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Had to get a new spindle and screws for a 46" deck. Bought aftermarket spindle and B&S bolts from Jack's Small Engines. The bolts/screws are standard flat end threaded, but are called HD Tap. Will these tap their own threads into the new spindle whose hole is too small for the bolt to go all the way through? What's the deal. Am I suppose to tap the holes using a tap? Using the screws provided? Doesn't appear to be enough sidewall in the hole to get a decent thread. Drill the holes out and put nuts underneath? Yikes, if one drops off while mowing. What do you guys do.

If the end of the bolt looks like it is a little smaller and has three sides to it, not round like a normal bolt, it is self tapping. Take one and drive it in each hole with an impact gun, before trying to assemble the spindle on the deck. Hopefully you have a gun, as they don’t go in easy. This will give you a good thread when assembling. No gun, you will probably have to tap the hole first.

Thanks, Rivet. They don't look like any self-tapping screw that I've ever used, but they are labeled HD tap. I'll give it a try this weekend using a battery-powered gun. Don't have a air gun.

I rebuilt my entire Murray 46 inch deck several years ago, ( see pics below ) I drilled out the spindle mounting holes to 3/8 inch, bought new cadmium plated hardware, at local hardware store, used a bolt & FLAT washer on topside, and flat washer, LOCK-WASHER & nut on bottom, everything to this day is hunky-dory,.. no problems, when you go to remove the self-tapping ( original OR replacements ) they tend to break during removal leaving some portion in the spindle, making MORE-WORK if you want to rebuild the spindle housing, however, I have found spindles cheap enough ( about $25.00 ea ) to just replace them new.

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Ooops forgot to mention, I had to drill the spindle housing holes to 3/8s also .... sorry!

Generally the spindles come un-tapped, the supplied bolts can be driven or ratcheted right in. Least I've had no issues on my former tractors.

The new bolts are self tapping and shakeproof.
I follow the same routine as Rivets describes except I put a touch of anti sieze on them befor fitting to stop them corroding solid in place.
If you cut a full thread with a tap, they will loosen up in service ( found that one out the expensive way ).
The mechanic up the road has a tap which he ground down a little smaller so it cuts a shallow thread that he uses to do the same job.
Whatever you do, don't try to fit them strait up as you really have to shove on the bolt hard to make it cut a thread

I'll be an outlier here and suggest that anytime you are tapping threads into material, rather than using an impact driver, you thread them in by hand.

Treat the fastener as if it were a tap; go in a half a turn or so, then back off a bit to clear the swarf, in a half turn, back off a bit and so on 'till you're all threaded in, then tighten up.

Boring and slow, I know. Maybe even a bit too late. Have you already done all of this?

All the new JD spindles come with the plain untapped hole.... I use a air impact and just run the self tappers in there... No problems with them at all.....

I've got a bunch of spindles that I should probably drill out. But like it was mentioned, spindles are so cheap now. it's pretty cheap just to replace them.

But that was before I learned how to replace the bearings without having to take the spindle bolts out. Doing that, it's only about $15 per spindle for new bearings.

Psychlopath said:

I'll be an outlier here and suggest that anytime you are tapping threads into material, rather than using an impact driver, you thread them in by hand.

Treat the fastener as if it were a tap; go in a half a turn or so, then back off a bit to clear the swarf, in a half turn, back off a bit and so on 'till you're all threaded in, then tighten up.

Boring and slow, I know. Maybe even a bit too late. Have you already done all of this?

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Not too late. Will work on it this weekend. Thanks for the input. Was thinking of buying a tap or another screw to dedicate for tapping. I’m sure I’ll be fine either way.

Turns out, I had the right size tap. It didn't take anytime at all to do it on the bench. Threads are thin, but appear sufficient. I plan to add split lock washers just because the built-in washer doesn't have ridges for grip. Might be overkill cause everything will probably rust on anyway. Anyway, time for a beer and baseball.

LarryJohnson said:

Turns out, I had the right size tap. It didn't take anytime at all to do it on the bench. Threads are thin, but appear sufficient. I plan to add split lock washers just because the built-in washer doesn't have ridges for grip. Might be overkill cause everything will probably rust on anyway. Anyway, time for a beer and baseball.

Click to expand...

I've gotten into the habit of cleaning the surfaces around the bolts and spraying them with some sort of paint or that rubber in a can stuff. It seems to stick pretty good (on a clean surface). Just a little dab'll do ya.