 Pistol
"11th Year" Silver Supporting Member
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06-08-12 12:38 PM - Post#2234797
I got my car sitting level today to check all the angles and wanted some feedback/opinions on where to go from this point, I have a vibration starting at 56 mph, I dont know if it gets better at a higher mph, once the vibration starts and it gets worse as I speed up.
I had the tires rebalanced and the drivshaft also, the vibration seems to be more towards the back of the car, I get it to vibrate more and when I push the clutch in the vibration is still there till I get down in speed,
Here are all the angles, this is not for racing, rear is leaf springs with Cal-tracks, Thank you for any help
Pete
Awl speeling misteaks r myn
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sidworks
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06-08-12 12:45 PM - Post#2234800
In response to Pistol
crankshaft-trans centreline should be parallel to the pinion centreline. they do not have to line up with one another , just be parallel
ron
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Pistol
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06-08-12 12:53 PM - Post#2234804
In response to Pistol
Air filter/carb is wrong, its down in the front 1.7
Pete
Awl speeling misteaks r myn
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Pistol
"11th Year" Silver Supporting Member
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06-08-12 12:57 PM - Post#2234808
In response to sidworks
So if my engine/trans is at 4.1 down in the back then the rear end should be up in the front at 4.1? I did add the front mount and tranny mount but I didnt change the spring perches, wouldnt that be more or less a factory setting?
Pete
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sidworks
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06-08-12 02:57 PM - Post#2234852
In response to Pistol
your motor may be a hair high3.5. the crankshaft and pinion must be in the same plane. The engine can sit 10" higher than the pinion as long as they are parallel. are you sure that that you measured the pinion angle correctly. Pinion must run uphill towards the frt. have there been any frame modifications back there?
There was an extensive thread on this just a couple weeks ago
ron
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 Johnny468
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06-08-12 03:58 PM - Post#2234871
In response to sidworks
This might help......
http://www.markwilliams.com/driveshafttech.aspx
Johnny
1965 Impala SS
505/4-speed/4.30
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Pistol
"11th Year" Silver Supporting Member
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06-08-12 05:01 PM - Post#2234885
In response to sidworks
I will have to take my drive shaft out again to recheck the pinion angle, I thought since it was a stock rear end that it would have the right degree angle, it may take a while to get back with figure because I cant get under the car anymore because of the amount of arthritis I have in my back, I went under there today and thought I wouldn't be able to get back out. 
Pete
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FleetsideLarry
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06-08-12 05:05 PM - Post#2234888
In response to Johnny468
to me, the statement in the link above that says the optimal angle for a driveshaft is 0° is a bit misleading. while that may be true for the driveshaft, it isn't for u-joints which are supposed to have some small working angle. for instance , this reference:
http://www.drivetrain.com/parts_catalog/drivetr ain...
which says at least a 1/2° constant working angle,
or this one (see page 5):
http://www2.dana.com/pdf/J3311-1-HVTSS.PDF
which says at least 1°
this means that you don't want the engine, driveshaft and pinion to be in a straight line. You do want to, as Sidworks said, try to get them a parallel as possible
of course I'm assuming we're talking a driver here, not a racer.
the provided drawings show a front u-joint angle of .6° and a rear u-joint angle of 6.7°
why do you have to remove the driveshaft to check the pinion angle?
Edited by FleetsideLarry on 06-08-12 05:10 PM. Reason for edit: No reason given.
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sidworks
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06-08-12 05:31 PM - Post#2234892
In response to FleetsideLarry
this means that you don't want the engine, driveshaft and pinion to be in a straight line. You do want to, as Sidworks said, try to get them a parallel as possible
the driveshaft is not a factor in the alignment of the crankshaft to pinion. ujoints will take care of the driveshaft if the c/shaft to pinion relationship is within accord.
ron
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sidworks
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06-08-12 05:52 PM - Post#2234902
In response to sidworks
pete; if you look at the rear flange; the one that is attached to the pinion. the face of that should be 90 degrees to the pinion. providing the your car is sitting level and that you can run a straight edge up against it, you should have an opening at the top which is equivalent to the drop of the engine in degrees.
in the other thread above he had bad springs which he replaced plus a 2 degree wedge
if you used afternmarket frt mounts some are higher than others making the frt of your eng a little higher. you may have to shim your rear mount up so that you are within 3- 3 1/2 degrees to get it all within closer tolerances if there is room to do so and if that is a problem
2 degrees doesn't sound like much but it did eliminate the other fellows vibration
good luck
ron
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Rick_L
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06-08-12 05:55 PM - Post#2234904
In response to Pistol
You need to have the engine/driveshaft angle and the pinion angle to be parallel under the conditions where you most use the car. If you have leaf springs, the nose of the pinion is going to move up under load. Slightly for a driver, maybe a lot on a drag race deal, though that deal is variable depending on your traction device if you have one.
So if your engine/trans is down 4.1º in the back, you want the pinion to be 4.1º up in the front when you're going down the road. So you need to put it at 3-4º static. Don't exceed 4º.
This has nothing to do with the driveshaft angle. This is determined in the end by the rear ride height. If your pinion angle and engine angle are parallel, then the angle at either end of the driveshaft is the same. I don't think it will ever be 0º unless the car is pretty low in back. You generally don't want the u-joint angle to exceed 1-1/2º to 2º or you will have a high speed vibration. Usually you are okay with reasonable ride heights.
I don't worry about the supposed wear problem even with a static 0º u-joint angle (even if true) because actual driving gives you enough movement that you are never at the same angle due to suspension movement - even on a "smooth" road.
Hope this helps.
Last thing, my 55 had the pinion down too far from the factory, yours seems to be that way too.
And one more last thing, not all leaf springs give you the same pinion angle. Some lowering springs for 55-57s have a reversed eye in front and stock in back. There's about 2º difference between those and stock front/stock rear, or reversed at both ends.
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Pistol
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06-09-12 06:36 AM - Post#2235065
In response to FleetsideLarry
why do you have to remove the driveshaft to check the pinion angle?
The drive shaft is in the way of getting a good reading of the pinion flange.
Last thing, my 55 had the pinion down too far from the factory, yours seems to be that way too.
this is what I need to recheck, hopfully that will be today 
You generally don't want the u-joint angle to exceed 1-1/2º to 2º or you will have a high speed vibration
this would be drive shaft angle to pinion angle, if I have 3 degrees on the pinion and 2 degrees on the drive shaft, then I should be good? at the moment I'm looking at 6.7 degrees if the pinion does have 2 degrees, would this be correct?
3- 3 1/2 degrees to get it all within closer tolerances if there is room to do so and if that is a problem
This would have an effect with my shifter, exhaust system, floor if I'm close, not looking forward to this
I want to say Thank you for all your help, I'll let you guys know what is going on
Pete
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Rick_L
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06-09-12 08:24 AM - Post#2235093
In response to Pistol
"This would have an effect with my shifter, exhaust system, floor if I'm close, not looking forward to this"
The stock engine angle is approximately 4º to the frame. You didn't say if your measureed 4.1º is to the frame or ground, but if your car has a level stance, you don't need to be moving the engine mounts. You rotate the pinion upward.
"this would be drive shaft angle to pinion angle, if I have 3 degrees on the pinion and 2 degrees on the drive shaft, then I should be good? at the moment I'm looking at 6.7 degrees if the pinion does have 2 degrees, would this be correct?"
I can't tell from the numbers you quoted whether it's correct or not. You are confusing me because you said eearlier that the pinion angle was 2º down. If you rotate the axle upward on a stock or near stock 57, you'll be decreasing the u-joint angle.
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Pistol
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06-09-12 03:04 PM - Post#2235211
In response to Rick_L
Rick 4.1 is level to the ground, and I think I have pinion angle of 2, front lower so I would need a 6 degree shims to be at 4 up.
Pete
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Rick_L
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06-09-12 05:41 PM - Post#2235255
In response to Pistol
6º shims may not be a good answer - you may be better off to cut the present perches off and weld new ones on.
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Pistol
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06-09-12 08:36 PM - Post#2235305
In response to Rick_L
I'm almost afraid to ask why
To tell you the truth I'm lost
If the motor and trans are at 4.1 with the car at level ride height and the drivshaft is at 4.7,is the angle differance between the two .6
If I put the rear pinion at 4.1 degrees then I would think that both would be parallel but the drivshaft would change angle by making the pinion correction?
By raising the front of the pinion to 4.1 where would the drivshaft end up?
Pete
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FleetsideLarry
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06-10-12 05:01 AM - Post#2235355
In response to Pistol
Pete, as Sidworks and Rick_L have pointed out, if you get the engine and pinion angles the same, the u-joint angles will be equal. That's the most important factor and, again, as they suggest, what you should be trying to achieve.
what you have now is a big difference in joint angles which may be the source of the vibration.
While they are correct in saying that the driveshaft ends up wherever it ends up, my point was that knowing the driveshaft angle provides you with information about your u-joint angles.
you could figure out your question mathematically, knowing the lengths of the driveshaft and pinion, but, at this point I think that would be "over-thinking" the problem.
Edited by FleetsideLarry on 06-10-12 05:02 AM. Reason for edit: No reason given.
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Pistol
"11th Year" Silver Supporting Member
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06-10-12 06:20 AM - Post#2235366
In response to FleetsideLarry
knowing the lengths of the drive-shaft and pinion, but, at this point I think that would be "over-thinking" the problem.
Larry thanks for posting this, it reassures of what I came up with
Just before you posted I came up with this same idea, my old brain just does not work as it use to, I couldn't figure out what shim I would need, at least now I know how to figure that out
Pete
Awl speeling misteaks r myn
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Rick_L
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06-10-12 07:25 AM - Post#2235384
In response to Pistol
I agree with Fleetside Larry.
Don't worry about the driveshaft/u-joint angle, it should end up ok.
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 aghaga
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06-10-12 07:53 AM - Post#2235394
In response to Rick_L
Does you digital level have a zero reset? I'm thinkin that if you zero the level while it is position vertically on the rear flange of the transmission and then check the rearend pinion angle, without resetting the level, you would get an actual difference in angle reading. An "0" degree would represent a parallel drivtrain.
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FleetsideLarry
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06-10-12 08:13 AM - Post#2235398
In response to Pistol
my old brain just does not work as it use to,
nor do these old bodies (I can get down to work under the car, I just can't get back up very well) 
also, remember (as I think Sidworks pointed out above) there are tolerances for these angles, so even a 2, 3, or 4° shim might aleviate the problem.
(p.s. I obviously just confused the issue by jumping into the discussion earlier, sorry)
Edited by FleetsideLarry on 06-10-12 08:16 AM. Reason for edit: No reason given.
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72novaproject
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06-10-12 09:08 AM - Post#2235414
In response to Pistol
This is the recent ChevyTalk thread mentioned earlier in this thread.
Recent pinion angle thread.
And the follow up thread with the results:
Follow up thread.
Steve
Edited by 72novaproject on 06-10-12 09:12 AM. Reason for edit: No reason given.
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Pistol
"11th Year" Silver Supporting Member
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06-10-12 03:20 PM - Post#2235507
In response to aghaga
Aaron I always check that before I use it, at times I need to reset it because I hit the wrong button 
Steve I saw that and followed it pretty close, and was doing a lot of reading online but it was mixing me up, you wouldn't believe some of the sites and what they say.
I ordered some steel shims and I'll install those and see where I'm at.
Thank you one and all for setting me straight and being patient with all my questions.
Pete
Awl speeling misteaks r myn
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Rick_L
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06-10-12 04:24 PM - Post#2235535
In response to Pistol
Remember that a 6º shim is going to be a lowering block too because of its thickness. Do you want that?
My personal opinion it that 72novaproject's thread has some confusion, discrepancies, and errors. Not so many in this thread.
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Pistol
"11th Year" Silver Supporting Member
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06-10-12 05:37 PM - Post#2235562
In response to Rick_L
Remember that a 6º shim is going to be a lowering block too because of its thickness. Do you want that?
Bummer I didn't think of that, good catch Rick
Pete
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 acardon
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06-10-12 08:29 PM - Post#2235622
In response to Rick_L
A 6 degree shim will only be a little over 1/2" at the thick end, so it will only lower it a little over 1/4", depending on how thick the thin end is. I had to make a 3.5 degree shim for my stock rear end to get the angles equal.
Don
66 Corvair (driving)
57 2dr HT (restoring)
56 2dr HT (waiting to be restored)
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Rick_L
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06-11-12 08:32 AM - Post#2235765
In response to acardon
How do you get the spring centering bolt to register in the axle perch with a 6º shim?
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sidworks
Senior Member
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06-11-12 08:42 AM - Post#2235771
In response to Rick_L
make it longer
ron
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Pistol
"11th Year" Silver Supporting Member
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06-11-12 03:31 PM - Post#2235916
In response to Rick_L
They use these http://www.zorotools.com/g/00056501/k-G2818365 ?utm... and I'll probably have to mill prt of the hole flat.
Pete
Awl speeling misteaks r myn
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Pistol
"11th Year" Silver Supporting Member
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06-11-12 03:34 PM - Post#2235918
In response to acardon
Don the 6 degree shim is roughly
Length - 5"
Height (thick end) - 0.61"
Height (thin end) - 0.08"
Pete
Awl speeling misteaks r myn
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