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Discussion Starter · #1 ·
The vibrations in my car were getting unbearable, so it went up on jackstands to find the cause this weekend. I pulled the driver's header, and modified it slightly with a BFH and a grinder to get the collector flange off of the TV cable adjuster, and clear the steering box better. I found a loose rear shock, and a loose front cross member (man, how did I miss those before?).

Then I decided to rotate the drive shaft 180 degrees. As I unbolted it from the differential, the u-joint fell apart in my hand. It's the worst looking u-joint I've ever seen in my life. One cap must not have gotten any grease, as the bearings had vaporized, the cap had a hole in the side of it, and a piece of metal was sticking out from the hole had already cut half way through the zirk fitting. That's the last part I ever buy from Kragen's Auto. That u-joint had 3800 miles on it. The other 3 caps were full of grease and looked fine.

After putting a new u-joint (NOT from Kragen's) the car is as smooth riding as a new car. Man, it's fun to drive it again!
 

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Congrats, vibrations are a bear to find.
 

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What kind of vibrations were you getting? I'm trying to track some in my 66. I only get them when driving between 50 and 60; not at higher speed and not at lower speed.
 

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Hiyas.. I'm sure you know this.
Most common cause of this type of failure is over-tightening the U-bolts. They are 5/16" and shouldn't have more than 12-15 Ft-LBs max. Otherwise, the caps will crush.
 

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When I first got my '70 fastback, it had a bad vibration at about 50 to 65mph. I changed wheels and tires. No help. Changed both u joints. No Help. Had to live with it for about 6 months. Then I did the swap to t-5 transmission. When I had the driveshaft out, I noticed it looked very rusty and pitted on one side.....Took the 4" grinder with wire brush on it to clean it up. It wasn't rust....When the car was undercoated, they had sprayed the driveshaft with undercoating on one side only.....This stuff was 1/4" thick and about 1 1/2" wide. I took all the undercoat off. Got car back on the road, and no vibration.....
Guess the car had vibrated it's whole life, and noone ever found out why....
 

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Good for you! Glad to see you have removed those 'bad vibes'.../forums/images/icons/wink.gif
 

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Same thing happend to a friend of mine. Took him forever to figure it out. Congrats!
 

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Discussion Starter · #10 ·
Hmmm ... actually, I did NOT know that, but it makes perfect sense. In fairness to Kragen's, I could see that could have been my problem, and not just a crappy u-joint. I hated that u-joint anyway, though, because the zirk fitting wasn't angled like it should have been. You couldn't get the grease gun on it with the one u-bolt installed.

Thanks for the tip, Eric.
 

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Discussion Starter · #11 ·
My vibrations were betwwen 50 and 60 as well. If I let off the gas, it got considerably better. Stepping on the gas at all during those speeds made the vibrations come alive in a big way.

I've been playing with it a lot the last week trying to determine exactly where it was comming from, and thought I had 2 distinct vibrations ... one from the front at lower speed and one from the rear at higher speeds.

Now that the vibrations are all gone completely, I now realize they were always there, just way worse between 50 and 60 mph. It now rides like a totally different car.

I didn't mention in my previous post, that I also had my front tires re-balanced. One was off by .50 oz and the other by .75 oz. The wheel shop guy I use says it's actually very common to have the tire "slip" on the rim right after they're mounted because of the lube on the wheel for mounting the tire. This slippage throws the balance out. He said he's seen 20's go around the block and slip 2 inches!
 

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I've had my tires checked for balance as well; 1 was only off about 1/4. I am however going to check the driveshaft; Ive had a bad feeling about those u joints for a while and just re-inforced it.
 

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Although I agree with your opinion of Kragen, one of us in the VMF is a Kragen employee.

We all need to be a little more sensitive and caring towards the feelings of others.

In the future, please refrain from using derogatory comments when describing your level of unhappyness with a particular vendor...

It makes me sad, and want to reach out for comfort...




...hehe...j/k
 

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Acutally, I've had no problems with Kragen or their parts at all - can't beat their gaurantee on brake pads!!
 

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I had a similar experiece w/ my '69 when I let off the gas, as in decellerating from highway speeds of say 65 to 40 on an exit ramp, I would get similar vibrations.... I took my stang in for its yearly inspection and the shop replaced the U-Joints and its been much better ever since! I recommend changing them if you have any vibrations on decellarating. Good luck!
 
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