Hi guys, couple of questions i need help answering, since i am removing my front frame mounts for repairs, do i need to drill out the rivet holes 1 size bigger or can i just put bolts that fit back inn and should i use nylon locking nuts or lock washers .

Thanks Ernie

 

Bolts ok, Id go with SS grade 8 with nyloc nuts and good size washer for both sides..

 

This subject sort of came up a while ago. Here's what I think I learned from the discussion.

The rivets are put into the frame hot and they are an interference fit. They're made of mild steel and they're supposed to be flexible. I've heard of replacing the mild steel rivets with high strength bolts, but that seems like a really bad idea. The hard metal of the bolts will chafe the mild steel of the frame.

If I have to replace rivets in a frame, I'll use good quality mild steel (grade 2) bolts and make sure that they are a force fit in the holes.

BTW, I'm sure you already know this, but grade 8 bolts are not better than grade 5 or grade 2, they're just different. They have a different application.

Edit: Whoops. I didn't mean to contradict what Mark said. I guess our posts got posted at the same time. Mark is an experienced mechanic, so give his thoughts serious consideration.

 

It is probably best if the bolts are a tight fit in the holes. Use grade 8 nuts, bolts and lockwashers. Loctite would be a good idea too! ...Overkill ...Terry

 

The big diffrence with grade 8 to 5 is that they have a much higher shear point.. I have always use SS grade 8 when replace rivits in all types of frames.. And I have never had a problem with them.. But I like the looks of SS and I work on boats for a livin.. SS grade 8 is all I have in stock for rebuilding trailers and mounting O/B engines..

Hey Paul, How you doin..

PS 54.. What part of NJ you in?

 

Wow, three different answers in three minutes! ...Terry

 

Thanks guys, but should i drill them out and use a bigger tight fit bolt ?

 

The tighter the fit the better..

 

Madathlon, i live in the southern part of New Jersey in Carney's Point about 5 or 6 miles frome the Delaware Memorial Bridge.

 

I was just wonding becouse I was station at Ft. Monmouth back in 90-94.. I miss the piers at times

 

??? The last time I replaced my rivets with bolts, my truck had over 100k miles and when the old rivets came out it was still a very snug fit with the bracket and frame. So not sure of that Idea about using softer hardware is necessary. If it did gouge the frame using hardened hardware. I would use the softer one instead of frame gouging...

 

Don't drill out the rivets unless you have a specific reason to do it. For example; if you know there's some serious rust between the frame members, it might make sense to remove the rivet and clean off the rust. Then reassemble using bolts that fit the hole tightly. If you can't find a bolt that will fit the original hole tight, drill the hole to a size that is a tight fit for the next bigger size bolt.

Otherwise, don't remove the rivets. They're designed a very particular way; they are a tight fit in the hole (they are an 'interference' fit that pre-stresses the frame and makes the joint stronger), they are made of mild steel so they won't chafe the frame rails and the mild steel will allow some flex without fracturing.

In extreme circumstances, such as a wreck, a mild steel bolt will bend but not break and hold the parts together, where a hard bolt will either fracture, or rip through the steel frame. Also, a mild steel bolt has a longer fatigue life.

If your vehicle lives in a harsh environment, like marine craft do, stainless steel is the way to go. Mild steel will corrode or just flat dissolve. (Stressed steel, like a tight bolt, corrodes more rapidly).

I was crew on a steel hull yatch. The hot brine from the exhaust system was leaking and dripping on the inside of the hull. You couldn't see the problem because there was no obvious sign that something was wrong, but when the boat got surveyed in a Seattle dry dock, they found the hull had dissolved down to about 1/8". We had picked the boat up in Portsmouth. Having the hull spring a leak in the engine compartment out at sea would have been a bummer.

 

rivets dont provide any flex at all where you guys get this i dont know as far as chafing i have yet to see any high test bolt ever chaf anything mild steel bolts when tightened allow for friction to be added to the joint and bolt shear is part of the equation, but old rivits are not no where near as stong as todays bolts and our frames are **** steel compared to the quality we have today due to better technology and more competition. even in old buildings rivets are replaced with bolts and its that way still today and will continue to be that way. this is one topic i really can say i do have knowledge in by trade. there is a type of bolt that is meant to be driven in like a rivet and has regular threads but for our application i dont believe it to be neccessary at all.

 

Hot rivoting can be done readily in the workshop. You will need a friends help. I made up a bucking bar and rivot tool. You can buy tools from specialty houses. The bucking bar is a rivot head tool welded to a heavy weight. I place the cold rivot in the hole and then heat the rivot with the torch. You need a helper to hold the bucking bar against the rivot head while you set the small end of the red hot rivot with the rivot tool. It forms tight in the hole. I have never had a problem.

 

Just to straighten out a misconception: In a situation where you have rotational movement in a joint, a pivot made from harder material will be worn down by a softer material, not vice versa as might be expected. A hardened steel shaft will wear before a nylon bushing it's turning in for an extreme example, due to imbedability of the softer material. Where clamping strength is needed, a hardened fastener, with fine threads is the way to go, being sure to torque the bolts with a torque wrench to spec for that size bolt. I'd use at least 1/2" or larger bolts to replace any rivets. Another difference between common bolts and hardened bolts is the way the threads are formed. The threads on a hardened bolt are rolled in, whereas a soft bolt the threads are cut in, weakening the bolt right where you need the strength. Look how easy it is to snap off a good sized frozen soft bolt by tightening it.