Check Bell Housing Runout In Under Ten Minutes With SST

There are components that bring so much benefit to enjoying our rides such as performance camshafts and overdrive manual transmissions. Sadly, many are hesitant to make the upgrade due to some important, one-time procedures. Just like dialing in a camshaft, checking a bell housing’s runout is important if you want to get the most out of your upgrade. Failure to ensure the bell housing’s runout is within spec could lead to driveline vibrations and even transmission failure. It is so important that Silver Sport Transmissions requires you to do this one-time process to validate any necessary warranty claims down the road.

Just like dialing in a camshaft, checking bell housing runout is necessary, and not necessarily a complex task, comprised of a few tools, a bit of math, and the help of a friend. Silver Sport Transmissions has just released this video of the simplest way they’ve found to ensure your bell housing is within spec and your transmission will feel right at home in your ride.

Shane explains the first step is to mark your first starting point and zero the dial indicator, which is directly connected to the flywheel and will spin with as your friend turns the crankshaft from the front of the engine. The tip of the dial indicator will spin inside the register hole of the bell housing. The transmission in this video is a TKO but a six-speed magnum transmission uses a plate that bolts to the bell housing with the same hole for a register point.

The area with the highest number becomes the new zero and William spins the engine 180 degrees from that spot to find the total indicated runout.

Shane and William begin by spinning the engine one revolution to ensure the dial indicator returns to zero at the starting point. Then, spin the engine again and focus only on the highest number indicated on the gauge. Don’t worry about negative numbers at this point. Then spin the indicator to the point where the highest number was achieved and re-zero your dial indicator.

Spin the dial indicator 180-degrees and note the total indicated runout. Ours was .015”, but remember, this is TOTAL indicated, so you need to divide this number by two to find the actual runout, which is the offset for the dowels you will need to use to bring the bell housing runout into spec.

Offset dowels are installed. They align the bell housing according to the measurements found by the dial indicator. The dowels press in and then are secured with an Allen wrench. Be sure they don't spin, as their clocking position is what aligns the bell housing.

At this point, you will remove the bell housing and install the offset dowels according to which direction you need to move the bell housing. Re-install the bell housing and begin the process over to check the bell housing has moved in the correct direction and is now within tolerance.

After re-checking the runout, Shane shows that this bell is now within tolerance with a .0025″ runout.

Truing a bell housing has confounded some enthusiasts and many have been hesitant to enjoy all the benefits of an overdrive transmission simply because this process has confounded them. With this recent video from SST, you can see how this necessary, one-time task is easily doable and is not the daunting, and prohibitive monger that many have made it out to be. Check out the video, and if you have any questions, be sure to contact Silver Sport Transmissions and you’ll surely be on your way to enjoying many smiles per hour in your greatly updated ride.

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About the author

Andy Bolig

Andy has been intrigued by mechanical things all of his life and enjoys tinkering with cars of all makes and ages. Finding value in style points, he can appreciate cars of all power and performance levels. Andy is an avid railfan and gets his “high” by flying radio-controlled model airplanes when time permits. He keeps his feet firmly grounded by working on his two street rods and his supercharged C4 Corvette. Whether planes, trains, motorcycles, or automobiles, Andy has immersed himself in a world driven by internal combustion.
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