Spring bracket bolt torque?

[gw33gp]

My leaf spring bracket finally arrived. I ordered the part from Ford and it came with (grade 10.9) 12mmx x 1.25 (fine thread) bolts and nuts. Unfortunately, there was no torque instructions. I have looked online and have found a fairly wide range of torque values (75 - 100 ft-lbs). Those values depend on if they are dry, zinc plated, oiled, etc. The bolts that came with the bracket have some kind of aluminum pigmented coating. A torque calculator online gave me 88 ft lbs for an aluminum coated bolt. I also find that nuts seem to have a lower torque requirement. The nuts that came with it are also crimp style lock nuts which typically have a higher torque requirement.

Should I just shoot for in the middle of the range I found and hope for the best, or does anyone have some actual torque numbers that would work for these bolts and nuts?

 

[PetroleumJunkie412]

(Grab impact)

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[Curious Hound]

What you got are most likely zinc coated. I would go with the spec for dry, zinc coated fine threads. And stay toward the high side of the spec due to the lock nuts you have.

 

[gw33gp]

I am a firm believer in torqueing to spec. I do a lot of fasteners just by feel but I am pretty sure they are close to spec. I don't trust impact wrenches. I have dealt with too many lug nuts that were installed improperly with impact wrenches. Sometimes I can't get them off and other times I broke the stud getting them off.

These bracket bolts don't look like zinc coated (unless zinc with overcoat), but the torque specs for dry zinc coated and aluminum coated are about the same.

 

[Snoranger]

The m12 x 1.25 lug nuts on my SxS call for 85 lb-ft... that’s for a tapered seat on aluminum wheels. Your exact spec for the spring hangers should be close to that.

 

[Curious Hound]

I would give them 1.73 oogas.

 

[Blmpkn]

I would give them 1.73 oogas.

How do oogas translate into ugga-duggas? I was going to suggest anywhere from 5-7 ugga-duggas.

 

[Curious Hound]

oogas. Are with a longer breaker bar.

 

[Snoranger]

oogas. Are with a longer breaker bar.

That makes sense. You need less effort with a longer breaker bar... That would eliminate the need for the extra dugga.

 

[Uncle Gump]

I'd like to tell you I used a torque wrench on mine... but that would be a lie.

I run them down with my impact...

 

[alwaysFlOoReD]

I use a 1/2" wrench and socket and hand tighten. My guess is 100 ft/lbs on grade 8 1/2" bolts and (edit: stover nuts) crimp-nuts. Then i use a paint pen to mark the nuts to the frame so i can tell at a glance if anything has moved. After a few checks i dont worry about it.

 

[sgtsandman]

In the past, I've just tightened them as much as a longer handled 3/8" ratchet would let me and they held tight fine. That being said, 90-100 lbs/ft would probably be better.

 

[Uncle Gump]

At least tell me you guys run them down to tight before breaking out hand tools/torque wrenches?

I just can't imagine pulling those crimp type lock nuts down by hand.

After this post though... when I get back after my rear bumper and have it off... I will certainly have a look see at the hangers and hardware. to ensure they're tight.

 

[sgtsandman]

At least tell me you guys run them down to tight before breaking out hand tools/torque wrenches?

I just can't imagine pulling those crimp type lock nuts down by hand.

After this post though... when I get back after my rear bumper and have it off... I will certainly have a look see at the hangers and hardware. to ensure they're tight.

There is a tool with a threaded stud that crimps them down tight before you run a regular fastener through them. The middle part is not threaded, just the end. So, the middle gets crushed down to swell in the hole and crimp on the blind side sort of like a pop rivet. The thread part serves as the nut after the rivnut is installed.

Like this:

 

[Uncle Gump]

There is a tool with a threaded stud that crimps them down tight before you run a regular fastener through them. The middle part is not threaded, just the end. So, the middle gets crushed down to swell in the hole and crimp on the blind side sort of like a pop rivet. The thread part serves as the nut after the rivnut is installed.

Like this:

I'm confused... you installed your spring shackles with bolts and Rivnuts?