Wanted - Exhaust Nut for Kanguro

jb666
Posts: 182
Joined: 02 Nov 2006 22:20
Location: Ashford, Kent

Wanted - Exhaust Nut for Kanguro

Post by jb666 »

Evening all!!

Another day in the shed reconstructing the Kanguro. When I took it apart both exhaust threads were shot. I got the nut out of one head but had to butcher the second nut to get it out.

I got both heads exhaust threads done by NLM and got two stainless nuts at the same time. I now go to assemble the exhaust and the new nuts bind after the threads engage and won't tighten any further. I do have mechanical sympathy and didn't force it. The remaining original nut runs down fine so I'd like to find another.

I did a search 'exhaust nuts' and found some references to different types of nut and a dislike of stainless in ally. There were also references to manufacturers abroad but no details.

So anyone got one nut they would be willing to pass on for beer vouchers? Can anyone enlighten me on the NLM stainless ones or do I have some expensive paperweights?

John.
harrymuffin
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Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Wanted - Exhaust Nut for Kanguro

Post by harrymuffin »

Just made two in phosphor bronze with holes rather than castlelations. Stainless ones you bought need the threads cutting deeper but you will still have fretting when you come to take out. If you can get the threads relieved then use a graphite type assembly goo as when the gooey stuff evaporates you will still have the slippy grahite to help with the undoing with copper grease the copper dries to a solid mass. Try it and see.
jb666
Posts: 182
Joined: 02 Nov 2006 22:20
Location: Ashford, Kent

Re: Wanted - Exhaust Nut for Kanguro

Post by jb666 »

Thanks for the reply. I'll visit my local engineering company and see what they can do.

As for the graphite grease I remember using it in the paper mill on steam trap pivots and Foliac sealant on steam joints. I'll try and acquire some next time I visit! I will also remember to use it sparingly as I often found it got everywhere however careful you were when you used it!!

Phosphor bronze items sound nice - if I was more confident on my thread cutting (and the leadscrew on my mates lathe wasn't so knackered!) I'd have a go myself.
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Wanted - Exhaust Nut for Kanguro

Post by harrymuffin »

Yes, Foliac is what we used on high pressure boiler fittings. In fitting these latest nuts I used a smear of home made link life - I have a large tin of graphite mixed with gear oil. The original nuts are made of brass, but Velocette made their screw in exhaust nuts from cast finned PB and I never had a problem undoing them and never broke a fin off. Nothing wrong with brass ones though and have made zinc plated steel ones which have given no trouble, the zinc being metalugically a lubricant - why you should use high ZDDP engine oil because of the flat tappets.
The threads are 1.5mm pitch so should have a thread depth of half that, so the minor diameter will be 1.5mm below the major. As this would produce a perfect interference fit if you can screw the nuts in, then you won't ever get them out again. The thread depth should therefore be deeper than 0.75mm and because of wear and tear usually find the thread depth is around 0.9mm to give a smooth rotating dry fit, round the tops of the thread with a chaser or thread restorer, but I do have to trial and error. QC at NLM was always hit and miss and on some remade stuff diabolical, which is probably what you are experiencing, they were after all salesman not people with any engineering expertise or nous. The new nuts I have made gone into new 500 heads.
I do have a couple of the 350 chrome plated nuts if you should get completly stuck, condition from what I have seen on a lot of engines would be put at reasonable to good. Castlelations used but cam be cleaned up with a dividing head and chrome turned off.
jb666
Posts: 182
Joined: 02 Nov 2006 22:20
Location: Ashford, Kent

Re: Wanted - Exhaust Nut for Kanguro

Post by jb666 »

Thanks for the reply - if I fail with rectifying the steel ones I'll give you a shout about a used one.

Thanks again,

John.
steveffs
Posts: 28
Joined: 31 Jan 2016 18:23
Location: epping essex

Re: Wanted - Exhaust Nut for Kanguro

Post by steveffs »

Hi Guys.

I have the same problem.. Got two "new" steel/chrome nuts from NLM and both wont screw in beyond two turns into the head without getting extremely tight. The threads in the head look undamaged so i presume i have the same issues. My first question is will a thread chaser open up and deepen the thread on the new nut? or second question will i need to take it to a engineers to get it re threaded with a die? ( does anyone know good one?)

Cheers

Steve
julianharty
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Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: Wanted - Exhaust Nut for Kanguro

Post by julianharty »

Steve,
As per viewtopic.php?f=4&t=766 the thread size should be 42mm x 1.5mm pitch, as a suggestion, how about buying a die and having a go at cleaning up the threads on the new nuts yourself?

There are dies available starting at just over £20 (and a week or two's wait for them to arrive) e.g. https://www.ebay.co.uk/itm/1pc-Metric-R ... 2549150847 (be careful to pick the correct one from the list). You'll also find used ones occasionally, and much more expensive ones too...

FYI I bought a M42 x 1.5 tap 2 years ago from a UK supplier for £41 which I used to clean up the threads in the cylinder head of one of my 350s.
jb666
Posts: 182
Joined: 02 Nov 2006 22:20
Location: Ashford, Kent

Re: Wanted - Exhaust Nut for Kanguro

Post by jb666 »

Interesting about the die/die nut - £20 plus carriage and import VAT etc from China v £300+ from UK ......

If you do get one let us know of your experience.

As an update I remembered I had a stache of used bits from my Strada and there was a usable (slightly mangled!!) nut that I tidied up and used. The hardest part was remembering where I had put the bits.

John.
julianharty
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Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: Wanted - Exhaust Nut for Kanguro

Post by julianharty »

The price difference is significant, however I saw prices of between £40+delivery (used) and around £170 from UK suppliers, £300 would be well beyond anything I'd want to pay even if it'd be the best tool that'd cut a 1000 threads, etc.

I may well buy either one from China or the used one in the UK. While it's not something I urgently need I know it'll come in handy and be good to have when I need it rather than several days/weeks later!

I'll update the forum if/when I use whichever one I end up buying.
julianharty
Posts: 478
Joined: 15 May 2016 16:34
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Location: High Wycombe Area (Bucks)

Re: Wanted - Exhaust Nut for Kanguro

Post by julianharty »

A quick update from me, I noticed one of the two dies from China had been sold, and I've bought the other one. I'm guessing mine will arrive within about 2 weeks and I'll try it on one or two spare exhaust nuts I have around. Steve, did you happen to buy the other?

PS: I did first try to buy the used one in the UK even though it was twice the price but ebay kept failing when I tried to pay for the item, so I gave up on that one.
steveffs
Posts: 28
Joined: 31 Jan 2016 18:23
Location: epping essex

Re: Wanted - Exhaust Nut for Kanguro

Post by steveffs »

Yep it was me. Awaiting delivery and will see if its any good. Now looking at buying tap to clean up the threads in the head. I found an old but mangled nut and it went clean in to the rear head but was very tight in the front. So although the threads look clean i must presume the front threads could benefit from a re tap looking into that now. Will keep you posted.

Cheers

Steve
'It must be a .....'
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Joined: 12 Sep 2010 12:25

Re: Wanted - Exhaust Nut for Kanguro

Post by 'It must be a .....' »

Hi, you could cut some deep slots at right angles to the threads on an old exhaust nut to make a thread cleaning tool.

Have fun, Ian
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72degrees
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Re: Wanted - Exhaust Nut for Kanguro

Post by 72degrees »

'It must be a .....' wrote:Hi, you could cut some deep slots at right angles to the threads on an old exhaust nut to make a thread cleaning tool.

Have fun, Ian
That's what I've done. It's in a box in one of the sheds somewhere. Worked surprisingly well on just mildly mangled, rather than non-existent, threads.
steveffs
Posts: 28
Joined: 31 Jan 2016 18:23
Location: epping essex

Re: Wanted - Exhaust Nut for Kanguro

Post by steveffs »

Hi all. die has arrived but i had already spent a few hours using an internal thread file on the rear port and i now have a fully functioning thread . so no need now to re thread the nut. I will clean up one of the old mangled nuts and let u know how it goes but as the die is so big i need to work out a suitable holder.

Cheers

Steve
julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: Wanted - Exhaust Nut for Kanguro

Post by julianharty »

Steve,
glad you've made good progress, my die hasn't arrived yet - hopefully it'll do so this coming week. Thanks for the tip about working out how to hold it. I'll let you know what I end up doing.
Julian
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