Drive Shaft Balance

[Don Jordan]

I mentioned this before and truly feel embarrassed to be bringing it up again but for those of you who would kindly share your valuable experience and knowledge I will appreciate it.

I spoke earlier about a 'growl' coming from the car. Rather than wait for it to break and then deal with it (my usual MO) I thought I would do some preventative maintenance. I put the car on stands and started it up and put it in gear. The drive shaft wobbles. I just changed the oil seal in the diff. so I had the drive shaft off. Since it was off I replaced the bearings (U joints). I can't believe I put it back together wrong. There aren't that many moving parts. There is a little wobble up by the trans but by the diff it is obvious. I will remove it tomorrow. I've never experienced such a malady before and am at a loss as to a remedy. Should I take it in to be balanced? It worked fine until I 'fixed' it.

If I could get my wife to show me how to do video on her phone I might try to down load a sample.

Thank you, gentlemen, I am in your debt.

d-

[Dodgeb4ya]

A wobbing driveline is a bad situation.

[_shel_ny]

Are you sure that there is a wobble. The drive shaft universals are there to transmit power from the transmission to the differential. That is not a straight line. Thus the universals. generally if there is enough "wobble" to see, it will be felt as well. Just my thoughts. I may be wrong. Would not be the first time.

Edited September 11, 2013 by shel_bizzy_48

[_shel_ny]

That video would go a long way to get some help

[_shel_ny]

Put the drive shaft from your other P15 in and see what happens. Should take less than an hour.

Edited September 11, 2013 by shel_bizzy_48

[Dodgeb4ya]

The drive line tube itself should not have noticeable runout.

[greg g]

Have you no shop in the area that modifies drive trains, lengthening or shortening drive shafts?  They would not only have the means to check your shaft for a bend, but would also have the means to correct it and balance the assembly.  I had a drive shaft shortened, had a u joint installed that fit a chevy yoke on the shaft to a ford yoke on the dif.  They also checked it for bends and balanced the whole shebang.  I believe it ran 90 bucks including two new u joints.  They can also assure the trans mounting flange is square to the shaft.

Edited September 10, 2013 by greg g

[Lloyd]

If it worked fine before you fixed it I would start there. I replaced the points and condenser on a Pontiac once. The engine spit, coughed and cut out bad when I started it. After adjusting timing, replacing timing chain and sprocket, then plugs as a shot in the dark I decided to look where I started.

I had forgotten to tighten down the condenser.

[Dave72dt]

I have to assume there is a slip joint somewhere in the driveline.  Was the slip joint separated from the main driveshaft at some point?  If so I would be considering an out of phase driveshaft.

[wdoland]

I was always told to mark the u joints so you can put it back the same way it came out so it wouldn't be out of balance.

Edited September 10, 2013 by wdoland

[Don Jordan]

I tried to down load a video but was told I am not permitted to upload this kind of file. I know it can be done I just don't know how,.

I'm going to take the drive shaft off and start at the beginning.

I'll keep you posted

[Young Ed]

I have to assume there is a slip joint somewhere in the driveline.  Was the slip joint separated from the main driveshaft at some point?  If so I would be considering an out of phase driveshaft.

 

Not really on these style of ujoint. Each end is free to move in and out within its housing. But there is no way to get it out of phase short of cutting and welding the driveshaft.

[desoto1939]

Don has the old style PIN and Trunion style not the modern cross style.  So there is a road that comes out of the end of the driveshaft that has a small ball on the end.  A pin then goes throught the hole in the ball end.

 

The pin needs to be centered between the ball end.  The entire  pin and trunion fits into a metal housing that has either a leather or rubber boot covering to prevent dirt, water and other crud from getting into the internal workings of the until.  The housing can slide forward and backwards as needed.  There is a metal plate that overs the end of the unit where the housing then bolts onto the end of the trans and at the differential end.

 

These unit are Known as Detroit U joints or Pin and Trunion U joint and they are getting very expensive $150 and up for the internal parts plus the housing.

 

Also there are different sizes for the various cars.  Double check an ebay seller and ask for measurements on the housing and flange size.  There are special Miller Tools to driveout the pins and also to center the pin in the ball end.I have the Miller tool that is used to drive out eh pin and center the pin and also the vise that is used to hole the ball in place and support the ball end. 

Rich Hartung

desoto1939@aol.com

[greg g]

Where is the video hosted, on your computer or on the web?? If it is on the web just post the link rather tha trying to embed it.

[desoto1939]

u joint tool

[Don Jordan]

Sometimes I feel like I'm living in a poorly written soap opera. All I wanted to do was stop the leak in the diff with a new seal. So I took off the drive shaft and noticed the bearing in the U joints (Pin & trunion) were messed up. I ordered from Bernbaum a new set with the rubber dust cover. So far no problem. Got the old seal out and a new seal in. When I went to get the pin and bearings in I just couldn't do it. I took it to my favorite machine shop and they told me the pin was (something like .003") too long. He cut it back and assembled the drive shaft. We now go to commercial break.

Put everything back and took the car out for a spin. Once up to speed I heard a growl that was not right. After inspecting most everything (I didn't suspect the drive shaft because it was all new) I put it on the lift, raised the back tires, put it in gear and let it run. One look and I could see the drive shaft had a wobble to it. Took it off - again. Looked at the yoke (not sure of the terminology) and it was off center. Pulled the plate off and saw that the pin had moved. Took it back to my (almost favorite) machine shop. They remembered me. Old Mike took a look and could not understand how the pin could have moved. I didn't have the guts to tell him it's just me.

Left it with him and he said to call tomorrow after noon.

On a side note the rubber boot I got from Bernbaum is already cracking. In order to replace it I'd have to take everything apart and I'm not up to it. I am a little disappointed in their inventory. I just want my car to run. It's typical that when I finally got all the bugs out and it starts and runs like a dream I still can't drive it.

Didn't mean to go on and on but that's the story. The diff still leaks.

[Dodgeb4ya]

Our local driveup line shop  told me they won't press pins on these Detroit type drive lines because they have seen the pins come loose. I guess the hole in the end of the drive line sometimes gets galled up when removing and replacing the pins regardless as to how they lube the pin. I too have seen them work loose and get off center.The original press fit is extremely tight.

Bob

[Don Jordan]

I wonder if they could drill a hole at the very top and put a screw in to hold it. I will find out this afternoon when I call.

[Dodgeb4ya]

I'd get the shaft converted to a modern type U-joint at this point if it were mine. Peace of mind is relaxing!

Edited September 11, 2013 by Dodgeb4ya

[desoto1939]

Do not convert the old driveshaft because you willbe using 50 plus old material.  If you are going to go to a new DS then get a completely new shaft tube made with the slip joint init and the new spicer ujoints. Have the unit balanced. Then get the extra two spicer u joints for the front and rear to have.  Then you can alwasy use a zert fitting to lube the ujoint every year.

 

The newer ds wil lrun about 350-400.  When you figure in the cost of the old style detroit ujoints which cost 150 and up so for two you already have spent 300 and then the time and money topress the pin in and rebuild another 50.  The DS shop will also align the shaft and install it in a short amount of time.

 

And now you have a modern shaft that anyone can work on.  If it is bent replace the entire unit.

 

JUst my 25 cents worth of data and now you should not have any issues with the driveline. If the old DS is cut you still have to get the parts and also rebalance the shaft.  Go New.

 

Rich Hartung

Desoto1939@aol.com

[Don Jordan]

You guys are certainly free spending the money I don't have. The trunnion U joint has lasted 60 years I'm hoping a new one will last another 60 which is about 40 more than I plan to last.

I asked how much to balance the shaft and was quoted $75. I'm retired - money doesn't flow in like it used to. When I hit the lottery I'll have all that stuff done.

To show you how inflation works most people give their 2 cents worth - Rich actually gave 25 cents. Everything is going up. I guess a penny for your thoughts would net squat.

d-

[Dodgeb4ya]

 When driveshafts vibrate enough they can fail in a scary way. Your new trunnion pin came loose in the driveshaft.The drive shaft hole is now too big for a tight press fit  Yes it costs money to fix things right sad to say. I've sure spent more than I like at times on my old stuff. The old car/truck hobby can cost an arm and a leg. Thats for sure especially if you try to cheat on vehicle safety items.

You should get it fixed right for the other drivers safety too.

See what the machinest says. The shaft cannot be balanced if the pin is loose or comes loose again.

Bob

Edited September 12, 2013 by Dodgeb4ya

[suntennis]

Is the movement of the driveshaft by chance caused by movement of the flange from the rear end? Is it possible the noise problem and the driveshaft movement are from a problem in the rear end? Have you checked the runout of the flange on the rear end?

[Don Jordan]

I put it up on a lift, got the tires off the ground, put it gear and let it run. The shaft had a wobble. I took it back to the machine shop and later I will share pictures of the problem and the fix.

[Dodgeb4ya]

Sounds like it got fixed with out too much trouble!