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Pinion angle guru's! Help needed!
#1620341
05/15/14 02:04 PM
05/15/14 02:04 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
OP
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OP
master
Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
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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!
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620343
05/15/14 02:23 PM
05/15/14 02:23 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
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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
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Re: Pinion angle guru's! Help needed!
[Re: DAYCLONA]
#1620344
05/15/14 02:41 PM
05/15/14 02:41 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
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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
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: skicker]
#1620348
05/15/14 03:15 PM
05/15/14 03:15 PM
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Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
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Overpriced Housing Central
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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.
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Re: Pinion angle guru's! Help needed!
[Re: RobX4406]
#1620352
05/15/14 03:44 PM
05/15/14 03:44 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
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Thanks Rob for simplifying that.
Im gonna install those shims like you suggested soon & report back. Thanks!
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620355
05/15/14 05:35 PM
05/15/14 05:35 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
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I Live Here
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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
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Re: Pinion angle guru's! Help needed!
[Re: DAYCLONA]
#1620356
05/15/14 05:43 PM
05/15/14 05:43 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
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Joined: Jan 2003
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S.I. N.Y.
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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
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: RJS]
#1620358
05/15/14 07:33 PM
05/15/14 07:33 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
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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!
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620359
05/15/14 09:54 PM
05/15/14 09:54 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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#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
Last edited by RapidRobert; 05/16/14 11:48 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Pinion angle guru's! Help needed!
[Re: RapidRobert]
#1620360
05/16/14 01:35 AM
05/16/14 01:35 AM
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Joined: Jan 2004
Posts: 8,294
fredericksburg,va
cudaman1969
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fredericksburg,va
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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.
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