YACT - shuddering, wobbling, vibrating

[paulxcook]

I have a '96 Crown Vic (Police Interceptor). It's not a great car by any means, but it was $2k and it will probably last me a while. When I first got it the ride was nice and smooth. Quite suddenly, though, it started to shudder horribly when I slow down to under 20 mph, and to a lesser extent when I speed up. Sometimes it doesn't, but if I drive for any appreciable amount of time it eventually starts.

I thought it might have something to do with the tires, so I rotated them and aired them up to proper PSI. I noticed one of the tires had a screw in it. I didn't have time to fix it, so I just pushed it in as much as I could until I could patch it. This seemed to solve the problem entirely for the next few days, but then the wobbling and shuddering came back. Later another of my tires blew on the highway, so I just replaced two of them (the blown one and the one with the screw in it), as those were paired at the rear of the vehicle anyway. I thought this would take care of the problem, and it seemed to at first, but now it's back to wobbling and shuddering again.

Would this probably be the shocks? Maybe the steering alignment? I notice it's not nearly as bad when I'm on a curve. It's only bad on straight roads. This seems like it could be caused by any number of things, but I'm not a car guy. I don't know how well I'm communicating how bad this is, but it was enough to make my wife nauseous prior to me rotating the tires the first time. Help?

 

[apac]

You and your car must have had one wild ride!

 

[jhayx7]

Does it do this when you brake or just when your driving?

 

[paulxcook]

Originally posted by: jhayx7
Does it do this when you brake or just when your driving?

Both. It does it when I speed up, smooths out to varying degrees as my speed gets up to around 40ish, then starts again as I slow down. If it was just when I slow down I would think I need new brake pads or something.

Originally posted by: apac
You and your car must have had one wild ride!

:roll:

 

[jhayx7]

You said it "wobbles" as well as shaking.. does it "wobble" up and down or sort of a fishtail side to side motion?

 

[paulxcook]

It wobbles side to side more than it shakes or vibrates, I suppose. If I roll along without giving it gas you can discern the point at which the car wobbles from one side to another. I'm not sure how to describe this. It's like you can feel the car slowly dip to the left, then the car quickly "throws" itself to the right, then it repeats.

 

[radioouman]

Make sure that all four tires are balanced.

Then look at tie rod ends and ball joints. You could have a bad shock, but those are pretty easy to detect. If your shocks have more than about 60,000 miles on them, it's probably time to replace them anyway.

 

[MX2]

Driveshaft unbalanced? Alignment on the front end?

 

[Sukhoi]

Alignment probably. But IMHO replace those other two tires too, before the alignment. I mean geez you found a screw in one and the other already blew out on an interstate. What the heck are the front ones going to do next?

 

[apac]

Originally posted by: paulxcook

Originally posted by: apac
You and your car must have had one wild ride!

:roll:

Oh come on, with a summary like that you're just ASKING for it!

 

[jhayx7]

Go have your tires balanced and have an alignment check. Sounds like you need new shocks as well if it is wobbling back and forth due to alignment/balance issues.

I think places like NTB will do a free alignment check.

 

[paulxcook]

Thanks for the advice guys. I'll have the alignment checked and the tires balanced. Hopefully the shocks aren't bad. This started pretty suddenly (it didn't develop slowly over time), can shocks just crap out suddenly like that? Wouldn't it also happen all the time, regardless of speed and/or direction?

As for the tires, they're from 2005 and have plenty of tread left on them. The screw was bad luck, and the other that blew out actually got a huge slash through it because of something sharp. I think the front two are OK.

Edit: apac, I know, I set myself up for it. But I have a disclaimer, dammit!

 

[jhayx7]

Originally posted by: paulxcook
Thanks for the advice guys. I'll have the alignment checked and the tires balanced. Hopefully the shocks aren't bad. This started pretty suddenly (it didn't develop slowly over time), can shocks just crap out suddenly like that? Wouldn't it also happen all the time, regardless of speed and/or direction?

As for the tires, they're from 2005 and have plenty of tread left on them. The screw was bad luck, and the other that blew out actually got a huge slash through it because of something sharp. I think the front two are OK.

Edit: apac, I know, I set myself up for it. But I have a disclaimer, dammit!

Yup, you can hit a pothole going fastish at the right angle and blow a shock.

 

[thirdeye]

Originally posted by: paulxcook
Thanks for the advice guys. I'll have the alignment checked and the tires balanced. Hopefully the shocks aren't bad. This started pretty suddenly (it didn't develop slowly over time), can shocks just crap out suddenly like that? Wouldn't it also happen all the time, regardless of speed and/or direction?

As for the tires, they're from 2005 and have plenty of tread left on them. The screw was bad luck, and the other that blew out actually got a huge slash through it because of something sharp. I think the front two are OK.

Edit: apac, I know, I set myself up for it. But I have a disclaimer, dammit!

I'd bet that between the balancing and alignment, your problem should be fixed.

 

[brandonb]

I had the problem with an old car of mine. Apparenly tires can have defects in the tread which are not noticible until they get low on tread. I had the same shaking around certain speeds due to the tread being warped/malfunctioned. I had to buy new tires. I'd suggest looking at your tires and seeing if they are getting low on tread. You mentioned you fixed two, but maybe one of the other ones is bad as well. If you bring it into a tire shop (one that deals with tires only) they should be able to detect it and let you know...

 

[paulxcook]

Originally posted by: brandonb
I had the problem with an old car of mine. Apparenly tires can have defects in the tread which are not noticible until they get low on tread. I had the same shaking around certain speeds due to the tread being warped/malfunctioned. I had to buy new tires. I'd suggest looking at your tires and seeing if they are getting low on tread. You mentioned you fixed two, but maybe one of the other ones is bad as well. If you bring it into a tire shop (one that deals with tires only) they should be able to detect it and let you know...

The tread looks ok to me, but again I'm no car expert. I'll probably take it to a tire place to have the alignment and balancing done anyway, so I can ask them about it while I'm there.

 

[Sukhoi]

Ah I thought it just blew out from fatigue. Nevermind me!

 

[crab]

4R70W torque converter shudder?

 

[AgentJean]

CV Axels?

 

[holden j caufield]

I think bad CV axles make more noise when you turn. I had a similar problem, it was a bad rim (major curbage) that threw the balance off. But it's hard to say without being in the car. Now when I got new tires the ride was fine but after awhile the bad rim would wear out the tire unevenly and the wobble would return. I definitely felt it more braking so at first I thought it was warped rotors but it the rim.

 

[Squisher]

Tierod ends, ball joints, or wheel bearing.

All bad if break with the car moving. Fix fast.

 

[AdamK47]

You know, instead of pushing that screw back in you could have bought a kit for less than $10 to fix it. It takes about 5 minutes to do.

 

[paulxcook]

Originally posted by: AdamK47
You know, instead of pushing that screw back in you could have bought a kit for less than $10 to fix it. It takes about 5 minutes to do.

I know. It was 9:30 at night when I first saw it, no time to go buy one. Then... well yes, I should have just stopped on the way home from work or something to buy one.

 

[Pegun]

check the alignment, flywheel and tie bars...all of the front end basically. This happened to my mercury sable a few eyars ago and it was said to be the bar between the axle and rims (tie bars) and it was going to be like 550 to replace so i didnt bother

 

[Black88GTA]

Originally posted by: Pegun
check the alignment, flywheel and tie bars...all of the front end basically. This happened to my mercury sable a few eyars ago and it was said to be the bar between the axle and rims (tie bars) and it was going to be like 550 to replace so i didnt bother

$550 to replace tie rods?? OMG :Q

I did this exact job, along with wheel bearings, front brakes, shocks, struts, and springs on my Trans Am in the parking lot at work on a single Sunday last summer. Parts were maybe $150 total for all 4 tie rod ends, couplers, and two ball joints, and the job was NOT difficult. Unless the Sable is vastly different, or has super expensive parts for some reason (not likely) that's a huge ripoff.

Anyways, I would guess that worn tie rod ends or wheel bearings would be a great thing to look at first. I'd have those at least checked out before doing an alignment - since if you do have these components replaced, you'll need to get another alignment anyway.

Out of balance wheels usually vibrate only between certain speeds (every car I've had with badly balanced wheels usually vibrated somewhere between 55 - 65 mph).