Did they "time" the drive shafts when they welded it?  Also if 2 piece drive shaft the u joints must be 180 when u couple them together.

-- Edited by hawkeye5766 on Tuesday 24th of January 2017 09:06:10 PM

I am also having vibration issues with mine. A little different though in that I have a vibration or shudder on acceleration in !st or 2nd. At higher speeds or levelling out it is perfectly smooth. This was there with the 283 and T350 trans. and is still there with the 350 and 700r4. When I had Wesley's Machine Shop cut the driveshaft I had them check the shaft and balance and they confirmed it was good. The angle between the trans. and the 1st shaft is at 4 degrees and the manual calls for a max. of 3 degrees. This is even after cutting 3/8 inch off the new hanger bearing housing and re-welding to lower it in the tunnel. I cannot shim the trans. up any higher due to the trans. dipstick jamming between the trans. and firewall. My fix for this was I obtained a flexible firewall mounted dipstick from Summit Racing. This should allow me to shim the trans. up a little more (hopefully) to get the angle within 3 degrees max. I also noticed that the yoke at the trans. doesn't seem to slip into the trans. far enough ( the hanger bearing is right at the rear of the slotted holes in the tunnel when the driveshaft is attached to the rear end) and I also thought a slip yoke would remedy this. My estimate for a slip yoke was $500 though. Your estimate is far more reasonable. I also obtained an adjustable rear upper control arm from Spohn Performance so I can play with pinion angles. Also there is not any problem with the rear end as I replaced the axle bearings and switched the crown and pinion assy. and the shudder is still there. I am currently working on this in my shop so I won't know how I will make out till spring.
Jim

Hi Jim, I never measured angles ,just made sure yoke was same height up from bottom of frame as the PG's was. I also had the vibration you only seemed only in low gear I think it is gone now. My center bearing is also at the rear end of slot. Will measure front shaft, yoke was out about 1.25 can check all that later. I think vibration was related to engine performance but not sure now,mine felt like engine had slight miss!! Just checked the quote for a slip yoke looks like $380.00 think i will do that next week Old cars sure are fun!!!! Laurie

Laurie, years ago I replaced the xmission in my truck with a used one from an auto wrecker. It vibrated from the start. It turned out to be the torque converter. Another torque converter solved it. By the way last night I measured my yoke going into the xmission and it also sticks out 1 1/4 inches. Good luck. We'll lick this thing yet.
Jim

New center bearing is going in, having slip joint installed in rear shaft. DonSSDD the shop that redid the front shaft and is doing rear one has been doing this for very long time they do good work I just tried to save a buck and it didn't work!!! Laurie

When we get driveline vibrations we tend to think that balance is the problem. On these particular X frame cars with the two piece shafts, 95% of the time the problem will be caused by improper angles or phasing.

Watch this video showing a simple one piece driveline...

https://www.youtube.com/watch?v=gmV4qwLfOMY

You can see and hear why improper angles can cause a vibration.

On a normal single driveshaft, as long as the output shaft of the transmission and the pinion are parallel with each other, you're fine. It gets a lot more complicated when you add a center U joint,, and it gets REALLY complicated on a long wheelbase truck with two drive axles and three of four drive shafts.

The problem usually arises on these X frame cars if the transmission has been swapped for something different like a 700R4 or if the ride height has been changed quite a bit.

If you happen to have a digital level and a program like the Road Ranger Driveline Analyser, you can usually solve all your problems with a few well placed shims. If not, you have to do quite a bit of reading and research to figure out what you have to do in order to get the driveline right on.

Sometimes, the simplest way to make the problem go away is to shim the transmission or center bearing so that the two driveshafts are running without any angle at the center U joint. I mean the two driveshafts should be completely straight. Like this _ _ not like this_ /  Then you only have the pinion and transmission output angles to worry about.

This is not the ideal setup because there will be no movement in the center U joint, which will cause it to wear out quicker than it should.

Once you have that, the normal way to do things is to have the pinion and the transmission output parallel with each other,,, BUT on these particular X frame cars, it's usually easier to use the "broken back" driveline arrangement. It's a little hard to explain but it works like this,,, if the driveshafts are sitting level to the ground,,, and the output shaft of the transmission is pointing down three degrees,,, then the pinion should also point down three degrees.

Here's a picture. The conventional setup is the one on the bottom but the less common broken back setup, top image will also work.

 

By the way, all of these settings should be done with the car at normal ride height.

 

Just got drive shaft back, "New slip joint" looks nice! Put new bearing in center bearing assy. welded strap around it should work Pictures should come later if camera and photo program ae nice to me. I think photos are here ya!! 1st is the drive shaft then the center bearing after modification. Noticed that top  round part with bearing was tilted to one side cut bottom to middle bent it over until it looked like bearing was centered over bolt holes then welded. Test it later when snow gone!!  Now on to change springs again and speedometer correction.   Laurie

-- Edited by Teich on Friday 27th of January 2017 02:55:41 PM

You got one of the poorly made ones. When I order them I usually ask them to bring in 2 or 3 and pick the best one. One had the plate on the bottom welded cockeyed, another, the spot welds let go while I was checking it out.
What you have done is solid looking now, but it looks like its not standing up 90 degrees, but that could be my eyes or the angle of the photo. Check it for that before installing it. If its not straight, the bearing will be cockeyed in the rubber bushing and it will fail early.

-- Edited by DonSSDD on Friday 27th of January 2017 03:54:57 PM

I had a '61 Parisienne bubble top 283, 4 bbl,3 speed stick on the floor back in the mid sixties and was having trouble with the stock hanger bearing
(probably caused by my driving skills) replaced it twice lots of vibration. A friend who worked the parts counter at our local Pontiac dealership found in the dealership manuals a heavy duty hanger bearing and we used it and no more problems. I wonder if this part is still available?

Teich wrote:

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This should work if not will look for billet one when at Back to the Fifties in June.  Laurie

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I bought a billet one ... $125.00. They look too pretty to hide in the tunnel. I want to get a slip yoke put on the shaft also. 

Thinking about drive line vibrations, the factory drive line has first joint( at trans) 90* rotation from rest of joints. Look trucks big or small all joints are lined up maybe this is low speed vibration the Jim has and I have some as well. I just might change mine to see what happens. Laurie