U-bolts bending under load?

UPDATE, SOLVED: When using anti-seize on u-bolts, do not torque them all the way to Toyota spec 90 ft/lbs
https://www.tacomaworld.com/threads/new-u-bolts-bending-while-tightening.557643/

I recently installed new grade 5 u-bolts that came with my Wheeler's 1.5" 3-leaf progressive AAL, and they're flexing/bending forward at the threaded ends. I used anti-seize on the threads and torqued to 90 ft lbs per Toyota. Is this anything to worry about?

When I installed them, I basically threaded all of the nuts on handtight, then cranked them down incrementally in a star pattern. My driveway does have a slight incline, but nothing severe--could that be the cause?

EDIT: added this pic since it best demonstrates what I'm seeing

 

Do you have the same number of exposed threads on all four (2 per u-bolt) nuts? Can only 'see' 2 in the picture...

 

Well I chopped the u-bolts with my angle grinder, but yes they are all pretty equal. Now I'm wondering if the heat from the the grinding/cutting is what caused them to flex/bow a little

 

If you some how got the u-bolt to the point it started to heat the axle housing Red hot you might have done something

Doubtful just cutting them you could .

 

Cool, thanks. Just wanted to make sure. Never really seen or heard of them bowing like that.

 

I really don't see what you're referring to. MAybe back up and take a pic?

 

Follow the threads from the top down to the bottom, they are definitely arcing outward (rightward in this photo) at the nut end. It's subtle, but noticeable.

But yeah, that pic doesn't show it as clearly as I would like.

 

It sounds like you installed them properly, but I can see the bend you're talking about.

Are both sides on both springs doing it? Maybe something wasn't seated right during assembly. There's a little shadow between the lowest leaf and the mount. There's no gap in there, right?

 

Yea, I guess i see it.

I don't think the perch on the axle is perpendicular to the angle the bolt sits at. Engineering was just 'good enough'.

edit: In other words the surface the nut sits on must not be perfect otherwise this couldn't happen.

 

Don't think it should be an issue, as long as everything is secure and tight. Maybe keep an eye on them

 

No, no gap. I was careful to keep everything clamped down hard with c-clamps when I installed the AAL and tightened the retainer nut. That shadow you see is because the overload leaf is cocked ever so slightly crooked (front end shifted outboard, rear end shifted inboard). Next time I feel like it I'll loosen u-bolts up and tap the overload back into place with a mallet.

The only thing I can think of that wasn't "right" during final torque is that I did it in my driveway. I let the the truck back down off the jack, all 4 wheels on the ground, as you're supposed to--but my driveway is slightly uphill, so I wasn't on completely level surface when I applied final torque.

 

They're most likely just settling. Just retorque and you will be fine.

 

I just checked with HQ, our ubolts are grade 10.9

Grade 5 seems kind of low for ubolts.

 

Wow I've never heard of grade 10 u-bolts. According to this (page 4 of 4), 9/16 grade 5 u-bolts (what I have) have a suggested torque of 90 ft lbs, which is what Toyota calls for on these.

But yeah, I'd like to have stronger bolts I suppose. I have had to re-torque these grade fives several times since install. I would notice axle wrap, which would remind me to check them and sure enough they were no longer at 90 ft/lbs. But that's pretty normal with new u-bolts, from what I've read they all need to be checked regularly, but especially a few hundred miles after installation.

 

To me it kind of looks like the saddle has slipped forward, looks like maybe there is a gap or marks from moving from its original place.

 

I recently replaced mine because I needed longer ones for 1" blocks I put in. I got some at Oreilys. When I got home I noticed they were a slightly smaller diameter. I returned them and found some that were the right size. Could these be a little thinner or are they oem?

 

Alright, I went out and parked the truck in a level/flat spot, loosened all 8 nuts, then brought them up to 30 ft/lbs in a bowtie/star pattern. Then brought them up to 60 ft/lbs. Then finally all up to 90 ft/lbs.

I noticed all of the u-bolt ends are bowing outward--the rears to the rear, and the fronts to the front. It's like @cruxofthebisquit said, the underside of the saddle is maybe not flat?

 

**It almost looks as if the saddle is bending/cracking/bowing which is allowing the u-bolts to then bow outward as well.**

@TrailRayted I didn't measure them to see if they are 9/16" but they came from Wheelers in a kit specifically designed for Tacoma/Tundra. They surely could have included the wrong size, but it's not likely.

 

I'm fairly convinced that these saddles are cracking and giving inside where I've marked in red below. That's a bit concerning. What are the chances of this? I would expect those to be overbuilt to withstand more than 90-100 ft/lbs, but they are about 20 years old so who knows. Thoughts? I can get a pair of them from Toyota for about $100

 

Little heavy on the torque.