Aluminum driveshaft installed and now have a new problem.

[Sublime/Sixpack]

The correct wedges under the rear spring perches should give you the 2 degrees down of the pinion in relation to the trans. output shaft. That's what you're after right?

Correct, but when the current output shaft is at 5* down from front to back the amount of change at the pig is beyond reasonable.  I'm no expert, but I'm basing my thoughts on what I've gathered on threads here and on google....,

Bob, if the output on the trans/GV is 5* down then you need to get the pinion at 7* nose down to achieve the desired 2* nose down result. 

Shim stacking may be difficult depending on where it is now ? 

There are two options the way i see it :

(1) Have custom shims/blocks made to correct the pinion angle. You will need longer u-bolts to make this work

(2) Cut the spring perches off the axle tubes and have them rewelded with the proper pinion angle adjusted into the axle housing

I'd be interested to see where your current pinion angle is at on the differential. 

If as you stated previously the pinion is pointed up...we know that the pinion angle is waaaay off and needs correction. 



Ron

[RECHRGD]

Just a shot in the dark here but the lighter DS would reduce the at speed vibration but possibly offer less dead weight against axle windup?   Could lowering height of the shackles or raising the front eye bolt holes somehow correct pinion angle just enough to stop bind up?    

Maybe, I'll be looking at any and all solutions.  This was going to be my final fix after years of living with a less than perfect set-up.  I feel like just taking off the GV and using it for target practice.....

I've followed your subject a long time and you have me never wanting to add G.V. at time.  

The funny thing is, most people have no problems at all.  I'm just lucky, I guess.....

[Sublime/Sixpack]

Bob, if the output on the trans/GV is 5* down then you need to get the pinion at 7* nose down to achieve the desired 2* nose down result. 

.
Ron
[/quote]


[/quote] I may have "yes nodded" too soon. Ron, this doesn't sound right to me.

[b5blue]

Bob we have the same luck!  (none)

[firefighter3931]

Ok, scratch my previous message....must have been having a brain fart.   I was thinking of mine which had the opposite problem that Bob is having....my trans output points up...not down  

Bob, here's a chart that you may or may not have seen.

Pull the driveshaft and using an angle finder place it on the trans seal and yoke flange as illustrated in the top of the pic. This will give us the differentials between the two. The idea is to get the centerline paralell.

If the trans seal is indeed 5* down then the pinion needs to be 5* up to achieve a 0* pinion angle. Then you have to subtract 2* to correct for axle windup under hard acceleration.

I'll be interested to see what numbers you come up with  


Ron


Here's the link : http://www.moparts.org/Tech/Archive/axle/8.html

[b5blue]

You linked to reply same topic Ron.

[cdr]

Ok, scratch my previous message....must have been having a brain fart.  I was thinking of mine which had the opposite problem that Bob is having....my trans output points up...not down 

Bob, here's a chart that you may or may not have seen.

Pull the driveshaft and using an angle finder place it on the trans seal and yoke flange as illustrated in the top of the pic. This will give us the differentials between the two. The idea is to get the centerline paralell.

If the trans seal is indeed 5* down then the pinion needs to be 5* up to achieve a 0* pinion angle. Then you have to subtract 2* to correct for axle windup under hard acceleration.

I'll be interested to see what numbers you come up with 


Ron


Here's the link : http://www.dodgecharger.com/forum/index.php?action=post;topic=109927.25;num_replies=28

all this that has been said depends on the trans yoke being higher up than the yoke on the rear end.

to make it real easy check that 1st & let us know.

[firefighter3931]

You linked to reply same topic Ron.

Geez, some days it just doesn't pay to get out of bed  Maybe i should just stop posting on Bob's thread, lol 

Thanks for the heads up Neal....fixed it ; proper link now in place. 


Ron

[RECHRGD]

OK, being that we know that the pinion needs to go down regardless of the other angles I went ahead and turned around the 4* shims that were giving it a 6.5* nose up angle.  That produced a 5* nose down angle.

Here is what I started with:  from front to rear the tailpiece of the tranny dropped 5*.  The DS angled up 2* to meet the pig.  From rear to front the pig angled up 6.5* to meet the DS.  This setup got me pretty close to the parallel but opposite recommended scenario, but with every thing going in the opposite direction that I need.

After turning the shim around this is what I am left with:  From front to rear the tailpiece still has the 5* drop.  The DS now angles down 1* to the pig.  From rear to front the pig now angles 5* down.

I can get about 1* of drop out of the tailpiece if need be, but no more.  I guess the next question is; just how critical is the parallel but opposite configuration?  I could use some 2.5* shims I have and that would put the pig at 3.5* down and probably get the DS on a slight upward angle.  The saga continues......

[cdr]

I WOULD want the 3.5 down.then go drive it

[RECHRGD]

I WOULD want the 3.5 down.then go drive it

That's what I was thinking too.  Looks like rain for the next few days so the drive will have to wait.

[Bobs69]

gear vendors has a good tech line.......

[fy469rtse]

Can I throw in something else into the equation, I remember one other member having vibration issues regardless of pinion angles and such ,
After all it turned out to be the slip yoke, something about 518 and 727 splines not quite the same, maybe? relying on memory , but vendors assume they are, have a look for thread , slight differances in out put shaft od 
Each would fit the 727 spline but not the other way round just a thought

[RECHRGD]

Can I throw in something else into the equation, I remember one other member having vibration issues regardless of pinion angles and such ,
After all it turned out to be the slip yoke, something about 518 and 727 splines not quite the same, maybe? relying on memory , but vendors assume they are, have a look for thread , slight differances in out put shaft od 
Each would fit the 727 spline but not the other way round just a thought

That was probably my old thread.  The different yoke didn't work.  Finally got into the livable range by spending hours and hours balancing the driveshaft while on the car.  Should have left well enough alone.....

[fy469rtse]

Can I ask a silly obvious question , you have tried other wheels too, a friends car had a vibration, tracked it down to perfectly balanced wheels just not straight, picked up on this only because I was following him ,

[RECHRGD]

Can I ask a silly obvious question , you have tried other wheels too, a friends car had a vibration, tracked it down to perfectly balanced wheels just not straight, picked up on this only because I was following him ,

Back when I was fighting the initial vibration problem, I even took the wheels off and ran the car up to speed with the rear jacked up.  The vib was still there.....

[Bobs69]

Has the drive shaft been high speed balanced?

[RECHRGD]

As I said before, at this moment, anyway, I'm not chasing a vibration.  I'm simply changing pinion angles so I can accelerate without the pig rotating out of its normal range and tearing things up.  When dealing with the original small driveline vibs after the GV install, I had two different driveshafts built and both were high speed balanced.  The only way I ever got the vibs down to a livable level was by rebalancing the DS on the car.  Spent many hours trying different weights at different spots.  The aluminum DS was just my last effort to kill off the last of the vibs by having less rotating mass.  Go read the original post.......

[Bobs69]

I read it.  Read it again like you said.  I'll watch to see how you solve this.  Guess I was one of the lucky ones.