Rivits on cross member

[1934clint]

Replacing cross member on 1934 pickup, are the three rivets on top of the frame flat or lefted round?

[Flathead Fever]

I will try and post some photos later tonight of the process of riveting in my '34 pickup front cross member. That was a learning experience, not as easy as I thought it would be. It shouldn't be attempted by yourself, not enough hands. Plus somebody should be standing by with the burn ointment.

The '32 frame I replaced the front cross member in had counter sunk flat rivets on the top. The '34 Pickup frame had round headed rivets. First thing I noticed is how many more rivets there are on a '34 cross member.

I bought a '34 pickup project that needed a new front cross member. It came with an extra NOS front cross member. But it was a lot thicker than the original. I thought maybe it for a 1 1/2 ton truck? The rivet pattern was identical to the pickup, the spring width was the same and so was the drop in the cross member. I couldn't see any reason not to use it. There is no way this one is ever cracking. You can see how thick it is in the photo. The only problem that I had with it was the pickup's front gussets (radiator mounts) did not fit. They had to bent in a press. It had to do with bent lower lip on the front of the cross member. The original cross member's lip was bent more at a 90 degree angle, the other one had a gradual curve to it. The curve prevented the gussets from fitting all the way up against the front of the dross member. I had to bend a curve in the gussets to match the cross member's lip

As you can see in the photo somebody cutout the large broken piece and welded in a new thick plate. The weld was strong enough. The problem was they welded on the backside of the cross member too. The welds were on the inside corners which prevented the spring from resting flat on the cross member. Only the very corner edges of the top leaf were resting on top of the welds. Since I had the NOS cross member I decided to replace it.

If you have taken rivets you know how tight they are and how superior they are to bolts. Even after grinding the heads completly off they will not punch out until you drill out most of the center of the rivet. I grind the heads down until I start to see them turning dark blue. At the point the head is paper thin. I stop grinding so I do not accidentally make grinder marks on the frame rail. Then I center-punch the rivet and drill it to relieve the pressure. I do not drill clean through the rivet. That leaves me some material for the punch to rest on when I knock the rivet out. Its a slow process taking out all those rivets without damaging the holes or marking up the frame

I was just going to take the rivets out between the gussets and the cross member and leave the gussets still riveted to the frame rails but the shape of the bent lip on the front of the NOS cross member required me to bend the gussets to fit it. The best way to bend them was to remove them and bend them in the press. There had to have been a different set of gussets to go with this NOS cross member. In the third photo you can see that gradual curve on the bottom lip. The rivet holes would not lineup without bending a gradual curve in to the end of the gusset.

I went ahead and sand blasted any surface rust off the inside of the frame while the cross member was out. I have one of those Harbor Freight sand blasters. They work okay but its a slow process and it makes a big mess.

A found another photo that shows a front view of the NOS cross member. You can see what a gradual bend that lower lip has. Here is a photo of the original with the less gradual bend in the lip.

[DavidG]

Round, as original.

[Flathead Fever]

I started a second page because of the number of photos. Its been about 25 year's since I tried to rivet something. There's a little bit of a learning curve to it.

My dad use to work out at Kaiser Steel which was an old fashion steel manufacturing plant that looked like you were in hell when the molten steel was being poured. Iron ore went in one end and steel in any shape desired came out the other end. They did a lot of riveting out there repairing the WWII era equipment equipment. What dad taught me was to stick the rivet through the hole and have it extend past the opening 1 1/2 times the diameter of the rivet. That gives you the correct amount of material to form the rivet head. But what I found out is that only works if the hole is exactly the same diameter as the rivet. When Ford riveted these frames the extreme force seems to have expanded the holes in the frame a little larger than the rivet diameter. It depends on the size of the hole. If the rivet is a nice fit, 1 1/2 times the diameter works good. If the rivet is a little loose you need a little more rivet length to fill the hole up completely and still have enough material to form the head. Rivets are dirt cheap so get some scrap steel and experiment.

The next thing I discovered was a regular old air hammer really does not have the hitting force needed to quickly form the rivet head. It will do the job but the rivet is cooling off so fast that an actual harder hitting rivet gun would work better. The other problem is you cannot always get a straight shot to hammer away on the rivet. The air hammer has to be perfectly straight or the red hot soft rivet will just bend to the side instead of straight down and form a nice head. You need the right rivet set to form the correct shaped head. You might even need to grind the tool out to get the desired rivet head shape if you really are trying to create a repair that cannot be told from factory. From what I have been told the factory had a hydraulic machine the cold squeezed the rivets all at one same time. I would have loved to have seen it operation.

Really large rivets like you see them building the Golden Gate bridge out of stay red hot for a long time. Because the frame rivets are so small they cool off really fast. Its about impossible for one guy to heat the rivet red hot, get it in the hole, buck it up, lineup the rivet gun and flattened it before it cools off. The only way I could do it by myself was to stick the rivet in the hole and then heat the part sticking through red hot. Drop the torch with it still on, buck up the rivet head, grab the air hammer and start riveting. I had a few failures that I had to drill out and do over. They were strong enough but my formed rivet head wasn't pretty. You really need a second person helping you and preferably not your wife.

Here is a photo of a rivet sticking through a hole that is a little larger than the rivet. It will be need to be cutoff longer than 1 1/2 times the diameter to have enough extra metal to fill up that gap around that rivet. Maybe an extra 1/8" longer. The whole cross member is bolted in tight and then one bolt is removed and replaced with a rivet at a time.

There is a little tool called a rivet jack. It can hold the rivet up tight against the frame so all you need to do is heat the other end and form the head. It worked okay except that the hammering would cause the tool to walk sideways and off of the rivet head and then the tool would fall to the ground. I ended up having to stick "C" clamps on it to keep it from moving. It was the only tool I could find to get it in that tight spot and hold the rivet tight.

Here is another photo. I can live with the look of that closest rivet head. The center rivet head did not form correctly. It cooled off too fast or maybe the wrong length? The length is real critical to what the shape of the head turns out like. That rivet would have held but it looked terrible so out it had to come. I probably could have taken a file and shaped the head to look more rounded. That nut laying over the third rivet is there because it happens to be 1 1/2 times the diameter of the rivet. I stuck the rivets through the hole and used that nut as a gauge for cutting off the rivet. Out of all the rivets a couple of the rivets were still loose in the hole after riveting. Those had to come back out and be replaced. I think a lot of those problems could have been solved with a real rivet gun instead of a little air hammer.

I burned my hand pretty good, twice. You would not believe how hot that rivet tool gets while its up against that red hot rivet for only a few seconds! It pops out of my air hammer and I have to pick it up and stick back in. It blistered me. One time was enough but to do it again the next day, I felt pretty stupid.

When it was done it was a quality repair and it looked a lot nicer than bolts. You couldn't pay me enough to do this job for somebody else. It's a lot of work.

[glennpm]

Very good work and write-up Flathead Fever!


Glenn

[deuce_roadster]

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Big Flats sells the rivets and a tools to go in an air hammer for round head rivets of various sizes and a waffle looking one too. You might look at their website:
www.bigflatsrivet.com/
I used to see them at Hershey each year.

[tubman]

I used the "lazy man's" method when I replaced the front crossmember in my '36 25 years ago. I sourced some "button head" cap screws and used them to bolt it together with the attendant lock washers and red Loctite. I then filled the recesses in the heads with JB WELD and carefully sanded them down. After I painted the frame, they looked close enough to rivets to fool me. I drove the car a lot over the next years with no problems, The last time I talked to the guy I sold it to, he was still very happy as well. If I were going to do a similar repair today with what I know now, I'd probably uses rivets.

The alternative ain't too bad , though.