Vibration at 60 and up

[70ChargerRT]

when we pull the driveshaft to check the angles, we will check the u joint too. If the joints were seized, you would think you would have the vibration all the time. I think the sagging springs have changed the rear pinion angle up, and it needs some shims to lower it.

You need to leave the driveshaft in the car to check all of the angles while the car is on the ground or even easier on a 4 post lift. Sagging springs can cause vibrations at higher speeds. Checking the angles is the easiest, quickest thing you can do before tearing anything apart after you do a visual of everything else.

 

[WileE]

check the trans mount first.

 

[moes]

Update. He contacted a drive line shop this morning about the problem, the owner of the shop said one of his tech guys used to work for a Dodge dealership for 30 years, and he will take a look at his car this afternoon. The car was loaded on a flat bed and is at the shop now.

 

[snake]

Update. He contacted a drive line shop this morning about the problem, the owner of the shop said one of his tech guys used to work for a Dodge dealership for 30 years, and he will take a look at his car this afternoon. The car was loaded on a flat bed and is at the shop now.

It will be interesting to know what is causing bad vibes

 

[moes]

Update. Just talked to Jeff, and he said the U joints were good, but the guy suggested replacing them and transmission mount due to age while the drive shaft is out, so he is. The problem with vibration was the pinion angles. They ordered U joints, transmission mount and shims to fix the problem, and they should be in tomorrow. I will let you know how it went.

 

[moes]

The shop called Jeff and said the car was ready. On the way home, he got it up to 60 and had no vibrations, then he put the pedal down and got it up to 100+ and still no vibration. He's one happy guy!!! I'm going to his place tomorrow to check it out before he puts it away for the winter.

 

[snake]

Well what was the problem,I am shure others on here would like to know.

 

[snake]

If your going to his house tomorrow post some pics of this car sounds like a great find.

 

[snake]

Bogus

 

[thegarage]

hey guys, a friend found an untouched 69 1/2 A 12 Super Bee with Butterscotch Yellow paint and automatic transmission in a warehouse that has sat for 30 some years. He changed all the fluids and went over the car. Did a tune up and put new tires on it. We just went for a drive, and it has a vibration from the transmission tail shaft area when speeds hit 60 and up. The car only has 45,230 miles on it. We checked the driveshaft, no movement, so the u joints and tail shaft bushing should be ok. I am thinking because it only happened when he was on the gas, he has to lower the axle pinion angle with shims. Any ideas?

I had a recent scenario where the vibration would begin around 45-50 mph and once above 70 mph it would fade away, but when letting off the accelerator to gradually reduce speed, the vibration would return until the speed was around 55-45 mph. What made the diagnosis difficult was the vibration wasn't related to the "speed', or mph, but more so in relation to the rpm's. I finally caught a lucky break when under the car looking for anything that showed wear and tear, even with a 24" pry bar trying to forcefully move something, and there it was - The transmission bellhousing was cracked to within 2-3" of either side, roughly 2-3" away from the mounting bolts. See picture to clarify what I'm talking about, I drew a red line showing the area that cracked. I did have a mild shift kit build with an 1800-2000 rpm stall torque convertor, running a 3:73 differential behind a mild build 383. That setup worked flawlessly for 6+ years before the bell housing crack appeared. And it was a gradual increase in vibration severity over several months, probably as the crack spread.

 

[Dans68]

Check for a broken transmission tailshaft mount. You may have to remove it to thoroughly check it. That will allow the transmission to shift position slightly under load if it has cracked badly or split.

 

[70ChargerRT]

The shop called Jeff and said the car was ready. On the way home, he got it up to 60 and had no vibrations, then he put the pedal down and got it up to 100+ and still no vibration. He's one happy guy!!! I'm going to his place tomorrow to check it out before he puts it away for the winter.

I figured that’s what the problem was. Glad you got it lined out. I’d almost bet that’s my problem. I hit 140 mph+ today outrunning this yellow jacket scat pack and didn’t even notice the vibration lol

 

[kiwigtx]

The problem with vibration was the pinion angles. They ordered U joints, transmission mount and shims to fix the problem, and they should be in tomorrow.

Car sitting for 30 years has killed the rear leaf springs.

Same thing happened to my car - it sat for nearly 12 years on blocks....springs were inverted thanks mainly due to all the heavy junk in the trunk when I found it ....books, manuals and old car parts shoved in there.

I threw those springs away just last month at the Scrap Dealers. Nobody wants knackered leaf springs.

 

[1966Canuck]

I also have a similar bad vibes........ 40 mph + on light acceleration I feel shuddering under drivers floor and felt in the steering wheel.
My U-joints are good and my transmission tail shaft is fine.
If I put the car in neutral at 50 mph it coasts smoothly with no vibration at all.2 days ago my opinion bearings on the left side took a crap.
I noticed both my rear tires tread is worn on the inside as well.
II have asked the repair shop to check the pinion angles as well as many of the other suggestions here. Is pinion angle something that I could check myself if they don't understand that ?

 

[1966Canuck]

they haven't Road tested it yet but my concern is If there is a problem with the pinion angle is it going to keep ruining pinion bearings ?

 

[Orig69]

they haven't Road tested it yet but my concern is If there is a problem with the pinion angle is it going to keep ruining pinion bearings ?

Is the transmission mount in good condition?

 

[70ChargerRT]

I also have a similar bad vibes........ 40 mph + on light acceleration I feel shuddering under drivers floor and felt in the steering wheel.
My U-joints are good and my transmission tail shaft is fine.
If I put the car in neutral at 50 mph it coasts smoothly with no vibration at all.2 days ago my opinion bearings on the left side took a crap.
I noticed both my rear tires tread is worn on the inside as well.
II have asked the repair shop to check the pinion angles as well as many of the other suggestions here. Is pinion angle something that I could check myself if they don't understand that ?

Yes you can check it yourself. You can down load the Tremec app and go to driveline angle finder. My pinion angle is way up causing my vibration. Your motor needs to be pointing down 1-4 degrees. My pinion angle is 5.10 looking up. They told me for beginners to buy 5 degree wedges if I can find them, if not try 4 to at least get my pinion close to 0 as possible. My engine is looking down. 3.6 with this T-56 swap.

 

[1966Canuck]

thanks to all. My bearings were toast on their own but the tech found a broken tranny mount.
I have to source one