Drivetrain Geometry

Powertrain Angle

Your car, no matter the make or model, was designed to have a -3° angle on the transmission. That is, the back of the transmission should be lower than the bell housing. You can measure this with a simple angle finder set on your output shaft or flange (image right). Your intake deck is machined at +3° so that when you lean your engine back at negative three degrees the carb will be level. Adjust your cross member to achieve the correct powertrain angle. If your body height, ride height or engine position has been modified you may need to shim the mount or purchase one of our Mega Mount low profile mounts to achieve the desired angle.

NOTE: EFI makes it possible to set more radical angles for your powertrain because it does not rely on level float bowls like a carburetor. However, the driveline angles at your u-joints are important for a smooth, steady driveshaft rotation. Even with EFI you should try to maintain the -3° powertrain angle.

Driveline Angles

As stated previously, the down angle of your transmission has a direct affect on the driveline angles. You should not use the height of your transmission to determine the accuracy of these angles. Your rear end should be adjustable to allow for fine tuning of the driveline angle. The diagram below is a good illustration of ideal driveline angles.

In the diagram Angle 1 is defined as the intersecting angle between the centerline of your transmission output shaft and the centerline of the driveshaft. Angle 2 is defined as the intersecting angle between the centerline of the driveshaft and the center line of your pinion.

The ideal angles are dictated by the optimum operating range of a u-joint, which is generally accepted to be between 1.5 and 3°. Referring to the diagram, Angle 1 and Angle 2 should be equal and opposite, that is if Angle 1 is 2.5° then Angle 2 should be -2.5°.

Setting your driveline angles properly will eliminate noise, harmonic vibration, and u-joint wear and tear.

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Conversion Crossmembers

Las Vegas, NV

The Modular Crossmember Systems hold two US Patents with a 3rd patent currently in pending status.


Conversion Crossmembers has been a leader in modular crossmember design and innovation since 2008. Previously operating in a white-label capacity to select vendors and aftermarket transmission companies, we now offer direct sales to consumer. All Conversion Crossmember sales includes a full product warranty as well as our unparalleled customer support.

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