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2003 Cobra issues

6K views 7 replies 5 participants last post by  SVTommy 
#1 ·
:scare:Bad vibration around around 60-70 mph.
Background:
My wife was driving to work one morning and someone stopped beside her to tell her she had a flat. We are not sure how far she drove on the flat tire. I put the spare on it and took it to Sears. We got Falkner 275/40ZR17 put on the car. Sears said they wouldn't do an alignment because they couldn't get it back into specs, so I took it to the Ford dealership.

They tried to do an alignment with not much luck either. In the meantime, we ordered Shelby Cobra Special Edition wheels from Sears. After they were put on the car, I had them check to see if the old wheels were bent. One of them was. I knew this could affect the alignmnet since the alignment device attaches to the wheel. I took it back to Ford, and they did get the alignment specs closer.

They told me they found a TSB about vibration and that I needed to have the rear end replaced for about $1400. (They were just guessing at this point. I wasn't about to pay $1400 and it not fix the problem.) I did research on TSBs as well, and found that there are new alignment specs for the 2003 Cobra, which my dealership did not use. I also found a TSB about driveline vibration (I think it talked about replacing the driveshaft and U-Joints).

Questions:
1. Could the tires themselves just not be the right mix for the car making it vibrate?
2. What type of shop should I take the car to for them to actually be able to tell me
what is making it vibrate?

Any ideas or suggestions would be greatly appreciated. I apologize for the long post.

2003 Cobra Vert/Basani Catback/K&N Open Air Intake/< 40K miles
 
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#2 ·
Vibration can be caused by a few things. Wheel and tire combo/ Drive shaft/Wheel weight ect.

I would put it up on jacks and make sure that everything in the suspension is tight. For example if the halfshft nut comes loose ( not sure that likely ) it could cause a nasty vibration. A wheel weight could have been knocked off. Improper balance of wheels and tires can cause a speed specific wobble. Dive shaft U joints could be going as well. There could be a number of things that could be your problem. A driveline shop should be able to tack it down for you but i would check what you can yourself.
 
#3 · (Edited)
can you tell kind of exactly where the vibration is originating, front, back, left front, etc.
and can you narrow down exactly a more specific speed where its the most prominent, say like its 65 where its the the worst. you look new around here, stick around and you'll get the answers to your questions, i hate vibrations on my vert., my problem usually originates from poorly balanced rims and tires and that typically always happens in the 60 mph range, i've taken my rims and tires and had them re-balanced and there was improvement, the balancing gods dont always get it right the first time.

be very skeptical about what ford tells you, they have no idea. but will be more than glad to help you out of the money in your wallet
 
#4 · (Edited)
I haven't really been able to tell where the vibration is coming from. My wife seems to think the front right.

The vibration is worse about 60mph. The tires were balanced at Sears when the tires were put on, then balanced at Ford. I'm assuming that Sears balanced them again after putting the new wheels on as well.

Also, this problem seemed to start after the new tires were put on. After we realized a wheel was bent, I thought that the new wheels would alleviate the problem, but no. She might have drove on the flat tire for 5 to 10 miles or so, hence the bent wheel. Could that have bent the rear axel and cause the vibration?

Would the alignment have anything to do with a speed specific vibration? Or just pulling problems. It just irritated me that the dealership couldn't figure out what was making it vibrate!!!
 
#5 ·
Welcome to ModularFords!

I had the driveshaft replaced under warranty, and my vibration went away. There is a TSB for this. This, of course, does not mean that is YOUR problem.

And yes, I have also heard of someone that had to have the entire rear end replaced to fix the problem. But again, not necessarily yours.

Especially since you say the problem didn't start until you changed to the new tires. To me, that definitely points to a tire/wheel problem. Just because the tire & wheel are properly balanced, does not mean it won't vibrate. If the combo isn't exactly round, you can still have a vibration problem. There are special machines that measure "road force", to determine this. Adjustments can be made to mitigate the problem. But if you have a bad tire, that won't fix it either. You'll need to replace the tire. (And they should do that under warranty!)

As far as alignment, I also could not get my car's alignment right when I first got it. It had the infamous pull to the right. I had it checked at a high-end shop that specialized in this sort of thing, and they said they could not get it in spec. I took it to the Ford dealer, and they had to drill out/slot the strut tower braces to get it in spec. And after all that, it still pulls a little bit. Alignment should not cause a vibration problem by itself, per se. If, however, the alignment is out for a while and the tires wear funny, then you may eventually get a vibration.
 
#6 ·
I will bet you its a bent rim or the wheel just wasn't balanced right. I went through the same thing when I got a flat and tried to drive it home. The rim had bent and the shop tried to balance it. Got a real bad vibration at about 55-60. Next shop found that the rim had bent. replaced the rim, balanced it, no worries ever since
 
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