VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Harmonic balancer loose

Hi all. I have a 1935 207 cubic inch six and I have found the harmonic balancer to be loose on the crank shaft. Upon removal and inspection, I found the crankshaft worn from being loose and the key way wallowed out on one side so that the key can rock. The key way is only worn or wallowed on one side of the key way. The shaft is also worn so that the interference fit no longer holds the damper on tightly. The damper has a very slight rock on the shaft when forced by hand when fully installed What are my options??? Will shaft loctite work?? They make it for key ways and also make loctite to hold bearings on shafts. Will a drilled and tapped shaft end bolt work, and do I need to removed the crank to accomplish? SKF makes shaft sleeves. Does that sound like a viable option? Has anyone had this issue and solved the issue effectively without a complete engine tear down??? What a bummer.

You can try drilling and tapping for a bolt. because the crankshaft is steel s fine thread and a heavy washer under the bolt.

I would do all of the above including the locktite. Also replace the pully with one that is not wallowed out. I have a 35 parts engine. If interested pm me.

I agree that the repair methods you are describing will work. Keyway damage at the crank nose is a common problem on some of the very early Miata’s. The recommended repair is to use Loctite 660 and a new crank bolt torqued properly.

There is a key point to follow when reassembling the hub to the crank. Make sure you have the good side of the key ways in the hub and the crank aligned and the key is against those surfaces. I would consider inserting a thin tapered pin or something like that into the worn side of the assembly to try and force everything to the “good” side.

I am assuming that the keyway damage does not extend into the cam drive sprocket.

Hello 35T, I am curious if you ever found a solution and what it was.