Crankshaft Pulley Removal Bolt

[Rick Glassman]

I am getting ready to pull off the crankshaft pulley from my '53 cub and when I went to install the ½”-13 X 5” grade 8 bolt it only turned in a couple of threads. I thought maybe there was still some dirt on the inner threads, so I ran my tap in there and same thing occurred, it came to a dead stop after about 2-3 treads. (I did not want to force it) I tried installing the bolt on another cub engine I have and had the same results. Is this correct?

[Glen]

Hi,
If you cleaned the crankshaft hole and threads, the bolt should turn in by hand all the way in, or be close to that easy.
Try running a die on the bolt, and see if it helps it.
Try oiling the threads.
Bolts and threads can vary from different companies.

You might need a different bolt if it won't turn in the hole.

When pulling the front pulley using a puller with threads on a rod, oil the threads with motor oil before beginning. Dry threads can have friction when pulling hard on a puller.

[staninlowerAL]

Sounds like your bolt might be a different thread size/count than what's in the crankshaft. Someone will probably be along shortly to post the correct size and thread count. Good luck.

[Rick Glassman]

Thanks for the help!

Here is an update. I tried a different bolt, and it appears the bolt size is 7/16"-14 is this possible? It goes into both of my cub pulleys/crankshafts and feels like it will tighten down. I have attached a picture of the crankshaft threads and you can see there is a little metal lip and that is where I think the ½” bolt stops. Is that little metal lip the end of the crankshaft?

[Glen]

Hi,
You could send a PM to tst, he probably knows the size of the bolt hole and threads in the front of the crankshaft. He repairs Cub engines.

Below is a post by tst about removing a front crankshaft pulley.

viewtopic.php?f=1&t=103607

Below is a post from the How To section about removing a front pulley.
When using a puller like this one, I would oil the threads on the long rod with motor oil before beginning, and work the oil through the threads on the cross piece.
Dry threads can have friction when pulling hard on a pulley, or other parts.

viewtopic.php?f=141&t=44517

Here is a How To about putting the pulley on again.

viewtopic.php?f=141&t=106362

[Bill V in Md]

Rick, I believe you identified the problem being the little metal lip or protrusion in the threads. I am attaching a photo I just took of that area on my cub and the threads are relatively clean. I can confirm that those threads are 1/2 -13 on my tractor, and a bolt of that size will fully engage the threads.

[Bob McCarty]

Is there any chance it's a 9/16" bolt that was in the wrong bin when you bought it?

[Nelson 634]

How about running a round wire brush down that hole and make sure it is free from dirt or corrosion. I have read on the forum somewhere about using gun barrel cleaning kit brushes for this purpose. I purchased a kit from Harbor Freight with multiple sizes and with the ability to chuck it up in a drill motor or impact driver. Clean'em out with penetrating oil or some thing similar. Then try running tap to clean up threads. Your picture leads me to believe dirty corroded threads. Just one persons opinion. Good luck

A second thought, what was on the end of the tap in the flutes? Should tell you what your dealing with.

[Rick Glassman]

I’ll clean and oil the treads and run the ½"-13 tap through there again. This time I will put some pressure on the tap. Thanks for the cleaning ideas and confirming the threads are ½”-13. I will practice on the spare engine first.

Thanks everyone!

[Glen]

Hi,
It looks like in your pic at your post Rick, that someone may have used a puller with a pointed end on the threaded rod, so it may have changed the shape of the end of the crankshaft, at the hole, and made it tapered, and a smaller size at the end of the hole.
Sort of hard to see in a pic if that is it.

You would need to repair the front end of the hole if that happened, if you want to use a bolt in the hole. I'm not sure how to fix it, you might need to use a round file, and enlarge the squished metal at the very front of the hole. But try to figure out if that happened before filing it.