Drive line angle questions

[sfont66]

Truck is a 72 C10 SWB with coil spring/ trailing arm rear suspension. My current angles have the transmission at 3.6 degrees down, and rear end at 2.3 degrees with pinion pointing up( sloping down from front to back) drive shaft is 1.3 degrees down. So in order to get the angles closer to correct, I have been trying to find a 1 degree or even a 1.5 degree shim for the axle. I see Cpp had them in the past but now I can only find 2,4, and 6 degree. Same at Speedway, and Brother’s/Holley. I find 1 degree shims at Summit, but not sure of fitment and they don’t have dimensions for length, and are special order.
I do have 2 degree shims on hand .
I have talked with Silver Sport Transmission, and I seem to recall they recommend that I try to keep the transmission at 3 degrees if possible, and I can’t raise it any further without cutting the floor of the truck.

So my question is: does anyone know where to purchase 1 degree shims, or should I install the 2 degree shims, making the rear 4.3 degrees, and then lower the transmission to the 4.3 degrees to make for more optimal driveline angles??
Can anyone see a problem with the engine /transmission being at 4.3 degrees down?
Any advice is appreciated
Thanks

[Richard]

Your current working angles are fine, actually real good. The 3 degree recommendation refers to the working angle of joint not a transmission, driveline or pinion. Your working angles are pretty close to being within 1 degree. Typically the pinion should be down 1-2 degrees to allow for wrap under acceleration.
Unless you have a vibration there is no reason to do anything.

[MySons68C20]

Originally Posted by Richard

Your current working angles are fine, actually real good. The 3 degree recommendation refers to the working angle of joint not a transmission, driveline or pinion. Your working angles are pretty close to being within 1 degree. Typically the pinion should be down 1-2 degrees to allow for wrap under acceleration.
Unless you have a vibration there is no reason to do anything.

So the goal is to keep them within 1 degree of each other correct?

[sfont66]

Originally Posted by Richard

Your current working angles are fine, actually real good. The 3 degree recommendation refers to the working angle of joint not a transmission, driveline or pinion. Your working angles are pretty close to being within 1 degree. Typically the pinion should be down 1-2 degrees to allow for wrap under acceleration.
Unless you have a vibration there is no reason to do anything.

Thanks for your reply
I only have what could be described as a very slight vibration while cruising at 75-80 in 6th gear. It’s possible it’s not even drivetrain related. I haven’t driven the truck for 5 months now(winter weather) and it will be another month or two before I can do so again, to investigate further.

[samert111]

I always understood that the trans output shaft centerline and pinion centerlines should be parallel to one another but not necessarily inline with one another to improve ujoint wear. The centerline to centerline difference to create a max 3° driveshaft angle.

[Richard]

Originally Posted by samert111

I always understood that the trans output shaft centerline and pinion centerlines should be parallel to one another but not necessarily inline with one another to improve ujoint wear. The centerline to centerline difference to create a max 3° driveshaft angle.

3 degrees references the operating angle of the ujoint, not a component. The components create the operating angle. Operating angle is what is important. Understand, it is not like the ujoint explodes if that number is exceeded. It is said the life of joint is decreased if above 3 degrees. I have had two previous 4x4's and my current one. Past two and current had and will exceed that 3 degree theshold. Never had a problem with ujoint life or excessive vibrations. My current build will have about a 15 degree driveshaft angle at ride height and 25+ degrees at full droop. It will give me about 5 degrees operating angle on the joints in the double cardan cv at ride height. Will live a long service life. The operating angles constantly change while driving with any suspension. Need to get them close at ride height. IMO many people over think this.

[MySons68C20]

Originally Posted by Richard

3 degrees references the operating angle of the ujoint, not a component. The components create the operating angle. Operating angle is what is important. Understand, it is not like the ujoint explodes if that number is exceeded. It is said the life of joint is decreased if above 3 degrees. I have had two previous 4x4's and my current one. Past two and current had and will exceed that 3 degree theshold. Never had a problem with ujoint life or excessive vibrations. My current build will have about a 15 degree driveshaft angle at ride height and 25+ degrees at full droop. It will give me about 5 degrees operating angle on the joints in the double cardan cv at ride height. Will live a long service life. The operating angles constantly change while driving with any suspension. Need to get them close at ride height. IMO many people over think this.

Great post!!^^^^^^

[2500HD]

Originally Posted by Richard

3 degrees references the operating angle of the ujoint, not a component. The components create the operating angle. Operating angle is what is important. Understand, it is not like the ujoint explodes if that number is exceeded. It is said the life of joint is decreased if above 3 degrees. I have had two previous 4x4's and my current one. Past two and current had and will exceed that 3 degree theshold. Never had a problem with ujoint life or excessive vibrations. My current build will have about a 15 degree driveshaft angle at ride height and 25+ degrees at full droop. It will give me about 5 degrees operating angle on the joints in the double cardan cv at ride height. Will live a long service life. The operating angles constantly change while driving with any suspension. Need to get them close at ride height. IMO many people over think this.

i agree with you and i think we are saying the same thing. if the componets are correct so will the ujoint operating angle. the one thing we may not agree on is what excessive vibration is. In my opinion any driveline vibration is excessive. Unless a vehicle has a big lift there is no reason the component angles and therefore the oprtating angles cant be really close. I just went though this on my truck and as it turned out the brake drums were causing the vibration.

[2500HD]

With your angels listed above i would raise the trans 1 degree and leave the rear alone. When raising the trans it will also cahnge the angle of the driveshaft to close to 2 degrees resulting in 2.6/2/2.3.

[sfont66]

Originally Posted by 2500HD

With your angels listed above i would raise the trans 1 degree and leave the rear alone. When raising the trans it will also cahnge the angle of the driveshaft to close to 2 degrees resulting in 2.6/2/2.3.

Thanks for your reply,

The transmission in my truck is a T56 magnum, and is fairly large, I have the high hump transmission tunnel, but even with the high hump, a portion of the rear of the transmission is very close to contacting the floor of the truck. I can’t raise the transmission any further without modifying the floor. I found a company that makes a extended high hump cover, and believe it would allow the transmission to be raised far enough to get to 2.6 degrees. Level 7 is proud of this piece, as they are fairly expensive, $355 plus tax and shipping.
This could be a solution though, with those numbers the drive shaft may be happier.

I’m not sure how to figure what the driveshaft angle would be if I added a 1 degree shim to the rear of current setup to plug the numbers into the driveline calculator, to get the operating angles, so my original plan may not be the best plan.

Again, I want to thank those that have responded with suggestions /advice, I appreciate it.

[2500HD]

Originally Posted by sfont66

Thanks for your reply,

The transmission in my truck is a T56 magnum, and is fairly large, I have the high hump transmission tunnel, but even with the high hump, a portion of the rear of the transmission is very close to contacting the floor of the truck. I can’t raise the transmission any further without modifying the floor. I found a company that makes a extended high hump cover, and believe it would allow the transmission to be raised far enough to get to 2.6 degrees. Level 7 is proud of this piece, as they are fairly expensive, $355 plus tax and shipping.
This could be a solution though, with those numbers the drive shaft may be happier.

I’m not sure how to figure what the driveshaft angle would be if I added a 1 degree shim to the rear of current setup to plug the numbers into the driveline calculator, to get the operating angles, so my original plan may not be the best plan.

Again, I want to thank those that have responded with suggestions /advice, I appreciate it.

Back to this. message the trans tunnel 1/2 to 3/4 to raise the tailshaft and be happy. start wide and raise over a wide area. you will not even notice inside the cab.

[sfont66]

Originally Posted by 2500HD

With your angels listed above i would raise the trans 1 degree and leave the rear alone. When raising the trans it will also cahnge the angle of the driveshaft to close to 2 degrees resulting in 2.6/2/2.3.

I was able to massage the transmission tunnel enough to allow the transmission to be shimmed up to 2.6 degrees, this made the driveshaft angle 1.7 degrees, and the rear remains unchanged, so it should still be the 2.3 degrees.
To me these angles are an improvement and should take away the slight vibration I was feeling at freeway speeds.
It will most likely be at least another month before I can do a test drive to prove these changes. (We received another 16” of snow in the past week)

I see the first pic loaded sideways, it was tough to get a good shot.

Originally I thought it would be easier to shim the rear up to correct my pinion angle, but after thinking it through, doing so would have made my operating angles worse. The drive shaft angle would have been less , and when doing the math, my operating angles would have been worse than when I began.

There is a lot of information out there when researching this subject, and sometimes a person can go down the rabbit hole with information that doesn’t directly apply to their specific application.
Many years ago my wife purchased a sign for the garage, can you find it? I guess for me this is true.

I asked for, and received valuable information from those who have experience setting up their own trucks.
Thanks again to all

[2500HD]

You could always get a little heat and an air hammer and message it a bit. i will not take as much as you think. 1/2 to 3/4 i bet.

[2500HD]

Thats great sfont66. If you have any vibrations now i am sure it is somthing other than driveline angles.