Hey all - has anyone replaced the frame rivets on their truck? There is an awful lot of frame flex on my F-5, leading me to suspect some of the rivets have loosened up over the years. I saw Ford has a TSB for their more modern trucks (TSB 97-4-7) stating to replace rivets with equivalent diameter Grade 5 hex-head bolts.

Any experience/thoughts/feedback?

 

They normally don't need to be replaced unless they have to be removed for some reason. The frame is supposed to flex, and rivets let it do that. Replacement with bolts is fine, just make sure they are real, Grade 5 or Grade 8 bolts. I wouldn't trust chinese stuff from Lowe's or Home Depot.

 

Are there any "acceptable deflection" criteria for these trucks? I understand a certain amount of torsional flex is desirable, but when I was changing the oil in my differential, I had the inner left hand tire up on a 4x4 block, springs did not compress, and the frame twisted to compensate. That degree of flex seemed excessive to me... but I'm still new to these trucks, and that's why I'm here asking folks who know these trucks better.

Amen. Of course, they usually save me from myself since they don't carry Grade 8 over 3/4"...

 

Replacing rivets is not that difficult. I did over 100 new rivets in another vehicle. The keys/basic process:
1. Correct sized/ shaped holes (may need to weld up and redrill holes)
2. Cutoff rivets to correct length
3. Torch rivet end to red hot
4. Helper with a bucking bar
5. Air impact gun with a proper sized rivet head bit. ( Mine came from Big Flats Rivets)
6. It is done about as quick as you can release the trigger on the air impact gun.

 

I replaced all of mine with Grade 8 bolts. I drilled all my rivet holes out to the next size bolt to ensure I had a good snug fit on them.

Somewhere I think I have a list of what all it takes....... set me back a couple hundred bucks for bolts washers and nylocks.

 

Here is a good source of structural-grade nuts/bolts.
Nucor Fastener | Our Products | Products | Structural Nuts

Good reading here:
http://www.fastenal.com/content/feds...al%20Bolts.pdf

 

I redid several on my current project frame. I got supplies and tools from Big Flats, and did them alone using a 1/2" thick bucking plate clamped holding the preformed heads. As said you need to heat the rivet glowing red, but to me heating the end too fast can limit the swelling of the shaft that is needed to squeeze the rivet to fully fill its hole. The newly formed rivet heads are not what provide a secure hold, it's the expansion of the shafts into their holes that do the job. Anybody that's removed frame rivets knows that simply grinding off the heads doesn't allow them to be driven out. Stu

 

I'm subscribing science I also need a couple of rivets replaced at the crossmember at the rear footstep support

 

I replaced my rear spring mount rivets with grade 8 but only because I had to remove them from the frame to get the spring pivots out.

I agree with Ross. Rivets are generally stronger than bolts in this application. See http://en.wikipedia.org/wiki/Rivet. Rivets provide optimal shear strength.

If you have a loose rivet it will have "rust dust" around the head (see second picture). I wouldn't replace them if you don't see this evidence.

 

A friend of mine restores model t's and rather than replaceing the rivits he has a couple tools for tightening them.I believe he heats them up red hot and with the "rivet " punchs he has pounds them tight.After they cool they should shrink and tighten more locking them.

 

So, in replacing rivets with bolts, what line up should one use? I'm bolting rear spring perches and was thinking; Bolt, washer, spring hanger, frame, washer, lock washer, double nut. The bolt i figured on getting would be partially threaded, the least threads in the hole, the stronger (my thinking)

Concerns? Ideas? Recommendations?

 

I used full threaded, SS, fine thread, grade 8 bolts as I wanted no chance that I would not have full clamp load as the fit to the holes would not be as tight as rivets. I used self locking nuts with no washers.

 

The only exception I take to this is the use of full threaded bolts. You want to utilize a bolt with the proper diameter shoulder for the hole and material thickness that it is installed in. For example on a 1/2" bolt the cross sectional area of a fine thread is only .438 (7/16) for a coarse thread bolt it's only .406 vs the 1/2" shank diameter.

 

Stainless steels aren't as good as the structural alloys. There are special grades of A325 alloy bolts that are weather resistant if that's a concern. Most A325 structural bolts are a good 50% higher tensile strength than stainless. SS bolts with SS nuts are likely to gall.

Re: full-threaded bolts; see the Fastenal link above about the importance of the unthreaded part of the bolt being long enough to go thru both pieces being bolted.

 

You are correct but I believe fine thread is thicker than coarse. Either way grade 8 bolts should be adequate. Since rivets should be considered to have a nominal clamp load, the clamp load of a ½" SS bolt at 75,000 to 120,000 psi (75-120 ksi) will increase the shear strength by half. Standard ½" rivets have a shear strength of 42 ksi and a ½" grade 8 is 60 ksi. So even without the clamp load it is well beyond the shear strength of a rivet. Of course if the bolt is loose in the hole as it might be if you reach the end of the threads then all this doesn't count which is why I went with the full threaded bolt.