Community Forums

41pu · 03-01-2016, 10:32 AM

Most NAPA Auto parts stores have these type of parts in sock.

TrapGame · 03-01-2016, 11:51 AM

Quote:

Originally Posted by 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.

Are you making a general statement or are you referencing something floating around out there that suggests the u-bolt was over-torqued from the factory?

I have been racking my brain to figure out why this happened. I just starting towing this trailer. I am well under the GVWR and GCWR, and even if I were slightly over, I am pretty sure that a 3/4" Grade 8 bolt would not be the weak point.

I have also considered that bad shocks would contribute to excessive jolt frequencies when simultaneously presented with side forces and loads. I am probably racking my brain for nothing because there really is only one answer - the bolt simply failed. Still - this incident has me shook.

wildmanbaker · 03-01-2016, 02:07 PM

Quote:

Originally Posted by TrapGame

Are you making a general statement or are you referencing something floating around out there that suggests the u-bolt was over-torqued from the factory?

I have been racking my brain to figure out why this happened. I just starting towing this trailer. I am well under the GVWR and GCWR, and even if I were slightly over, I am pretty sure that a 3/4" Grade 8 bolt would not be the weak point.

I have also considered that bad shocks would contribute to excessive jolt frequencies when simultaneously presented with side forces and loads. I am probably racking my brain for nothing because there really is only one answer - the bolt simply failed. Still - this incident has me shook.

The factory may have over-torqued the "U" bolts, I have no way of knowing. Manufactures have a habit of not taking disassembly and reassembly into account when designing things, and have to have the fasteners stressed past its point of elasticity, requiring replacement whenever they are removed. This is especially true with heads and blocks. The making them smaller, lighter and of course less structure, to hold a seal, and not big enough to hold a fastener that can do the job repeated times, requires the size fastener to be overstressed. These days, when a manual says to replace fasteners, I will always replace them, especially if I or me family will be in the vehicle.

Crankshaft · 03-02-2016, 04:35 AM

Quote:

Originally Posted by 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.

So what does one do when when they are installing a Roadmaster add on sway bar? The bar mounting plate is held in place by the U bolts. Does this mean that I have to put new ones in when I put the sway bar in? There were some F53 chassis that had U bolts that were not long enough for the mounting plates so the U bolts had to be replaced but mine are long enough and I thought they wouldn't have to be replaced.

mel s · 03-02-2016, 06:32 AM

Quote:

Originally Posted by Crankshaft

So what does one do when when they are installing a Roadmaster add on sway bar? The bar mounting plate is held in place by the U bolts. Does this mean that I have to put new ones in when I put the sway bar in? There were some F53 chassis that had U bolts that were not long enough for the mounting plates so the U bolts had to be replaced but mine are long enough and I thought they wouldn't have to be replaced.

Crankshaft
I have read that if U-bolt nuts are removed the U-bolts must be replaced with new.
See: https://www.eatondetroitspring.com/reinstalling-ubolts/
Mel
'96 Safari

wildmanbaker · 03-02-2016, 08:58 AM

If you follow Mel S's link, it should answer most of the questions about reusing fasteners, and why some shouldn't. Sometimes we have to learn lessons the hard way, but hopefully some will not have to do so.

TrapGame · 03-02-2016, 09:32 AM

I agree that u-bolts should never be reused. I have followed that practice in all of my vehicles.

Keep in mind, though, gentlemen - the snapped u-bolt in the opening post was not reused. It had not been touched from the day it left the factory as far as I can tell. Of course, I cannot confirm that.

DMTTRANSPORT · 03-02-2016, 09:39 AM

Betts Spring if you have one in your area

Crankshaft · 03-02-2016, 05:54 PM

Quote:

Originally Posted by TrapGame

I agree that u-bolts should never be reused. I have followed that practice in all of my vehicles.

Keep in mind, though, gentlemen - the snapped u-bolt in the opening post was not reused. It had not been touched from the day it left the factory as far as I can tell. Of course, I cannot confirm that.

I have now read that they should be replaced and there is even a YouTube video on the subject. From what I can gather replacement is needed mainly due to the threads being rolled not cut. When the nut is tightened on rolled threads they are deformed. Theory is that when you reinstall the nut to the same place on the threads, there is not enough threads to achieve the same torque to hold the U bolts in place. Add in the original stretching of the U bolt and failure is going to happen.

With the Roadmaster sway bar kit, the mounting plate mounts to the U bolts and puts the nuts in a new location on the threads. The U bolt is still stretched but the nuts has new threads to attach to. Still no excuse for not replacing the U bolts.