CJ, your's looks to be bent the opposite of mine. Another words, I would have to add more catser to get where your's is at, a lot more. From previous posts that seems real wierd.
Time for a DC front shaft plus a DC rear shaft?
- Thread starter hobbes
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While the actual driveshaft angle is important, the difference between flanges in degrees is where you will get the growl.
When you lift the front of an 80 you decrease the amount of positive caster. It also tilts the pinion up. If your truck had 1 degree + of caster from the factory and you lifted it 2 inches, it could change the caster more than 2 degrees - giving you a -1 to 0 caster. This will sometimes make the truck road walk and follow grooves in the road more. The OME bushings should correct about 2 degrees bringing your caster back up to close to stock. The bushings will also tilt the pinion down to a point where the shaft flange angles on the front are now back within the 1-1.5 degrees at which the driveshaft will spin in harmony. This is why Robbie earlier stated that front driveshaft work is usually not needed at 2' of lift when caster correction bushings are used, but there is a point where single ujoints are not comfortable spinning at angles that they were not intended. If you have a truck that sits higher than the normal 2", your front shaft, regardless of the difference in flange angles, could be running out of its designed range of motion. This is where a CV shaft comes in. The CVs work best if the pinion is pointed directly at or pretty close to the tcase flange allowing the CV to take the now sharper angle with ease.
I think that the reason you have some vibration with either shaft is because you have issues with both shafts. The rear pinion needs adjusting to match the output angle, and the front is now either out of the 1-1.5 degree spec or is out of the ujoints operating range.
My old 97 80 series had J springs on the front and 860s on the rear giving it a flat stance, and also about 4" of lift in the front even though they are 3" springs. When I bought the truck it did not have correction bushings and had the matching 2" front springs. It had a vibration in the front shaft. When I did the J springs and bushings the vibration was still there and worse. I then used Christos correction brackets that he uses on his 6" kits and removed the OME bushings. This combination gave the truck 5 degrees positive caster and brought the front pinion down to within 1 degree of the tcase. The vibration was almost completely eliminated. Most people would not have noticed. I think the residual vibration was due to a wear pattern on the ujoints and possibly making them work out of their range of motion.
I had a moral to this somewhere but forgot what it was. Sorry for the ramble.
G
When you lift the front of an 80 you decrease the amount of positive caster. It also tilts the pinion up. If your truck had 1 degree + of caster from the factory and you lifted it 2 inches, it could change the caster more than 2 degrees - giving you a -1 to 0 caster. This will sometimes make the truck road walk and follow grooves in the road more. The OME bushings should correct about 2 degrees bringing your caster back up to close to stock. The bushings will also tilt the pinion down to a point where the shaft flange angles on the front are now back within the 1-1.5 degrees at which the driveshaft will spin in harmony. This is why Robbie earlier stated that front driveshaft work is usually not needed at 2' of lift when caster correction bushings are used, but there is a point where single ujoints are not comfortable spinning at angles that they were not intended. If you have a truck that sits higher than the normal 2", your front shaft, regardless of the difference in flange angles, could be running out of its designed range of motion. This is where a CV shaft comes in. The CVs work best if the pinion is pointed directly at or pretty close to the tcase flange allowing the CV to take the now sharper angle with ease.
I think that the reason you have some vibration with either shaft is because you have issues with both shafts. The rear pinion needs adjusting to match the output angle, and the front is now either out of the 1-1.5 degree spec or is out of the ujoints operating range.
My old 97 80 series had J springs on the front and 860s on the rear giving it a flat stance, and also about 4" of lift in the front even though they are 3" springs. When I bought the truck it did not have correction bushings and had the matching 2" front springs. It had a vibration in the front shaft. When I did the J springs and bushings the vibration was still there and worse. I then used Christos correction brackets that he uses on his 6" kits and removed the OME bushings. This combination gave the truck 5 degrees positive caster and brought the front pinion down to within 1 degree of the tcase. The vibration was almost completely eliminated. Most people would not have noticed. I think the residual vibration was due to a wear pattern on the ujoints and possibly making them work out of their range of motion.
I had a moral to this somewhere but forgot what it was. Sorry for the ramble.
G
CJ, is that bottom arrow where the indicator pointed with the protractor on the drive shaft?
- Thread starter
- #25
Okay, my truck is sitting in my driveway which is a hill but I don't think that matters since the angles are relative to each other. It's night so I might need to double check my angles in the morning, but measuring the angles using the pictures in landtank's post (#18) for the front shaft I get 3 degrees on top of the axle housing and 1 degree on the top of the driveshaft. So a difference of 2 degrees. But like I said it's night.
When I measure the rear shaft I get 10.5 degress on the shaft. I couldn't see a good spot on top of the rear axle, so I used a rib on the diff that points to the pinion and got 3.5 degrees, so a difference of 7 degrees. I need to check to see if those ribs are parallel to the ground (but it is within .5 degrees of the front axle reading). I do have the standard "stink bug" look. I haven't wanted to get a front spacer to help level the truck since I was thinking that would make the caster worse on the front.
I'll try to find a parking lot tomorrow that's more level, but I don't think that will make a difference (but the light will).
Any opinions on the angles? The front seems close.
Another question I have is that if I hit a bump in the road I can feel the vibration increase for an instant. I assume this is do to the axle moving up on the suspension compression and throwing the weight out of balance a bit more.
thanks....john
When I measure the rear shaft I get 10.5 degress on the shaft. I couldn't see a good spot on top of the rear axle, so I used a rib on the diff that points to the pinion and got 3.5 degrees, so a difference of 7 degrees. I need to check to see if those ribs are parallel to the ground (but it is within .5 degrees of the front axle reading). I do have the standard "stink bug" look. I haven't wanted to get a front spacer to help level the truck since I was thinking that would make the caster worse on the front.
I'll try to find a parking lot tomorrow that's more level, but I don't think that will make a difference (but the light will).
Any opinions on the angles? The front seems close.
Another question I have is that if I hit a bump in the road I can feel the vibration increase for an instant. I assume this is do to the axle moving up on the suspension compression and throwing the weight out of balance a bit more.
thanks....john
It sure would work better if you could measure the flanges of both pinion and output of tcase. I can't imagine 7 degrees difference on the rear shaft. That thing would jump out of the truck at that.
G
G
The front shaft is the same as mine and I have a DC shaft up front. Ideally you want to be at 0* + 1* so you're real close there. If your caster was on the light side you could go as far as adding 2* more and get it pretty much dead on.
Hard to say the DC front shaft will solve all your issues but it would most likely help at least.
I have the stock shaft in the rear on mine. If you find some way to get a good reading on yours I can take the same reading on mine for comparison.
Hard to say the DC front shaft will solve all your issues but it would most likely help at least.
I have the stock shaft in the rear on mine. If you find some way to get a good reading on yours I can take the same reading on mine for comparison.
- Thread starter
- #28
Gary/Rick,
I'm leaving on Monday or Tuesday to drive to Ohio. I'm probably going to pull the front shaft for the sake of my sanity before leaving. If I understand Gary correctly I'll measure the angle on each driveshaft, drop each shaft and use the face of the pinions to get the most accurate angles. I'll try to do that tomorrow (but it's supposed to be 40 and raining so this will be a good motivation check). I'd do it tonight, but no garage right now.
The good part about doing that is that we can hopefully get some relative angles to what I was using. That'll make the math easier for the next guy if we can identify a place to measure the angle w/o pulling the shafts.
thanks...john
I'm leaving on Monday or Tuesday to drive to Ohio. I'm probably going to pull the front shaft for the sake of my sanity before leaving. If I understand Gary correctly I'll measure the angle on each driveshaft, drop each shaft and use the face of the pinions to get the most accurate angles. I'll try to do that tomorrow (but it's supposed to be 40 and raining so this will be a good motivation check). I'd do it tonight, but no garage right now.
The good part about doing that is that we can hopefully get some relative angles to what I was using. That'll make the math easier for the next guy if we can identify a place to measure the angle w/o pulling the shafts.
thanks...john
- Thread starter
- #29
Yep, the weatherman got it right. 40 degrees and raining.
Here are the measurements I took:
Front driveshaft: .5 degree measured on the shaft
Front diff pinion: 4.5 degrees
Front xfer case pinion: 5.5 degrees
Rear driveshaft: 11 degrees measured on the shaft
Rear diff pinion: 6.5 degrees
Rear xfer case pinion: 5.5 degrees
Summary: I seem to have about 1 degree difference between my diff and xfer case pinions front and rear. The shaft angles don't mean much with the truck sitting on a hill (other than their relative difference to the pinion angles).
One thing Nay mentioned above that I may not have made clear is that the vibration does oscillate (cyclical vibration).
I'm very willing to re-verify everything I've done troubleshooting. I've got to be missing something. The factory marks on the front shaft were perfectly aligned. I thought about putting the rear shaft 180 degrees out of phase just to see what would happen. The front shaft is currently sitting in a box in the back of the truck. I'll drive it like that over the holiday (unless I can come up a fix over the next 36 hours).
Could I have a hidden tire problem that the Road Force balancer doesn't pick up?
The vibration is there no matter acceleration/deceleration. It seems a bit worse on acceleration but that may be nothing more than staying in a specific MPH band longer due to the rapid power-off deceleration with the 33" tires.
Thanks....John
Here are the measurements I took:
Front driveshaft: .5 degree measured on the shaft
Front diff pinion: 4.5 degrees
Front xfer case pinion: 5.5 degrees
Rear driveshaft: 11 degrees measured on the shaft
Rear diff pinion: 6.5 degrees
Rear xfer case pinion: 5.5 degrees
Summary: I seem to have about 1 degree difference between my diff and xfer case pinions front and rear. The shaft angles don't mean much with the truck sitting on a hill (other than their relative difference to the pinion angles).
One thing Nay mentioned above that I may not have made clear is that the vibration does oscillate (cyclical vibration).
I'm very willing to re-verify everything I've done troubleshooting. I've got to be missing something. The factory marks on the front shaft were perfectly aligned. I thought about putting the rear shaft 180 degrees out of phase just to see what would happen. The front shaft is currently sitting in a box in the back of the truck. I'll drive it like that over the holiday (unless I can come up a fix over the next 36 hours).
Could I have a hidden tire problem that the Road Force balancer doesn't pick up?
The vibration is there no matter acceleration/deceleration. It seems a bit worse on acceleration but that may be nothing more than staying in a specific MPH band longer due to the rapid power-off deceleration with the 33" tires.
Thanks....John
What I am reading here is folks sticking protracters on front axles and rear ribs and presuming that there is a known relationship between that and the pinion angles.
It is unknown to me how accurately the pinions / output shafts / flanges are alinged to the surfaces you guys are using for reference points.
I would reiterate what waggoner said that you should be pulling the drive shafts and mearuring your dif and transfer case flange angles.
It is unknown to me how accurately the pinions / output shafts / flanges are alinged to the surfaces you guys are using for reference points.
I would reiterate what waggoner said that you should be pulling the drive shafts and mearuring your dif and transfer case flange angles.
Since the vibration persists with either shaft removed it might be worth the effort to swap tyres front to back before the long trip.
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Rich said:
Agreed, but no need to pull the shafts, there is room to get a good reading on the edge of the pinion flange if the shaft is turned correctly.
- Thread starter
- #33
Rich,
All above measurements in post 29 were taken off the pinion faces when I pulled both shafts this morning. I reinstalled the rear shaft, put the front one back in its box until I can come up with something.
B, I rotated the tires 2 weeks ago front to back (putting one tire that was on the front into the spare location and putting the spare on the right rear).
Thanks...John
All above measurements in post 29 were taken off the pinion faces when I pulled both shafts this morning. I reinstalled the rear shaft, put the front one back in its box until I can come up with something.
B, I rotated the tires 2 weeks ago front to back (putting one tire that was on the front into the spare location and putting the spare on the right rear).
Thanks...John
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What I was trying to get at is what the angle at the front pinion to the drive shaft is, period. You asked about a DC shaft, and that angle wants to be 0* +1.
So holding the protractor like this:
_______________
|.........................../
|....................../
|................../
|............../
|........./
|...../
|./
You can place the top edge along the bottom of the drive shaft and then mark the position of the needle.
Then remove the drive shaft and place the left side against the drive flange and then calculate the difference to see how much angel there is at that point.
Looking at the protractor from the left side of the truck, if the needle is on the left side of the marker then more caster correction would reduce the angle.
My pics where for a fast but not as accurate way to just get an idea of where you were.
Again I was only focussing on the question of a DC shaft and not whether or not it would fix your problem.
So holding the protractor like this:
_______________
|.........................../
|....................../
|................../
|............../
|........./
|...../
|./
You can place the top edge along the bottom of the drive shaft and then mark the position of the needle.
Then remove the drive shaft and place the left side against the drive flange and then calculate the difference to see how much angel there is at that point.
Looking at the protractor from the left side of the truck, if the needle is on the left side of the marker then more caster correction would reduce the angle.
My pics where for a fast but not as accurate way to just get an idea of where you were.
Again I was only focussing on the question of a DC shaft and not whether or not it would fix your problem.
- Thread starter
- #35
Rick,
From the driver's side of the truck, the front driveshaft angle measures .5 degrees to the left of the vertical. The front pinion is 4.5 degrees to the left of vertical.
That's 4 degrees difference, unless I've measured something wrong.
The xfer case is 5.5 degrees to the right of vertical, so 6 degrees off the driveshaft.
From the driver's side of the truck, the front driveshaft angle measures .5 degrees to the left of the vertical. The front pinion is 4.5 degrees to the left of vertical.
That's 4 degrees difference, unless I've measured something wrong.
The xfer case is 5.5 degrees to the right of vertical, so 6 degrees off the driveshaft.
Well at that amount of angle I don't think a DC shaft is going to work. You would need to add 3* of additional caster correction to get it in the range needed.
Now if your current caster was 1* or less then you could add that 3* of correction
the end result would be:
Caster = 4*
Drive angle = 1*
That's in theory, your actual results would be slightly off but I think it would be close enough to work properly.
Now for a standard shaft I beleive, but not sure, you want the diff angle and T-case angle to be as close as possible. That's why it was suggested to read the flanges and compare them verses what I was suggesting. I don't know the allowable error for that but somebody here does I'm sure.
Now if your current caster was 1* or less then you could add that 3* of correction
the end result would be:
Caster = 4*
Drive angle = 1*
That's in theory, your actual results would be slightly off but I think it would be close enough to work properly.
Now for a standard shaft I beleive, but not sure, you want the diff angle and T-case angle to be as close as possible. That's why it was suggested to read the flanges and compare them verses what I was suggesting. I don't know the allowable error for that but somebody here does I'm sure.
- Thread starter
- #37
My current caster is a positive 1.6/1.9. I'd probably need to pull the OME bushings and put back in the OEM bushings then rotate the axle via Slees caster plate to make it work. I just don't have that kind of time right now. I'm mad I didn't keep the original springs.
Since I have the front shaft out, I'll pause here and look at getting the balance checked on the rear shaft. If/when I get the rear shaft working, I'll come back to the front. I'll just live w/ 2WD and no ABS for the week I'll be in the snow.
I do appreciate the time you all have taken.
Merry Christmas....John
Since I have the front shaft out, I'll pause here and look at getting the balance checked on the rear shaft. If/when I get the rear shaft working, I'll come back to the front. I'll just live w/ 2WD and no ABS for the week I'll be in the snow.
I do appreciate the time you all have taken.
Merry Christmas....John
This is just a shot in the dark here, FSM states troubleshooting for vibration (in order):
1. Sleeve yoke spline stuck.
2. Propeller shaft runout.
3. Propeller shaft imbalance.
You didn't mention this but you do know that the front driveshaft is supposed to be out of phase?
I know this might not apply after the lift, but it is something else to check.
Another possibility is that the centerline of the differential (in a vertical plane) is not in line with the centerline of the transfercase output (due to the shifting of the axle with the lift); thus creating a compound angle with its own set of harmonics.
Check out http://www.4xshaft.com/ then look under 'Tech Info'
Good luck,
Boyd
1. Sleeve yoke spline stuck.
2. Propeller shaft runout.
3. Propeller shaft imbalance.
You didn't mention this but you do know that the front driveshaft is supposed to be out of phase?
I know this might not apply after the lift, but it is something else to check.
Another possibility is that the centerline of the differential (in a vertical plane) is not in line with the centerline of the transfercase output (due to the shifting of the axle with the lift); thus creating a compound angle with its own set of harmonics.
Check out http://www.4xshaft.com/ then look under 'Tech Info'
Good luck,
Boyd
Worn driveshaft splines could be an issue,, but it isn't normal to be out of center when only going up 2". The Panhard will not pull the axle over that much.
On the DC shaft thing. It is better to have the pinion pointing within a degree or 2 directly at the rear output, meaning no angle, but I have seen them work fine at 3 degrees from straight.
Gary
On the DC shaft thing. It is better to have the pinion pointing within a degree or 2 directly at the rear output, meaning no angle, but I have seen them work fine at 3 degrees from straight.
Gary