Re: Rivets vs. Grade 2 Bolts


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Posted by Jeff on Wednesday, April 04, 2001 at 12:58PM :

In Reply to: Re: Rivets vs. Grade 2 Bolts posted by Matt Wilson on Wednesday, April 04, 2001 at 1:03AM :

Getting the inner and outer frame rails apart would be a major job. I took apart a rusty 1935 frame that was not nearly as beefy as a power wagon frame and it took quite a lot of work. I also took off the spring hangers on a 41 truck because of the rust behind them and rehung them with grade 8 bolts. No problems afterwards, but it wasn't used off road. I know others who use bolts on spring hangers also, they all used grade 8 bolts.

As far as putting a frame back together, I think "clamp load" is the major factor to consider when holding two pieces of frame rail together with bolts or rivets. If the two pieces of steel are flush and clamped together tightly, the friction between the two surfaces provides the force to hold them together rather than the shear strength of the bolt or rivet. If a bolt or rivet with the highest strength loosens up, it will still shear off.

Original rivets were preheated to elongate them, then placed in the hole and pounded into shape. When they cooled the rivet shaft shrank, providing a great clamp load. If the vehicle was overloaded or used in such a way that the rivet shaft stretched, the friction between the two plates decreased and the rivets then sheared off after the plates started to side-slide.

On my 1941 truck, I used grade 8 shoulder bolts torqued to their maximum torque spec to achieve maximum clamp load. The shoulder should extend beyond the first piece of steel plate being clamped. Allen head bolts can be torqued higher and thus produce more clamp load than hex head bolts because of the way the head is machined. The head on a hex head is undercut a little thus it won't handle as much force as an allen head. But an allen head bolt looks a little strange on an old truck, a hex head looks more applicable. I also used matching grade 8 hex nuts and washers (on both sides) and a permanent threadlocker on the threads.

There are also retaining compounds that are used in slip-fit bearing applications to increase friction between the bearing outer race and the housing to prevent spinning. I would definitely use this between the two plates being clamped if I was doing this again. This should help increase the friction between the two plates.

If you want to go with rivets, there was a posting several forums ago about someplace in Chicago? that could supply rivets in any size. I know someone who does this, the rivets have to be preheated and it took two people to insert them. It looked like a lot of work and those rivets weren't nearly the size of a rivet on a power wagon frame.



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