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Stainless bolts into aluminum

Discussion in 'The Hokey Ass Message Board' started by flyboys101, Apr 2, 2013.

  1. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Need some help with a project I have. A bit off topic of old cars but I know the knowledge of the Hambers will be helpful.

    I will be bolting steel tracks into a 6" aluminum square tube post (1/4-20 bolts). An arm with a camera attached will ride along these tracks. Kinda hard to describe I guess. It all mounts to an atv.

    The question I have is, steel bolts would work fine to hold the tracks, plenty of holding power. But the allen head bolts hold water and rust easily.

    I was thinking about using stainless button head allen bolts instead (1/4-20). I know that stainless galls aluminum more then steel and is more brittle. Need the holding power of steel but not rust or break easily.

    Do I-
    - use anti-seize on bolts so not to tear up threads (will they come loose with
    vibrations?)
    - leave then bare ( will they gall up before I get a good torque on them?)

    - use thread locker on them

    I don't see the tracks ever coming off of post often, if ever. But can't rule it out either.
    Thanks for you help.
     
  2. BaBa
    Joined: Jun 2, 2011
    Posts: 97

    BaBa
    Member

    I would go with anti seize and lock washers.
     
  3. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Thanks, don't have space or clearance for lock washers, should have mentioned that I guess. Appreciate input.
     
  4. 19Fordy
    Joined: May 17, 2003
    Posts: 7,079

    19Fordy
    Member

    Blue thread locker. I am assuming you won't be taking this aprt very often.
    You can still remove the bolts if you use blue thread locker. Red thread locker is much more difficult to lossen.
     

  5. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,871

    seb fontana
    Member
    from ct

    I have found you can't get much torque on a button head allen before the hex strips out, just not deep enough..Regular hex head or socket head would be way better..
     
  6. Diavolo
    Joined: Apr 1, 2009
    Posts: 814

    Diavolo
    Member

    Unless you get rated stainless, they will be weaker than regular steel. Go with anti seize and a lot of it. Should be fine.
     
  7. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    I agree on stripping out.
    It will be close if I can get away with a regular allen head. Clearance around track is tight.
     
  8. noboD
    Joined: Jan 29, 2004
    Posts: 7,543

    noboD
    Member

    I agree. AND use anti seize.
     
  9. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Thoughts on where I can get rated stainless bolts at 1/4-20 x 1/2" size? Thanks for input.
     
  10. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,886

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL



    Do you have Fastenal stores in your area? Also, McMaster-Carr has a lot of neat and hard to find hardware....they have a website.

    Ray
     
  11. Homemade44
    Joined: Feb 7, 2007
    Posts: 527

    Homemade44
    Member

    You will have another problem with corrosion. Aluminum and stainless are on opposite ends of the nobility chart. If they get wet you will have rapid corrosion. If you can use steel bolts the corrosion will be a lot less.
     
  12. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Fastenal didn't have any stainless over a grade 5. Have not checked with Mcmaster carr yet. Think I might have to go to arp or someone.
     
  13. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Thank you, thank you. I was worried about that too. Everything will get wet so I guess steel is the way. Just wish there was a way that the allen head bolts won't rust.
    The black oxide flash rusts so fast. Powder coating and I won't be able to get wrench in, plus wrench would take coating off.

    Anyone have any ideas on a way to keep rust off of the steel bolts and still be able to use a proper wrench?
     
  14. Jimbacca
    Joined: Jul 17, 2011
    Posts: 243

    Jimbacca
    Member

    I picked up alot of stainless bolts for the GMC now studebaker. The guy I got them from said stainless is grade 5.

    From experience it gets brittle like chrome bolts over time. Anti seize or locktite is needed or the bolt and nut will fuse together when they get age. They do look great polished though.

    Good luck
     
  15. 54nomore
    Joined: Nov 5, 2012
    Posts: 137

    54nomore
    Member
    from illinois

    you could pack the "socket" of the bolt heads with grease or even melt wax into them. The wax could be melted out with a propane torch or even a hot air gun if you needed to disassemble.
     
  16. SimonSez
    Joined: Jul 1, 2001
    Posts: 1,632

    SimonSez
    Member

    Won't the anti-sieze will take care of that by preventing direct contact?

    I have used stainless bolts into aluminum intakes with copper based anti-seize on exposed engines and not had any corrosion issues.


     

  17. I think You have that exactly opposite from the truth. I work at a place that makes nothing but aluminum canoe and kayak accessories, and we use nothing but stainless hardware on thousands of aluminum parts, for many years. We have NEVER had a problem with corrosion from it. But Lots of corrosion problems with regular steel nuts and bolts used on aluminum.
     
  18. Homemade44
    Joined: Feb 7, 2007
    Posts: 527

    Homemade44
    Member

    If you can treat the stainless or aluminum with something so it is not in contact with the aluminum it won't corrode. There are products available to coat non ferrous materials with to stop the galvanic corrosion from happening. Check the nobility chart and see where aluminum and stainless are in relationship to each other. What I stated is correct.

    Here are links to a nobility chart.

    http://www.sancarlosradiator.com/VoltageDrop/nobility.htm

    http://www.corrosionist.com/galvanic_corrosion_chart.htm
     
    Last edited: Apr 2, 2013
  19. I'm just giving my experience with it, I refuse to go by the book with metals... the books are always wrong. I made these rack adapters 5 years ago... all raw stainless hardware, nothing added. They've been in many lakes and beaver ponds over the last 5 years, never treated special... Huh?, there's not a single spot of corrosion.
    100_3266.JPG
    I repaired hundreds of boats over the years, and I can always tell when the bolts are not stainless... because the aluminum next to plain steel looks like white cauliflower, that's corrosion.
    We use stainless hardware ONLY with all of our aluminum boating accessories. Including thousands of stainless rivets. It doesn't need to be sprayed with anything to stop corrosion. Check the site-http://store.springcreek.com/Vehicle-Racks/Spring-Creek-Truck-Racks-c699/
     
    Last edited: Apr 3, 2013
  20. Come on, now.
     
  21. Blue loctite. It will lube the threads for installation and seal them from any moisture when it dries.
     
  22. jazz1
    Joined: Apr 30, 2011
    Posts: 1,496

    jazz1
    Member

    I use stainless bolts on my aluminum boat ,,no Loctite and never seen any corrosion...but then I use stainless cause steel would start to rust right now on my scow,, we have a "plug" on the cavitation plate to prevent corrosion which possibly protects the whole boat.
     
    Last edited: Apr 3, 2013
  23. A quick look at this chart states that the corrosion is from different metals SUBMERGED in seawater. Since most of us don't drive submarines, stainless bolts in aluminum should be fine.

    That being said, some grades of aluminum are better than others. I have seen some that just storing outside will cause severe oxidation. If the aluminum is powder coated, or better yet anodized, then there would be no corrosion at all.
     
  24. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Thank you all for your input. Just wanted to follow up on some of the posts.

    I won't be bolting thru the aluminum but bolting into the threaded aluminum.

    I noticed the pictures sent looked like they were being bolted thru. But agree that steel does fall apart quicker then the galvanic reaction I might see. Tough call. Pick one that rusts quickly or the other that will corrode within.

    It won't be submerged into sea water but it may see some action down near salt water. So something to consider.

    Anyone have any experience with coating a steel bolt head to keep corrosion down and still be able to use a wrench on it?

    Thanks again.
     
  25. plodge55aqua
    Joined: Jan 4, 2009
    Posts: 1,710

    plodge55aqua
    Member
    from Alberta

    Aircraft Shop....
     
  26. flyboys101
    Joined: Jul 13, 2011
    Posts: 71

    flyboys101
    Member
    from nj

    Great idea, didn't think of that.
     
  27. McMaster Carr makes a 286 (NAS1352) alloy steel allen cap screw that is extremely strong. I'd look at those if strength is a concern. They are a 160KSI bolt where the stainless 300 series equivalent are around 80KSI.

    Bob
     
  28. In my one experience with galvanic corrosion, exposure to sea air (Japan) was enough and the problem wasn't corrosion as we think about it, it was that the stainless and aluminum parts corroded together like they were welded. Over 10,000 psi of pressure didn't pry them apart. So, if things getting stuck together is a problem ... otherwise, I wouldn't worry about it.
     
  29. Since my first post I have been trying to think of a case where I bolted steel into aluminum and could not think of any. Outside of fixtures at work, that get one time use, nothing I have done would qualify. When I have threaded aluminum for long term use I always use a steel threaded insert.
     
  30. 63comet
    Joined: Jan 31, 2006
    Posts: 508

    63comet
    Member

    How much torque do they need on them? I'm pretty sure you can actually find that size stainless screws at most hardware stores. A screw head wouldn't hold water and grime as much as an Allen head. If its a situation where high torque isn't necessary you could even use nylon bolts. Nylon doesn't corrode.
     

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