Seat belt reinforcement plate attachment

[Rick_L]

My main argument against the epoxy is how do you know you achieved the bond strength advertised? I work with epoxies, urethanes, and potting materials at work often. What we find is that they are very sensitive to what you're applying them to and they are also sensitive to process variables and surface prep. Also to shelf like, storage conditions, etc. I think you'll know whether you have good plug welds. If you don't think they are strong enough, increase the quantity of them, or increase the diameter of the plug.

[chevynut]

Rick, did you change your position on this?

"The plate's attachment to the sheetmetal needs only minimal strength."


If it only needs minimal strength, then what's the big deal? I assume it's because the plate is in shear? The way I look at it is that the epoxy bond strength is about 4 times the shear strength of the bolt. Even if I only got 25% coverage, It would be just as strong. I think I can do way better than that. Epoxies are used to put airplanes together and to hold panels on cars. I think today's epoxies are very good, and this area has no moisture, heat, or anything like that.

I have never done a plug weld through a 1/8" plate onto 20 gauge sheetmetal. Seems like it might be trickier than two pieces of sheetmetal together. The 1/8" plate is on the side that I need to weld from.

[Rick_L]

In a way I changed my position. In my original reply, I was thinking of a seat belt mount on the floor - on a horizontal surface. Then you came back and said you were doing the 3 point mount - on a vertical surface. There is a difference in the loading between the two.

As for the epoxy vs. the welding - well I know which one I'll count on if I weld it. Also, I did my plug welds from the thin side - the easier side.

[chevynut]

If I plug welded it from the thin side it would be from inside the inner quarter. I don't think that's feasible. I should have done it when the quarters were off the car, but who was thinking about seat belts then?

I'm a little concerned about being able to plug weld reliably from the thick side, although I could try it on some scrap pieces.

I suppose another option would be to use grade 8 bolts to mount the plates.

[Rick_L]

Why don't you put the 1/8" plate behind the sheet metal? Then you could plug through the sheet metal rather than the 1/8" plate. And the retractor mount bolt would also hold some of the load. In fact I would not do it any other way. If you epoxied it on the outside, you would be relying 100% on the epoxy.

[chevynut]

I thought the whole point of the mounting plate was for it to be on the opposite side of the sheetmetal as the retractor. If I put it inside the quarter, it will be on the same side as the retractor. I welded a nut onto the plate, so I would have to cut a hole in the sheetmetal for clearance, so I don't see how the bolt would support anything. I would have to take the nut off the plate and use a loose nut, which I could do.

If I epoxy the plate to the "outside" which is inside the car, both the epoxy and the mount bolt are holding the retractor.

Maybe I didn't make it clear. The retractor is going between the inner quarter and the outer quarter. The plate would be on the inside of the car, just behind the side panel. So the sheetmetal would be between the retractor and the mounting plate. Maybe I need a picture.

[Rick_L]

Ok I get it now.

[markm]

Do you smoke cigarettes also?

Hell no , but I am not a pussy either. The goverment and insurance companies want met to so. hell no.

[Maddog]

OK, but you lost me after "want"

[Geoff]

Lazlo,

Please post pictures of how you're doing your seat belts. I always like the creative solutions you come up with.