someone please help me understand this.

[trudysduster]

The vibration in my Duster. Been dealing with this for a long time. Come to the conclusion that it is in the engine being imbalanced, or is it. I can feel a slight imbalance sitting still but I have said all along that the vibration feels like a u-joint type but I know it isn't. I am still checking it out until Winter time and rebuild the engine. I had this car to a reputable spring shop and he told me that he set the pinion angle at 3* down. Still vibrates. Here is what I did today. I drove the 73 Dart Sport today to the bowling alley. 4 speed, 8.75 rear and 3:55 gear. I wanted to make sure there was no vibration in it. I pulled this rear housing out of a 67 Coronet and bolted it right under the Dart. My housing was narrowed at Moser Engineering 15 years ago. I don't remember what they asked me about it or how I wanted to use it but the housing was narrowed to be used at the drag strip. That is what I intended on using the car for. I drove the dart Sport, got in it, let off of it, ran it on the interstate at 70 mph and no vibration. So I figured if I check the pinion angle on that car and set the Duster to match I shouldn't have a vibration. Came home put the Dart up on jack stands and leveled the car front to back with a 4' level, pulled the driveshaft and checked the pinion angle. This is what the dart showed. put the gauge on the back of the spline of the tranny. looking at the gauge it showed 1* to the left of the 90. checked it underneath of the tailshaft and it was close to that number. Went back to the rearend and turned the yokes side to side and put the gauge on the part where the strap goes and it showed 3* to the right of the 90. I am assuming that is 4*. not sure if it is up or down but that is what confuses me.
Put it all back together and did the same thing to the Duster. Leveled it perfect. pulled the driveshaft, measured it the same places and this is what I got. Tranny showed 5* to the left of the 90 and the rearend showed about 3* to the left of the 90. In doing some reading I thought one should be up and the other should be the opposite. Mopar Performance said it should be 5-10 with 5-7 optimal. I also read somewhere that ideally it should be at 0. Now my question to you guys is : with these numbers is my pinion angle off. I think so and have said so all along. also if my tranny is 5* to the left of the 90, where do I need to set the rear at to make it right. I am thinking that when Moser set up this rearend, they set the perches wrong. Right now I have a 6* shim according to the spring shop under the perches. It is going from front to back I guess pushing the rear upwards. So without a lot of mumbo jumbo I don't understand about pinion angles, with these numbers, what do I need to do. With both angles being to the left of the 90 I am assuming that both angles are down. Need all the help I can get to correct this. do I shim it and get the right angle and then cut and weld new perches at the right position. I can do that. I am really interested to see if this is where the grind vibration is. Thanks, Bill

 

[bbrroowwnn]

here read this thread and watch the video.....just posted this 2 days ago...they must be parallel

Driveshaft Angle?

 

[bbrroowwnn]

When you say "one degree to the left of 90" is it 89 degrees or 91 degrees? big difference as one is up and one is down.....Use the terms up and down when describing

 

[67Dart273]

I'm confused, Bill. "numbers to the left" means nothing I cannot see what you are seeing. You have GOT to determine whether they are up or down. Don't get confused by "level" the point is you want one shaft in relation to the other, PERIOD.

But to compare them, you certainly need to reference them.

To put this yet another way, the car does not need to be level. You could for example jack the car so that the CRANK (pan rail) is level. That then would be zero, and you can simply then compare the pinion to that zero.

The point is it does not matter as long as you can reference the crank / transmission centerline (pan rail) to some point, and then compare the pinion. But you certainly need to determine up vs down.

I tend to "simplify" things in my own pea brain. I have one digital level which "is not clear" in my mind which way. So I usually tip it until it zeros, and then tip in in a direction which I "know" is up or down, and notice which way the reading is going.

Or hang the gauge right next to the pinion, EG, and level it and look at it which way the pinion is tipped, etc in relation to the gauge.

 

[66fyssh]

That's a great video bbrroowwnn!! The playing card on the sprockets give good audio of what happens when the angles are off. Thanks!!

here read this thread and watch the video.....just posted this 2 days ago...they must be parallel

Driveshaft Angle?

 

[trudysduster]

When you say "one degree to the left of 90" is it 89 degrees or 91 degrees? big difference as one is up and one is down.....Use the terms up and down when describing

I am going to say 89* then. I don't know which side of the 90 is what. I am assuming that the 89 would be 1* down. that is what the dart shows. My Duster then shows 85 * on the tranny or 5* down and the rears show about 87* or what 3* down. so does this mean that the lines will intersect at some point and not parallel. I was thinking about shimming the tranny up 5* so it would be at 90*. and leave the rear at 87.

 

[trudysduster]

I'm confused, Bill. "numbers to the left" means nothing I cannot see what you are seeing. You have GOT to determine whether they are up or down. Don't get confused by "level" the point is you want one shaft in relation to the other, PERIOD.

But to compare them, you certainly need to reference them.

To put this yet another way, the car does not need to be level. You could for example jack the car so that the CRANK (pan rail) is level. That then would be zero, and you can simply then compare the pinion to that zero.

The point is it does not matter as long as you can reference the crank / transmission centerline (pan rail) to some point, and then compare the pinion. But you certainly need to determine up vs down.

I tend to "simplify" things in my own pea brain. I have one digital level which "is not clear" in my mind which way. So I usually tip it until it zeros, and then tip in in a direction which I "know" is up or down, and notice which way the reading is going.

Or hang the gauge right next to the pinion, EG, and level it and look at it which way the pinion is tipped, etc in relation to the gauge.

well as far as the level goes, I was told by another member back when I was trying to figure this out that the car should be on jack stands and it needed to be level. Why I don't know but that is what he told me. Anyway that is where it is at. I have done some reading on google and it says that optimally they both should be 0 or at 90* so both lines are parallel and will not intersect. If I raise the tranny to where the gauge reads 90 and then leave the rear at 87 or 3* down would that work.

 

[trudysduster]

I'm confused, Bill. "numbers to the left" means nothing I cannot see what you are seeing. You have GOT to determine whether they are up or down. Don't get confused by "level" the point is you want one shaft in relation to the other, PERIOD.

But to compare them, you certainly need to reference them.

To put this yet another way, the car does not need to be level. You could for example jack the car so that the CRANK (pan rail) is level. That then would be zero, and you can simply then compare the pinion to that zero.

The point is it does not matter as long as you can reference the crank / transmission centerline (pan rail) to some point, and then compare the pinion. But you certainly need to determine up vs down.

I tend to "simplify" things in my own pea brain. I have one digital level which "is not clear" in my mind which way. So I usually tip it until it zeros, and then tip in in a direction which I "know" is up or down, and notice which way the reading is going.

Or hang the gauge right next to the pinion, EG, and level it and look at it which way the pinion is tipped, etc in relation to the gauge.

so let me ask you this then. If my rearend is 3* down, then my tranny should be about 2* up then to allow for rearend wrap up during normal driving and starts. So with my tranny at 5* down and the rearend at 3* down that is wrong. If I bring the tranny up to about 0-2* and leave the rearend where it is at I should have my 5* then.

 

[66fyssh]

I'm learning right along with you Bill.

As I understand the video, the trans output and the rear pinion need to be straight. But then spring wrap comes into play and the rear pinion should be down a degree or two to allow upward travel.

So, yes, it appears both being down is wrong. If you set the trans at 1* up, that will allow for spring wrap of 2* to end up with 1* down. The offsetting angles of trans at 1* up and rear at 1* down (after spring wrap) should work.

Now, I'm not sure moving the trans is the best way to accomplish this. What do you think @67Dart273? Would it hurt to do it that way?

 

[trudysduster]

I'm learning right along with you Bill.

As I understand the video, the trans output and the rear pinion need to be straight. But then spring wrap comes into play and the rear pinion should be down a degree or two to allow upward travel.

So, yes, it appears both being down is wrong. If you set the trans at 1* up, that will allow for spring wrap of 2* to end up with 1* down. The offsetting angles of trans at 1* up and rear at 1* down (after spring wrap) should work.

Now, I'm not sure moving the trans is the best way to accomplish this. What do you think @67Dart273? Would it hurt to do it that way?

lets see what they say. I am not really interested in learning all there is to know about pinion angles and how they work. What I am interested is someone telling me what I need to do to correct this. If I need to raise the tranny up, I can shim it. If I need to adjust the rear up or down, I can do that. if the tranny should be at 0 and the rearend should be down a couple of *s down to allow for wrap up, I can get it there. If I am understanding all this I have read, when under acceleration the wrap up should not overtake the parallel line. If tranny is at 0, then under load it should not raise up past 0. question is how much will it raise under load. My depend on how good the springs are. Is that where the 5* down comes in according to Mopar Performance. If that is correct, tranny should be at or about 0* and rearend should be at 5* down. Is this right guys. I need to get this fixed. I have had about 10 years of this crap and it is getting old.

 

[trudysduster]

lets see what they say. I am not really interested in learning all there is to know about pinion angles and how they work. What I am interested is someone telling me what I need to do to correct this. If I need to raise the tranny up, I can shim it. If I need to adjust the rear up or down, I can do that. if the tranny should be at 0 and the rearend should be down a couple of *s down to allow for wrap up, I can get it there. If I am understanding all this I have read, when under acceleration the wrap up should not overtake the parallel line. If tranny is at 0, then under load it should not raise up past 0. question is how much will it raise under load. My depend on how good the springs are. Is that where the 5* down comes in according to Mopar Performance. If that is correct, tranny should be at or about 0* and rearend should be at 5* down. Is this right guys. I need to get this fixed. I have had about 10 years of this crap and it is getting old.

I guess they didn't have anything to say. 66fyssh, I will let you know what the outcome is. I will get this figured out.

 

[trudysduster]

I guess they didn't have anything to say. 66fyssh, I will let you know what the outcome is. I will get this figured out.

I tried to raise the tailshaft to try and get it to 0* and I cant go up any because I am hitting the bottom of the floor board. So the tranny will have to stay at about 5* down. I managed to get a pic of the gauge on the spline of the end of the tailshaft. not too good of a pic as the driveshaft is in the way but you can clearly see it is about 85. So with the tranny down about 5 * do I raise the rear up to compensate. I believe it is about 3 * down. pic didn't turn out as the mufflers are in the way. I already have a 6* shim under the front of the rear. Moser had to have set this up wrong unless it is set for strip. Don't know. If I bring the rear up over 0* will that correct this.

 

[Bad Sport]

..

 

[trudysduster]

..

View attachment 1714937461

well since my tranny angle is 5* down and I cannot get the tailshaft raised because it will hit the floor, I am going to raise the pinion angle from 3* down to 3* up so that it will be 5* up under load to cancel out. will see what that does.

 

[trudysduster]

well since my tranny angle is 5* down and I cannot get the tailshaft raised because it will hit the floor, I am going to raise the pinion angle from 3* down to 3* up so that it will be 5* up under load to cancel out. will see what that does.

problem finally solved.

 

[AJ/FormS]

No,No No.
Don't mess with the Tranny, and the nose of the diff should always point down to the ground to keep oil in the bearing.The front angle must be like this ^,driveshaft going down relative to the tranny.
And the rear must be like this V, driveshaft going up relative to the diff.
The car being level matters not a bit.
But if you raise the car, the jackstands have to support the axle tubes and the car should then be raised at both ends to maintain the same weight over the rear springs, cuz if the spring arch changes, so will the pinion angle.
So then it's best to have the raised-up car sitting with the same body-rake, as it had on the ground. This reading is best done on a 4-post drive-on hoist.
Getting back to the angles;.
If the driveshaft goes down from the tranny at a 5* angle relative to horizontal ground plain, and the tranny pan is 2* down at the back, relative to the horizontal; Then the driveshaft is said to be 3* down; (5 less 2); the difference between the driveshaft and the tranny.
If the driveshaft goes down from the tranny at 2* relative to horizontal, and the tranny is 2*down at the back also, relative to horizontal, then 2 less 2 =0, and it is neutral. The measurement is zero difference between the pan and the driveshaft.
Unless the car is severely lowered,the driveshaft will always go down relative to the pan.Correcting for such a driveshaft-going-up situation would be impossible.
For cancellation of vibration due to the u-joint oscillation, the rear angle should match the front; when loaded.This is not always possible. If the car has a lot of power, enough to wrap up the springs, some amount of additional nose-down will be required to prevent u-joint failure. How much depends on how soft the springs are, and how much torque the power-house is putting down.
So whatever the front angle is, you must have at least that, at the back, and some additional amount to protect the U-joint when under full power.Typically, the rear is set up with 5 to 7 degrees; 2 to 4 for the match-up and the rest for wrap-up.Just remember, this angle is between the driveshaft and the pinion. It's really hard to measure it directly, so we measure the installed D/S relative to the horizontal,then remove the D/S and measure the yoke, also relative to the horizontal. Then a bit of math and it's all over.

If you were to raise the tranny, you would increase the pan to D/S angle,(a bad thing),and then you would have to increase the pinion angle in compensation. This would make a mess of things. But if you were able to lower the tranny far enough to make the pan angle equal to the D/S angle, then you would be able to reduce the pinion angle that much more.
However a zero angle is bad. The u-joint needs to run 1 or 2 degrees to shuttle the grease around, but more importantly to prevent the same bunch of needles from doing all the work, all the time. You want 1 or 2 minimum at the front.
You cannot remove the D/S, and measure the tranny and pinion, subtract, and come up with a number. That number has no meaning. The numbers have to be relative to the driveshaft.
The important thing to remember is each angle has to be measured relative to the driveshaft.The front needs to be a minimum of about 2 degrees,and the rear needs to be more than the front.

 

[trudysduster]

No,No No.
Don't mess with the Tranny, and the nose of the diff should always point down to the ground to keep oil in the bearing.The front angle must be like this ^,driveshaft going down relative to the tranny.
And the rear must be like this V, driveshaft going up relative to the diff.
The car being level matters not a bit.
But if you raise the car, the jackstands have to support the axle tubes and the car should then be raised at both ends to maintain the same weight over the rear springs, cuz if the spring arch changes, so will the pinion angle.
So then it's best to have the raised-up car sitting with the same body-rake, as it had on the ground. This reading is best done on a 4-post drive-on hoist.
Getting back to the angles;.
If the driveshaft goes down from the tranny at a 5* angle relative to horizontal ground plain, and the tranny pan is 2* down at the back, relative to the horizontal; Then the driveshaft is said to be 3* down; (5 less 2); the difference between the driveshaft and the tranny.
If the driveshaft goes down from the tranny at 2* relative to horizontal, and the tranny is 2*down at the back also, relative to horizontal, then 2 less 2 =0, and it is neutral. The measurement is zero difference between the pan and the driveshaft.
Unless the car is severely lowered,the driveshaft will always go down relative to the pan.Correcting for such a driveshaft-going-up situation would be impossible.
For cancellation of vibration due to the u-joint oscillation, the rear angle should match the front; when loaded.This is not always possible. If the car has a lot of power, enough to wrap up the springs, some amount of additional nose-down will be required to prevent u-joint failure. How much depends on how soft the springs are, and how much torque the power-house is putting down.
So whatever the front angle is, you must have at least that, at the back, and some additional amount to protect the U-joint when under full power.Typically, the rear is set up with 5 to 7 degrees; 2 to 4 for the match-up and the rest for wrap-up.Just remember, this angle is between the driveshaft and the pinion. It's really hard to measure it directly, so we measure the installed D/S relative to the horizontal,then remove the D/S and measure the yoke, also relative to the horizontal. Then a bit of math and it's all over.

If you were to raise the tranny, you would increase the pan to D/S angle,(a bad thing),and then you would have to increase the pinion angle in compensation. This would make a mess of things. But if you were able to lower the tranny far enough to make the pan angle equal to the D/S angle, then you would be able to reduce the pinion angle that much more.
However a zero angle is bad. The u-joint needs to run 1 or 2 degrees to shuttle the grease around, but more importantly to prevent the same bunch of needles from doing all the work, all the time. You want 1 or 2 minimum at the front.
You cannot remove the D/S, and measure the tranny and pinion, subtract, and come up with a number. That number has no meaning. The numbers have to be relative to the driveshaft.
The important thing to remember is each angle has to be measured relative to the driveshaft.The front needs to be a minimum of about 2 degrees,and the rear needs to be more than the front.

AJ, I have no idea what you just said. all I got out of it was that I cant run a pinion at a pos. angle because the bearing will not get oil to it. I don't know a lot about a lot that goes on here but I do know this. I have a 73 Dart Sport that is running an 8.75 with 3:55 gear for several year now. I personally pulled this complete rearend out of a B body ( Coronet ) sitting along side the dart and bolted it up under the Dart. It has no shims under it nor did it have any under the Coronet. the pinion angle is at 3* up and that is what it was running from the factory as far as I know. Owner told me he had the car most of its life and nothing was done to it. Now if that car came out of the factory at 3* up and I have been running it for years at 3* up how come the pinion bearing is getting oil. 5* is only about 1/8", maybe 3/16" higher than o*. If a person keeps oil in the rearend at a proper level the bearing should get plenty of oil. I have no choice but to raise the pinion angle due to the tail shaft is 5* down and cannot be raised because of the floor. I believe putting the Schumacher mounts caused this problem. The only way around this is to lower the engine and that is not an option. from what I have read a pos. angle can be ran as long as the angles of the tranny and pinion cancel themselves out. They do now. I have no grind vibration now. It shouldn't matter if the tranny is up or down or reversed as long as the angles cancel out. I just have the rear setting where the tranny should be and the tranny where the rear should be. If 3/16" height isn't allowing the pinion bearing to get oil, it is a very poor set up. I could be wrong here. Will find out down the road.

 

[AJ/FormS]

The important things to remember is that all angles are relative to the driveshaft.The ground plain has nothing to do with it, except it is a convenient reference from which to work.
And that the rear suspension has to be at it's normal ride height.This is NOT relative to the ground obviously, cuz it's up on stands. Rather, the shock extension can be your guide. If you have only the rear of the car jacked up, it will shift weight to the front and unload the rear springs. And that will mess up the pinion angle. You have three choices; 1) do the measuring on a drive-on hoist, or 2) jack up the front also, such that the normal front to rear rake is maintained, or 3) re-establish the the rear ride height using shock compression as a reference, and adding sandbags into the trunk to get it,back down.

On an A-body with leafs and a street ride-height, I cannot imagine a situation that would require shimming the tranny up.Don't do it. You will make a lot of work for yourself, that you will just have to undo.

Try this; grab a piece of paper and draw a line about 8 inches long, from left to right. Label the left end "A" and the right end "B".Make a dot in the center or thereabouts, and label it "C".Go to the right end of the line and make a dot about 1/4 inch above the line, and label it "D". Connect the dots C to D. Ignore C to B. Now you have a V. Orient the V so it looks like a V. The line A-C represents the driveshaft. The line C-D, represents the pinion angle. The angle at C represents the 5 to 7 degrees nose down.
Notice there is no ground plain.
If you want to know about where the ground plain might be; draw a new line, approximately parallel to line C-D, and extend it out to the left until it runs under "A". Label it X- Y.
If you want to, you can draw a lie to represent the tranny . Go to point "A", and add it it there, going to the left and about parallel to the line X-Y. Label the end point "Q". The angle that line A-C falls away from A-Q represents the tranny angle, and should be about 2* .It will vary with ride height.

 

[trudysduster]

The important things to remember is that all angles are relative to the driveshaft.The ground plain has nothing to do with it, except it is a convenient reference from which to work.
And that the rear suspension has to be at it's normal ride height.This is NOT relative to the ground obviously, cuz it's up on stands. Rather, the shock extension can be your guide. If you have only the rear of the car jacked up, it will shift weight to the front and unload the rear springs. And that will mess up the pinion angle. You have three choices; 1) do the measuring on a drive-on hoist, or 2) jack up the front also, such that the normal front to rear rake is maintained, or 3) re-establish the the rear ride height using shock compression as a reference, and adding sandbags into the trunk to get it,back down.

On an A-body with leafs and a street ride-height, I cannot imagine a situation that would require shimming the tranny up.Don't do it. You will make a lot of work for yourself, that you will just have to undo.

front of car is on jack stands. car is level front to back. I have no intension on jacking up tranny at this point. If you have read my posts, I made mention that the tranny will not go up due to the floor. I am going to leave it as it is. The vibration is gone.

 

[AJ/FormS]

If your pinion is nose up relative to the ground 3*, and you have enough power to wind up the springs and send the pinion more than the compensated for, 5 to 7*, then when under full load your pinion angle could be 3+ 5to7 +Say 3 = 11 to 14 relative to the ground. Just make sure the oil can get up there