Pinion Angle again and again and again.

[808muscle]

Auto trans, Shaftmasters DS, J&M adjustable UCA.

I tried -1,-1.5,-2.0,-2.5,-3.0 and all have the same results.... vibration on decel from 60 to 80 mph. Today I set it at -3.5 and it seems this is as far as my UCA will go(control arm is all the way towards motor). Was not able to test drive it up to 80 mph so I dont know if its gonna do anything. I really am not expecting much to be honest.
The vibration is a slight rumble tone NOT like my first shaftmaster DS which had a nasty vibration. I believe the shaft is balanced as shaftmaster sent it to me on their dime to Maui and was my second unit. The telescoping end is at the rear on this unit. My car is not lowered but does have J&M non adjustable LCAs.
What are you guys with auto trans setting your PA at? Is it possible I should be at a + number?
The tech at J&M told me to measure the PA with my digital gauge by zeroing out the unit at the base of the trans (pic) and then setting the gauge on the pinion flange.
Just to be clear turning the control arm sleeve of the UCA towards the motor moves the degree reading more into the negative position? Correct? I ask because with a digital gauge held upside down (magnetic on bottom side) has the arrows point up or down. I am assuming when the arrow points up^ and the gauge is upside down that is a negative reading.

 

[AnotherS197GT]

Have you tried clocking the driveshaft?

 

[808muscle]

Oh yeah did that with the first one. I truly believe the shaft is fine but my UCA setting is wrong some how. Just want to make sure my assumptions on using a digital PA gauge was correct.

I forgot to mention after the DS and UCA install I had set the UCA sleeve all the way to the rear. I did not get any vibration but had a loud hum like noise when accelerating above 95 mph. I didnt like that sound so I started messing with the PA....... loud hum on acceleration went away and was replaced with the vibration on decel instead.

 

[AnotherS197GT]

Is your UCA staying locked? Mine was good for a few days before it worked itself loose. I had my buddy reset the pinion and tack weld it so it wouldn't move. Few months later and I've still got no vibration. I've still got my stock D/S for now though.

 

[gil_t2]

Are you setting just the pinion angle or the difference between the DS and the Pinion?

 

[808muscle]

Are you setting just the pinion angle or the difference between the DS and the Pinion?

I zero out my digital gauge on the trans base then take the pinion flange reading which is currently set at -3.5

 

[cobra mike]

Dude mine vibrates too, I tried everything, im going to take it out and locally rebalenced.

 

[808muscle]

Most people shorten their uca when making the PA adjustment. Has anybody had to lengthen the uca to get the proper PA?
I think I'm reading the digi gauge wrong.

 

[GeorgeInNePa]

Most people shorten their uca when making the PA adjustment. Has anybody had to lengthen the uca to get the proper PA?
I think I'm reading the digi gauge wrong.

To get the recommended number with my OEM two piece shaft, I had to lengthen the UCA.

 

[BruceH]

How about taking it to a shop to check the balance like the poster above is doing? Could save you alot of headaches.

 

[randys06v6]

Bad u-joints? Check em while on the car. Grab with ur fingers two sides of the joint bearing and if it shakes too much then it's prolly bad lol. I had to replace mine on my single piece aluminum. Gave me the shakes like crazy on decel and sometimes on acceleration

 

[808muscle]

How about taking it to a shop to check the balance like the poster above is doing? Could save you alot of headaches.

I wish I could but I live on an island without one available.

I bought a digital angle gauge so I wouldn't be confused....it has made it worse. Lol. If i shorten the uca the arrow on the gauge points up and I get vibrations. Anybody with a one piece driveshaft have to lengthen their uca to get the proper PA?

 

[808muscle]

I am an idiot. Are these gauges (pinion flange) reading positive or negative? Trans bell housing base is reading 0 on both gauges.

 

[CPRsm]

Have you tried the old shaft ? Guessing if you decel the vibration is worse if you engine brake harder?
Can't tell if they are negative by the pics. I always look at it like you have it there, then rotate it until it hits zero so I know which way it is pointed.

The first pick you will end up rotating it counter clock wise to hit 0. Because of this, you know the left side , at 2 deg is pointed up, and the right, down.

 

[cobra mike]

I wish I could but I live on an island without one available.

I bought a digital angle gauge so I wouldn't be confused....it has made it worse. Lol. If i shorten the uca the arrow on the gauge points up and I get vibrations. Anybody with a one piece driveshaft have to lengthen their uca to get the proper PA?

I did, dident help, tried it normal way by setting pinion parallel, and taking 2 degrees out, then tried making saft to pinion 1.5 degrees, still vibrates, but mine is only at high speed. So normal driving isent a issue.

 

[bigwilly43729]

I am an idiot. Are these gauges (pinion flange) reading positive or negative? Trans bell housing base is reading 0 on both gauges.

Looks like whatever you have the dial one sitting on is going down towards the rear of the car. I think that is negative.

I'm sure you already did, but make sure the car is at ride height as much as possible when you do this. Ramps are your friend here.

To tell if you are going positive or negative:

-note the angle that the pinion is at
-make a few turns on the UCA
-note the new angle. This will tell you if you are increasing or decreasing it. Make a note of which way will increase and decrease the angle; I wrote mine on the body of the car with a sharpie so I could see it when I got under there.

I'm pretty sure lengthening the UCA will make the pinion go down, increasing the angle. Someone correct me if I'm wrong though.

I don't want to be the bearer of bad news, but I had the exact same problem you did a long time ago with a Shaftmasters shaft. Would be fine on acceleration up to 90, got vibes on decel. Didn't matter how the angle was set. I even paid a shop to set it; same thing. Automatic transmission & adapter plate on the pinion as well.

Got a Powerhouse and it all went away. Hope this isn't your issue, but I wouldn't be surprised.

If all else fails, maybe this will help:



I ended up using a digital angle finder for piece of mind, but I have two of the dial type as well. They work fine.

 

[rayS197]

Wow, I thought you had resloved this issue! good luck.

 

[dysan]

Something to check is the condition of the crappy rubber bushing that's on the top of the differential that the other end of the UCA attaches to. When mine was shot I had a vibration that I couldn't get rid of so I had a poly bushing installed and it helped tremendously.

 

[GeorgeInNePa]

Looks like whatever you have the dial one sitting on is going down towards the rear of the car. I think that is negative.

I'm sure you already did, but make sure the car is at ride height as much as possible when you do this. Ramps are your friend here.

To tell if you are going positive or negative:

-note the angle that the pinion is at
-make a few turns on the UCA
-note the new angle. This will tell you if you are increasing or decreasing it. Make a note of which way will increase and decrease the angle; I wrote mine on the body of the car with a sharpie so I could see it when I got under there.

I'm pretty sure lengthening the UCA will make the pinion go down, increasing the angle. Someone correct me if I'm wrong though.

I don't want to be the bearer of bad news, but I had the exact same problem you did a long time ago with a Shaftmasters shaft. Would be fine on acceleration up to 90, got vibes on decel. Didn't matter how the angle was set. I even paid a shop to set it; same thing. Automatic transmission & adapter plate on the pinion as well.

Got a Powerhouse and it all went away. Hope this isn't your issue, but I wouldn't be surprised.

If all else fails, maybe this will help:



I ended up using a digital angle finder for piece of mind, but I have two of the dial type as well. They work fine.

Making the UCA longer will point the pinion up.

Making the LCAs longer will point the pinion down.

 

[808muscle]

Wow, I thought you had resloved this issue! good luck.

Nah, it's like herpes.......it won't go away fucking pinion angle bullshit!

I set it and am going racing Friday and Saturday night. Bringing tools if the vibration is bad.