Frame....How many rivets can I remove??

[Prathbun]

I am working on a 69 frame. Will I be compromising the frame strength by replacing rivets with bolts?? I don't want to remove every rivet but I have removed the rear cross member (gas tank relocation) the reinforcement plates over the rear frame arches (for rust clean up) and I have moved my transmission cross member.

I will be replacing each rivet with grade 5 hardware. I'm also wanting to see if I can have the frame lined up (or straightened to true) at a local frame shop before final assembly. Ultimately I'll be painting or powder coating the frame.

Any input?

Thanks in advance!!!

[sailed2japan]

Ditch the grade 5 and use grade 8 or 10. Get bolts that have about 1/4" of shank (the unthreaded part under the head) so the part that is aligning the frame and cross members has a tight fit and won't wear out as fast from the frame twisting around. I also suggest investing in teflon lock nuts for everything.

If your frame isn't bent and you just want to make sure that the rails are parrellel and square you can measure from corner to corner making an X across the frame. If your measurements are off you can pull the frame back straight by using a come-a-long on the long leg of the X. You'll need to have a crossmember installed at the back of the frame while straightening to get the correct results.

Remeber if it's worth doing, it's worth doing right. I little extra $$ of hardware can save ALOT of headache.

[LockDoc]

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I agree with sailed2japan. One other thing, make sure the bolts fit in the holes snug. If you have to drill them out to the next size to accomplish that I would do it...

LockDoc

[msgross]

I suggest buying your grade 8 bolts and washers from tractor supply (in bulk and cheap) and buying the nylock nuts online or from another supply place. I ended up using lock washers and regular nuts.

[Shane]

Grade 5 will work fine as this is a "shear" application (side load) as opposed to a "stretch" (pull) or "torsional load (twist).

Actually the rivets are better than the bolts as they tend to let the frame flex more than a bolt would.

[LockDoc]

Originally Posted by Shane

Grade 5 will work fine as this is a "shear" application (side load) as opposed to a "stretch" (pull) or "torsional load (twist).

Actually the rivets are better than the bolts as they tend to let the frame flex more than a bolt would.

75% of the movement of a frame is torsional. That would be the "flex" you mention in your second paragraph. ???? I wouldn't want the liability of recommending grade 5 bolts to anyone for a frame application, but to each their own.

LockDoc

[BAGNDRAGIT]

im going to agree with LocDoc, i wouldnt reccomend anything under grade 8 bolts.

Safety first kids!!!!!

[Shane]

You are absolutely correct sir, the frame is under torsional force but the bolts aren't, they are under shear forces. In other words, as the frame "twists" it tries to "shear" or cut the bolts in half.

Nutshell version: The bolts aren't being twisted, the frame is.

I would be almost be willing to bet the 40 year old rivets that are being removed are LESS than Grade 5 as far as strength.

[Sully 2-72]

I used grade 8 because they were free!. I found this website with info on the difference between grade 5 and grade 8


http://www.rockcrawler.com/techrepor...ners/index.asp

[kwmech]

10 mm bolts actually fit very well when replacing the rivets, unless you want to drill up to 7/16s. 3/8 bolts fit kinda loose in the hole.



and PS I've always used grade 8 for the last 25 years and never had a problem

[mosesburb]

Grade 8, 7/16-20 bolts, hardened flatwashers, steel locknuts (not nylock). I have been using this setup for years with no issues.

[dwcsr]

They do actually make a Frame bolt that uses a frame nut. They are also called flange bolts in Grade 8 and are for this purpose. It eliminates the need for lock nuts and hardened washers and lock washers. One nut one bolt torqued is all you need.

[GR8-68]

Originally Posted by dwcsr

They do actually make a Frame bolt that uses a frame nut. They are also called flange bolts in Grade 8 and are for this purpose. It eliminates the need for lock nuts and hardened washers and lock washers. One nut one bolt torqued is all you need.

so where can you find these at?

[LockDoc]

Originally Posted by Shane

You are absolutely correct sir, the frame is under torsional force but the bolts aren't, they are under shear forces. In other words, as the frame "twists" it tries to "shear" or cut the bolts in half.

Nutshell version: The bolts aren't being twisted, the frame is.

I would be almost be willing to bet the 40 year old rivets that are being removed are LESS than Grade 5 as far as strength.

Here is a simple test that anyone can do. It will show what the stress is on frame fasteners during flexing. Drill a hole in the ends of two short pieces of angle iron (a foot or two long). Put them together with one angle inside the other at 90 degrees and put a bolt in it. Leave the bolt a little loose so you can see what is happening at the joint. Grab the ends of the angle iron and twist both of them. You can see the torsional stress put on the bolt. If the bolt was small enough or you were strong enough you could actually bend the bolt. Second, with one of the pieces of angle clamped in a vise pull up or push down on the other one. You can see the pulling stress put on the bolt at the joint. Next, remove the assembly from the vise and hold the open ends of the angle iron. Try to pull the ends together like a pair of loppers or bolt cutters. This will put shear pressure on the bolt. Even though it can be said that the frame flexes as a unit, different stress is put on each individual component as flex occurs. These are all movements frame components will experience during flexing and it can be seen that all three types of stress are put on the fasteners holding the frame together.

LockDoc

[jorgensensc]

Not to stir the pot (since I don't know the correct answer myself), but I thought this discussion was had once or twice before and the consensus was that grade 5 was better because they would (bend) and flex more than grade 8 before breaking. I could just be getting old and be misrememberin' too.
SHawn

[jorgensensc]

now after reading the article above I would have to agree that grade 8 is better. Good thing I have always used grade 8
Shawn

[Shane]

Did anyone find out what grade the original rivets are ...

[BLACK AND BLUE 67-72]

Because there is effectively a head on each end of an installed rivet it can support tension loads (loads parallel to the axis of the shaft); however, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). Bolts and screws are better suited for tension applications.

The stress and shear in a rivet is analyzed like a bolted joint. However, it is not wise to combine rivets with bolts and screws in the same joint. Rivets fill the hole where they are installed to establish a very tight fit (often called interference fit). It is difficult or impossible to obtain such a tight fit with other fasteners. The result is that rivets in the same joint with loose fasteners will carry more of the load—they are effectively more stiff. The rivet can then fail before it can redistribute load to the other loose fit fasteners like bolts and screws. This often results in catastrophic failure of the joint when the fasteners "unzip". In general, a joint composed of similar fasteners is the most efficient because all fasteners will reach capacity simultaneously.

The commonly used high strength structural steel rivets were designated ASTM A502 Grade 1 rivets.

[dwcsr]

Originally Posted by GR8-68

so where can you find these at?

One is http://www.pointe-products.com/itemc...-(Frame)-Bolts

Google flange bolt

[GR8-68]

Originally Posted by dwcsr

One is http://www.pointe-products.com/itemc...-(Frame)-Bolts

Google flange bolt

thankyou sir, looked like a good site to add to the favorites list

[shaneschevys]

I have always used a 7/16 wheel stud & lugnut when I have removed & replaced cross members. I have never had any problems.