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As replacement of my brake disc bobbins needs doing, I thought I'd get a tap to clean out the disc-bolt holes properly. I didn't do it when I replaced the discs, which I suppose was remiss of me, but nothing's come loose and the brakes work OK!

Anyway, I assume I need an M8 tap, the disc bolts being M8x25. Searching on eBay gives me choices....confusing choices! Do I need -

1. a taper tap?
2. a plug tap?
3. a bottoming (!) tap?

Now, I should be able to remember this sort of stuff, because as an apprentice in the RAF I had to drill and tap holes, and do other stuff. But I can't, because once I left Halton, I never, ever used those 'skills', or many of the other things they taught me!

Pete

cut a slot down the length of an old disc mounting bolt and it should clean out the threads, I've done this in the past as recommended on this forum .. The alloy threads can be damaged either way though especially by a thread tap.

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Thanks for the reply and info - old bolt it is then! It looks as if the worn 'pillar' was an issue with 1100/1150s rather than the 1200s, so, hopefully, bobbins and washers should sort the noise!

Pete

If you cut an old bolt you run the risk of leaving a burr along the slot you have cut = f***ed thread, or proper tool for proper job. Taps normally come in a set of three, taper,2nd cut and a plug, depending on depth of the hole use either the 2nd or plug. Don't forget some lubrication and 3/4 turn fwd and 1/4 turn back, all that training will come flooding back

Al.

Hmmmm. I do remember 'forward and back', now you mention it! I've just got off the phone to a mate who has a good selection of taps, so once the wheel's off, I'll be popping round with it - moral support, and all that! Actually, the 'wheel off' has come at a fairly convenient time - I picked up a pair of PR3s for a good price at the weekend, so said mate is fitting them as well!

Although I can't remember something as straightforward as tapping a hole, strangely enough I can remember how to dismantle and service the launcher ring gear on a Bloodhound Mk II SAM, every step of it! Very handy that.

Pete

Check the tap against the bolt before you dive in, metric taps can be 1mm or 1.25 mm pitch.

Al.

Al wrote:Check the tap against the bolt before you dive in, metric taps can be 1mm or 1.25 mm pitch.

Al.

Never simple, eh!

Well at least if you worked on rockets you knew when you sent it on its journey you didn't have to hang around and service the bloody thing when it landed like me

Al.

We only ever sent one on its merry way....then went out on the lash in celebration!

Easy life!!!

Al.