Help me with my damper installation

June 1, 2017 | By Staff


I’m putting a rebuilt damper back on my 1951Chevrolet and I need to torque the nut holding the vibration damper to the specs in the manual. To find out how I could stop the engine from rotating, I did a little research and discovered these possibilities:

1. Stuff 6 feet of sash cord through a spark plug hole when that piston is beginning a compression stroke.

2. Screw a bar to threaded holes in the pulley.

3. Stop the flywheel with a large screwdriver on the starter ring gear.

4. Wedge a piece of wood between the flywheel and bell housing.

In a related area, a suggestion was made to first cool the crankshaft snout with crushed dry ice in a Ziploc bag for 15 minutes, and warm the damper pulley by soaking it in 200-degree water for 15 minutes. What is your advice?


On a Chevrolet I have inserted a chunk of wood in the bell housing between the housing and the ring gear with good results. You simply remove the clutch inspection pan and then find a piece of soft pine that you can wedge between the starter ring gear on the flywheel and the bell housing. After that you can torque the vibration damper and pulley into place easily.

The rope trick works just as well too. It is critical though, that you bring the piston up on the compression stroke so the valves are completely closed. Otherwise you will bend a valve when you begin torqueing down the damper. Clean nylon rope is the best, and to make it slip in and out easily shoot it with a little WD40. Push it into the sparkplug hole until the combustion chamber is firmly filled. This rope trick is also handy for changing valve springs and keepers without having to remove the head.

One thing that may be obvious but is worth repeating in case it isn’t, is that you never want to try to mount a vibration damper by pounding on it with a hammer. It is fine to use a socket and tap it into place, but pounding on it will damage it and knock it out of alignment.

Cooling the crankshaft snout with dry ice or even wet ice is a good idea, as is heating the damper up to no higher than 200 degrees using hot water in order to get it onto the crankshaft. The damper has an interference or press fit, so if you can open the clearance using a temperature differential, that’s great. But never try to ream or open the fit using files or emery paper. A lose vibration damper could be dangerous to your engine and radiator.

There are a number of tools available for pulling and installing vibration dampers that can make life easier for you. For example, Alltrade carries a Harmonic Balance Puller and Installer Kit ( that will help make the job easier. Along with visiting their website, you can pick one up at an automotive tool shop or order it from Amazon.