Replacing Hot Rivets on a 65 frame

[GreyFox]

My Transmission crossmember has shed 4 of the 6 hot rivets connecting the frame to the crossmember.
Having a bit of trouble finding a hot rivet gun available. May have to purchase one -
Anyone know the size of the frame rivets on a 65 frame?

[Keith Seymore]

Not sure about '65 but I can say with authority that the squarebody rivets ('73-87) were not installed hot. They were cold headed.

Also - (again squarebody) a 3/8" grade 8 bolt was used on the assembly line as a repair for any mis hit or missing rivets.

I checked the generic info packet from the GM Heritage Center pgs 168-169 and it just says frames are "riveted" (does not specify hot vs cold, nor does it specify size)

https://www.gm.com/content/dam/compa...olet-Truck.pdf

Hope that helps or gives you some food for thought.

K

[Keith Seymore]

One other thing - when I lowered my trucks I cut all the rivets on the rear spring hangers and replaced with bolts.

My red truck was a daily driver for 30 years and 200k miles with no issues.

K

[GreyFox]

Excellent thank you for the heads up and the link. The bolts don't look as good as the big rivets. The hot rivet air tools are expensive and I have 4 to replace on the transmission crossmember. At least I hope the sm420 and the sm465 can use the same crossmember.
I have a C20 so I could use hot rivets on the new rear cab mounts. I can find several places to use hot rivets

[AlaskaK10]

On a 66 K10 rivet size was 3/8" hole size in frame was larger almost 7/16 to allow for rivet expansion. 3/8 X1 or 3/4 would be what you want the longer the rivet the larger you can buck the heads. I had planned on doing all rivets on my frame but at the last minute the company that was going to install the had a major failure in there rivet press and would delay my project for a period of time that was to long. I opted to bolt my frame together using 3/8 flange head bolts and lock nucts grade 8. Since 7/16 flange bolts had such a large head i made a bushing to fit in the 7/16 existing frame hole that reduced the size to 3/8". Kept the head size smaller and looks good. If you go the way I did make you bushings about a 1/16" smaller in height than the two frame parts your joining to allow for compression when you impact them togeter also use red loctite. The tube for the bushing I used was from Mcmaster car part # 89955K749
It already has a center hole that can be easily drilled out to 3/8"

[Keith Seymore]

Originally Posted by GreyFox

Excellent thank you for the heads up and the link. The bolts don't look as good as the big rivets.

You could use a button head cap screw to emulate the rounded rivet head -

K

[GreyFox]

Thank you both - Food for thought especially the button cap bolt. Not sure what grade they are. I would think 5 but not sure.

[Keith Seymore]

.....

https://www.mcmaster.com/

K

[AlaskaK10]

Problem I found with the button head is they only cover the rivet hole by a small fraction if you use 3/8. Remeber the hole once the rivet is removed is real close to 71/6 diameter. If you dont use a bushing like I did the bolt will not be centered in the hole. You can go to 7/16 but the head looks to big.

[rideblue00]

GreyFox, those button heads may not be able to be tightened down enough because the allen hex in them will be kind of small. A socket will tighten down a flanged hex head bolt better(more torque can be applied). In my experience, im not a fastener engineer(I am a machinist). Since this is on the frame, I personally would want a flanged bolt. IMO

[vince1]

Years ago I was working on a Model A frame and I used a wheel bolt with a dimpled head welded to a rivet set for an air hammer. I heated the rivets red and they riveted quite nicely resulting in an original looking round headed rivet.

[ACK]

This has been one of the more interesting threads in quite a while, should be added to the FAQ section after it has run its course.