driveline angle

[dhigdon@southerntank]

I'm building a 67 c10 swb. I have a 700r4 and 12 bolt gm rear, 4/6 drop. My driveshaft is at 1.5 degree angle. Seems I read you need at least 3 degress of angle. Is this setup going to be ok?

[Lee H]

Drive line angle will change with the cab, box, etal installed.

[Jason Banks]

I'm not sure the angle of the actual driveshaft is as critical as making sure the angle of the pinion on the differential and the angle of the engine are equal.

I found this page - https://4xshaft.com/blogs/general-te...veshaft-angles
The 2nd video gives a great explanation.

You are going to want to check all this once the whole vehicle is assembled and all the weight is on the suspension.

I'd make sure the back of your transmission is angled down slightly and then adjust the differential with shims once the weight is on. It looks like you are using a factory transmission crossmember that doesn't have much adjustability, other than shimming the transmission up.

[Richard]

The working angle of the ujoint is what matters, not the driveline angle. Driveline angle + trans angle and driveline angle + pinion angle determine working angle at ujoints. Working angle should not be zero, If over 3 degrees it is not really a problem as well. I see problem of people believing both angles should be set the same, not allowing for load at axle. Angles should be equal under load. That is the main reason some experience vibration issues. Angles constantly change while driving. With a modified vehicle the key is finding the sweet spot for average driving conditions.

[72SB]

OP, you want the engine/trans angle and pinon angle to be equal but opposite and ideally not more than 3 degrees each.

Once you get the Truck weight on all 4 tires, you may need to either add shims between trans and mount and/or angled shims on the rear end

If, for example you wind up with 3 degrees down on motor/trans but 2 1/2 up on the diff, doubt you will feel any vibes but you could just put 1/8" shim under trans to make it 2 1/2 degrees also.

[Richard]

Originally Posted by 72SB

OP, you want the engine/trans angle and pinon angle to be equal but opposite and ideally not more than 3 degrees each.

Once you get the Truck weight on all 4 tires, you may need to either add shims between trans and mount and/or angled shims on the rear end

If, for example you wind up with 3 degrees down on motor/trans but 2 1/2 up on the diff, doubt you will feel any vibes but you could just put 1/8" shim under trans to make it 2 1/2 degrees also.

Yes, you want the ujoint angles close to parallel. But that is while driving.
Setting them that way at a static position may cause problems. The pinion will twist up even with a trailing arm or link suspension under the load of driving. That is the point I was trying to convey. Pinion may need 1-3 degrees more operating angle depending on type of suspension to eliminate any vibrations. Just trying to help out. I see many posts about drivetrain woes. The ujoints move in an ellipse. Nothing exact about their operation during suspension movement.

[Keith Seymore]

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[Keith Seymore]

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[Keith Seymore]

Those are from 30+ years ago, but the science hasn't changed.

K

[Richard]

Thank you for posting that information again for people that do not know it. It is important information to know. I am fortunate to know that information and have the knowledge and ability to apply to different situations. There is textbook and application. I stand by my recommendations. I have two GM vehicles that are in stock form. A 2000 truck and 2020 Blazer. I am going to take the time in the near future to measure the working angles on shafts to see if they support textbook or what I see. Worked for over 40 years making adjustments to engineer/textbook specifications to make products work in real life in my career. Custom application.