pinion angle update

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trudysduster

trudysduster

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I went to Harbor Freight and bought the magnetic angle guage you guys told me. neat little tool. I measured under the pinion housing and got a 10 reading I assume nose up. I measured under the driveshaft just in front of the u-joint and got a 3 reading. So with that I am assuming I should get a 6 degree wedge from Summit and shim the rearend and bring the nose down so it reads close to a 1.The reading I got at the tailshaft and front u-joint was almost 0 so I am also assuming that the pinion is where my vibration is in the car. You know what they say about assuming.What is your opinion on this guys. I appreciate it. This car is not used for racing at all. Maybe a once in awhile tire smoker but mostly cruising.Thanks,Bill
 
Are you getting a vibration?
 
I have the car on jack stands and they are under the front frame rails in the front and under the springs in the rear. Stroker, I do have a vibration as mentioned in a previous thread called vibration problem a few days ago.
 
FWIW I just installed an 8 3/4 rear in my Dart and have the pinion angle set at -2* I have no vibration at cruise or when I have the pedal to the metal.

I had jack stands under the rear so that the weight of the car was on the suspension when I checked it.
 
You cannot assume your pinion angle is "nose up" unless and until you measure the angle of the DRIVE SHAFT YOKE itself. The angle you are wanting is the difference between the drive shaft angle and pinion angle. THAT'S what you're looking for. As I said in the other thread, the Mopar Suspension manual ninth edition is your friend here. I cannot stress that enough. It states 5-7* nose down in relation to drive shaft angle. It has absolutely nothing to do with the ground as a reference. And yes, you are supposed to measure it with the weight of the car on the wheels or axles. Theoretically, as long as the suspension is at the correct ride height, you could flip the car upside down, sideways, on end or at any angle you wanted and measure the working angle of the drive shaft and get it right. Because that angle has no other basis other than the actual difference between the pinion and drive shaft angles. My guess is, you are 10* nose down and need to be 5-7*. Remember, you can be nose down with the pinion pointing up at the floor pan (and that's usually how 99% of cars are) when you look at it because it hasn't a thing to do with the ground or the body of the car. It's all about the drive line.
 
And after all of this I bet the driveline is out of balance or bent, and it's not the angle at all.
 
TrailBeast said:
And after all of this I bet the driveline is out of balance or bent, and it's not the angle at all.
Click to expand...

And you know what? You win the prize. Nine times outta ten, the factory got the pinion angle really close. Unless one has been swapped and cannablized all to hell and such, they are generally pretty close.
 
You need weight on the car at all 4 corners to be accurate. You WILL get false readings if you do not.
 
I want to thank all you guys for your input. I dont know jack **** about this angle stuff. That is why I asked. I told you what I read on the guage and where I read it at and how the car is sitting. I dont know if the nose is up or down. I just purchased the book you talk about from Mancini but have not gotten it. The driveline is not bent because I just spent $200.00 getting it lengthened and balanced. I just had new joints put in. I thought I could get some info from you guys but I dont know much about it. All I can do is tell you what I measured and where. I guess I will have to save up $130.00 -$180.00 and take it to the spring shop and let them set the angle. I thought I had it figured right but I guess not. Thanks anyway.
 
Hang in there you can get it. Just need some help through it. Post pictures of each of the two measurements. And then we can tell you what you have and how to read them.

I did this with that Habor Freight ~$30 digital gauge they sell. It's very small and I did all the measurement with just the rear end housing on jackstands. The pads on that gauge are small enough to put on the end of the driveshaft yoke.

I have pictures of my two measurements, but won't be able to post them until friday night.
 
If you have a vibration only under load or a decel load then you have a pinion angle issue....

Like mentioned earlier you need to make the pinion 3 to 5 degrees opposite the shafts angle.

I hope you aren't wasting time, pinion angle vibes are very different then vibes at speed and cruising.... which if you have those, don't make other issues for yourself
 
Look dude, I cannot stress enough, the best thing for you to do is get the Mopar Suspension book. If you're gonna keep your car pretty much stock suspended in the rear, that's all you need. It's not hard to understand. There are good illustrations that explain it all very well. Even if you find out the problem is not the pinion angle, you will have a wealth of information instead of a bunch of differing opinions on a web forum.


trudysduster said:
I want to thank all you guys for your input. I dont know jack **** about this angle stuff. That is why I asked. I told you what I read on the guage and where I read it at and how the car is sitting. I dont know if the nose is up or down. I just purchased the book you talk about from Mancini but have not gotten it. The driveline is not bent because I just spent $200.00 getting it lengthened and balanced. I just had new joints put in. I thought I could get some info from you guys but I dont know much about it. All I can do is tell you what I measured and where. I guess I will have to save up $130.00 -$180.00 and take it to the spring shop and let them set the angle. I thought I had it figured right but I guess not. Thanks anyway.
Click to expand...
 
This is the handy and small ~$30 digital angle finder from Harbor Frieight. I borrowed this from someone.

The first picture did not capture the blinking up and down directional arrows.

Then I installed 4 degree shims to get 4 degrees differance (rear end down relative to the driveshaft).

Last picture is of me getting cute by polishing the shock stud in hopes that it prevent sqeaking and make and easy sliding surface. I did the washers too. Have no idea if it will work, but didn't cost me anything.
 

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That isn't correct, quite a few of the detroit end yokes has a slight angle to it where you used the angle finder, you need to take the reading off of and across the end yoke saddles where the strap kits hold the joint in. . . . .

OR a perfectly square extension off the joints cap
 
Supershafts said:
That isn't correct, quite a few of the detroit end yokes has a slight angle to it where you used the angle finder, you need to take the reading off of and across the end yoke saddles where the strap kits hold the joint in. . . . .

OR a perfectly square extension off the joints cap
Click to expand...

YUP! Whattya know? We agree on sumffin! I'll also add this to the mix. Instead of taking that measurement off the drive shaft for the drive side, it shouldda also been taken off the ujoint cap on the drive shaft side. But of course, when doing that off the ujoint caps, you need to make sure they are perfectly verticle, or the readings will not be correct.

Imagine that. Wonders never cease.

Edit: Proof of your statement can clearly be seen in that pic, too. Look at the side of the pinion yoke. It clearly tapers going toward the front of the car.
 
Can you use the snubber mount on the center to get the angle and use the pulley on the crank?
 
ok folks sorry for being the village idiot but in the above pic's on the gauge i see the numbers 260 and 230. how does this apply to the 2,3,4 or 5 degress we have been speaking of????
 
terry said:
ok folks sorry for being the village idiot but in the above pic's on the gauge i see the numbers 260 and 230. how does this apply to the 2,3,4 or 5 degrees we have been speaking of????
Click to expand...

That is actually 2.60 and 2.30

On this gauge the there are up and down arrows that flash on and off to show you which direction the gauge is tilted.

Sorry, I could not catch the with the camera under the car. But they are both angled upward toward the motor. So they were basically parallel. I ran a 4 degree wedge and ended up with about a 3 degree split.

But from what others have said there could be a chance the machined surface I used was not paralled to the centerline of the pinion.

Terry, I borrowed the gauge from a friend. So I couldn't check yours. And apparently it was done wrong.
 
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