of it & feel the variations of runout to determine roundness. Nice saving $60+ dollars too.
I guess you have calibrated fingers as well
I am sure you can tell the difference between .01 and .04 inches with your fingers
I spent $30 total for a road force balance on both of my front wheels. In my case, the tires were in the right spot. Had they needed to rotate them it would; have been $5 per wheel more. It was well worth the $30
Sure there can be incompetent tech's, that can be with any service. The place I went is a high end indy and they know their stuff.
To each his own
[QUOTE=JayG;11989192]I guess you have calibrated fingers as well
I am sure you can tell the difference between .01 and .04 inches with your fingers
Don't need to if you understand the simple concept I am attempting to explain for the benefit of all.
Obviously you are clueless if you think .04" radial runout will cause a vibration. Maybe if you took more than 420 101 in college you could appreciate these simple concepts.
PRODRIVER and JAYG -- Great discussion.
PRO-D, thanks for that very informative DIY procedure. That's something that took you years to figure out, but just minutes to bring me/readers up to speed! I want to try it.
JAYG, you make a point that hits home. I have spent hours and hours chasing a problem, and then end up taking it to someone who does the job for a living, and they get it done in minutes. Maybe this is one of those cases.
I think the first thing I better do is put the car up on blocks, remove the wheels, take off the tires, strip off the chrome myself, then check the trueness of the wheels. The wheels need to be cleaned up anyway.
I can make decisions after that regarding changing wheels or pursuing other causes of the vibration.
I will check with the PO's dealer/mechanic in CA to see if the motor mounts were ever changed. If not, with 165K+ miles on the car, certainly worth changing them out.
In fact, might consider redoing the entire suspension.
[QUOTE=Byprodriver;11989252]
Why are you being an ***?
The point I was making was that while you could see a big variation, there is no way you could detect small variations with any accuracy. And no I was not saying .04 runout wound necessarily cause a detectable vibration.
All you explained is exactly what a road force balance does. Read their website
I am looking into removing some chrome from the bead area on my wheels and in speaking with some wheel pros, that may be a problem as there could be corrosion under the chrome and would then require a lot more refurbishment. Probably more than a DIY
As you noted, it often makes more sense to pay a pro a few $ than spend hours chasing something that ultimately you end up having a pro do.
[QUOTE=JayG;11989986][QUOTE=Byprodriver;11989252]
Why are you being an ***? Really???? A bit ironic, now 12 days since I helped you solve your wheel/tire problem! Your short history on this & other forums is full of unending comments of little if any use.
All you explained is exactly what a road force balance does. Read their website
The OP has free access to a "conventional" balancer & I explained how he can use it to determine if his wheels &/or tires are contributing to his problem. My understanding is that this is the main purpose of this forum. Why should I read the website after explaining what it says?
Since the issue was still present with a new set of tires, evaluating non-balance-related items - like bearings - might also be prudent. While it would be AWESOME if the issue could be cured with a good balance, swapping out all four tires does make that seem potentially less likely.
While I don't care to get into the road-force vs. spin balancing pecker war, I have twice been unable to have an issue resolved with a spin balancer; in both cases, my favorite Discout Tire and their Hunter RF machine were able to sort out the problem.
I had my front tires rebalanced at Goodyear and they did a terrible job. Ended up taking to a diff. shop to get them balanced. Just my two cents…most places just don't care enough to a hi end job!
[QUOTE=Byprodriver;11990270][QUOTE=JayG;11989986]
Yes some of your comments on my bead seal problem were helpful others were not. That is the way the cookie crumbles.
Your comment "
Maybe if you took more than 420 101 in college you could appreciate these simple concepts
" was you being an ***
Even when one feel they know everything about a subject, it never hurts to review information and usually one gains additional knowledge
I (and many others) find it really interesting that some people that have 1000's of posts feel they are the only ones that contribute anything of value. These are open public forums for the purpose of free exchange of knowledge, ideas and general banter. Some of the "old" guys especially on this forum seem to think they own it. Generally I try not to make personal attacks on others. I contribute where I can and have many posts that many have felt to be useful
Getting back to the issue at hand, I simply was saying (to me) it makes more sense to pay a few $ and get the job done quickly and properly than to mess around for an hour or so and maybe get it done
[QUOTE=stasha;11989863]PRODRIVER and JAYG -- Great discussion.
PRO-D, thanks for that very informative DIY procedure. That's something that took you years to figure out, but just minutes to bring me/readers up to speed! I want to try it.
Actually it took 1 day of my 2 week training for my 1st automotive job at National Tire Warehouse in 1985. 2 weeks of training required before you were allowed to speak to a customer. These days nobody gets adequate training in tire balancing or they don't take the time to get it right.
