Vibration Affected By Temperature

[Martman]

So I have a dreaded vibration from about 62 to 72mph. I have done the usual to isolate components. It is speed triggered and not rpm triggered. I have not had the car that long but I have replaced the diff fluid (mobile 1) when I first got it when I was planning to replace rear wheel bearings. Then I realized the noise I heard is a clicking from the diff that could be pinion or carrier bearings. So I have not focused on that since I will get new gears in the future.

But I noticed something yesterday that I normally would attribute to tires. The temp was the coolest (59) it has been here in Ky in the morning since I have had this car and the vibration was only slightly noticeable if you were paying attention to it.

Outside of tires what else would be affected by the outdoor temp in regards to a vibration?

 

[No.11]

Not sure if it's affected by temperature, but based on the fact that it's a speed dependent vibration I would say it sounds like a driveshaft issue.

 

[mikestang63]

an out of balance tire will become noticeable around 45-50mph and smooth out around 65-70. It will also be impacted by changes in temp as the tire expands in hotter weather.

 

[Mustang5L5]

an out of balance tire will become noticeable around 45-50mph and smooth out around 65-70. It will also be impacted by changes in temp as the tire expands in hotter weather.

Agree.


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[Martman]

I am leaning towards driveshaft or drivetrain. The more I focus on it it is more generalized vibration. I get some serious steering wheel and front vertical shake as well that could be tire related but I think it is two separate issues. I am going to check and more than likely replace ujoints. I have seen on here and other places to rotate the driveshaft half turn and remount. Why is this? Are they based on an offset balance with something else in the drivetrain?

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[Martman]

Un-freaking-believable. So the PO of this Stang has surprised me on every level of work partially completed but this blows me away. So I get the rear of the car up and started doing a spot check on driveshaft and weights. And what do I find at the rear u-joint. 1 missing bolt and 2 loose. So to say the least I would say that may cause a vibration. Going to pull the drive shaft and check everything on it but does anyone know the specs on the bolts for the driveshaft on a 91 so I can buy some more?

 

[Mustang5L5]

http://www.cjponyparts.com/ford-dri...12/p/HW1701/?gclid=COGV3JT13c4CFQJZhgodJEQLOg


I'd get these vs trying to match up hardeare. You'll want the 12 point to properly torque them down. Throw the others out.





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[Martman]

I am going to try the dealer tomorrow to see if they have them so I can get it ready by Monday. What is the best way to check the u-joints with the driveshaft off the vehicle. I have always checked them on the vehicle? Or should I just go ahead and replace them since this thing has obviously been wobbling/vibrating?

 

[mikestang63]

I am going to try the dealer tomorrow to see if they have them so I can get it ready by Monday. What is the best way to check the u-joints with the driveshaft off the vehicle. I have always checked them on the vehicle? Or should I just go ahead and replace them since this thing has obviously been wobbling/vibrating?

go ahead and just get new ones. Why take a chance. Good catch!

 

[No.11]

I am going to try the dealer tomorrow to see if they have them so I can get it ready by Monday. What is the best way to check the u-joints with the driveshaft off the vehicle. I have always checked them on the vehicle? Or should I just go ahead and replace them since this thing has obviously been wobbling/vibrating?

If you have the $, this is a perfect opportunity to upgrade to an aluminum driveshaft

 

[Martman]

Well as much as I would love to, and I have the dollars, my wife doesn't agree. Lol so I am having to ease her into this "it's going to be badass some day babe!"

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[mikestang63]

Well as much as I would love to, and I have the dollars, my wife doesn't agree. Lol so I am having to ease her into this "it's going to be badass some day babe!"

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Damn if I had a dollar for every time I heard-- " the wife doesn't agree with me spending money on the car" I'd be rich. Ask her why she needs 50 pairs of shoes and 20 handbags....lol

 

[Martman]

Oh I know and mine hasn't had to work in 9 years. Smh well you know what they say "happy wife happy life". I got new u joints and bolts and have the ujoints on the driveshaft and need to get it back in. It is so damn hot here in KY right now my fat ass is roasting in the garage. But better than cold.

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[JD1964]

To check the ujoints with the shaft off the car, rotate the cups. They should spin free without any lumpy feeling. Rotate the cross back and forth too. All movement should be consistent without points of extra resistance.

On the rear part you can even remove the cups. Check the needle bearings to make sure none are broken. Wipe the bearing surface on the cross clean and check it for groves. It should be smooth all the way around with no groves. Put some grease in the cups before pushing them back on.

 

[Martman]

I replaced both but before took a pry bar to see if there was movement between them and while there wasn't they seemed loose in movement. But I didn't want to take a chance so I replaced them with some moogs.

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[No.11]

Well as much as I would love to, and I have the dollars, my wife doesn't agree. Lol so I am having to ease her into this "it's going to be badass some day babe!"

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that's exactly why it was the perfect time. You gotta exaggerate the damage. "babe my driveshaft could fall off causing my car to flip over"

 

[Martman]

This is why you should never let your wife know how much you are worth dead. Mine would have been thinking, "What's wrong with you dieing in such a horrific crash?" $$$$$$

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[Martman]

Okay so I replaced the ujoints but the damn thing is still vibrating. However it is a bit different. Now it comes on a little earlier and is oscillating. Can the oscillation be due to the phasing/indexing? I marked everything when I took it off but that doesn't mean the PO did as needed.

So should my next steps be to get it up on jackstands and do some 60-70 mph runs and check the vibration and then unbolt the back and rotate the driveshaft and try again? I am not sure how rotating the driveshaft on the pinion flange changes the result and I would be glad if someone could point me to a link or describe why that is the case. Driveshaft phase of the couplers is one thing but replacing u-joints shouldn't change that.

 

[mikestang63]

rotate the drive shaft 180 and see if that helps. Usually an alum replacement driveshaft solves this .

 

[Martman]

Do I take it all the way out and rotate or just unbolt the back and rotate rear flange 180?

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