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Discussion Starter #1
I was hoping I could get some advice on an issue I am having that I cannot figure out. When I am driving my 1995 4.6L T-Bird on the highway or even sometimes the back roads the car will vibrate on and off. You can feel it but you can also hear it with the passenger seats (springs in the back of the seat).

Example: last night I drove home from a friends, I was driving about an even 80Mph the whole way home. On and off the car vibrates then smoothes out for about a few seconds then back again, over and over. Seems to not matter what MPH I am doing so if I did this at 70 it usually does the same thing. The other night I would driving about 60 + and it seemed pretty smooth but that is not consistent since I could take it out now it most likely will vibrate. It is so light on the back roads at times that I can barely tell unless I am really checking for it, so I can recrete it on the highway. Feels like the car is going to break up from the shaking.

I am completely lost... is it a vacuum leak? Transmission? Rims? Tires (they are almost a year old) I actually swap out the tires thinking they were an issue that it didn't make a difference. Is it struts or springs?

Any advice would be very appreciated :)

thanks

1995 T-Bird
4.6L
FlowMaster true dual exhaust (complete redone)
stock rims
BF Goodrich Radial T/A
most of the front end has been redone besides the rack and springs and struts
Taylor wires

If you need more information about the car please let me know
 

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My guess would be:

  • U-Joints
  • The Driveshaft itself - That wonderful 2 piece crimped design that Ford gave to all of us.
  • I've also heard that a bad transmission mount and worn transmission cross member bushings can cause vibration.
Vibration between 60 and 80 MPH is almost definitely at least one or a combination of the above issues.

Other sources of vibration:

- Tire balance
- Tires not mounted correctly
- Loose lug-nuts
- Not centered on the hub
&/or
- Worn unevenly due to mis-alignment and/or improper inflation issues.
 

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Discussion Starter #4
thanks guys, I had the wires checked and they said they were fine and I have new plugs. I actually thought about plugs and wires and it was needed but it didn't seem to do a thing. What is great is that I have write up a list of things and have the checked out.

thanks :)
 

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My guess would be:

  • U-Joints
  • The Driveshaft itself - That wonderful 2 piece crimped design that Ford gave to all of us.
  • I've also heard that a bad transmission mount and worn transmission cross member bushings can cause vibration.
Vibration between 60 and 80 MPH is almost definitely at least one or a combination of the above issues.

Other sources of vibration:

- Tire balance
- Tires not mounted correctly
- Loose lug-nuts
- Not centered on the hub
&/or
- Worn unevenly due to mis-alignment and/or improper inflation issues.
I'm with Trunk; I had this exact problem.

Mine was the driveshaft; if you drive 80+, you need an aluminum 1 piece driveshaft.

If you don't do anything, with the DS bad, it will waste the rear tailshaft bushing and seal in the transmission (and kill the tranny without constant monitoring of the fluid level); and possibly screw up the rear diff gears.

If the tires are balanced right, check the driveshaft. Mine rattled when I took it off.

There is a yellow lug on the front wheels; this needs to align with the valvestem; not matching it up can cause vibration, but usually at slower speeds.

good luck!
 

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even though i just sold my 95 i still had the same problem. start by replacing your ujoints.. mine turned out to be the entire driveshaft.ujouint setup. went to the JY and pulled a ds out of a 93 mark 8 (one piece aluminum) its a direct fit, solved my shaking right uptil the torque converter went out and the bands broke in the transmission lol
 

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I'm with Trunk; I had this exact problem.

Mine was the driveshaft; if you drive 80+, you need an aluminum 1 piece driveshaft.

If you don't do anything, with the DS bad, it will waste the rear tailshaft bushing and seal in the transmission (and kill the tranny without constant monitoring of the fluid level); and possibly screw up the rear diff gears.

If the tires are balanced right, check the driveshaft. Mine rattled when I took it off.

There is a yellow lug on the front wheels; this needs to align with the valvestem; not matching it up can cause vibration, but usually at slower speeds.

good luck!
didnt read all of your post there..lol now i know why my tailshaft seal went out :tongue:
 

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Discussion Starter #8
thanks guys I will surely have it looked at. I've been dealing with some crazy stuff on the car lately but I feel sad to even think about dumping it. For the money I would make on it my though would be to just keep it for a project car. Only crappy part is I have no place to work on it :(
 

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Discussion Starter #9
would you guys know any other symptoms if the Driveshaft being worn or gone? The tire mounting is possibly an issue since they said it was hard to mount the tires on my rim because of some damage but I am not replacing the rims right now.
 

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Discussion Starter #11
thanks for that information..... I will have to listen for it. I recall this being an issue but didn't give it much thought. Would you say it is easy for a mechanic to determine if the U-Joints are bad?

thanks
 

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Oops Wrong Thread
 

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Discussion Starter #13
Monday I am having the U-Joint looked at and the transmission itself

Hopefully a clean bill of health :)

next I have to consider struts and springs and trying to decide what to get and not break the bank
 

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If it were a specific rpm or speed it was doing it at I'd say you're jsut hitting the natural frquency of the car, thus making it vibrate more. My Taurus' is around 75, I get past that it stops. Fun little tidbit though, it's not a massive shake, but does it so much that you can feel it a BIT more. Gotta love physics. or hate it....whatever floats your boat.
 

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Discussion Starter #15
well I found out the u-joint and drive shaft and transmission are completely fine. I find the wear part about the issue is on one highyway the car seems to vibrate less but still does it off and on through steady acceleration. The highway I take to work, is much worst. It is almost like air is is causing the issue, too much air??? Air lifting the car? or effecting the front end??

I know that sounds weird but if I took you out for a ride on the highway where it runs the best you would think I was nuts to complain but if I took you out on the other one you would feel it more. You can feel it sitting in the passenger seat as well as the drivers seat.

I have stock struts and springs, could they have any effect on this? Or maybe my rims are that screwed up that I will never get a good balanced tire or tires.

thanks
 

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well I found out the u-joint and drive shaft and transmission are completely fine. I find the wear part about the issue is on one highyway the car seems to vibrate less but still does it off and on through steady acceleration. The highway I take to work, is much worst. It is almost like air is is causing the issue, too much air??? Air lifting the car? or effecting the front end??

I know that sounds weird but if I took you out for a ride on the highway where it runs the best you would think I was nuts to complain but if I took you out on the other one you would feel it more. You can feel it sitting in the passenger seat as well as the drivers seat.

I have stock struts and springs, could they have any effect on this? Or maybe my rims are that screwed up that I will never get a good balanced tire or tires.

thanks
I know its high speed but could this be another case of torque converter shudder?
 

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I was thinking that but I think he's just hitting the normal resonance of the car. But for ****s and giggles... sully to test to see if it's the TC does it go away if you just lightly tap the brakes. Just enough to get the lights to come on not apply them. But remain at a constant speed. This will cause the converter to unlock. But I still think it's either a mount or just normal resonance.
 

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Discussion Starter #18
I was thinking that but I think he's just hitting the normal resonance of the car. But for ****s and giggles... sully to test to see if it's the TC does it go away if you just lightly tap the brakes. Just enough to get the lights to come on not apply them. But remain at a constant speed. This will cause the converter to unlock. But I still think it's either a mount or just normal resonance.
I could test this tonight when I leave work. Usually the best testing is in the morning, night time traffic gets in the way of all my testing :)

I had tried driving at that speed and putting it into neutral to rule out the trans but I recall it not making a difference. There was a thought about having the wheels balanced while on the car, I would figure that isn't possible but I do not know.

Could this be a vacuum leak? or would I notice other side effects? How about a broken spring or strut? or damaged either one of those?

thanks guys for all the help:wavey:
 

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Discussion Starter #19
Guys I was considering this kit and wanted to see what others think. I do not know the company and their product so any advice would be great.

http://www.racinglab.com/tokico-hpk-suspension-kit-ford-006.html

I plan to have the coils and struts looked at to see their condition, the front end guy I regularly use said he recalls that there is an issue with one of my springs :eek:

thanks guys
 
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