steel bolts stuck in AL

It isn't the zinc in the aluminum alloy, it's that the zinc in the alloy is in contact with the steel bolts.

of time, because

strength anyway.

fault was

often alloyed with

presence of water, the

looks like drilling

all new. My version

an eye on

stainless a good

I'll give a

Naw, heli-coils won't work. If the next larger size thread is too much then so is the o.d. of a h-c! phil

Depends on why he can't go up a size -- if it's a limit in the aluminum piece you're right, but I'm having a hard time thinking of a scenario for that. If it's something like the size of the head in the piece that bolts to it, or some wonky hand-turn wingbolt he can't find in another size.....

Maybe I'm misunderstanding what Steve is saying, but I don't see how a lump of aluminum alloy and and a bolt would become "thousands of little batteries." I took that to mean that the zinc and aluminum are finely segregated, and not truly alloyed.

But if you've got the right interpretation, I doubt there's enough difference between the galvanic potentials of aluminum, zinc, and aluminum die casting alloy to make much difference in the case at hand.

size,

thread

the

thinking of a

head in the

he can't find

-------- Here is what Karl posted: I've got six aluminum pickup topper clamps that used steel bolts.

---------

These clamps are not very wide so that would be a problem. There would not be much wall thickness left with the next larger size. I'd say that's why.......;>) phil

I have two sons so I understand your logic. But I wouldn't screw around with helicoils. I'd silverbraze sheetmetal tabs to steel nuts, assemble the clamp, hammer the tabs around the bottom of the clamp so the nut can't turn, disassemble and give the modified nuts an hour in the zinc bucket. (Hardware store bolts are more like 10 minutes' worth of zinc.) Stainless bolts, nuts and tabs could skip the zinc.

I've used clamps very much like these with zinc-plated bolts, no problems. Use of antisieze or silicone is certainly a good idea, though I didn't and got away with it. These clamps shouldn't get wet from rain or road spray when used to secure a topper or tonneau cover. Non-copper-based anti-sieze is handy stuff anyway. I use it routinely on light bulb bases since bulb bases and sockets started being made of aluminum rather than brass. I've not had one stuck bulb since I started doing that years ago.

"Kingserts"? I'm not familiar with them, but I am familiar with "Keyserts" -- threaded OD (different pitch than the ID, unlike a Helicoil) which screws into a tapped hole, then a special tool drives two or four projections down through the threads in the metal block (there are already grooves for the threads in the Keysert), thus locking it into place.

I've seen them advertised in stainless, and I've used some small ones in a metal which looks like zinc plated steel -- the ones which I have are all nearly black, though I don't know what they looked like when new.

They do require a larger tapped hole because of the different thread pitch on the OD from what is accepted on the ID.

Enjoy, DoN.

I have a few thread insert gizmos that are like the type you described DoN, but don't know the brand, because they were in a box of hardware items that I picked up somewhere. An obvious resemblence is the different thread pitch of the OD/outer thread to mate with the item to be repaired (or strengthened).

The metal thread adapter/reducer portion looks a little strange, a kind-of charcoal color, not at all like shiny cut steel.

There are 4 shiny staking pins (triangular in cross section), and when I looked at info about these types of products (don't recall which particular brand), it was recommended to use the manufacturer's driver for driving the pins. Many manufacturers have special drivers/arbors/etc for their products, which may not actually require anything more complicated or special than a pin with a shoulder or flange feature which could easily be made in a lathe.

The seized screws are less of a problem or fault, as they are a feature, IMO.

I would assume most truck owners that have bed caps don't intend to be removing the cap regularlly, and want an inexpensive mounting device so they don't have to drill holes in the bed sides.

The manufacturer wasn't trying to build an infinite life product (at the original price) for various reasons.

When the steel seizes in the aluminum bracket it somewhat insures that the mounting is secure. If the screws could loosen from vibration or getting bumped while loading materials in the bed, the cap could potentially separate from the bed.

Redesign of the clamps should include a feature that positively locks the clamp, IMO. Maybe sometimes it's better to let rust happen.

That would be "Keensert"...

Pictures here;

O.K. That is about what I have, except much smaller with only two keys, not four.

I was lucky to acquire the driver with the inserts, and they have both a pin to hold it concentric while driving with the keys, and a part which is struck with a light hammer to drive all of the keys at once.

The name "Kensert" comes from a concatenation of parts of "keyed insert".

And I got the name from markings on the driver tool.

Enjoy, DoN.