General Bellhousing Alignment Instructions

General Bellhousing Alignment Instructions

In order to properly install an American Powertrain transmission, we require you to have proper bellhousing alignment with the engine block. Even with brand new components this is an important step for smooth shifting and minimal wear.

Bellhousing alignment is crucial for proper clutch function and reliability of the related components. Due to manufacturing tolerances of engine blocks and bellhousings, it is possible for the transmission centerline and crankshaft centerline to be misaligned. The result of this misalignment may be hard shifting, pilot bearing wear, transmission mainshaft bearing wear and failure of clutch disc hub.

Bellhousing Alignment

First, check bellhousing for bore concentricity. Install magnetic base to flywheel or pressure plate, then install the indicator to measure the bellhousing bore(shown above). Rotate the crankshaft and mark down the indicator readings (marking the bellhousing works well). The maximum out of concentricity is .005″.

Bellhousing Alignment

Next, the bellhousing face should be checked for parallelism to the back of the block for proper bellhousing alignment. Install the indicator(as shown above). Rotate the cranksahft and mark down the readings – be sure to push the crankshaft against thrust bearing for accurate measurement. The maximum out of parallelism is .002″.

To correct off-center condition, select the offset dowel pin pair that is closest to one-half of the indicator reading. For example if the reading is .016″, 1/2R = .008″ so use .007″ dowels. If the reading is .024″, 1/2R=.012″ so use .014″ dowels.


The bellhousing was offset toward the top of engine and slightly to the left, as viewed from behind. To align the bellhousing, install two .014″ offset down pins with the maximum offset positioned roughly at the 5 O’clock position.

Bellhousing Alignment
Offset Down Pin Chart

We Are Here To Help

After reading this if you’re still scratching your head or have a question or to, please feel free to reach out! We deal with this every single day and can walk you through the process.

Give us a call at (931) 646-4836 or Contact Us Here

Article courtesy of Centerforce Clutches

3 thoughts on “General Bellhousing Alignment Instructions

  1. I have a 1968 b body dodge, when I go to drive the car transmission shifts great. After around 25 miles shifting through gears gets harder and progressively harder to shift. Stop and shut the car off it shifts through gears same as when driving. Seams to work great when cold as it warms up gets progressively harder to shift.Thanks any response is appreciated.

  2. Can the runout be checked without the flywheel in place. Putting the magnetic base directly on the crankshaft?

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