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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620363
05/17/14 05:27 PM
05/17/14 05:27 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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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
Last edited by RapidRobert; 05/17/14 06:32 PM.
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: 1MYTGTX]
#1620365
05/17/14 09:07 PM
05/17/14 09:07 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I dont understand my self either. Holler back on how it does
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: 1MYTGTX]
#1620367
05/18/14 12:59 PM
05/18/14 12:59 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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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
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Re: Pinion angle guru's! Help needed!
[Re: DAYCLONA]
#1620368
05/18/14 01:31 PM
05/18/14 01:31 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
OP
master
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OP
master
Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
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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.....
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620372
05/18/14 04:01 PM
05/18/14 04:01 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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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
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Re: Pinion angle guru's! Help needed!
[Re: DAYCLONA]
#1620373
05/18/14 04:04 PM
05/18/14 04:04 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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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
Last edited by DAYCLONA®; 05/18/14 04:05 PM.
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Re: Pinion angle guru's! Help needed!
[Re: DAYCLONA]
#1620374
05/19/14 06:40 PM
05/19/14 06:40 PM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
OP
master
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OP
master
Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
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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!!
1MYTGTX
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Re: Pinion angle guru's! Help needed!
[Re: 1MYTGTX]
#1620375
05/19/14 06:56 PM
05/19/14 06:56 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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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
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Re: Pinion angle guru's! Help needed!
[Re: dan6412]
#1620378
05/20/14 12:34 AM
05/20/14 12:34 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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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)
live every 24 hour block of time like it's your last day on earth
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