R12 Exhaust Stud
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Thread: R12 Exhaust Stud

  1. #1
    1000+ Posts REN TIN TIN's Avatar
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    Default R12 Exhaust Stud

    Guys,

    Do any of you know the size of the exhaust studs on the R12 manifold.
    (Part number 7700521051 on the attachment and it's a R12TS manifold if that makes any difference).
    I have to replace some but the ones on there are too rusty to measure accurately.
    I'm guessing they're about a M6.
    I've got to separate the manifold from the exhaust pipe and I'm pretty sure one or all three will snap when I try to undo them. (Even after applying copious amounts of penetrating oil and the blowtorch).
    I'm sure if I buy some replacement studs none will break and if I don't buy them all will break.

    R12 Exhaust Stud-r12-manifold.jpg

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    Cheers
    Ren
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  2. #2
    Too many posts! JohnW's Avatar
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    Sorry, not sure whether they are the same as R8/10. Did they come with brass nuts like the R8?

    Let it soak another week?

    Good luck as usual!
    JohnW

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    1000+ Posts robmac's Avatar
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    Every French car I'm worked on has M8 studs securing the manifold to the head.

    The studs are often available in "universal" styles from speed shops or generic parts wholesalers, because there is a crossover to Japanese vehicles using the same thread studs.

    I generally use Stainless steel nuts, instead of brass because they still have anti seize properties, are readily available, are cheap as chips and are lot less likely to strip than brass nuts.

  4. #4
    COL
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    Those studs that hold the exhaust to the manifold are 8mm Diameter 1.25mm pitch and 38mm long.

    I would be using a impact socket (6 sided) instead of a 12 point socket to remove the nuts so that you do not rip the corners off the nuts and make it harder to get apart.

    On re-assembly I would be using something like Kopr kote on the threads.

    All the Renaults I have seen have used steel nuts which get affected by the heat, but you could use stainless nuts like Rob suggested which will not be affected by heat as much.
    Regards Col

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    Too many posts! JohnW's Avatar
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    Interesting - both of mine have brass nuts. They are tightened with extreme care! And Kopr-Coat....
    JohnW

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    1000+ Posts schlitzaugen's Avatar
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    Well, you got your answer about the size, no need for me to reinforce the above.

    About nuts, now.
    Brass nuts are fine, actually very good, because they will never get welded to the studs no matter what. Rob may be right with SS, but then again, exhaust manifolds don't need to be tightened to high heaven. Brass nuts never gave me any trouble ever. The grease used is just copper (or nickel, or silver if your pockets don't care) to prevent welding of said nuts. Brass nuts of course don't need any of that stuff. That's the whole point of using them.

    Better than brass nuts however, there is another option. Again you have to have deep pockets. Go to your local Honda dealer and buy some of their OEM exhaust nuts. They are copper plated and have a slit in the dome to prevent coming undone. Again, I have never worked on a Honda and found problems with taking exhaust manifolds off. The copper is corroded in time, but they still come off clean and you can replace then. They also have copper coated studs in sizes you can use on a Renault.

    Recently, I have seen in WA some shops have generic copper coated exhaust studs, but am not sure of the quality.
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  7. #7
    1000+ Posts REN TIN TIN's Avatar
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    Thanks guys.

    The nuts that are on there are steel. The manifold is off the car so I could always grind the nuts off if necessary or use a nut splitter.
    I don't know if these are the original nuts from factory or a previous owner fitted them.

    Personally, I always use brass nuts on the exhaust studs and a smear of copper grease.
    I haven't used stainless steel. They'd be stronger than brass but as mentioned earlier, strenght isn't a huge issue on the exhaust pipe.

    But I have to get these nuts off first and then I can replace the nuts and studs.
    There are plenty of generic exhaust studs for sale on fleabay but of course one needs to know what size to buy first.
    I don't need to go too fancy. New steel studs and brass nuts will last until I die, what happens afters that doesn't trouble me.

    Cheers
    Ren
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  8. #8
    Too many posts! JohnW's Avatar
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    The good thing is that you aren't going to be stuck with studs broken but still in the head if the manifold is off. Interesting about the Honda nuts!
    JohnW

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    1000+ Posts renault8&10's Avatar
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    Quote Originally Posted by JohnW View Post
    Interesting - both of mine have brass nuts. They are tightened with extreme care! And Kopr-Coat....
    The OP is talking of the bottom three studs at the base of the manifold though. This is eqivalent to the clamp arrangement for the muffler on an R8/10. I normally just undo the nuts and reuse those and the studs on my white R10 which uses a similar R12 manifold. Haven't had an issue in nearly 20 yrs but they can suffer from rust issues.
    Last edited by renault8&10; 23rd April 2016 at 04:32 PM. Reason: Autocorrect, clamp to clump!
    KB


  10. #10
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by renault8&10 View Post
    The OP is talking of the bottom three studs at the base of the manifold though. This is eqivalent to the clump arrangement for the muffler on an R8/10. I normally just undo the nuts and reuse those and the studs on my white R10 which uses a similar R12 manifold. Haven't had an issue in nearly 20 yrs but they can suffer from rust issues.
    Ah, I missed the point somewhat. Thanks Kevin.
    JohnW

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  11. #11
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    Default Nuts to you too :)

    Hi
    Seeing as this has developed into a 'nutty' discussion with some useful information I will put up my based on my general experience.

    Brass nuts are just as strong as steel nuts. BUT they can suffer from thread damage and stripping easily if the stud thread is burred or damaged. I always use an anti sieze grease on any exhaust parts. Just good practice.

    SS nuts can be a bit soft and not as strong as normal steel nuts. Depends on the grade. Same for studs.
    Jaahn

  12. #12
    1000+ Posts schlitzaugen's Avatar
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    Quote Originally Posted by renault8&10 View Post
    The OP is talking of the bottom three studs at the base of the manifold though. This is eqivalent to the clamp arrangement for the muffler on an R8/10. I normally just undo the nuts and reuse those and the studs on my white R10 which uses a similar R12 manifold. Haven't had an issue in nearly 20 yrs but they can suffer from rust issues.
    I realised that. They are the same size, M8, and everything I said applies.

    I just remembered, you can buy the copper plated nuts with the side split dome from some of the WA better car part shops. Again, their origin is unknown, so you kinda are on your own. I have used them and so far so good.
    ACHTUNG ALLES LOOKENPEEPERS

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  13. #13
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    Brass nuts are OK up in Brisbane, but they will come off if you use them in Tasmania, especially in winter.
    59 Floride likes this.


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  14. #14
    1000+ Posts schlitzaugen's Avatar
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    Not sure about that. They might crack and split if the material is crap and it gets too cold, but I don't think Tasmania has that kind of temperatures.
    Sweden, maybe.
    ACHTUNG ALLES LOOKENPEEPERS

    Das computermachine is nicht fur gefingerpoken und mittengrabben. Ist easy schnappen der springenwerk, blowenfusen und poppencorken mit spitssparken. Ist nicht fur gewerken bei das dummkopfen. Das rubbernecken sightseeren keepen hands in das pockets-relaxen und watch das blinkenlights.

  15. #15
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    maybe if attached to a brass monkey
    jaahn likes this.
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