VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Best pulley retaining compound?

My crank pulley has come loose and starting to make some noise. When I put the engine together I used Loctite 680 retaining compound which only last a couple hundred miles. Any recommendations on which compound I should use? Is Loctite 660 the best for this application? Any other tips or tricks to prevent the pulley from working loose again?

-Tyler

From what I can find on an internet search, looks like Loctite 660 is a better product for gaps up to 20 thousanths. Specs that I saw gave 15 thousanths for Loctite 680. Don't know what is necessary to remove the failed 680. Light sanding is what I am thinking. Any other better comments? Would knurling help?

The hole in the pulley might NOT have parallel sides. If the pulley wobbled much, over time it could have worn more on the outside edges than in the middle. Just speculating. It would be good to inspect and measure carefully to understand the exact situation.

After you have a really good idea of the problem (including a detailed inspection and measuring of the crank shaft end), then you can contemplate possible solutions.

One idea is to bore out the hole in the pulley and make a steel sleeve that would bring the hole back to specs. Keep in mind that if the crank is worn, the hole in the sleeve would need to be sized properly so as to provide a shrink/interference fit to the crankshaft. I do not know what the proper clearance should be for such a fitting.

When I put the crankshaft pulley back on the front of my '28 engine after rebuilding the engine, I heated the pulley up to 500 degrees on my BBQ, got it to the block quickly, and it slipped onto the crank easily. After it cooled, it was totally stuck on.

Another avenue to explore is to get another used, but good pulley from someone's stash. There are lots of parts blocks laying in basements and garages. This solution is LOTS less work and probably quite inexpensive.

Cheers, Dean

Thanks for the replies! I suspect Dean is correct with the pulley being more worn on the edges, when I used 680 on it last time, the pulley had a small but noticeable wobble, I suspect this was probably the reason the retaining compound ultimately failed.

Other than being noisy, is there any major issues with having this pulley be loose? Do you tend to see equal wear on the pulley and crank or does one tend to wear more than the other?

-Tyler

TJPlatt

I had a very loose pulley. I purchased the cleaner and locktite 660. This stuff is great and so easy to use. I have almost 9 months with no signs of any play

Thanks Qman. I went ahead and used the Loctite 660 on it and replaced the woodruff key which was pretty worn, so far so good. My clearance was right at 0.015" which is the maximum of the 680 compound so I think that coupled with the worn woodruff key caused it to fail last time.

I'll plan to re-sleeve and broach a new key way on the pulley next time I need to replace the mains but hoping this will last me until then.

-Tyler

So the Loctite 660 lasted a total of ~250 miles before the pulley pulled itself loose again. My guess is that the considerable "wobble" of the pulley is what did it in so quickly. I went ahead and bought another pulley off of ebay which i should get in about a week.

In the meantime I pulled my existing pulley off and am planning to have it sleeved. My crank OD is ~0.810" so my questions is, what should I sleeve my pulley ID to? Where these originally an interference or a clearance fit? I was thinking I'd size it to ~0.809" or for a shrink fit but the guy at the machine shop was thinking it may be better to size it ~0.811" and use a retaining compound, I'm thinking that may be the way to go.