Weird vibration

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Princess Valiant

Princess Valiant

A.K.A. Rainy Day Auto
FABO Gold Member
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So there i was cruising in my dart like i always do......it's a daily driven car.

68 dart with the original slant six, a 1976 cast iron OD 833 and the original 7 1/4 rear end.

I am cruising down the highway imagining that i am drafting Richard Petty and suddenly at 80mph i hear a very loud "BBBRRRRRRRRRRRRR" i slow down because it skeeered the crap out of me and the sound and vibration shook the whole car. As soon as i slowed down to 75 it went away and everything was smooth again.

So i get a little brave and push it back up, and when i hit 80 "BBBRRRRRRRRRR" again.

No idea what it is, i stopped and checked .....trans and rear fluid check out, only happens at 80 or above.

Freaky

Any idea what it is???
 
Threw a wheel weight?
Slipped belt?
U joint going out?

I dunno but these are the first things i'd check.
 
Is it something you just hear or can you feel the vibration? Few things along with what moparmat mentioned.

Worn Engine Mounts
Needs Front end alignment
Worn Shocks
Bulge on a tire
 
If it comes in at certain speeds then goes out when you change the speed, it's a harmonic vibration...

they are usually caused by out of balance... Something in the drive train is out of balance...
 
krazykuda said:
If it comes in at certain speeds then goes out when you change the speed, it's a harmonic vibration...

they are usually caused by out of balance... Something in the drive train is out of balance...
Click to expand...
One of the first cars I drove was a Duster my Dad had. Had a vibration just at 67mph. every time... never figured out the cause
 
Rainy Day Auto said:
So there i was cruising in my dart like i always do......it's a daily driven car.

68 dart with the original slant six, a 1976 cast iron OD 833 and the original 7 1/4 rear end.

I am cruising down the highway imagining that i am drafting Richard Petty and suddenly at 80mph i hear a very loud "BBBRRRRRRRRRRRRR" i slow down because it skeeered the crap out of me and the sound and vibration shook the whole car. As soon as i slowed down to 75 it went away and everything was smooth again.

So i get a little brave and push it back up, and when i hit 80 "BBBRRRRRRRRRR" again.

No idea what it is, i stopped and checked .....trans and rear fluid check out, only happens at 80 or above.

Freaky

Any idea what it is???
Click to expand...

Do you have a tach in that car???

See what RPM it comes in and out of...

Then go to another gear and see if it comes in and out at those same RPM's or not...

If it comes in and out in all gears at the same RPM's, then I would check something on the engine side; Flex plate, engine, etc...

If it only comes in and out at those speeds in one gear only, then look on the output side of the drive train... Back side of the trans, drive shaft, u-joints, axle, tires... (I said back side - Heh, heh, heh....)

Try to figure out if it happens in only one gear, or all of them at the same time (RPM)...


Isolate if it's engine speed related or vehicle speed related....
 
Last edited:
zkx14 said:
One of the first cars I drove was a Duster my Dad had. Had a vibration just at 67mph. every time... never figured out the cause
Click to expand...

There is a weight that bolts to the rear tail shaft on the trans that's supposed to help dampen vibration... I've seen it on a few...
 
zkx14 said:
One of the first cars I drove was a Duster my Dad had. Had a vibration just at 67mph. every time... never figured out the cause
Click to expand...

Did you take your GF's out in it???? :poke:

Warm them up with the vibration and go from there... :D
 
Also check if any of the rubber seals under the hood may have come partially undone, causing the seals to flap at speed.
 
My money is on a U-joint, It might not be loose but I bet if you take out the driveshaft the joint will be bound up tight.
 
ovrerdrive 833 aluminum case are notorious for front bearing ? retainer wear. have to wonder if that could cause such.>??
 
brian6pac said:
My money is on a U-joint, It might not be loose but I bet if you take out the driveshaft the joint will be bound up tight.
Click to expand...

Agree. Pull the shaft so you can move the U joints through their angles, and feel for dry, raspy "feel"
 
I have also had a bad pilot bearing cause a whip in the drive line at high speed
 
Rear axel bearings or bent axel!!!

Don't ask me how I know
 
Don't forget to look at the driveshaft for balance and possible bend.
 
Some men just feel the need to prove they are pigs.

It shows your disrespect for the ladies here & women in general.
 
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