Exhaust nuts. Which metal?

Discussion in 'Mech Tech' started by Zebedee, Feb 18, 2018.

  1. I've got stainless exhaust studs fitted to the cylinder heads so what sort of nuts should i use?
    Steel nuts virtually dissolve infront of your eyes and i've been told stainless nuts on stainless studs suffer from galling and might refuse to come undone again.

    That leaves either brass nuts or copper flashed steel ones. Not sure if you can even get solid copper ones.

    Which is the better bet and is more likely to come undone in the future? :confused:
     
  2. Dont know the best and Only on normal studs but I've always used copper flashed ones and they have been ok
    . Still usually need a bit of wd or similar but have come undone ok.

    Sent from my SM-J500FN using Tapatalk
     
  3. Got brass on all mine although studs are normal steel ones. Its a bleedin revelation i tells yah. Had so many snapped studs or spending hours getting em off work ver the years. Had my silencer off and on yesterday. Re used them too. No problem. Also the ones i have are quite deep, deffo a full not and a bit i reckon which is ideal. Also if on stainless then they will strip way before the studs do if your a bit heavy handed. I dont think brass reacts with stainless!
     
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  4. Oh yes and i put copper slip on the threads too.
     
  5. I used to use brass ones - you can get brass M8s off fleaBay - but on new engine I used the smaller-head CSP jobs, which make it much easier to get the damned exhaust on. I'd try to avoid steel - they just weld themselves on.
     
  6. Flakey

    Flakey Supporter

    They do an m8 in brass that takes a 12mm socket instead of 13 great for those that are tight to get the nut on under the bends
     
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  7. Fitted stainless most places and add copper slip pretty sure its high temp too,
     
  8. I've always used stainless with copper slip. Can't say that I've had any issues
     
  9. snotty likes this.
  10. Milky

    Milky Sponsor

    Use vauxhall corsa manifold nuts they are 8mm thread but the heads size is reduced so you can use 10mm socket.Really ideal with restricted access.
     
    nicktuft likes this.
  11. Meltman

    Meltman Sprout Lover

    Stainless on stainless should be fine.
     
  12. nicktuft

    nicktuft Supporter

    Agree the longer the nut the less pull on the thread. Of course the stud has to be well bedded in the head all the same.
    Type 4 do have issues here as they tend to pull through due to metal fatigue. Be wary over tightening.
    I have had a stud mount re-welded and tapped. Wasn't cheap but doable.

    HeadsH-ex004.resized.JPG
     
    Dicky likes this.
  13. Stick to the torque setting in t4 exchangers eh!
     
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  14. I found stainless on stainless worked great where there was little or no heat but they galled badly on exhaust manifolds and unscrewed the studs instead of coming undone even after using threadlock on the studs and copper slip on the nuts.

    I found brass ones on a turbo diesel T3 and they came undone dead easy. The steel ones were just a blob.

    They're the ones i have in my ebay watch list at the moment. ;)
     
  15. mcswiggs

    mcswiggs Supporter

  16. £22 plus the postage for 8 nuts is slightly more than reassuringly expensive. :eek:
     
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  17. I've also found that stainless on stainless can freeze. They become impossible to undo.
     
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  18. mcswiggs

    mcswiggs Supporter

    Oh, I think the K Nuts have gone up. I know £22 is spenny for something so small, but for hassle free motoring it’s a good investment. Plus you can put a bit of wire through them and hey presto an emergency present of silver earrings for the wife.
     
    snotty likes this.
  19. I bought the missus a pair of M14 x 60 earrings for Xmas. 10.9s! I spoil that woman.
     
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  20. mikedjames

    mikedjames Supporter

    Copper coated steel with 12mm flats . Replace once a year.

    And the steel studs seem to last ages too.

    Stainless is a can of worms. With steel nuts it makes the steel nuts corrode worse than steel on mild steel too...as well as problems with galling of plain stainless on stainless.

    E.G. this document on how to rot motorbikes along with how to use the nomograph presented .. steel has different electrolytic potential to stainless...

    http://www.voc.uk.com/net/docs/14/14-425-19.pdf
     

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