Snapped U-Bolt, Rear Axle, 2004 F53 Chassis, Pooped Pants

[TrapGame]

Welp, make that two people that have had a U-Bolt snap on their f53 chassis. Mine is a 2004 chassis. Coming home last night towing a 4000-pound trailer. I heard a pop. Wife tells me it was just something in the drawers. I dropped something in my drawers.

I drove the next 40 miles with a lump in my throat but I didn't really feel anything different. I snoop around this morning and this is what I find:





Initially I worried that the sway bar "mod" put undue stress on the bolt, but you would think a sway bar link would snap well before a bolt.

I also now have a small leak where the driveshaft meats the pumpkin which suggests the axle shifted just a bit.

Any input on part numbers, etc. would be greatly appreciated.

FML

[Larry n Jude]

Scary ride for you. Quite common for truck chassis though. Find a shop that deals in truck chassis and spring repair. They always make u-bolts from stock because there are many sizes and lengths. If you remove the broken one they can copy it or will tell you how to measure it to make a new one. It only takes a few minutes to bend. Or, they can replace them for you. Always best to replace both u-bolts, even better to replace all on that axle. Good luck, Larry

[TrapGame]

I'll change all four on the axle.

You don't think I can get the stock u-bolts from ford?

[mel s]

Originally Posted by TrapGame

Welp, make that two people that have had a U-Bolt snap on their f53 chassis. Mine is a 2004 chassis. Coming home last night towing a 4000-pound trailer. I heard a pop. Wife tells me it was just something in the drawers. I dropped something in my drawers.
I drove the next 40 miles with a lump in my throat but I didn't really feel anything different. I snoop around this morning and this is what I find:
FML

TrapGame
I thought I owned the only coach that had strange things happen.

Last January. when I hit a dip in a rural Louisiana highway), both of the 5/8" U-bolts holding my front axle to the right front spring snapped at the top, (where they wrap around the spring stack).

It wasn't discovered until after I had driven the coach another 4,000 miles with a loud squeek under the the right front seat.

BTW a non-professional friend and I found, (and replaced), the broken U-bolts.... after I had PAID 3 different "professional service shops" to inspect the suspension in an attempt it find the cause of the squeek.

Mel
'96 Safari, 146k miles

[Larry n Jude]

You probably can get them from Ford, they will order them from somewhere and will cost a lot more. All the same quality. Larry

[twinboat]

I do almost all of my own repairs, being a retired heavy equipment mechanic.

If my U bolts broke, I would be driving to a spring shop.

They have multipliers and motor drivers to screw the old nuts off.

Once the U bolt gets lose, the hammering from an impact gun gets lost. Now your pulling on a wrench.

Besides, you get a free re-torque.

The pinion seal leak is a separate issue.

[TrapGame]

I can fix the pinion leak and I can probably just cut the broken bolt off without much issue. I just need to find the correct replacement u-bolts. Grade 8, please!

Anyone know where to look other than a local suspension shop?

[Pigman1]

Go to a local truck or suspension shop. You'd also be wise to get the rear axle aligned at the same time. If things shifted enough to break a grade 8 u-bolt, there's no telling what else moved around back there. They can align it and tighten all u-bolts at the same time.

[97 TropiCal]

I have had good luck with this company.

Michigan Truck Spring
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[TrapGame]

So, the overriding consensus here is that this crap just happens and that it isn't necessarily a weight or load issue? I mean, the rated break strength for a 3/4" grade 8 u-bolt is 50,000 lbs. - surely this one was simply defective - or it wasn't grade 8, right?

[CadillLinc]

X2 with TrapGame. It could have been a defective u-bolt, not Grade 8 or possibly over-torqued and stretched previously. If you want to bother, a metallurgist can examine the fracture surfaces and tell you why it failed (fatigue, corrosion, tensile, etc.) Going forward, the new u-bolts should be Grade 8 with rolled threads, not cut threads, and should use Grade 8 all-metal locknuts with a hardened washer, then torqued to the correct value. You may want to re-torque after 1000-2000 miles. Do all 4 on that axle.

[TrapGame]

Originally Posted by CadillLinc

X2 with TrapGame. It could have been a defective u-bolt, not Grade 8 or possibly over-torqued and stretched previously. If you want to bother, a metallurgist can examine the fracture surfaces and tell you why it failed (fatigue, corrosion, tensile, etc.) Going forward, the new u-bolts should be Grade 8 with rolled threads, not cut threads, and should use Grade 8 all-metal locknuts with a hardened washer, then torqued to the correct value. You may want to re-torque after 1000-2000 miles. Do all 4 on that axle.

Thanks, bub.

I looked at Ford for replacement u-bolts (only) and they wanted $65 each.

I called the people at Michigan Truck Springs. All 4 bolts, nuts and washers are on the way for $75 shipped.

[97 TropiCal]

Originally Posted by TrapGame

Thanks, bub.

I looked at Ford for replacement u-bolts (only) and they wanted $65 each.

I called the people at Michigan Truck Springs. All 4 bolts, nuts and washers are on the way for $75 shipped.

.....................Im glad Michigan Truck was able to help you.....They are top of the line and good pricing. Good Luck.

[wildmanbaker]

Apparently the "U" bolts are over-stressed on installation. The FORD shop manual says to not re-use them, but replace them when they are removed. Similar to their head bolts on many of their engines.