Crossmember Rivets

K

keeeef

Member
Just wondering why crossmembers were riveted and not bolted in. Just bought a used rear crossmember for my 36 pickup and don't have much experience of rivetting.
 
Rivets are much stronger than bolts and of course have much less tendency to loosen when the frame flexes.
 
Just to add, rivets expand when squeezed or bucked and fit the bore of the drilled hole much more securely than a bolt. Many steel bridges and buildings that were constructed with rivets over a century ago are still standing and in use today.

In aviation, pins and bolts are utilized more now than ever before but the bore of the drilled hole is reamed to fit the pin or bolt tightly and small increment oversizes are available to repair these if they become loose in service.

Hanson Rivet has all sorts of replacement rivets and they can be heated with a torch to make bucking the rivet easier but they aren't easy for the larger sizes and special equipment has to be either purchased or fabricated to aid in bucking or squeezing them. It helps if you have like minded friends who can get together and do multiple jobs at one time so as to have the help it takes to move and position frames and such for best access & grip on the big pneumatic air hammers and bucking bars.
 
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I learned a great way to heat rivets helping a friend put in a crossmember.

Put the rivet in the hole cold and position bucking bar. get a stick welder cutting electrode-ours were from harbor freight. Turn the welder up to about 180amps-may vary. Touch the electrode to rivet end and the entire rivet heats completely through. Cherry to white hot. Then hit it with the air gun.

A lot simpler than using a torch and sure expansion in the hole.

John
 
john in illinois said:
I learned a great way to heat rivets helping a friend put in a crossmember.
Put the rivet in the hole cold and position bucking bar. get a stick welder cutting electrode-ours were from harbor freight. Turn the welder up to about 180amps-may vary. Touch the electrode to rivet end and the entire rivet heats completely through. Cherry to white hot. Then hit it with the air gun.
A lot simpler than using a torch and sure expansion in the hole.
John
Click to expand...

OK, so you're saying to put the rod onto the end of the rivet and hold it there without creating an arc? How long should it take to heat up a 1/4" rivet?
 
PeteVS said:
Has anyone used this method for shrinking sheet metal?
Click to expand...

I have heard of people doing some thing like this. Would have to be cautious not to burn thru the sheet metal I would think.
Also have heard of people using a MIG welder with the gas shut off to create a hot spot as well. I can't claim to have done it myself.
Torchie.
 
Pete when you use a cutting rod made for cutting steel with an arc it does not deposit any metal. You arc to the rivet and it is instantly hot. Then you drive it.
John
 
John,

Thanks for the great tip. I have Rivets and Riveting Air tool from Big Flats but couldn't figure out how I was going to heat the Rivets. What stick welder do you recommend? I have a MIG & TIG but no stick and have to do some riveting soon.
Thanks,
Bruce/CT
 
Rivets are NOT stronger than bolts. However, properly installed rivets can be crushed tightly into non-precision holes which tends to reduce movement or "working" at the joint. A very desirable circumstance for a crossmember attachment.
 
Keef, You don't HAVE to rivet the crossmember in. As your truck is somewhat non-stock you could bolt it in and back the bolts up with some strategically placed welds. Or just weld it in completely.

Mart.
 
Thanks guys for all the suggestions. I had a couple of small cracks in the crossmember and lots of help in a previous thread. I ended up drilling small holes to stop them spliiting further, deep v'd the cracks and welded them up with the recommended 'soft' mig wire. Then wandering round a swapmeet here in the UK yesterday I found a perfect '36 crossmember for sale at £10!!

I only have a mig so no way of heating up rivets unless I get help. Might try Mart's suggestion of bolting and welding as it's not a restoration project more of a get it on the road and use it truck or may run it this year with the repaired crossmember and keep a close eye on it.

Thanks again, always get great advice on the Barn
 
JWL said:
Rivets are NOT stronger than bolts. However, properly installed rivets can be crushed tightly into non-precision holes which tends to reduce movement or "working" at the joint. A very desirable circumstance for a crossmember attachment.
Click to expand...

True. Another way of looking at this is, rivets are made from Low Carbon (soft) steel. Rivets are designed and strategically placed to allow the riveted members to flex. Their used to be a field of Heavy Engineering that dealt with rivets, their size, application, layout and spacing, sadly all that knowledge is gone now.
 
keeeef said:
Thanks guys for all the suggestions. I had a couple of small cracks in the crossmember and lots of help in a previous thread. I ended up drilling small holes to stop them spliiting further, deep v'd the cracks and welded them up with the recommended 'soft' mig wire. Then wandering round a swapmeet here in the UK yesterday I found a perfect '36 crossmember for sale at £10!!

I only have a mig so no way of heating up rivets unless I get help. Might try Mart's suggestion of bolting and welding as it's not a restoration project more of a get it on the road and use it truck or may run it this year with the repaired crossmember and keep a close eye on it.

Thanks again, always get great advice on the Barn
Click to expand...


You'll be okay if it is for road use and not uneven terrain. Remember, for every rivet removed and a bolt installed, the missing shear strength of the compressed connection will transmit through some of the frame's rivets so keep it on paved roads and you'll be fine.

Lonnie
 
One thing a person should keep in mind is that a bucking a hot steel rivet in effect is a forging process that closes the metals bond structure up a bit during the process. I would venture that they are not much softer than a grade 5 type bolt since both can be easily drilled with a high speed steel drill bit. They put enough of them in the frame gusset locations and for braces to strengthen the joints pretty well. You can use bolts, but bolts will loosen in service unless they fit the hole very tightly and even then, they should be periodically retorqued. Those old frames flex a lot more than modern ones.
 
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