Date: 29-03-24  Time: 11:29 am

Author Topic: Helicoil  (Read 3602 times)

stu1318

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Helicoil
« on: 29 December 2017, 08:55:27 pm »
Hi there I need to helicoil as bolts snapped when taking exhaust off😑so what size do I need to use helicoil......im pretty stupid at sizing cheers 😌

celticbiker

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Re: Helicoil
« Reply #1 on: 30 December 2017, 08:49:43 am »
Have you got the old bolt out yet?
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stu1318

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Re: Helicoil
« Reply #2 on: 30 December 2017, 09:23:54 am »
Yes got part of a bolt  so do I measure that??

ram

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Re: Helicoil
« Reply #3 on: 30 December 2017, 11:37:17 am »
Yes got part of a bolt  so do I measure that??
measure the dia of the stud pref with calipers but you should be able to see size with decent rule. prob 8mm or 10mm, your pitch is distance between teeth
helicoil drill sizes here:
https://www.thorintl.com/Drill-Sizes-HeliCoils-Metric.shtml
« Last Edit: 30 December 2017, 11:38:13 am by ram »

celticbiker

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Re: Helicoil
« Reply #4 on: 30 December 2017, 01:28:13 pm »
It will probably be an M8x1.25, I'd be inclined to replace it with a stainless stud and brass nut to prevent this from happening again.
Kit required can be found here on eBay


https://www.ebay.co.uk/itm/THREAD-TAP-REPAIR-CUTTER-KIT-M8-x-1-25-x-8mm-Helicoil-Compatible-NO-CASE/201454190107?hash=item2ee79afe1b:g:s2YAAOSwk~xZiKkL
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stu1318

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Re: Helicoil
« Reply #5 on: 30 December 2017, 10:34:51 pm »
Excellent cheers for the replies 👍

agricola

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Re: Helicoil
« Reply #6 on: 31 December 2017, 05:38:09 pm »
It will probably be an M8x1.25, I'd be inclined to replace it with a stainless stud and brass nut to prevent this from happening again.
Kit required can be found here on eBay


https://www.ebay.co.uk/itm/THREAD-TAP-REPAIR-CUTTER-KIT-M8-x-1-25-x-8mm-Helicoil-Compatible-NO-CASE/201454190107?hash=item2ee79afe1b:g:s2YAAOSwk~xZiKkL


Isnt there a danger of a galvanic reaction here, the parts are likely to get wet?

Mustang

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Re: Helicoil
« Reply #7 on: 03 January 2018, 04:47:22 pm »
It will probably be an M8x1.25, I'd be inclined to replace it with a stainless stud and brass nut to prevent this from happening again.
Kit required can be found here on eBay


https://www.ebay.co.uk/itm/THREAD-TAP-REPAIR-CUTTER-KIT-M8-x-1-25-x-8mm-Helicoil-Compatible-NO-CASE/201454190107?hash=item2ee79afe1b:g:s2YAAOSwk~xZiKkL


Isnt there a danger of a galvanic reaction here, the parts are likely to get wet?
that's what I wonder. There is a feature in this months practical sportsbike a where they are drilling out a ss stud from a bandit engine, it's siezed and snapped.

agricola

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Re: Helicoil
« Reply #8 on: 03 January 2018, 08:02:56 pm »
I wouldnt use brass on stainless steel, in fact I wouldny use brass at all

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Re: Helicoil
« Reply #9 on: 03 January 2018, 09:10:17 pm »
I wouldnt use brass on stainless steel, in fact I wouldny use brass at all
I'll admit I'm not up to speed with galvanic corrosion but I made some brass nuts for my FZS600 exhaust (M6) some years ago and had no problem removing them since. They are just on the standard studs, not stainless though. I recall in my past life we used brass nuts holding the exhaust manifolds on lorry diesel engines. So I'm wondering if there is a reason you wouldn't use brass at all.
 Maybe I should look up a chart of the reaction between dissimilar metals.

celticbiker

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Re: Helicoil
« Reply #10 on: 03 January 2018, 09:39:31 pm »
Same here, never had a problem with brass nuts on stainless and ptfe paste or tape will prevent  it from happening in the head but I've never had a problem there either.
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agricola

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Re: Helicoil
« Reply #11 on: 04 January 2018, 02:10:49 pm »
Brass is soft. A reaction with a dissimilar meatl plus road crud could lead to threads locking, this increases the risk of brass threads stripping or the hex rounding off. Its a personal choice.

Hugh Mungus

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Re: Helicoil
« Reply #12 on: 04 January 2018, 08:43:12 pm »
I thought the idea of using brass nuts on exhaust studs is that if they do seize you can just break them off without ruining the threads as it's easier than trying to break steel nuts.

slappy

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Re: Helicoil
« Reply #13 on: 04 January 2018, 09:10:14 pm »
Many many years ago I replaced an exhaust on a neighbours daughters Honda Melody, complete with basket on front, and the nuts on the exhaust studs were brass or something very similiar. They just rounded off straight away and I ended up using a small chisel to split the nuts, easy to do with brass ones. But put steel ones on as replacements.

tommyardin

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Re: Helicoil
« Reply #14 on: 04 January 2018, 11:08:17 pm »
Many many years ago I replaced an exhaust on a neighbours daughters Honda Melody, complete with basket on front, and the nuts on the exhaust studs were brass or something very similiar. They just rounded off straight away and I ended up using a small chisel to split the nuts, easy to do with brass ones. But put steel ones on as replacements.


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tommyardin

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Re: Helicoil
« Reply #15 on: 04 January 2018, 11:37:49 pm »
As far as brass is concerned I would never say it was a soft metal, I did a year working as an improver flatbed lathe operator and capstan turner for a year or so after leaving school, we spun a lot of brass and it is not an easy material to turn and needs lots of soluble cutting oil or it screams and chatters  and you will never get a good finish on it. (Paraffin is one of the best lubes for turning brass, thumb push oil can or a spray bottle)

Brass exhaust nuts was often used years ago on plain steel studs, but, they stopped that because of price differences.

Stainless steel nuts on stainless steel bolts or studs can gall or cold weld, in fact you are better off using stainless nuts on plain or mild steel studs with copper slip on exhaust studs going into the head and also a smear on the manifold nuts.


You will often get a form of electrolysis with different metals mating, but plain steel nuts on plain steel studs on a motorcycle manifold/headers where is is subject to extreme heat and wet is asking for trouble the little buggers are going to corrode, and being M6 studs of course there is a good chance they will shear off.

I take all my header nuts off but one at a time every year (I only ride in the summer) smear of copper slip and back on again, then, remove the next one and so on, it takes about three quarters of an hour to do all 8 nuts, a fraction of the time it will take to remove a broken stud if you lucky enough to be able to get it out without having to remove the engine to drilled it out and helicoil it.


I have to admit to having stainless steel studs and nuts on my FZS 600 headers, but as I do remove them on a regular basis I have not had a problem with them.
Stainless steel ordinary hexigon nut with a stainless steel dome lock nut on the top stops the weather getting to the studs.


A quick addition:
Copper slip on the stud going into the head also gives you a chance that if the nut will not come off there is a chance that the stud will unscrew instead of shearing.
« Last Edit: 04 January 2018, 11:43:56 pm by tommyardin »