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Pinion angle guru's! Help needed!

Posted By: 1MYTGTX

Pinion angle guru's! Help needed! - 05/15/14 06:04 PM

Chasing down a cyclic vibration for years that I get between 60- 75 mph. Wheels balanced numerous times, brand new high speed balanced drive shaft etc.

Finally getting around to checking pinion angles! Please see attached pics.

First is at trans.....looks like 2º





Next is taken at rear... looks like 4.5º



My question is....what do I need to do to get an optimal reading? Is this an optimal reading? I was proactive & ordered up some 2.5º shims from Rick E. on eBay. Will these help?

Thanks in advance!
Posted By: ditchdrift

Re: Pinion angle guru's! Help needed! - 05/15/14 06:21 PM

at ride height the output shaft and pinion shaft should be parallel with each other unless you a running a double cardan type driveline. With that being said, im not sure if 2.5 degrees is enough to cause a vibration like that.
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/15/14 06:23 PM

Were all the reading taken with the vehicle on all 4 tires/suspension loaded?, meaning on the ground, or 4 post lift?....


2 degrees down on the tranny driveline angle, correct?, and 4.5 degrees on the pinion up (nose up), correct?...if so, you can either effect the tranny with some shims on the tail mount, to achieve a 0 baseline, either way your pinion needs to come down, if you leave the 2 degrees down on the tranny, your pinion should be 1-2 degrees down stationary reading, your pinion will rotate upward 2-4 degrees UNDER acceleration depending on your rear suspension/vehicle rake, which would theoretically raise your pinion UNDER acceleration to approx. 2 degrees up, putting it on the same parallel driveline angle as the transmission, you also need to calculate that your U joints have at least a 1-2 degree deflection for them to properly rotate...


mike
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 06:41 PM

half way Mike.....fronts were on ground. I had the rear loaded on jack stands.

For what ever reason there is a washer in between each bolt of the trans mount. Might have been an early attempt a few years ago...dont remember putting them there!

Thats the thing. not really sure how to read the gauge. I thought the trans side was +2º (because it was to the left of the 90º mark) and the rear was -4.5º (because it was to the right of the 90º mark)

I feel if I pull those washers out I might get to 0º on the trans side...

Chris
Posted By: RobX4406

Re: Pinion angle guru's! Help needed! - 05/15/14 06:42 PM

Both of those readings look to be down, so the pinion angle is -6.5*. Usually too much for a street car.

When you get the 2.5* shims, place the fat end towards front of car to roll pinion up and that should get you a -4 pinion angle which is about the max I'd run on a driver car.
Posted By: Copper Dart

Re: Pinion angle guru's! Help needed! - 05/15/14 06:50 PM

Quote:

Both of those readings look to be down, so the pinion angle is -6.5*. Usually too much for a street car.

When you get the 2.5* shims, place the fat end towards front of car to roll pinion up and that should get you a -4 pinion angle which is about the max I'd run on a driver car.




Too much pinion down.
I would bet that can/would cause your vibration issue.
Posted By: skicker

Re: Pinion angle guru's! Help needed! - 05/15/14 07:06 PM

Quote:

half way Mike.....fronts were on ground. I had the rear loaded on jack stands.



Chris



If the rear was on jack stands and the fronts were on the ground neither reading is correct. The protractor is designed to be used on something level. Best way to check would be on platform lift. That way the car is at ride height and loaded and you'll still be able to see what your doing.
Posted By: RobX4406

Re: Pinion angle guru's! Help needed! - 05/15/14 07:15 PM

Quote:

Quote:

half way Mike.....fronts were on ground. I had the rear loaded on jack stands.



Chris



If the rear was on jack stands and the fronts were on the ground neither reading is correct. The protractor is designed to be used on something level. Best way to check would be on platform lift. That way the car is at ride height and loaded and you'll still be able to see what your doing.



Doesn't really matter as long as the suspension is loaded and at ride height.

The relationship of the pinion and trans yoke are the same. Merely the difference in observed angles and the plank they are attached.
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 07:16 PM

Quote:

Quote:

half way Mike.....fronts were on ground. I had the rear loaded on jack stands.



Chris



If the rear was on jack stands and the fronts were on the ground neither reading is correct. The protractor is designed to be used on something level. Best way to check would be on platform lift. That way the car is at ride height and loaded and you'll still be able to see what your doing.



Ugh I was afraid of that. Really dont have access to one.

The proper way to measure is to have drive shaft out correct? Next time I will take drive shaft out and lower car fully on ground....might be able to snake under there to get another reading...
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 07:20 PM

Quote:

Both of those readings look to be down, so the pinion angle is -6.5*. Usually too much for a street car.

When you get the 2.5* shims, place the fat end towards front of car to roll pinion up and that should get you a -4 pinion angle which is about the max I'd run on a driver car.



Thanks Rob! Hopefully that should do it. You think I should leave those washers under trans mount?

Chris
Posted By: RobX4406

Re: Pinion angle guru's! Help needed! - 05/15/14 07:41 PM

I'd leave the washers because the trans rear will nose more down which will increase the angle.

Right now, the trans is down 2*. To get the pinion so the angle is "0", you need it UP 2*. That gets it parallel with your trans output shaft. From there you roll it down whatever you need.

Another way to figure out if what you are working with is pointing up or down. When you get your reading, pivot the angle finder so it's at "0". If the opening of the V created is up, then the item measured is pointing up, Opening Down, it's pointing down. In your case both items would pivot at the top point creating the opening of the V at the bottom or down.
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 07:44 PM

Thanks Rob for simplifying that.

Im gonna install those shims like you suggested soon & report back. Thanks!
Posted By: RobX4406

Re: Pinion angle guru's! Help needed! - 05/15/14 07:49 PM

http://www.moparts.org/Tech/Archive/axle/8.html

The rossler trans pic in that link is a great example of how to do this.
Posted By: skicker

Re: Pinion angle guru's! Help needed! - 05/15/14 08:40 PM

Quote:

I'd leave the washers because the trans rear will nose more down which will increase the angle.

Right now, the trans is down 2*.



If the car was jacked up and on stands in the rear the trans is not- may not be down 2*. Depending how far the rear tires were off the ground there could be maybe 3* of variance. I agree the split between the two is the same. Its just a hinky way to figure it out.
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/15/14 09:35 PM

Chris, the things to keep in mind, the suspension needs to be loaded when using the inclination meter, it doesn't matter the rake/angle of the vehicle, as long as the dimensions you are taking are done completely front to rear along the driveline for that moment/set-up, and any changes are based on the current data taken, also your pinion rolls up 2-4 degrees during acceleration, and that your U joint angles should be 1-2 degrees deflection along the various planes measured for proper U joint rotation to avoid vibration/binding, you don't want a U joint with 0 degrees between planes, the pic below is what your driveline angles should look like UNDER acceleration, not a static set up, 0 or nose down is the preferred angle for the pinion, but a lot of factors will determine where the driveline angle needs to be

Mike

Attached picture 8145636-2joint_angle.gif
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 09:43 PM

Thanks Mike. AS per the readings I got do you think the 2.5º shims will help?
This is a stock suspension car set up for cruising, not racing. Thanks
Posted By: RJS

Re: Pinion angle guru's! Help needed! - 05/15/14 10:00 PM

Chris I know you have been chasing this off and on for a few years. Now even though the car doesn't get miles like a street car I would think that U-Joint failure would have reared it's ugly head by now or seal problems. That is of course if you haven't changed them since the original build.
Ronnie
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/15/14 11:33 PM

Nah Ron, nothing like that at all. All good in those areas. With Carlisle fast approaching once again, I'd like to finally nip this in the bud for the 3 hour ride!
Posted By: RapidRobert

Re: Pinion angle guru's! Help needed! - 05/16/14 01:54 AM

#1 #1 What I would do is get the wheels up on blocks on all 4 corners so you have room to work & add cardboard/tile etc under each block till you get it level side to side and end to end. Then as said if the trans is down 2 then you want the pinion up 2 (& vice versa) then move the pinion down an addit'l amount to account for pinion climb (iirc you said cruising/no hot rodding so not much might be needed) so add in the addit'l down amount the guys here recommend. You can raise the trans with washers above the mount or lower it by slotting the 4 bolt holes in the crossmember as needed within reason so that you might not have to use the rear axle shims or even rewelding new perches but find/post your angles. The only other caveat is you dont want the shaft angle on the front end of it to be the same angle as the trans and on the back end of the shaft you dont want the shaft to be the same angle as the pinion (need 1-2 deg difference on each end of the shaft). in other words you dont want the shaft and trans in a straight line and the you dont want the shaft and the pinion in a straight line. Keep in mind you are wanting to check the relationship between the angle of the trans and the angle of the front of the driveshaft (which is the front ujoint angle) and the relationship between the angle of the pinion and the angle of the rear of the driveshaft (which is the rear ujoint angle) cuz it is the ujoint angles that we want correct. We're only measuring degrees away from horizontle to get a baseline to get our angle numbers from as the car could be climbing up a hill & the ujoint angles would be the same. I hope that helps rather than making things more confusing. EDIT For the vibration check the amount of yoke engagement into the trans (want ~3/4-7/8"). My driveshaft was slightly too short & it caused a part time vibration in my 904/65 dart that came and went. The correct shaft quieted it. Also your shaft may not be balanced good enough, iirc yours is new but mistakes do happen
Posted By: cudaman1969

Re: Pinion angle guru's! Help needed! - 05/16/14 05:35 AM

Quote:

#1 #1 What I would do is get the wheels up on blocks on all 4 corners so you have room to work & add cardboard/tile etc under each block till you get it level side to side and end to end. Then as said if the trans is down 2 then you want the pinion up 2 (& vice versa) then move the pinion down an addit'l amount to account for pinion climb (iirc you said cruising/no hot rodding so not much might be needed) so add in the addit'l down amount the guys here recommend. You can raise the trans with washers above the mount or lower it by slotting the 4 bolt holes in the crossmember as needed within reason so that you might not have to use the rear axle shims or even rewelding new perches but find/post your angles. The only other caveat is you dont want the shaft angle on the front end of it to be the same angle as the trans and on the back end of the shaft you dont want the shaft to be the same angle as the pinion (need 1-2 deg difference on each end of the shaft). in other words you dont want the shaft and trans in a straight line and the you dont want the shaft and the pinion in a straight line. Keep in mind you are wanting to check the relationship between the angle of the trans and the angle of the front of the driveshaft (which is the front ujoint angle) and the relationship between the angle of the pinion and the angle of the rear of the driveshaft (which is the rear ujoint angle) cuz it is the ujoint angles that we want correct. We're only measuring degrees away from horizontle to get a baseline to get our angle numbers from as the car could be climbing up a hill & the ujoint angles would be the same. I hope that helps rather than making things more confusing


This was what i was going to suggest, make 4 square boxes with 2x12s lay a 3/4 piece of ply on top with stops on the ends so it won't roll off. Easy to get under for checking or fixing. Drive shaft is probably out of balance too.
Posted By: NITROUSN

Re: Pinion angle guru's! Help needed! - 05/17/14 05:33 AM

You must have a mis-match of parts on your car. What is the component configuration on your car?
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/17/14 06:31 PM

Quote:

You must have a mis-match of parts on your car. What is the component configuration on your car?



Stock 727 trans, stock mount.....stock drive shaft, stock 8 3/4" rear...stock Hemi leaf springs (NOT Super Stock) stock hangars etc....

Nothing mis-matched as far as I can see
Posted By: RapidRobert

Re: Pinion angle guru's! Help needed! - 05/17/14 09:27 PM

I would suggest going ahead & getting it (the tires) up on blocks & leveled side to side and front to rear cuz we need a tight ship on this one & yes Dayclona is right that the rake is unimportant since if for instance it was way tilted up front to rear & the trans was down say 10 from horizontle and the shaft was down 12 from H then the shaft is 2 deg down cuz it is where the shaft (ujoint) is in relation to the trans which is what we're after. If the trans was down 10 and the shaft was only down 8 then the ujoint would be 2 deg up which means at the other end we'd want the pinion up 10 & with the shaft only 8 up, the shaft (ujoint) is 2 down in relation to the pinion. It's all about the angle of the ujoints to the shaft. (1) need at least 1-2 deg away from a straight line on each end (2) but not too much of an angle (or the ujoint will bind if real excessive or just wear out prematurely if moderately excessive) (3) need angles equal and parallel but in different planes (ideally), 1 up/1 down (plus the slight extra pinion down depending on intended app). I'd say the vibration is either (1) driveshaft balance (2) not enough yoke engagement into the trans (3) ujoint angles. Keep us posted. EDIT another thing to keep in mind is an imaginary driveshaft suspended in air with the left (higher) end at 10 o'clock and the right (lower) end at 4 o'clock the left end is so many degrees up (from horizontle) and the right end is so many degrees down (from horizontle) with the number on each end being the same with the car leveled side to side and front to rear but it is a good idea to check the shaft angles at each end before you pull it to then check the trans/pinion angles
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/18/14 12:06 AM

Thanks Robert I kinda get what you are saying. Put the 2.5º shims in today the way Rob suggested. Tomorrow AM Im going out on highway early to see how it does
Posted By: RapidRobert

Re: Pinion angle guru's! Help needed! - 05/18/14 01:07 AM

I dont understand my self either. Holler back on how it does
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/18/14 03:08 PM

Sad to report that after the shim install the cyclic vibration is still there

Ugh
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/18/14 04:59 PM

Quote:

Sad to report that after the shim install the cyclic vibration is still there

Ugh






Chris, while you posted your angle findings initially as 3 degrees down on the tranny, and 4.5 degrees up on the pinion, you had some hesitation on those values as being accurate IIRC, have they been confirmed?...if they were, and you installed the 2.5 shims you ordered to rotate the housing nose down, that's still not enough to counter act the transmissions 3 degree down angle, or the pinion's upward 2-4 degree rotation on acceleration, as I posted earlier, among other things to consider are: is the driveshaft facing the correct way, has the balance ever been checked/redone?, condition of the tranny mount? lots of questions/variables to confirm

Mike

Attached picture 8148081-angle.jpg
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/18/14 05:31 PM

Quote:

Quote:

Sad to report that after the shim install the cyclic vibration is still there

Ugh






Chris, while you posted your angle findings initially as 3 degrees down on the tranny, and 4.5 degrees up on the pinion, you had some hesitation on those values as being accurate IIRC, have they been confirmed?...if they were, and you installed the 2.5 shims you ordered to rotate the housing nose down, that's still not enough to counter act the transmissions 3 degree down angle, or the pinion's upward 2-4 degree rotation on acceleration, as I posted earlier, among other things to consider are: is the driveshaft facing the correct way, has the balance ever been checked/redone?, condition of the tranny mount? lots of questions/variables to confirm

Mike



Mike the initial readings were 2º down on trans & 4.5º down on rear end (using the example that Robx gave me by putting gauge to 0 the gaps opened up on the bottom...)

The drive shaft was is/new & balanced on 2 separate occasions. Trans mount is/was new also when I started battling this a few years ago.
Not sure what yo mean about the drive shaft "facing" the correct way?

I have not remeasured the angles as of yet.....
Posted By: DoctorDiff

Re: Pinion angle guru's! Help needed! - 05/18/14 05:44 PM

Are you sure your transmission is 2 degrees down?

Looks like the angle finder is not seated against the output shaft in the first picture.
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/18/14 06:19 PM

Quote:

Are you sure your transmission is 2 degrees down?

Looks like the angle finder is not seated against the output shaft in the first picture.



Yes Cass, its fully seated....just the angle of the pic
Posted By: DoctorDiff

Re: Pinion angle guru's! Help needed! - 05/18/14 07:39 PM

If the transmission slopes 2 degrees downward toward the rear and the pinion slopes 4.5 degrees downward toward the front, you need to raise the front of the pinion 4.5 degrees to yield a 2 degree negative pinion angle.

In other words, the thick part of the 4.5 degree wedge must face the front of the car.
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/18/14 08:01 PM

Quote:

Quote:

Quote:

Sad to report that after the shim install the cyclic vibration is still there

Ugh






Chris, while you posted your angle findings initially as 3 degrees down on the tranny, and 4.5 degrees up on the pinion, you had some hesitation on those values as being accurate IIRC, have they been confirmed?...if they were, and you installed the 2.5 shims you ordered to rotate the housing nose down, that's still not enough to counter act the transmissions 3 degree down angle, or the pinion's upward 2-4 degree rotation on acceleration, as I posted earlier, among other things to consider are: is the driveshaft facing the correct way, has the balance ever been checked/redone?, condition of the tranny mount? lots of questions/variables to confirm

Mike



Mike the initial readings were 2º down on trans & 4.5º down on rear end (using the example that Robx gave me by putting gauge to 0 the gaps opened up on the bottom...)

The drive shaft was is/new & balanced on 2 separate occasions. Trans mount is/was new also when I started battling this a few years ago.
Not sure what yo mean about the drive shaft "facing" the correct way?

I have not remeasured the angles as of yet.....






Chris, sorry I thought I had read your pinion was 4.5 degrees UP.....ok, so 2 degrees down tranny/4.5 degrees down pinion, IMHO if I was initially setting up the pinion, and the tranny was at 2 degrees down, and I could not effect it's angle with any adjustment, then I would rotate the pinion to 0 degrees in relation to the tranny, so that upon ACCELERATION my pinion would ROTATE UPWARD a minimum of 2 degrees (now matching the transmission parallel plane)to a ROTATIONAL maximum of 4 degrees (now over shooting the transmission parallel) that's when you can use the other guide I posted about driveline vibration based on pinion angle to decide whether more or less pinion angle is needed based on your current base line


FYI regarding the "correct install of the driveshaft" that's in regards to the front/rear orientation of the stock shaft,...the taper goes towards the rear...

Mike

Attached picture 8148229-driveshaft.JPG
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/18/14 08:04 PM

I just looked at what Doc Diff/Cass and I just posted.... it's basically the same info Chris, just that I have a habit of drawing it out some (plus I'm a one fingered typer, so it takes awhile)


Mike
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/19/14 10:40 PM

LOL Mike. The shaft is new so there is no taper to it. It was made as a straight piece.

Granted I do have to remeasure everything but right now since the addition of the 2.5º shims, going by my original measurements, I should be 2º down at trans and 2º down at rear.

Adding that much more shim to the rear is advisable?

What if I took the washers out from the trans mount? Doing that should bring the trans closer to 0º right? Im confusing myself!!
Posted By: DAYCLONA

Re: Pinion angle guru's! Help needed! - 05/19/14 10:56 PM

Quote:

LOL Mike. The shaft is new so there is no taper to it. It was made as a straight piece.

Granted I do have to remeasure everything but right now since the addition of the 2.5º shims, going by my original measurements, I should be 2º down at trans and 2º down at rear.

Adding that much more shim to the rear is advisable?

What if I took the washers out from the trans mount? Doing that should bring the trans closer to 0º right? Im confusing myself!!





Chris you could take the shim out of the tranny, I wouldn't do it, as it will tilt your exhaust downward more at the head pipe, possible interference between the oil pan and center link, and a host of other issues, and yes 4.5/5 degrees shim is a lot to stack, IMHO I'd cut the perches off the axle, install new perches without welding them, set it up in the car to where it needs to be 0 degrees if you keep the tranny at 2 degrees down, then finish weld it, then if need be you can play with 1-2 degree shims to raise or lower it based on roadtesting


Mike
Posted By: 1MYTGTX

Re: Pinion angle guru's! Help needed! - 05/19/14 11:00 PM

For shitz & giggles Im gonna try the easy approach & take the washer out of the trans mount. Ill report back!
Posted By: dan6412

Re: Pinion angle guru's! Help needed! - 05/20/14 04:15 AM

I know you stated that the drive shaft is a newly built shaft, but I would have it rechecked.
I had the very same problem you seem to be having. I checked every thing like you are doing. Was about to give up and decided to to take the drive shaft in and have it rechecked by a different drive line shop and that was the problem out of balance drive shaft also the guy at the driveline shop told me that the cups on some of the imported u-joints are not 100% true resulting in vibration too.

Dan
Posted By: RapidRobert

Re: Pinion angle guru's! Help needed! - 05/20/14 04:34 AM

What Dan said I've heard of that several times. While you're in there see how much front yoke engagment you have into the trans extension housing (suspension loaded)
Posted By: skicker

Re: Pinion angle guru's! Help needed! - 05/20/14 06:12 PM

I know this is only worth about .02 but last time this happened to me I took the driveshaft loose at the rear and spun it 180*. I know it seems stupid but sometimes it will lesson the vibration or cancel it when it is cyclonic.
Posted By: NITROUSN

Re: Pinion angle guru's! Help needed! - 05/22/14 04:32 AM

You should not have this problem with an un-modified car and basically stock factory components and settings. No matter what you do seems to do nothing for the problem. I would be looking at the possibility of bad bearings either axle or differential.
Posted By: 71cudaddict

Re: Pinion angle guru's! Help needed! - 05/26/14 01:48 AM

Just went through the same type of vibration drove me crazy 70 challenger 727 8 3/4 276 highway gears shake would start at 70 and stay hard to about 90 would seem to smooth out after that but still there. Tried different shafts Trans mounts pinion 2 degrees down ,tires & wheels ,put it on jack stands got to 75 @3200 rpm shook bad removed the tires same removed drums no shake DONT STEP ON BRAKE just shut off the car and put in neutral put tires on with out drums tested once more on jacks with just tires & no drums no vibe. Got 2 used drums put on it's like a new car no vibe. The drum that I took off looked fairly new & had no weights. Good luck
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