How good is JB Weld?

[Cargirl]

Not my Reatta but a different project. The drivers side read view mirror in my 1970 Pace car is damaged. It has a base and that is screwed into the body of the mirror.That area is damaged and it can't be screwed in like it should be.  Due to the type of metal used it can't be welded. I am considering using JB Weld to attach the base to the mirror but am unsure if it could with stand highway speed of 70 MPH.  Just how good is JB Weld? I have use it for the magnet sensor on my old Reatta and it really set up well.Any thoughts?  These are sport mirror and are on year only, very rare and very costly to replace, I would love a quick and effective fix.

[Barney Eaton]

can you post a picture of the mirror and broken area.

PS I have several GM sports mirrors.....give me the details on what is unique about 1970 and I will look.

[KDirk]

JB weld is pretty good on steel and cast ferrous metals. I've used it on brass and even aluminum with decent results, but I'm guessing what you have is what we call "pot metal" in the plumbing business; a zinc based composite casting material used a lot in cars for parts that get chrome plate  (like emblems, door handles and side mirrors, before they were all plastic). In plumbing, many faucet bodies and bathtub spouts/trip plates.are made from this stuff.

 

Depending on the surface area that can be "jb welded" and whether you can embed reinforcing material in the JB weld to span the crack, you may or may not get decent strength from such a repair. As a short term fix, it may work, but I'd be looking for a replacement mirror.

[Cargirl]

Here are the photos and the problem is pretty easy to spot. These type mirrors came stck on Pace car, Cutlass SX and I think were optional on the 442. One year only unfortunately. I think KD is right, I was just throwing up a Hail Mary!!

[DAVES89]

Someone who has a 3D printer could make what you want. Or another place to go is to a fabricator. While the piece is broke at the section where the holes are, another part could be made that follows the inside profile of the that part. 

 Or better yet try making the part yourself. Get a piece of aluminum or tin [even a soup can would work as you are just building a prototype] and then trim it to fit flat on the back side of your broken part, drill holes to match what should be there, then using double sided tape, tape your new part in place. Reassemble and see if it works. If it does then build a better piece or have a shop make it for you. I think what you are looking at is fixing the area where the holes broke out when I think you should be building a backing plate.

 In my opinion repairable. 

Edited May 2, 2018 by DAVES89 (see edit history)

[Barney Eaton]

That is pretty bad, but this is what I would try.

(1) make a steel, aluminum, brass, etc plate that will fit inside from the back......make the side fit as snug as possible and make it as long as possible.

(2) put the mounting holes in the plate that are needed to attach to the mirror head.

(3) now mix up the JB Weld and bond the plate you made to the inside back of the base.

You need to keep the JB Weld away from the mounting holes.

(4) a little extra JB Weld on the top where there is now a recess will not hurt.

The plate you make does not need to be fancy,  just fit the inside as snug as possible and span the broken area.

Found my stash of GM sports mirrors.

Edited May 4, 2018 by Barney Eaton (see edit history)