JB Weld

A

aermotor

Well-known member
JB Weld is discussed quite often but I have not seen much mention of PC-7. I have used PC-7 for many different things and find it to be better than JB Weld. What have other experienced with it?

John
 
Never heard of it. Maybe it's not sold in the Midwest? When I was growing up the Auto Parts stores here all had two valves with their faces epoxied together with JB Weld. It was like steel. I've used it to patch a cracked block (water jacket external leak) on a '76 Camaro and it worked.
Really curious to hear experiences with something BETTER!
 
Check out: pcepoxy.com. I heat it with a heat gun after mixing and during application, it turns sort of liquid and can be forced deeper into cracks and get a head start on curing. This is my procedure - right or wrong - but it works well for me. Without any scientific tests, it seems stronger than JB Weld.

John
 
Good idea on heating it to thin it and make it flow into the crack better. Wish I'd have thought about that on my cracks, but since my two cracks never leaked, I think the fix will be fine.
 
I used it to fill/repair some cracks and missing chunks of a steering wheel. The heat gus helps it to get down to the bottom of the cracks. Wheel still looks good after 7 yers. ken
 
I have a rear main bearing cap with a piece broken out of it. The piece was put back into the bearing with J B Weld in the 1970s and it is still working.

J B Weld is an epoxy adhesive with a metal filler additive which increases its strength, and enables it to be machined (threaded, etc.).

Surface cleanliness is imperative when using products like J B Weld.
 
I have used PC7 for many applications. I to think it is better than JB weld. I have patched holes in Gas tanks ( Both plastic & metal ) It will withstand very high temperatures . If you mix the two part adhesives, it has the consistency of putty, and can be smoothed out with isopropyl alcohol. I f you have a bad weld joint, it can be used to fill & smooth the joint so it looks professional. Try it you'll like it. I buy it at my local hardware.
 
Hi John,

Almost 99.99999999% of "all" failures with J B Weld, PC-7, & similar products occurs when one does not follow directions and "thoroughly" clean and prepare the mating surfaces.

Many will "never" learn how to use these specialty products because they do not have the mental ability to even conceive that Scotch tape will not adhere to a surface covered with axle grease.

In extreme cases, where adhesion is most important, mating surfaces can be slightly drilled with a few holes and recesses, and/or dovetailed to insure better adhesive gripping to the parent material which can tremendously increase the mating surface areas of the adjacent adjoining surfaces.

These wonderful mixed epoxy type products are witnessed and seen every day with "smiles"; but not always recognized ......... every Dentist knows how to use them!
 
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LOL

I love your analogy re scotch tape. Sad, but true. I've used both JB Weld and PC - 7. My failure with PC -7 was due to inadequate prep work on my part. I used JB on badly grooved backing plates. So far, so good.

JB Weld is made in Sulphur Springs, Texas, where we live. I plan to see if they give tours.
 
Adhesives can be a sticky subject. :D

I've heard of PC-7, but never tried it. Where I worked for a couple years we also had the 2 valves glued together with JB Weld.
 
A few years back, after looking at a few Model A rear axles that I have with damaged key-ways, I decided to call Devcon to see if these axles could be repaired with their product.

I spoke to a technician at Devcon who told me he had already repaired an enlarged, damaged key-way in a vintage car axle with their Devcon product.

He said he:

1. First cut a slight dovetailed looking joint on the full length of one side of the enlarged key-way.

2. Next he drilled a few tiny holes at different angles so the Devcon could grip the axle.

3. He then rubbed a new metal key with a thin layer of automobile wax, and set & clamped this waxed new key in the key-way adjacent to the soft, uncured Devcon.

4. After the Devcon cured, he removed the key to examine same and installed a new hub on the repaired axle.

5. At the time i spoke with him, he said it was still holding after (5) years or so.

I never tried a similar repair; but appears it may work.

One thing I later noticed back then was that Devcon was much more expensive than J B Weld and similar products.
 
Just a Humble Model A Guess:

If anyone would seek professional advice from a true and 100% real, "Professional Model A Fortune Teller", (naturally sitting in a tent at midnight with a lit 1930's kerosene lantern), my "Guess" is that J B Weld would never be recommended to repair open cracks in over-stressed & damaged original steel, two-blade Model A radiator fans.
 
There are two basic kinds of cracks, one due to overload and one due to fatigue. The fatigue crack is not repairable in the original type Ford 2-blade fan. The best that can be done with a fatigue crack is to slow its growth.

The overload crack can be avoided, but may not be repairable.
 
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