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Exhaust manifold nuts M8 and turbo nuts M10 on S4 - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


Exhaust manifold nuts M8 and turbo nuts M10 on S4


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Hi all, choices for nuts: S/S aerotite, k (kaylock), high temperature k, copper covered, other.    Comments please.Thanks.

Are they both 1.25 pitch thread?

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  • Gold FFM

I used the high temp K-nuts from Demon Tweeks on mine only a matter of a month or so ago on the recommendation of several other members here.

https://www.demon-tweeks.com/uk/demon-tweeks-metric-hi-temp-aerospace-locknut-k-nut-243561/

Norfolk Mustard S4s #1 :)

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Hi, thanks for replies. Is it M8x1.25 and M10x1.25 or not? Is there a source at at a cheaper price than Demon Tweeks? Has anyone used the much cheaper    ordinary temperature K nuts?

 

 

 

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55 minutes ago, stevefh said:

Hi John, I intend to use them with the lock tabs if they will bend over the integral washer.

Looking at the Demon Tweets nuts I'm not sure the tabs will be long enough & if you're using the lock tabs why do you need the lock nuts?

Cheers,

John W

http://jonwatkins.co.uk

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Hi John, I understood they would corrode less and are smaller across the flats than the M10 and M8 aerotite standard nut sold by SJ   etc. so easier to fit/remove. Does anyone know the thread pitch of my required M8 and M10 nuts?

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On 21/04/2021 at 06:09, jonwat said:

The problem of not using lock tabs is you risk the studs unscrewing from the head & falling out. :thumbdown:

 

Ahhh - ohhh  epiphany!!!  I thought I was so smart using lock nuts AND nord lock washers...but the torque is low, never occurred the studs could back out! in which case the expensive nuts and washers would be useless

The nice thing is with an ALunox or similar and the smaller nuts its much easier to re-install.

 

Sorry no help on the thread pitch, I ordered mine from JAE and they knew which ones to send.  Does the parts diagram show it?  Sorry dont have time to look just now.

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Hi, I have looked at the parts diagrams that I know of and they do not show the thread of the nuts or studs.

Hi, I have counted the threads on a bolt that fits the M10 k nut I have and it seems to be 1.5 pitch

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I would use it so rarely, so I accurately count the troughs over the maximum length and use a calculator.Are M10 nuts/bolts usually 1.5 pitch on uk cars?

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The likelihood of the exhaust manifold to head studs working loose is very low if you install them with the recommended Permabond A025 high temperature retainer adhesive.

The exhaust manifold to head studs are M8 x 1.25 thread and the exhaust manifold studs for the turbo are M10 x 10 thread.

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  • Gold FFM

They're standard M8 and M10 studs on mine, not fine pitch. If you order the nuts from the link I posted earlier they will definitely fit.

I've used the Permabond on the studs in the head on mine as @sailorbob and the manual state. I've used a Loctite equivalent on other cars in the past and never had a stud wind out using it before.

Norfolk Mustard S4s #1 :)

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  • 1 month later...

My advice is to use the aerotight nuts everywhere on the exhaust. I haven't lost a stud yet but I've lost several turbo to manifold bolts. The other advantage of aerotight style is that they can be had with a smaller hex size than normal, making them much easier to fit. I used stainless on the turbo bolts last time but they still corroded quite quickly, so went to titanium.

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