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When you use bolts on your frame...

DavidB

DavidB

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...whether to replace all your rivets or bolt suspension brackets on in different positions, always use a bolt that has a shoulder - the part under the head with no threads - that passes thru the two pieces you are bolting together. The bolt will probably be too long, so you will have to cut off the extra, but having the threaded part of the bolt going thru the 2 pieces of metal will cause problems. It will fit loose and work the nut loose. On the flip side, make sure the shoulder isn't too long, which would make the nut botom out on the shoulder instead of pulling the 2 plates together. Stover or crimped nuts are the best.
 
Why do you tell us this, what made you think about it?

Thanks,
Mike
 
Because I keep seeing it done incorrectly. Just trying to make people's lives easier and safer.
 
This is new to me. I know exactly what you're talking about, but I don't see why it would make that much of a difference whether there was threads or a shoulder passing through the pieces being bolted together.
 
Excactly. Also less area for the pieces to push against with the threads. The threads will cut and wallow the holes in the plates. Ideally the hole should be drilled so that the bolts "tap fit" in on the shoulder. Nice and snug. I saw a guy's B-52 bracket lost all but one bolt because of this.
 
Thanks for posting this.. I probably wouldn't have known otherwise :o

What's the best way to cut bolts down?
 
Plasma, torch, grinder, hacksaw...take your pick. :D Not a bad idea to cut it off than then beat the end of the bolt so it mushrooms a little bit which will prevent the nut from coming off if it works loose.

While I'm preaching safety...nylon lock nuts are usually grade 2. They're OK to hold a bolt in a shear load, but not a clamping load. Don't use them on your ubolts! Use a high nut or stover. Or a grade 8 nut with a nyloc on top.

Something else I saw once was a nyloc nut on the sector shaft holding the pitman on. Wasn't all the way up to the nylon and almost came off. Not a place for a nyloc anyway.

In a pinch, you can make a locknut with a regular nut by peening one side a couple times with a punch, or just plain smash it sideways with a hammer.
 
...whether to replace all your rivets
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Is it a good idea ro replace all my factory rivits? Now that I think about it my
K5 is 31 years old. I may look into that.
Thanks for the info DavidB
 
I haven't tried it. When I box my frame and cage it all, I'm just gonna weld everything together solid.

Wouldn't be a bad idea, as long as all your bolts, etc. fit nice and tight. Lots of work I imagine. It definitely isn't going to make your frame all super nice and rigid like boxing and/or a complete cage.

retroblazer - raffo racing
The frame is boxed from end to end. Frame flex is minimal based on the fact that in the ten years that I've race the truck we haven't had but one cracked tube in the cage.
Click to expand...
 
DavidB said:
...whether to replace all your rivets or bolt suspension brackets on in different positions, always use a bolt that has a shoulder - the part under the head with no threads - that passes thru the two pieces you are bolting together. The bolt will probably be too long, so you will have to cut off the extra, but having the threaded part of the bolt going thru the 2 pieces of metal will cause problems. It will fit loose and work the nut loose. On the flip side, make sure the shoulder isn't too long, which would make the nut botom out on the shoulder instead of pulling the 2 plates together. Stover or crimped nuts are the best.
Click to expand...

This is not necessarily true.

If there is a bearing load on the bolt (shear loading) then yes, it’s best to place the bearing loads on the shank however this is generally bad design practice. If the bolts are sized correctly and tightened properly than there will be no shear loads on the bolts, shear loads will be carried through the assembled parts by the clamping force of the bolts and the friction between the parts (someone already gave us a sermon on this in another thread today), and the bolt will only see tension loads.

Keeping the bolts from coming loose is dependent on how much you “stretch” the bolt when it’s tightened. If you clamp two pieces of 3/16in steel together with a ½” bolt the region of the bolt that is “stretched” is only 3/8in (+ washer thickness) this is less than the diameter of the bolt, and will likely work itself loose as the bolt relaxes. The reason for this is that when you tighten a bolt with a wrench the bolt is “twisted” and “stretched”. After the bolt is tightened, and is subject to vibrations and such, it will try to relax, or twist back until there is no torsional preload left in the bolt. If the amount of “stretch” is too little, than the all of the initial “stretched” preload is lost and the bolt is now loose. To avoid this situation, the easiest thing to do is increase the “stretch length” to at least 2x the diameter of the bolt, and torque to the appropriate amount. This scenario assumes steel or high stiffness material for the assembled parts.

The factory riveted connections avoid the loss of preload issue because they are not “twisted” to generate the necessary clamping force, which makes them ideal for fastening together thin pieces of metal.

Another common method to reduce loss of preload is to actually reduce the diameter of the bolt shank. This results in even more “stretch”. An example of this would be the carrier end cap bolts used on the 10 bolt axles and many other axles.
 
Replace all of the rivets with bolts for "peace of mind"?

They are very hard to get out which means it probably isn't worth doing and the rivets probably weren't going anywhere anyway.

I've never seen the factory rivets back out or get loose. If they did, I would bet there was some serious abuse going on. I would not think of bolts as an upgrade.
 
Hell, I though this was common knowledge. With a bit of common sence it should be.
 
To properly stretch a bolt, a guy is gonna hafta calculate it out and torque 'em all with a torque wrench. I'm not about to crawl all over and under my truck with a torque wrench checking every bolt and doing it again periodically. Having the bolt/shank fit the hole is only gonna help, and I've seen things come apart when not done this way. A bolt that is loose in a hole is no good, no matter how you slice it. Also, I doubt if a few 3/8" or 7/16" bolts could generate enough clamping force to eliminate sliding in thin, flexible metal.
 
All my rivets/xmembers/brackets are loose and sliding all over. You can see the marks in the paint/steel. Mine is a special case of abuse though. :D I would be surprised to have a rivet actually come out, but mine are loose.

Blue85 said:
Replace all of the rivets with bolts for "peace of mind"?

They are very hard to get out which means it probably isn't worth doing and the rivets probably weren't going anywhere anyway.

I've never seen the factory rivets back out or get loose. If they did, I would bet there was some serious abuse going on. I would not think of bolts as an upgrade.
Click to expand...
 
When I remove a rivet to mount something I drill it out to .498. A 1/2 Grade 8 bolt is about .495/.498 or there abouts. There is minimal room for movement. It acts likes a loose fit dowell pin.
 
Well you could just put everything together and tap through both peices of metal then the thing would be tight. I have done that a couple of times on a hot rod tapped through 2 peices of 1/8" worked very well
 
blazinzuk said:
Well you could just put everything together and tap through both peices of metal then the thing would be tight. I have done that a couple of times on a hot rod tapped through 2 peices of 1/8" worked very well
Click to expand...



true, but Im not THAT ambitious. :D
 
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