Tail / Driveshaft Angle..???

Can anyone tell me the correct and proper angle at the driveshaft / tailshaft connection? A tranny guy has told me that I have too little on my 360/727......it is pretty slight.........How much difference would raising the back of the tranny a quarter to half inch make relative to possible vibrations?

Anybody have a pic of a proper set-up? (727-A)............. I'd like to have a definitive answer on what the factory did..........

I've been told that the angle itself can cause harmonic vibration if it's too little, and others have said it doesn't matter at all............

..............and can you check the torque converter for balance weights by peering through the dust cover?........Never had to check it before like this......Can you see them or not? :read2:

http://www.rosslertrans.com/Pinion Angle.htm
http://restomod.us/PinionAnglePage.htm

OK..........It appears that my pinion angle is good (as mech's have said before).........but at standstill, I have about 2 degrees downward angle of the driveshaft (or a hair less)...........not much.........I'm wondering if that's about right......pinion angle illustrations don't really answer it.........

Now, it seems to me that under acceleration, the line would be nice and straight.....(which is optimal).....or MAYBE just a tiny bit out at the tailshaft / yoke connection..........

Now, please tell me how this would cause a vibration in that area at a "cruise" on your gas pedal (zero pressure torque).............??

Just makes no sense to me..........this is what yet another trans man has told me..........and again, they're talking a couple to few hundred bucks more to raise the tranny tail a bit and correct the problem.............Just seems like more hit and miss........problem is that they use my cash for the target practice.........

They have shims you put under your axel for this. You don't have to jack with the trany at all. If you really wanted to do it right. Just cut the spring seats off and weld them back on where ever you need to to get the angle right.

That's logical, BUT the rear pinion angle is OK..........

......it's the angle of the driveshaft yoke to the tailshaft that they say is screwed up..........The car was a 904 car, and has been converted to a 727..........he believes the front angle must be adjusted........

But again, it escapes me how the front angle being about 2 degrees at park would cause a vibration at cruise speed.............????

pastortom1 said:

That's logical, BUT the rear pinion angle is OK..........

......it's the angle of the driveshaft yoke to the tailshaft that they say is screwed up..........The car was a 904 car, and has been converted to a 727..........he believes the front angle must be adjusted........

But again, it escapes me how the front angle being about 2 degrees at park would cause a vibration at cruise speed.............????

Click to expand...

I see now. I will do some looking for you when I get home all my books are there. Sounds a little strange to me though. If the rear is good how can the front be off? I will look and get back to you. Will get it figured out. Some one here will know what is going on.

Good luck.

pastortom1 said:

Can anyone tell me the correct and proper angle at the driveshaft / tailshaft connection? A tranny guy has told me that I have too little on my 360/727......it is pretty slight.........How much difference would raising the back of the tranny a quarter to half inch make relative to possible vibrations?

Anybody have a pic of a proper set-up? (727-A)............. I'd like to have a definitive answer on what the factory did..........

I've been told that the angle itself can cause harmonic vibration if it's too little, and others have said it doesn't matter at all............

..............and can you check the torque converter for balance weights by peering through the dust cover?........Never had to check it before like this......Can you see them or not? :read2:

Click to expand...

Here's an article that gives you both the tranny to shaft and shaft to pinion angles and yes you will be able to see the converter balance weights after removing the dust cover. If they are there they will be tack welded to the front face of the converter (the face that bolts to the flex plate). http://www.moparts.org/Tech/Archive/axle/8.html

Terry

OK boys.............I'm a goin' under !:toothy10:

with the links scamp sent you, you might try 5 deg. pin. ang. I have a service manual for 67 ply. and even they dont give an exact degree. they just give a chart with there special tool that`s just a graduated level tool. what I`v always read, is what ever angle the shaft comes off the tranny, the same angle from shaft to pinion? I need to get mine corrected too, cause I rearched the springs for clearance. mine starts to viberate around 70 mph. It used to be way worse cause of tire balance issues. had my rebuilt shaft checked by another balancer and said it was good. running mags without weights on outside of rim can cause viberation problems. goodluck let us know how it turns out.

Tom , The Angle itself CANNOT cause a vibration. Though, an excessive angle will increase the wear rate of the U Joints. A worn u-joint could cause vibrations very silmilar to a flat spotted tire. (Ask me how I know) PM me, I'm not that far from you.

Happy New Year ! Eric

pastortom1 said:

Can anyone tell me the correct and proper angle at the driveshaft / tailshaft connection? A tranny guy has told me that I have too little on my 360/727......it is pretty slight.........How much difference would raising the back of the tranny a quarter to half inch make relative to possible vibrations?

Anybody have a pic of a proper set-up? (727-A)............. I'd like to have a definitive answer on what the factory did..........

I've been told that the angle itself can cause harmonic vibration if it's too little, and others have said it doesn't matter at all............

..............and can you check the torque converter for balance weights by peering through the dust cover?........Never had to check it before like this......Can you see them or not? :read2:

Click to expand...

I didn't see how the angle alone would cause this harmonic either......makes no sense.......he wants to increase the angle further, which in theory could make any actual vibration at that area WORSE at a normal zero torque cruise speed.

My balancer seems to be OK........I can't get in there myself to see the converter, so I'm gonna have to wait until tomorrow when they check it outm to see what's up........From all that I'm feeling, I believe the torque converter needs a flexplate OR needs to be swapped out, AND I think the output shaft needs to be changed as well....and maybe the front yoke to be safe.

I'll post some results on their diagnosis tomorrow or Thursday........:read2:

pastortom1 said:

I didn't see how the angle alone would cause this harmonic either......makes no sense.......he wants to increase the angle further, which in theory could make any actual vibration at that area WORSE at a normal zero torque cruise speed.

My balancer seems to be OK........I can't get in there myself to see the converter, so I'm gonna have to wait until tomorrow when they check it outm to see what's up........From all that I'm feeling, I believe the torque converter needs a flexplate OR needs to be swapped out, AND I think the output shaft needs to be changed as well....and maybe the front yoke to be safe.

I'll post some results on their diagnosis tomorrow or Thursday........:read2:

Click to expand...

The torque convertor being out of balance is not taking out the tail of the trans .

you need to go to a chassis shop that has the proper tools to measure and check your angles , does the car have an original a body rear in it ? what about your rear springs , what type ?

I allmost forgot to ask the simplest of questions. Are you having the vibrations moving or standing still? Assuming it's moving, is there any speed it is more pronounced? Or Condition ... Accelerating, Maintaining speed, or Coasting? If it's standing still by chance, then it can only be the Engine/ Verter Balance as those would be the only things spinning.

Eric

Eric's right. If it vibrates in park it's an engine balance problem. If it vibrates moving it's a driveline problem. If it does vibrate in neutral that is an engine balance problem and if you remove the starter and inspection cover you can roll the engine over by hand and you should be able to easily see if the converter has weights on it. they will be located on the front side of the verter between 2 of the bolts. They will also be exactly opposite of the counterweight on the harmonic balancer so if you put the counterweight on the balancer on the top the weights on the verter will be on the bottom.

If I remember right for every 1/4" you raise the tailshaft of the trans it will increase the output shaft angle by 2 degrees. You do need to get the angles right on the front and the back to make the U-joints last a good long life and if the angles way off it can cause a vibration. You also have to take into consideration how engine torque twists the rearend upward when setting the angles and that means if the car is just mainly street driven you don't need as much downward angle on the rearend as you would a racecar. I have mine set up with the trans. up 1 degree and the rearend down 5 degrees. 1 degree up on the trans. minus 5 degrees down on the rearend leaves a 4 degree difference while standing still. I plan on racing mine some so that's why I have that much angle but if you don't race 2 degrees difference is enough. BTW: when setting up mine I first tried the rearend 7 degrees down (6 degrees difference) and it had a little vibration while cruising so it is true that too much angle can cause a vibration.

BTW you can easily check the trans. output shaft angle by placing the angle finder on the harmonic balancer because it's a perfect straight line throughout the driveline.

And I'd like to add that if any shop want's to charge you several hundred dollars just to make a shim and install it under the trans. mount their rip offs. That's an hour job at most with $5 worth of metal.