The International Cessna^® 170 Association

I am replacing all 4 bolts on Cleveland brakes - P N 103-11600

I want to negate any inherent dissimilar metal corrosion situation

New bolts from Aircraft Spruce have just a small patch of blue locktite applied to the threaded portion.

Why such a small area w blue locktite? There must be a significant reason that I am unaware .

Can some one provide answers?

It's easiest to apply a small strip of the stuff.
It spreads around the threads and does it's job as the bolt goes in anyway.

I've always just put a drop on the threads and let it chase around as it goes in the bolt.

I dont think locktite will do anything for corrosion resistance tho.

Speaking of corrosion resistance I noted a raised "X" on bolt head. I googled and it apparently means steel alloy NOT corrosion resistant !

Which explains the cadmium coating. I googled and the cadimun.org folks say it is very important in conjunction with aluminum- however they plainly state that the cadmium coating is "sacrificial" meaning it's protection for cleveland brakes is temporary.

So I have a new bolt that is NOT corrosion resistant. Said Bolt is cadminum coated which is sacrifical.

Need chemistry.

While I agree with the concept of reducing corrosion wherever possible, is this issue a real problem for anybody? In the 43 years I have been using and maintaining Cleveland wheels and brakes I have never had an issue with corrosion in the brake caliper threads. For me, removing, cleaning, repairing as required, painting as needed, then re-assembling the brake assemblies on at least an annual basis has been sufficient to maintain them. I also change out the brake fluid annually but have seen more wear/corrosion issues with the piston/o-ring/cylinder interfaces and guide pins than anything else.

I use "o-lube" which comes in a tube ( slightly brown in color, not the super o-lube which is white) on all components during assembly (not hot engine parts). Stuff always come apart like it was new.

I use permatex antiseize, and change my brake fluid every 20 years if I remember it, (or if I reseal my calipers due to a leak (which has occurred once in 40 years on the Baron) and never had a problem, whatsoever.

Grady,
The cadmium provides sufficient protection. If you regularly service your brakes as you should, the bolts will last quite a while, and then you just change them out with new when needed.

That lock bolt is only spec-ed for six or so insert cycles. Nothing lasts forever. The last time I bought them, they had a plastic insert, not Loctite.

If you really want to protect against corrosion, use AN4-H17A drilled-head bolts slathered with anti-seize and safetyed in place.