Bad vibration at 3000 RPM's and up

stevesLX · Feb 19, 2007

O.K. This vibration was here before I did the motor and tranny work. I bought the car back in November and it did it then. However there were some other problems the car had and I concentrated on that stuff first. The car has always done this since I bought it. And I thought wheels and tires also but I sold the ones that came with the car when I bought it and got new ones. It still does it. This is what I have replaced and done and to no prevail still vibration. rear shocks and springs, front shocks and springs the shocks and springs are just OEM replacements. Tie rod ends , ball joints, steering rack, power steering pump, lower end of motor rebuilt, tranny rebuilt to incluse 3 of the actual gears, Aluminum driveshaft was balanced and U joints were said to be good. The car had a 5 lug swap done to it before I bought it. I know the front spindles are off a 94 not sure how they did the rear but I measured the rear one time and if I recall right from hub to hub it was something like 61 1/2 or 62 inches. The list of mods I had for this car claims the axle to be 28 spline 4.10 gear. Dont know if its normal when I was pulling the drive shaft out to pull the tranny the nflange on the driveshaft that bolts up to the rear when I removed it there was some fluid that dripped out from back there at the rear end. But thats that.

GTOreturns · Feb 19, 2007

Is it the stock drive shaft? If so you need an aluminum one. I had the same problem after my gear change, as most 5.0's do. The Aluminum DS solved the problem.

stevesLX · Feb 19, 2007

Its not the stock drive shaft. It is a aluminum drive shaft thats in there and I just had it balanced and the U joints checked on it they were fine.

BigHairyMonkey · Feb 20, 2007

i might be a dumbass, but what about wheel bearings or tie rod ends?

stevesLX · Feb 20, 2007

The tie rod ends I just replaced like a month ago. I haven't touched the wheel bearings but w/in the past 2 months this car has been in for 3 alignments because of all the steering problems I have had and those 3 alignments were done at 3 differn't places and all 3 places said my wheel bearings felt good.

91notchbk · Feb 20, 2007

If it is an engine vibration you will feel the vibration when revving the motor at a stop. Also, since you push the clutch in the vibration is still present indicates you can probably eliminate the engine as the source. It is good practice to test various components and use the process of elimination to find the cause. To test the transmission you can raise the rear of the vehicle and support it on jack stands. Next, remove the rear driveshaft. Run the car and see if the vibration is present. If it is present then your transmission is the problem. If it is not present then you can eliminate it as the problem. To test the drive shaft you can run the car with the rear supported on jack stands and take a coat hanger and touch it to the rotating driveshaft. (Be careful since you are working next to a rotating shaft) If it makes a line all the way around the shaft then the shaft is not the problem. If it skips an area on the shaft (indicating a heavy spot) then the driveshaft may be causing the problem. You may also want to make sure the u-joint on the pinion flange is centered and tight. You also may want to rotate it 180 degrees if it wasn't marked from removal. If these components check out ok then you may want to look at a tire or wheel. I would start with the transmission and driveshaft first since the problem started after you removed these components. Good luck.

stevesLX · Feb 20, 2007

No No No. This problem has been here since I bought the car back in November. It has always had this vibration since I have owned it. I just rebuilt the motor and tranny new suspension driveshaft balanced and U joints. New wheels and tires. Thats everything I have done. The car still vibrates at 2500 and above and gets worse as the RPM's and speed increase. The car did this before I even replaced any of this stuff. IT HAS ALWAYS VIBRATED SINCE I BOUGHT THE THING.

Mr Grim · Feb 20, 2007

I would lean heavily toward the differential being the culprit, if everything else has been swapped/rebuilt. It is also possible that you have a bad wheel-bearing.
If the rear-end is stock, it could just be worn out. If a gear-swap was done, it is possible that the lash wasn't set right. It is a very meticulous process to properly set up the diff, and a lot of shops will/do take shortcuts due to the time and effort to do it right. Do a search on swapping gears and you will see what I am talking about.
Please let us know the outcome, and Good Luck!
-Grim

Just saw that Hairy Monkey already mentioned a wheel-bearing. Unless the bearing is completely shot, it may "feel" good turning it by hand, but be out of tollerance and vibrate at higher RPM's. The bearings I would suspect are the axel bearings since you mentioned that it was in for alignment and they probably only looked at the front.
On the bright side, this would be a good excuse to swap the gears since the rear-end would have to come apart anyway...That is, if they haven't already been swapped and the problem really is in the rear-end!

stevesLX · Feb 20, 2007

O.K. I appreciate it. One more thing the gear that is in there is a 4.10. I think I am going to go with changing the wheel bearings first for starters. I assume thats just like changing the wheel bearings on the front or is there more to it?

86bluecobra · Feb 20, 2007

there is more to it. It involves taking the back off the diff, removing the axles and brakes i believe.

91notchbk · Feb 20, 2007

stevesLX said:
No No No. This problem has been here since I bought the car back in November. It has always had this vibration since I have owned it. I just rebuilt the motor and tranny new suspension driveshaft balanced and U joints. New wheels and tires. Thats everything I have done. The car still vibrates at 2500 and above and gets worse as the RPM's and speed increase. The car did this before I even replaced any of this stuff. IT HAS ALWAYS VIBRATED SINCE I BOUGHT THE THING.

Even though the problem existed prior to the swap you will still want to test the various components to find the source. Engine, transmission, driveshaft, axles, wheels tires, etc. I would NOT take the shade-tree approach and just start swapping parts. Parts changers end up spending lots of time and money and in the end you may be stuck with an empty wallet and still have a vibration. Spend the time to understand the vibration and isolate each component and test the component before you guess and swap potentially good parts. Your problem is easily solvable with a couple hours of time and a good diagnostic approach. Just my two cents. I worked as a technician at a dealership for many years and have learned that good diagnostic skills (isolating components and testing) and an understanding of the vehicle systems is the FASTEST and most EFFECTIVE method for isolating causes.

mustang65luvr · Feb 20, 2007

After reading everyone's posts, I would have to say the problem most likely is in the rearend. like Badlilstang says, check your pinion angle. You will need an "angle finder" to do this, you can pick one up at Sears, or home depot or whatever. Also, check the pinion bearings for wear by wiggling the DS flange. Maybe check the rear axle bearings for wear. Being that you say the people you bought it from did rearend work, I would think there is something goin on there. Hope this helps!

86bluecobra · Feb 20, 2007

You say the car has stock suspension? If so any chance one of those stock rubber bushings on either your upper or lower controlarms has completely disinegrated? Do you have any clunk noises aswell?

Badlilstang · Feb 20, 2007

86bluecobra said:
You say the car has stock suspension? If so any chance one of those stock rubber bushings on either your upper or lower controlarms has completely disinegrated? Do you have any clunk noises aswell?

Agreed, that would cause some noise/vibes also.... all else fails.. bring it to a shop and have them diagnose the problem and then if you can, do the repairs your self. Im starting to think pinion bearing but again you would feel that in the shifter big time.

stevesLX · Feb 20, 2007

Are we talking the pinion bearing in the rearend or the motor.

86bluecobra · Feb 20, 2007

I believe they were talking about the rear end. But by any chance is there any clucks aswell? are the bushings good in the control arms?

Badlilstang · Feb 20, 2007

stevesLX said:
Are we talking the pinion bearing in the rearend or the motor.

Rearend.. Rear of motor is Pilot bearing.

91lxttrim · Feb 20, 2007

I'm having the same problem and I feel it BIG TIME in the shifter handle. I replaced the u-joints last night, no difference. I used to be able to make the vibration go away by letting off the gas fast then it would feel SOOoo smooth once i gave it gas again. Mind you this is all at highway speeds (70-75mph). But it would come back when change speeds slightly with the accelerator.

I have 4.10s also and thinking of going turbo so I plan on switching gears to 3.27's so we'll see if it goes away then.

Any other ways to single out the gears as the culprit?

There have been some good pointers for the other diagnostics, Thanks

Badlilstang · Feb 20, 2007

91lxttrim said:
I'm having the same problem and I feel it BIG TIME in the shifter handle. I replaced the u-joints last night, no difference. I used to be able to make the vibration go away by letting off the gas fast then it would feel SOOoo smooth once i gave it gas again. Mind you this is all at highway speeds (70-75mph). But it would come back when change speeds slightly with the accelerator.

I have 4.10s also and thinking of going turbo so I plan on switching gears to 3.27's so we'll see if it goes away then.

Any other ways to single out the gears as the culprit?

There have been some good pointers for the other diagnostics, Thanks

You have no vibration when sitting still and revving the motor up slowly? Kinda gotta follow everything we mentioned above. Hopefully who ever did your gears set them up right and they got a good wear pattern. On these older foxes I always replaced the carrier and pinion bearings if they were the originals. If you get new gears make sure you do this and make sure whoever does the rear end knows what they are doing. You don't eyeball this kind of installation.. you must have a way to check your slack.

stevesLX · Feb 20, 2007

Well I guess I will pull the drive shaft and run the car through the gears on jack stands and see what happens. Another problem that has been a headache since I put the motor back in is valve train noise. I listed a thread on it today but have had no replies. If anyone knows anything about this it would be of great help to me. I apologize for being any of a annoyance to you all but I am a newbie and just want to get all this right and be able to enjoy this car which I have yet to be able to do.

Bad vibration at 3000 RPM's and up

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