Cylinder base stud repair?

lcrken · Aug 23, 2015

FWIW, the true Heli-Coil inserts, manufactured by Emhart Technologies, are normally supplied in 304 stainless, but they also produce them in Inconel, Phosphor Bronze, Nitronic 60, and Titanium, and will supply them with coatings that include dry film lubricant, cad plating, a black coating they call "Primer Free", and silver plating. I doubt if we could find any of those in in small quantities for use in our Nortons, except maybe the phosphor bronze, but it's interesting to see how many varieties there are. I used to see them in a yellowish-green color used in some missile designs, and I assume that was the milspec cad plating, but that was decades ago.

Their catalog includes recommendations on corrosion protection measures, including "using a non-hardening sealer or compound on the threaded assembly."

http://www.noblefix.com/PDF/Helicoil/He ... alogue.pdf

Personally, I've installed a lot of Heli-Coil inserts (with no sealers or locking compounds) in Norton (and other) crankcases, heads, cylinders, etc., with no problems except occasionally having one pull out from over-tightening. But use of some sort of compound to resist galvanic corrosion does sound like a good plan. In most cases, I now use a solid insert like Timeserts (usually carbon steel with zinc phosphate plating) instead of helical inserts, mostly because they are stronger. I particularly like their line of Bigserts for use where a hole is wallowed out too large (like from a helical insert failing) for the normal insert.

Ken

lcrken · Aug 23, 2015

As happens a lot now, I'm a little behind the times. Emhart is now Stanley Engineered Fastening.

http://www.stanleyengineeredfastening.c ... s-platings

Ken

texasSlick · Aug 23, 2015

needing said:
Hi texasSlick.
Having a helicoil and the alloy interact as nature intended would surely fix it more securely in place so the locktited steel stud cannot dislodge it i.e. the stainless steel helicoil becomes 'as one' with the crankcase.
Ta.

If the dissimilar materials react, nature will provide you with dust as JM Leadbeater has posted.

Slick

Anonymous · Aug 23, 2015

texasSlick said:
needing said:

Hi texasSlick.
Having a helicoil and the alloy interact as nature intended would surely fix it more securely in place so the locktited steel stud cannot dislodge it i.e. the stainless steel helicoil becomes 'as one' with the crankcase.
Ta.

Click to expand...

If the dissimilar materials react, nature will provide you with dust as JM Leadbeater has posted.

Slick

Yep, he sure did but it is only grey dust upon removal. Prior to that it is called galvanic corrosion that locks a stud (or helicoil) into the aluminium alloy (forever generally until the same hamfist owner pulls that out as well).

Note that locktite products also resemble 'dust' upon removal.
I am with Mr Leadbeater re concern of stainless steel use for critical parts i.e. pretty over functional. Depends what you own the bike for, I suppose.
Ta.

gripper · Aug 23, 2015

Most studs fitted to Commandoes will have rolled threads, these are smooth and don't tend to gall in the hole. Stainless steel studs tend to be cut threads and as such will have a rough surface. These tend to gall or "pick up" in alloy castings, often bringing the alloy thread out with them. Copperslip might help, but better not to go there in the first place. Stainless base nuts on steel studs is probably not a problem.

Anonymous · Aug 23, 2015

gripper said:
Most studs fitted to Commandoes will have rolled threads, these are smooth and don't tend to gall in the hole. Stainless steel studs tend to be cut threads and as such will have a rough surface. These tend to gall or "pick up" in alloy castings, often bringing the alloy thread out with them. Copperslip might help, but better not to go there in the first place. Stainless base nuts on steel studs is probably not a problem.

Yes. Correct, stainless steel is a galling material as well.
Ta.

texasSlick · Aug 24, 2015

Re: Compatibility of fasteners with base metal:

Here is a simple chart:

http://r.search.yahoo.com/_ylt=A0LEVrzr ... 6hSmYktgI-

The following shows a cold galvanizing product that should provide cathodic protection when applied to stainless fasteners used in aluminum base metal. It is not up to NASA standards, I'm sure, but it can be obtained rather easily. This product applies a zinc coat, and from the chart above, one can see that zinc in aluminum is compatible.

http://www.rustoleum.com/product-catalo ... und-spray/

Slick

texasSlick · Aug 25, 2015

texasSlick said:
Deets55 wrote:

. Would red locktite on a helicoil insert have the required anti-galvanic protection? Most installation instructions for helicoils say to use red locktite.

I went to the Henkel (LockTite Parent Co) website and did a search for the answer. All I could turn up on the site is LockTite provides "corrosion protection". I contacted Tech Support for a more definitive answer, and will append this post if/when I get an answer.

. I received this answer:

Loctite will provide corrosion protection in the areas where it has been applied.

Can you confirm which red Loctite you are using? If it is anything other than the Loctite 263, then you'll need to use a primer such as Loctite 7649 or Loctite 7471.

Thank you,
Alexandra Malaspina
Henkel

Slick

Stephen Hill · Aug 25, 2015

I have seen how stainless fasteners don't get along with aluminum, particularly in a marine environment. In a marine environment, the items are constantly bathed in water, and where I live, usually salt water. The water acts as an electrolyte, which is required for galvanic corrosion. I doubt that helicoils installed in the base of a Norton engine would face similar conditions. I think the constant bathing of oil, and lack of water, would limit the corrosion substantially. If corrosion occurred at all, it would be at the interface between the helicoil and the aluminum casting, and would tend to lock the insert in place, more than compromise its holding ability. Now if you threw your Norton off the end of the dock and pulled it out three years later, different story.

Stephen Hill
Victoria, BC

Nater_Potater · Aug 25, 2015

texasSlick said:
Re: Compatibility of fasteners with base metal:

Here is a simple chart:

http://r.search.yahoo.com/_ylt=A0LEVrzr ... 6hSmYktgI-

Wonderful chart! I now have that one squirreled away for future reference.

Nathan

Deets55 · Aug 25, 2015

texasSlick said:
texasSlick said:

Deets55 wrote:

. Would red locktite on a helicoil insert have the required anti-galvanic protection? Most installation instructions for helicoils say to use red locktite.

I went to the Henkel (LockTite Parent Co) website and did a search for the answer. All I could turn up on the site is LockTite provides "corrosion protection". I contacted Tech Support for a more definitive answer, and will append this post if/when I get an answer.

. I received this answer:

Loctite will provide corrosion protection in the areas where it has been applied.

Can you confirm which red Loctite you are using? If it is anything other than the Loctite 263, then you'll need to use a primer such as Loctite 7649 or Loctite 7471.

Thank you,
Alexandra Malaspina
Henkel

Slick

Click to expand...

Slick,
Thanks for following up on that. I have always had good luck with Helicoils but have never used them in a high stress area. Timserts or equivalent for spark plugs.
Pete

gripper · Aug 25, 2015

We used to have a cleaning solution in the UK called Gunk. It would bring up all the bright alloy bits up quite shiney and smelt good but it must of had some acid in it because with an oil tight engine, studs and nuts would quickly become one item. The latest version still cleans quite well but it just smells like diesel to me.

Cylinder base stud repair?

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