You have a range of options for this repair.
For a "perfect" job, you should have a steel fabrication shop rivet the joints for you.
These will be the tightest, strongest, and most original looking. They might be able to
bring their equipment to you if you can't take the frame down to them. This is my
recommended approach.
You could rivet these yourself if you have a big enough rivet rivet hammer, the correct
size rivet sets, and some hefty bucking bars (basically just heavy chunks of steel in
various shapes to get into nooks and crannies). However, doing a good rivet job takes some
practice, and it is especially difficult if it's a tight space that you have to work in.
However, large steel rivets seem to be more forgiving than aluminum rivets. I've found
that the smaller the rivet, the touchier they are. Also remember that if you buy a rivet
hammer, it's advertised capacity is sometimes listed for aluminum instead of steel. A
hammer that will rivet say, 1/4-inch aluminum rivets will only handle 3/16-inch steel
rivets. A good quality rivet hammer that can handle large steel rivets (say 5/16-inch)
might set you back about 800 dollars or more for a new one. Rivet squeezers are even more
expensive. Maybe you could rent or borrow such equipment somewhere.
The next best option is to use close-tolerance bolts. If you want a really tight joint and
you have the patience, you can use a broach to finish the holes to an exact diameter, then
use close-tolerance bolts that have to be gently driven into the hole with a brass hammer
or drift. This will give you the tight fit of a rivet and will provide a full-strength
joint. Admittedly, it's more work and expense, but it WON'T come loose.
If the first two options are not practical, at least use high-strength bolts in their
place. Most typical "carriage" bolts are only grade 3 at best (you might be able to find
some stronger ones somewhere). However, you really ought to use grade 8 bolts at these
critical joints, just to be on the safe side. Make sure you use the correct "grip range."
The bolts should fit as tightly as possible in the holes to prevent shifting of frame
elements. This is the great advantage of rivets...they expand to fit very tightly in the
holes, eliminating any play that can eventually cause things to loosen up.
If you're not familiar with "grip range," that's the unthreaded part of the bolt between
the head and the threaded area. Generally, you want a grip range that is just slightly
less than the thickness of the metal that the bolt is passing through. This allows the
smooth sides of the bolt (therefore more surface area and slightly larger diameter) to be
in contact with the sides of the hole, giving you a stronger, more snug joint. It still
won't be a "press fit," but there will be less air between the sides of the bolt and the
frame if you use the right grip range. Any good fastener supplier will be able to provide
bolts in a wide variety of grip ranges.
As far as appearances are concerned, you can round off the head of a bolt to where it
looks like a rivet, but don't take too much off, since you still need the full tensional
strength of the bolt. I suppose that if you don't have a lathe, you could chuck the bolts
in a drill press and use an angle grinder to round the heads as they are turning in the
drill press. It's not as elegant as a real lathe, but this doesn't have to be precision
work. Be extra careful, as this is obviously not an 'approved' way to use these tools and
of course I don't recommend it.
There are some anaerobic compounds made by companies like Loc-Tite that are designed for
fitting worn parts tightly together again, such as a pulley on a worn shaft, but they are
a pretty sloppy way to make up for good workmanship, and it makes it VERY hard to take
things apart later (if you want to take them apart). I don't recommend this approach. This
is the kind of repair I might make if I were stranded in some backcountry road in the
Amazon Basin and I had to make sure my makeshift repair would last me until I got back to
civilization.
Some people will say that these don't have to be very tight joints, but consider the
tremendous mechanical advantage that a long frame member has...it's in essence a very long
lever that prys, bends, twists, pushes, and pulls from every imaginable angle, exerting
tremendous pressure at the joints. If you look at serious 4x4 off-road machines, you'll
find that they often weld frame members or reinforce the junctions in other ways because
even rivets will loosen up under those circumstances.
I suspect that you won't be driving your vehicle like a maniac, and you may be able to get
by just fine with a bunch of grade 8 bolts of the correct size and grip range, but I'm
just trying to give you an idea of the range of possibilities that you have for this type
of repair.
One other thing that you can do to make a bolt look less obtrusive is to use
smaller-profile all-metal stop nuts, such as are used on aircraft to save weight without
losing strength. These have a hat-shaped cross section and are self-locking. I forget the
MS or AN number series, but they're pretty common.
I believe that there are also some high-strength "rivet substitutes" that are sometimes
used in aircraft, but I need to dig out my old catalogs to find them. It seems to me that
they require special tools for installation.
Regards,
Alan
(Salt Lake City, Utah)
Rick wrote:
> What are people using when they need to replace removed rivets on a MB
> or GPW frame? I have to re-attach some of the shackle brackets and the
> rear cross member on my GPW frame.
>
> I have been told by some to use carriage bolts or slotted screws and
> solder or fill in the slot, or have the head of a bolt machined to look
> like the head of the rivet. This will work fine on the rear cross
> member, but replacing the front lower bumper brackets and shackle
> brackets you will still be left with a nut on one side. As far as real
> riveting goes, I have no idea at all.
>
> Any help here would be appricated.
>
> Thanks
>
> Rick Perotti
>
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