Tricks to setting pinion angle?
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
U joints speed up and slow down as they go around. They do NOT run at a constant velocity.
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
Angles are ONLY needed to prevent loading on one set of needle bearings. If only one spot on the universal constantly took the load it would cause a few needles to Birnelle??? This is a wash board road effect. A few needles would be flattened into the cap. By causing a slight rocking of the universal the same spot isn't constantly loaded.
I try to make the angle as little as possible to prevent excess speed change, greater the angle the more speed up and slow down. So make the angle as small as possible and the motor ALWAYS points down, that is why the intake is machined like it is. The pinion must point up equal in angle.
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
Angles are ONLY needed to prevent loading on one set of needle bearings. If only one spot on the universal constantly took the load it would cause a few needles to Birnelle??? This is a wash board road effect. A few needles would be flattened into the cap. By causing a slight rocking of the universal the same spot isn't constantly loaded.
I try to make the angle as little as possible to prevent excess speed change, greater the angle the more speed up and slow down. So make the angle as small as possible and the motor ALWAYS points down, that is why the intake is machined like it is. The pinion must point up equal in angle.
Racer
Joined: Nov 2006
Posts: 435
Likes: 7
From: Wake Forest NC
U joints speed up and slow down as they go around. They do NOT run at a constant velocity.
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
Angles are ONLY needed to prevent loading on one set of needle bearings. If only one spot on the universal constantly took the load it would cause a few needles to Birnelle??? This is a wash board road effect. A few needles would be flattened into the cap. By causing a slight rocking of the universal the same spot isn't constantly loaded.
I try to make the angle as little as possible to prevent excess speed change, greater the angle the more speed up and slow down. So make the angle as small as possible and the motor ALWAYS points down, that is why the intake is machined like it is. The pinion must point up equal in angle.
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
Angles are ONLY needed to prevent loading on one set of needle bearings. If only one spot on the universal constantly took the load it would cause a few needles to Birnelle??? This is a wash board road effect. A few needles would be flattened into the cap. By causing a slight rocking of the universal the same spot isn't constantly loaded.
I try to make the angle as little as possible to prevent excess speed change, greater the angle the more speed up and slow down. So make the angle as small as possible and the motor ALWAYS points down, that is why the intake is machined like it is. The pinion must point up equal in angle.
Melting Slicks
Joined: May 2005
Posts: 2,826
Likes: 3
From: Tennessee
Very interesting....I'd never heard it explained like that before. My only question is your last sentence....That may be true for a vette with a fixed rear end, however, on a car with leaf springs, the pumkin will rap up once torque is applied. Ideally, you would want the pumkin pointing down, no more than 3 degrees. This way, when torque is applied, the driveshaft will be "pushed" towards the trans instead of being "pulled" away from the trans. This is how it was explained to me.
Richard
Richard
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Very interesting....I'd never heard it explained like that before. My only question is your last sentence....That may be true for a vette with a fixed rear end, however, on a car with leaf springs, the pumkin will rap up once torque is applied. Ideally, you would want the pumkin pointing down, no more than 3 degrees. This way, when torque is applied, the driveshaft will be "pushed" towards the trans instead of being "pulled" away from the trans. This is how it was explained to me.
Richard
Richard
On a car with spring leafs yes you can point the pinion down and count on the twisting of the spring to bring everything in alignment under load but isn't ladder bars, slapper bar and 4 links used to hold the rearend from wrapping up?? Most leaf spring cars need help with the rear springs winding up??
If the tranny points down on a spring car as well as the pinion pointing down and you are driving along at a steady state , light power while cruising you will run into vibrations. Do we really want that??
No
In our fixed rearend cars point the pinion up equal to the amount in degrees that the tranny points down.
Melting Slicks
Joined: May 2005
Posts: 2,826
Likes: 3
From: Tennessee
Richard
Former Vendor
Joined: Nov 2005
Posts: 683
Likes: 1
From: Mounds View Minnesota
U joints speed up and slow down as they go around. They do NOT run at a constant velocity.
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
...
The angle tells weather it is to speed up or slow down. If you run both ends of the drive shaft at the same angle both ends will speed up and slow down in unison??? and you will feel this speed up and slow down.
If the angles are opposite but equal they will cancel each other out, one speeds up and one slows down so the average speed is constant.
...
if you look at the driveshaft you will notice that the u-joints are mounted 90 degrees out of phase. This is what causes the cancellation of the vibration, one end of the driveshaft is slowing down while the other end is speeding up, thus the average speed of the shaft stays constant.
So it's abvious that the angles need to be as equal as possible.
Any angle mismatch will cause the speed of the drive shaft to change twice per rev, which causes the axle and thus the drive wheels to change at the same rate causing that vibration you feel in the seat of your pants as the whole car speeds up and slows down twice per driveshaft revolution...
If you build a driveshaft with the U-Joints in phase they will both be speeding up and slowing down at the same time for even more vibration.
Last edited by Corvette Engineering; Jun 29, 2007 at 01:35 PM.
Pro
Joined: May 2005
Posts: 592
Likes: 1
From: Shreveport Louisiana LSU
As Richard has said, you MUST have the two angles. They should be the same but opposite. You can NEVER have a drive shaft straight in line with either the tranny or the pinion or you will have vibration. If your tranny points down 2 degrees, the pinion must be pointed up the same. All drive shafts are built with the knuckles of the u joints in line or the same vibration will occur.
If a tranny was pointed directly at the pinion in a straight line with no angle the driveshaft will tend to flop.
Drop the driveshaft and get an angle finder. Go for opposite but equal.
If a tranny was pointed directly at the pinion in a straight line with no angle the driveshaft will tend to flop.
Drop the driveshaft and get an angle finder. Go for opposite but equal.
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Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Interesting discussion here. So, how does the engine being offset to the passenger's side play into this? Does the lateral relationship between crank CL and pinion CL just end up in a "wash out" concurrently, as I suspect, or does that complicate these dynamics??
Pro
Joined: May 2005
Posts: 592
Likes: 1
From: Shreveport Louisiana LSU
Same thing, if it is offset but the face of the pinion is parallel to the back of the tail shaft, you will have the proper relationship. Sounds like maybe the motor mounts should be loosened/adjusted for this small adjustment, if the laser is only off 3/4 on the pinion if I remember correctly.
To explain the tranny to pinion, think of these / / , the one on the left is the tranny tail the one on the right is the pinion. This is the equal dimension you want. You do not want this / \ !
To explain the tranny to pinion, think of these / / , the one on the left is the tranny tail the one on the right is the pinion. This is the equal dimension you want. You do not want this / \ !
Thread Starter
Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
I dropped the driveshaft this weekend,as curiousity has gotten the better of me,and bolted a jig up to the pinion to measure the angle.
The way I did this may not be the correct way,so follow my thinking. First I took a measurement of the crank pulley with the car on the ground. Then I jacked up the car and tried to again duplicate the crank angle I measured on the ground by adjusting my jack stands.
With the car in this position I measured 90 degrees on my protractor jig,equal to zero on everybody elses pinion angle.The yoke angle measured 92 degrees,indicating to me the trans does point down 2 degrees as was posted here earlier. I figured I needed to raise the trans a bit,so I removed the trans mount bolts and jacked the trans up. Turns out it then hit the tunnel. I ended up putting it back the way I started with it.Ran out of time to mess with it.
So having measured and verified a 2 degree difference,what can be done to correct this on the pinion side. I assume it has to come up 2 degrees,but the mount doesn't look like I can move it very much before it will hit the frame.
Is this a big deal?Or can 2 degrees off be OK,but not perfect.
Here's a link to my jig.
http://www.finitesite.com/markwallas/pinion1.jpg
The way I did this may not be the correct way,so follow my thinking. First I took a measurement of the crank pulley with the car on the ground. Then I jacked up the car and tried to again duplicate the crank angle I measured on the ground by adjusting my jack stands.
With the car in this position I measured 90 degrees on my protractor jig,equal to zero on everybody elses pinion angle.The yoke angle measured 92 degrees,indicating to me the trans does point down 2 degrees as was posted here earlier. I figured I needed to raise the trans a bit,so I removed the trans mount bolts and jacked the trans up. Turns out it then hit the tunnel. I ended up putting it back the way I started with it.Ran out of time to mess with it.
So having measured and verified a 2 degree difference,what can be done to correct this on the pinion side. I assume it has to come up 2 degrees,but the mount doesn't look like I can move it very much before it will hit the frame.
Is this a big deal?Or can 2 degrees off be OK,but not perfect.
Here's a link to my jig.
http://www.finitesite.com/markwallas/pinion1.jpg
Last edited by The Money Pit; Jul 1, 2007 at 11:47 AM.
