pb4ugo
SILVER Star
I grinder or drill to cut/grind the rivets heads off and a punch to pound the rivet shanks out.
Welding in new box frame (1 Viewer)
- Thread starter GeoW5
- Start date
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I would not be afraid of removing the old and replacing. If the torque tube and rear cross member are still there, the frame is still square. If the rivet holes line up, it is still square. Leave the bumper attached except for the welded section,of course, while fitting. Plenty of folks on here have replaced rivets, just search some of the build threads for their procedure.
pb4ugo
SILVER Star
He'll likely have to remove the bumper to spread the rails apart to get the new crossmember in. I used a high lift jack to spread them apart. I didnt take much force. He should be fine. Like you said the rivet holes should square the frame. It is a high flex area, the frame rails move all over the place when driving and turning the wheel. Use the search function, this has been done b4. .
I think using a grinder is quicker and easier to remove the rivet heads.
brian
SILVER Star
neither. grinder works well.
pb4ugo
SILVER Star
I'd wouldn't want a any bumper welded to my frame either.
Cut then measure?
pb4ugo
SILVER Star
You can measure if you want. There's 12 rivets locating that crossmember.
Hi-Lift jack is a crude tool. It can't dial sxxx-in.
pb4ugo
SILVER Star
Your way over thinking this. 1 person could probably spread the rails while someone else is installing the crossmember.
The heads of my factory rivets don't look like that on the inside of the frame rail, as in Efjayforty's post.
Am I mistaken, did the factory swage the rivets from the top and bottom? It looks like they were upset/mushroomed in a very cold(ish) manner on the inside of the frame?
Am I mistaken, did the factory swage the rivets from the top and bottom? It looks like they were upset/mushroomed in a very cold(ish) manner on the inside of the frame?
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Malleus
Far west of Siegen
Yes, they would have been cold forged/swaged. The way to do it with a torch is to heat them before there are installed, cherry red, block the back with a swage block and pound it with an 8-lb hammer and another swage block. That's the way steel scyscrapers were built, although there was a little more artistry, what with the throwing and catching red hot rivets and all.
jim land
SILVER Star
I do not see nothing bad about using round head hex bolt with an oval lock nut
This is what i use on my bj42 new rear crossmember and daily driving it for 4 years with no trouble
This is what i use on my bj42 new rear crossmember and daily driving it for 4 years with no trouble
I'm not sure that this is a bad way to do it either. I'd drill them for a cotter pin, and use a lock-washer, check them regularly. However, none of the screws on my skid plates made it to now, but all the rivets around it are apparently fine?
But, think about the diameter of the hole and the diameter of the rivet. They are basically the same. The diameter of a bolt, for strength purposes is at the "root" of the thread, and not the shank of the screw/bolt. For substituting, you could go a size larger or whatever. I would never use heat treated fasteners in this kind of application, as they are particularly incompatible with minor rusting over the long run. I see some stuff that would probably fail a spark test in that regard, but, I don't know. The factory used really low-grade fasteners for structural stuff, likely for this reason.
Eyedaho
SILVER Star
What's a spark test in this application?
V8FJ4078
SILVER Star
Rivets installed red hot, clamped and then air hammered with tool we made to roll them over.
Spring plates and hangers replaced on my frame.
It looks like you got the frame almost as hot? Is that sand blasted?
Spark testing - Wikipedia
McMaster-Carr
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My guess is that the frame rivets are not much more than what a blacksmith used to call, "iron." The fancy fasteners are engineered to do different stuff. The frame rivets need to be more ductile to prevent fatigue.
Edit: I'm not an engineer. However, I think that the difference between using soft fasteners and hard fasteners (like SAE grade 8) is static vs. dynamic loading, and, resisting shear vs resisting tension along the length of the fastener. In this case, the load is not necessarily consistent as the frame does its natural flex so it is a dynamic load, and although it makes a tight sandwich between the rivet heads, there could be shear forces applied across the rivet or bolt shank. A fastener akin to an SAE grade 8 would be awesome for holding together head bolts to the block, as the fastener needs to do just a load in one direction, really well. Again, we are talking more about end-of-service qualities, not something that you'll see right away, it is from fatigue.
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I am a mechanical engineer. I sort of understand what you're trying to convey here. Threaded fasteners can be specified for a wide range of loading scenarios. You're correct in that those rivets will see, simultaneously, several different loads of varying magnitudes, and fully reversed. In design we would use these loads and a separate equation for each condition to check for failure. The vector contributions of each load would be considered for each case and a calculation would be made. Either the fastener would fail, or it would have some factory of safety. Since fasteners are standardized, the sizes and grades are known. If there was a case in which the fastener would fail, or fail to meet the required safety factor, it would be upsized, finer threads, or a higher grade would be used. I must be honest and say that I have never done any engineering work with rivets, but because there is still a clamping load, I suspect that the equations to check for failure would be similar. There are many different theories and equations that can be used for threaded fasteners (Goodman, Soderberg, ASME elliptical, Gerber etc.). Note that with threaded fasteners the preload is applied by twisting the fastener, as it is a spherical wedge, but with hot rivets, the preload is applied by the cooling, and subsequent shrinking of the base material. Again, I have never performed any calculations for rivets, but I suspect that the final preload of the grip is high and so then would be the factor of safety against joint separation. Could you use a threaded fastener to get the necessary preload? Probably. But what size and grade would you need to use? The application of the rivet, the initial temperature, the final cross-sectional area, the area of the head, the TTT diagram, and other factors would be far more variable than the torquing of a bolt. I suspect that Toyota used rivets because they are cheap and have excellent long-term holding capabilities. If I were in this position I would use a high grade of bolt, torqued to 90% yield, only to hold the pieces together for riveting. Remove one fastener at a time and hot rivet. It's the right thing to do, and the only thing that won't fall apart on the trail.
