High speed vibration, But not all the time Options

[porschecb]

New tires, new wheels, new shocks. 55 and up shake/vibration in the steering wheel. But here's the kicker. It come & goes. I can go for maybe a mile or even 2 or 3 and everythings fine then for some reason it starts back up again for maybe a mile or so then quits. Tried diff. speeds and seems like it makes a diff. but can't tell for sure. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) and! it just stated. maybe a year after all the new stuff installed. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

[lapuwali]

Try to tie it to the road surface you're driving on. I've had cars that would start vibrating like they have a wheel out of balance over some road surfaces, but not all. If it's been a year since the "new" stuff was installed, it's not "new" anymore. If the car's been sitting a great deal, the tires could be slightly flatspotted. You might also have lost a wheel weight. It could be wheel bearings. You could have picked up a nail in one tire that's not yet causing a slow leak, but has thrown that tire out of balance.

Can you actually it feel it through the wheel, like the wheel wiggles in your hands, or does it feel more like the whole car is vibrating? Try swapping the wheels around on the car (put a front on the back and a back on the front), and see if that changes the vibration. If so, it's not the bearings, and more likely the tires. Keep swapping to see if you can isolate which tire it is, and examine that tire closely.

[porschecb]

The wheel doe's wiggle in my hands. Did the whole tire issue(s). What bugs me is that is is as smooth as glass for while then it slowly starts to shake then it slowly fades away.

[jsteele22]

Hope this isn't a dumb/obvious suggestion but have you raised the front end and tried shaking the roadwheel ? If anything is loose (wheel bearings, ball joint, tie rods) then it would lead to some wobble; no idea why it would be so intermittent, though. I just tracked my front end vibration down to a shot tie rod, updating to turbo tie rods since its a tiny increment in cost.

[airsix]

Front tires out-of-round from bad toe caused by adjusting front ride-height without doing an alignment afterwards? Look for abnormal wear on the inside edge of the tires (where you can't see it easily unless you stick your head under the car).

To check, jack up front end so front tire barely clears the ground. Rotate tire. Gap between tire and ground should remain constant. If tire goes half-way around and then wedges against the ground you know your problem.

-Ben M.

[porschecb]

Took it to my mech. Put in the air and checked everything, even he has no clue. Nothing loose everything is tight and looks good. The intermit. thing has him to. Maybe air under car was thought by him. My car is real low and has a front spoiler (snow plow type).

[marks914]

Sound like wheel bearings to me, I had the sam problem.
Mark

[airsix]

Do the "out-of-round test" I mentioned.

-Ben M.

[Rusty]

Have you done any panic stops.... or really aggressive stops? You could have flat spotted one or more tires. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

Otherwise, I'd look at wheel bearings and have all the tires checked for balance. Even new tires can throw a weight from time to time.

Is this on a 914?

[porschecb]

QUOTE (Lawrence @ Sep 16 2005, 02:30 PM)

Have you done any panic stops.... or really aggressive stops? You could have flat spotted one or more tires. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) Otherwise, I'd look at wheel bearings and have all the tires checked for balance. Even new tires can throw a weight from time to time. Is this on a 914?

Have less than 300 hundred miles on tires/balance is fine/no hard stops/and yes it is a 914.

[lapuwali]

Like I said, less than 300 miles in a year means it sat on those tires for quite some time. Tires can often go out of round that way. Sometimes this is temporary, and they'll eventually go back to normal after a few heat cycles. Sometimes, this doesn't happen. Try Ben's test for out of round, and try moving tires around on the car. If it doesn't change and you can't determine if they're out of round, then start checking bearings and balljoints again.

Very rarely, tires are out of round from the factory, so it's possible it's nothing you did, it's just a bad tire.

One of the benefits of a tight, solid car like a 914 is you can feel everything. One of the negatives of a tight, solid car like a 914 is that you feel EVERYTHING.

[black914]

I just added a bump steer kit by Weltmiester because I was having the same problem. If your front end was lowered at some time in the past, you may want to try this. The kit is composed of two aluminum spacers that raise the rack about an inch. Be cautioned that the bolts supplied with the kit are not long enough. I had to buy two longer bolts to install the kit. I got the kit at Performance Parts for only 20 bucks. I installed the kit, took it on the highway to about seventy, and my problem was no longer there. Try this on your car...it is a cheap fix if it repairs your problem.

[goose2]

Sounds like a "harmonic" vibration. Something somewhere has a bit of looseness...it'll be smooth until just the right bump or rut or road surface gets a vibration going at just the right frequency...then it perpetuates itself or gets worse until you slow up, hit the brakes, or do something to break the cycle. This would explain the irregularity of it. Checked the inner tie rod ends and the steering rack bolts? Toe setting?

[Elliot_Cannon]

I had a problem just like that. It turned out to be loose wheel bearing. Tightened and adjusted the bearings and problem went away.
Elliot

[brp914]

depending on your wheels, they may be hub centric, not lug centric. so they put it on the balancer using the hub as the center, but when installed on the car the center is different.

In any event, I used to have this problem so I would bring the car to a place that could balance the wheels on the car. It might take a couple go-rounds but they could get it silky smooth. Problem is, you gotta find such a place, then they have to do it right, then you have to mark your wheels relative to the rotors so that if you take them off, you'll be able to put them back the same way.

[TravisNeff]

Bent wheels will do that to you. My other 914 had a horrible shake, and it would come and go as you said. When I had the tires off I brought the wheels to a tire shop and had them check for roundness. Basically they stuck the raw wheel on a balance machine and used a white marker on the wheel. Wheels with a mark on the full circumference were straight, marks on part of the wheel only - were bent.

That will cost you about 50-75 bucks to check it that way. I am sure you had your wheels/tires balanced when installed - check to see how many weights are on each wheel. Wheels with more than a 1/4 ounce on them have a problem of some sort. You can have the tires moved or spun on the wheel to see if that corrects it, or that is an indication that your wheel is bent. Since you only have a couple of hundered miles on the tires I would pull them all off, put the wheels with the smallest amount of weights on the front.

[Tobra]

QUOTE (goose2 @ Sep 16 2005, 05:48 PM)

Sounds like a "harmonic" vibration. Something somewhere has a bit of looseness...it'll be smooth until just the right bump or rut or road surface gets a vibration going at just the right frequency...then it perpetuates itself or gets worse until you slow up, hit the brakes, or do something to break the cycle. This would explain the irregularity of it. Checked the inner tie rod ends and the steering rack bolts? Toe setting?

Super Beetles are notorious for symptoms just as you describe, and are a strut front suspension floor pan vehicle. Tie rod ends or ball joints get a little worn and at certain speeds, on certain roads, they shimmy and shake, on a SB you can also get this with worn struts. If the wheels are round, and nothing else pans out, it may just be some worn out stuff causing problems.

[porschecb]

It took me this long figure out! IT WAS MY TIRE PRESSURE!!!! Yep to low. New tires, low profile, 205/55/15. Could not tell my air over time was slowly leaking out. Do not drive on the freeway much. Looks the same every time i take the cover off plus i am amost blind (little by little they all went down) from 31+- to below 23+- bring it back up to 31 and I am good to over 80 mph + with no problem! Learn something every other day. (IMG:style_emoticons/default/piratenanner.gif) (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/biggrin.gif)