Author Topic: Tap size for 8 x 1.25 Helicoil  (Read 40850 times)

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Offline Skonnie Boy

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Tap size for 8 x 1.25 Helicoil
« on: October 19, 2011, 12:21:45 PM »
Hey, I have 8 x 1.25 helicoils and a whole mess of taps.  What I don't have is the kit, where the right sized tap is provided.  Would a 10 x 1.25 tap work for providing a home for said helicoil?  They seem to be the same diameter.  Any advice?
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Offline dave500

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #1 on: October 19, 2011, 12:42:44 PM »
i always thought helicoils had there own odd ball taps?maybe ring a bolt supply shop and find out?

Offline Skonnie Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #2 on: October 19, 2011, 12:50:57 PM »
Yeah, the size of the provided tap (needed to bore out the hole for the helicoil) seems to be a proprietary secret.

And I thought I was so clever by buying a metric tap and die kit.  Oh, well...  $41 later...
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Offline dave500

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #3 on: October 19, 2011, 12:57:46 PM »
itll be handy further down the track.

Offline Skonnie Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #4 on: October 19, 2011, 01:35:21 PM »
Yes.  If we weren't put on this earth to accumulate tools and parts we'll never need, then I don't know what for.
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Offline crazypj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #5 on: October 19, 2011, 01:39:28 PM »
Pretty sure it is just a 10x1.25.
 I know 6mm uses 7x1.00.
 Some of the other sizes are specials though 
Re-coil are exactly the same but much cheaper (and available in Autozone, Pep-Boys, etc)
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Offline mrbreeze

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #6 on: October 19, 2011, 02:19:37 PM »
There is no such thing as "too many tools" !!! ;D
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Offline City Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #7 on: October 19, 2011, 02:36:08 PM »
Hi Skonnie.I just measured my helicoil M8x1.25 tap.It appears to be 10x1.25 but may be 3/8ths and the pitch gauge does not fit perfectly.Maybe drill a test hole in a scrap piece and test with a 10x1.25 tap and coil.The coils themselves are inexpensive right?      Rock On
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Offline bryanj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #8 on: October 20, 2011, 01:20:24 AM »
Are you sure it's not 9x1.25? iTs best to buy the proper helicoil tap as the threads need to be correct to hold the coils.

Of all the rethreading inserts i think only Keenserts use a "Standard" outer thread
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Offline MRieck

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #9 on: October 20, 2011, 05:10:30 AM »
Taps for helicoils are labeled "STI". I have bought bottoming taps for the inserts as blind holes present problems with the standard taper taps.
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Offline crazypj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #10 on: October 20, 2011, 08:19:48 AM »
6mm insert is 7mm OD when fitted.
Anyway,  I've never measured 8mm insert (not sure why, I measure just about everything  ;D)
 measure thickness of insert across 'diamond' and double it (the steel wire cross section <>)
 It will be around 1mm so 8mm+1+1 = 10mm.
 Obviously, if it's less than 1mm section you will need a smaller tap (and larger if it's bigger)
$40.00 is overpriced.
Try Victor machinery Exchange in NY, they have kits and single taps (but they do have a minimum order)
 I usually have trouble spending too much, minimum is never a problem  ;)
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Offline Skonnie Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #11 on: October 20, 2011, 08:38:41 AM »
Yeah, I noticed how close the 8 and 10 x 1.25mm were.  The coils themselves are inexpensive. 

Its all a moot point, though.  The tap I had didn't have any taper to it, making it near-impossible to carve out a new path.  I spent $40 and got the kit.  Had to do this now, otherwise I got no way to work.  Aside from having to negotiate the frame, it was pretty easy.  Done a few helicoils before.

Oh, and for bonus points, I'd fixed it earlier with JB Weld.  If anyone tells you you can't fix a stripped header bolt mount with JB Weld, they're wrong.  You can't really tighten the hell outta it, but it works.  Also, if you add a blob on the bolt behind the header mount, it acts as a stopper, preventing the bolt from falling out even if it becomes unscrewed.  It worked for a couple thousand miles this summer.  Love that stuff.

 
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Offline 754

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #12 on: October 20, 2011, 09:18:21 AM »
 So mic the od of the tap and let us know..
 Cant measure the coils as they close up on installation..
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Offline fmctm1sw

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #13 on: October 20, 2011, 12:06:24 PM »
I have a kit at home that came with the tap, I can measure it later today.  I'm pretty sure I bought it to thread a mirror mount...
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Offline crazypj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #14 on: October 21, 2011, 12:35:32 PM »
I guess I could have just measured mine, couldn't be bothered though   ::)
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Offline fmctm1sw

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #15 on: October 21, 2011, 12:43:07 PM »
ahh, I measured and forgot it.  I wrote it on my shelf, I'll post it when I get home...
Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline fmctm1sw

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #16 on: October 21, 2011, 01:28:03 PM »
ahh, I measured and forgot it.  I wrote it on my shelf, I'll post it when I get home...

.3785 is what I got...
« Last Edit: October 21, 2011, 01:31:10 PM by fmctm1sw »
Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline crazypj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #17 on: October 22, 2011, 07:28:42 AM »
That's 9.6mm
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Offline 754

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #18 on: October 22, 2011, 08:40:55 AM »
 That would be very very close to a 3/8 x 20 tpi tap... just off the top of my head..

 so now we know, dont even THINK of using a 10 x 1.25 tap..
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Offline Skonnie Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #19 on: October 23, 2011, 12:22:07 AM »
Amen to that.  The 10 x 1.25 was about 24mm, while the supplied tap was about 23 or less.  I don't have batteries for my caliper, so I just eyeballed it. 

Needless to say, to future generations of SOHC searchers, don't use a 10 x 1.25 tap to provide a home for your 8 x 1.25 bolts.  The taper's all wrong anyway.  And stay in school, don't do drugs.  And so forth.
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Offline dave500

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #20 on: October 23, 2011, 12:33:16 AM »
« Last Edit: October 23, 2011, 12:36:03 AM by dave500 »

Offline crazypj

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #21 on: October 23, 2011, 11:59:24 PM »
After looking through those charts, 10x1.25 is the ONLY non Helicoil tap you can use.
 Spec is 9.8mm to 10.35mm
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Offline 754

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #22 on: October 24, 2011, 07:15:36 AM »
 I woud use a 3/8 a 20 but not a 10 x 1.25.

 btw KBC has an amazing assortment of non standard pitches, if you ever have a need for them, fairly cheap too..
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Offline Skonnie Boy

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #23 on: October 24, 2011, 01:50:18 PM »
KBC?  That some sort of canuck operation?  Man, what I wouldn't give for a Harbor Freight located in the city.

Lord help me if I ever need something with non-metric thread pitch.  Because then I'd likely be working on a British bike, and I'd be proper screwed.

Oh wait, bad pun sorry. 
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Offline 754

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Re: Tap size for 8 x 1.25 Helicoil
« Reply #24 on: October 24, 2011, 07:35:34 PM »
KBC Tools is a USA company.. they have a pretty good selection of stuff..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way