Weld vs. rivets

[chuck]

Why are some parts welded on while others are riveted on? Body mounts come to mind. Anyone know which is better and why?

 

[Broncobowsher]

I know they were still using rivits up intil recently. My understanding is that Rivits allow flexing while weld is solid. solid sounds good, but if there is flex goinging into solid, solid usually cracks.

Another fun one, Rivits and bolts on the same part.

Some of the other things I have seen. Rivited on brackets can take a hit, break off. Get a new bracket and bolt it on and keep the frame. Rivits over bolts? Rivits are cheap to install (at the factory), stay tight, are evident if removed after assambly. Rivit is strong and cheap.

I remember looking at an old frame, '50 something Chevy. Could not find a single weld (at least factory weld) on it. All rivited together.

Modern stuff is engineered on super computers, all the stress is carefully engineered, and they are welded. Heavy trucks are still rivited, watch semi trucks. The frame is limp as a noodle, and last forever.

 

[Viperwolf1]

I think the rivets were used to prevent warping or weakness in the frame compared to welding. Now while some areas of the frame were welded it was in an area that was well supported by crossmembers. You wouldn't want to weld in an area that didn't have additional support.

 

[broncosbybart]

while not an expert on the subject, i'd probably guess that back in the day fitment had a lot to do with it. i wasn't around back then, but i'd guess that they had joe welder slapping the crossmembers onto the frame rails at a pretty quick pace and that the alignment wasn't as perfect as would be needed for the radius arm perches, and possibly body mounts. wierd thing is (if memory serves correct) that the rear spring mounts are welded, no???

 

[TN1776]

X2 on the flex factor... if I had to guess.
A friend of mine is restoring an FJ40 and similarly, some frame components are welded and some riveted. Of the parts he replaced on his frame, he was instructed to bolt new parts on that were originally riveted (as cold riveting at home is not something everybody can do) and weld on pieces that were originally welded.

Anybody here with a Mechanical Engineering degree care to chime in?

 

[rcmbronc]

One of the reasons on some vehicles is that the frame is usually made from a high strength steel and welding to this with common assembly line procedures was not a good idea. Take a look at most large truck frames, most I believe are riveted or bolted together. It also typically is faster to manufacture the frame using rivets on some mounts, before the age of robotic welders. One thing about certain mounts when welded to frames is that they provide sources for critical high point stress at any location that a 90 fegree turn is introduced to the welded on bracket. That is why a flat plate should not be directly welded to a frame rail parrallel to the long length of the rail. Stress risers will occur at the point that the plate turns 90 deg. to go vertical. All plates welded to a frame should be diamond pattern to gradually turn in relation to the bending stress in the frame rail.

Riveting is as good as bolting and welding as far as strength. It also helps to replace pieces in the field for repairmen like the body mounts. They can take the rivets out and bolt on a new body mount.

Bottom line is welding is a good practice, just make sure you match the welding procedure to the frame material and also look out for induces stress risers when welding a bracket on.

 

[feitctaj]

Honk- wrong

The reason is its cheaper to rivet or bolt then weld

Why did GM make the Corvette fiberglass- one reason - Cheaper;D

 

[feitctaj]

re Heavy trucks are still rivited, watch semi trucks. The frame is limp as a noodle, and last forever.

no, class 7 and 8 truck frames are bolted together, I was at the Kenworth plant last year watching the assmbly and they bolt them, and My binder I drive is bolted

 

[Skiddy]

Rivets are faster and cheaper. Remember when ships and steam engines were riveted the problem with them is expansion and contraction would loosen the rivets and leak or blow. one of the reasons ASME was developed for pressure containing anyway not that none of this really matters to broncos. I could do a strength calcs for both but I am too lazy;D most of the better grade steels SA-516-70 are around 50,000 ultimate total load (lbs) and 70,000 ultimate unit stress (psi) lower for say SA-36 but not a whole lot.
my thinking for the bronco is they had more time in one department than the other as to how fast they could get them out. OK really I dunno?:?

 

[73stallion]

i was thinking speed. they stamp out a frame with holes in it. it takes seconds to install a rivet, as opposed to the time it takes to weld a bead. besides, look at how crappy the welds on our frames were from the factory. i can't remember how many hours i spent grinding welds on jones' frame to make them nice looking....

 

[welndmn]

Rivets are faster and cheaper. Remember when ships and steam engines were riveted the problem with them is expansion and contraction would loosen the rivets and leak or blow. one of the reasons ASME was developed for pressure containing anyway not that none of this really matters to broncos. I could do a strength calcs for both but I am too lazy;D most of the better grade steels SA-516-70 are around 50,000 ultimate total load (lbs) and 70,000 ultimate unit stress (psi) lower for say SA-36 but not a whole lot.
my thinking for the bronco is they had more time in one department than the other as to how fast they could get them out. OK really I dunno?:?

I agree.
Rivits were used where they could get their machines, where if they could not get one in there, they welded or bolted it.

 

[67ster]

In the early 80s we spent countless hours drilling ,grinding and punching out rivets on a Ford Class 8 frame , everything was bolted together for flex. The cab and cage were double shear suported in urethane biscuits for flex and it held up well even through a couple rollovers. --However the entry of Stewart/Corral had several braces welded directly to the chassis and it too survived -- go figure. He was one hell of a lot faster too! I'll say one thing about rivets , being they are ductile enough to be bucked and peened , they also fill the hole they are in about 150% !

 

[69 Fl. Bronc]

One off the funniest books I've ever is Rivethead by a guy who worked in the auto plants. Ever wonder about quality? Think alcohol and drugs. A lot. Good read if you can find it.

 

[Jeepster]

One off the funniest books I've ever is Rivethead by a guy who worked in the auto plants. Ever wonder about quality? Think alcohol and drugs. A lot. Good read if you can find it.

I laughed....Having have worked for GM I can attest to the fact that most operations are geared towards "foolproof" assembly...kinda like the operation it takes to make a Big Mac. Quick,easy,good 'enough.

 

[67ster]

Yes ,but that was GM , I know that Ford was paying the welder that did the front crossmember in the '67 by the pounds of wire he used !!

 

[TorchRedTulsan]

Honk- wrong

Why did GM make the Corvette fiberglass- one reason - Cheaper;D

%) I own a Corvette. The reason for using fiberglass was weight savings. Lighter weight = faster/more efficient use of power

 

[feitctaj]

%) ;D your right and in 53 lighter was the big thought along with better efficiency, right

 

[TorchRedTulsan]

Yeah, because hand built, hand assembled was so much cheaper, which is the way they were produced in 1953. Virtually every fiberglass panel was hand crafted. Doesn't line up with the "because it's cheaper" argument.

But let's not hijack the weld vs rivet thread. I know nothing about welds vs rivets so I have to say C: Whatever you guys think ;D