Question about pinion angle and driveshaft angle

[ironworks]

Originally Posted by 65_LS1_T56

Andrew is correct. Tire size does not affect the angles. If you put larger diameter tires in the rear, the rake of the car changes, so does the relative angles with respect to true level. The working angles however do not change with just a tire size change. Picture a car going down a hill (same as a larger rear tire), the driveline angles do not change.
If the axle is moved relative to the rest of the chassis (ie ride height change with coilovers for example), then the working angles do change.

True but who just bolts on taller rear tires and doesn't lower it further.

But just raising the rear of the car without a rideheight adjustment changes the engine angle. Most engines need to have downward angle for float level adjust mentioned and engine oil level. Yes the working angle does not change but other issues do. But like I said who stuffs bigger rear tires under a car and doesn't lower it further. Let alone have a 6 or 7 inch rise in the drive shaft.

[abadsvt]

I don't have the motor and trans mocked up yet but I know the rear pinion yoke should be 11.1" off ground to center and guess the trans yoke will be around 7" off ground. So that will leave approx 4" rise over 36-40" long drive shaft. That shouldn't be that much of an angle. So I will just setup the irs to go with 2 degs up. Thanks guys. Really appreciate the help! Pics will come soon. Just want more done before. Have a great day!

Josh

[andrewb70]

Originally Posted by ironworks

True but who just bolts on taller rear tires and doesn't lower it further.

But just raising the rear of the car without a rideheight adjustment changes the engine angle. Most engines need to have downward angle for float level adjust mentioned and engine oil level. Yes the working angle does not change but other issues do. But like I said who stuffs bigger rear tires under a car and doesn't lower it further. Let alone have a 6 or 7 inch rise in the drive shaft.

You're conflating two different issues. The operating angles do change when the rear suspension is lowered or raised. This is because the position of the pinion relative to the transmission changes.

Changing front ride height or installing taller or shorter tires, front or rear has zero effect on the operating angles.

Andrew

[TheJDMan]

Originally Posted by andrewb70

You're conflating two different issues. The operating angles do change when the rear suspension is lowered or raised. This is because the position of the pinion relative to the transmission changes.

Changing front ride height or installing taller or shorter tires, front or rear has zero effect on the operating angles.

Andrew

Exactly!

[ironworks]

Originally Posted by andrewb70

You're conflating two different issues. The operating angles do change when the rear suspension is lowered or raised. This is because the position of the pinion relative to the transmission changes.

Changing front ride height or installing taller or shorter tires, front or rear has zero effect on the operating angles.

Andrew

Originally Posted by TheJDMan

Exactly!

Yes. I agree also. But the original poster is not talking about a ride height adjustment with tires or even coilovers. He is working to build a chassis.

[andrewb70]

Originally Posted by ironworks

Yes. I agree also. But the original poster is not talking about a ride height adjustment with tires or even coilovers. He is working to build a chassis.

Yes, and when building a chassis the position of the pinion relative to the transmission is important, hence why he was asking about that in his original post. Then in post #2 you brought in talk of tires, which is why we are talking about tires at all..LOL