Broken Shackles

[Duramax1]

Has anyone experienced broken shackles? Both of the bolt holes on the two shackles which attach the shackles to the rear spring on the passenger side of the Sundance became elongated enough to finally give way allowing the spring to flip upwards and rest against the frame. A further examination revealed that the bolt holes on the two shackles which are attached to the rear spring on the street side of the Sundance are also elongated but not to the extent where they will no longer keep attached to the spring. I have no idea what caused this as I have not gone over any curbs etc. The Sundance has travelled 30,000 miles. The other four shackles which are attached to the front springs on both sides of the Sundance do not show any signs of elongation. Any idea as to the cause of this failure?

 

[jnbhobe]

Sounds like normal wear and tare to me since there is no lubrication at those points. I would replace all the shackles with wet bolts so it they can be greased a few times a year. I have also heard of never lube bushings but never tried them.

 

[danemayer]

I'm amazed you got 30,000 miles. The standard shackles and bushing can wear out much sooner than that.
Lippert's Mobile Outfitters sells Never Fail Bushings - you should look at getting them along with the wet bolts.

 

[ParkIt]

30,000 miles could be enough to cause stress on the shackles to stress fracture, its not something people think about on their annual check list. There was also one company that had some issues with the springs and shackles right around the time yours was built, not sure who Heart Land uses for those so it could be a couple of things combined that caused it. You may want to take pictures and email them to Heart Land tomorrow and see if they have any explanation or other reports of the same happening with other rigs built round the same time just in case and what they would recommend on a new spring, shackles and bolts though as Jon mentioned, wet bolts are much easier to maintain overall.

One thing you may want to also check is your tow rig. You'd be surprised at torque transfer when a bearing (left side in your situation) is worn out and needs to be replaced.

 

[ParkIt]

I'm amazed you got 30,000 miles. The standard shackles and bushing can wear out much sooner than that.
Lippert's Mobile Outfitters sells Never Fail Bushings - you should look at getting them along with the wet bolts.

Wonder if they are using Poly bushings, they can take a beating.

 

[mobilcastle]

I am putting in never fail bushings soon-I put greasable on my last rig and after 6 months most did not want to take grease-long story to fix that. Good luck.

 

[brianharrison]

Wonder if they are using Poly bushings, they can take a beating.

Modified Polyamide - Link to Mobile Outfitters.

I installed them last year - plan to pull them this year and check for wear.

Brian

 

[wdk450]

We also all need to be checking our equalizers on a regular basis. I have read on this forum that the rubber block type need to have the rubber replaced every 3 years or so. My RV repairer found my old equalizers rubber blocks damaged, and I moved to the Dexter heavy cast metal scissoring against a rubber cylinder equalizers: http://www.dexteraxle.com/e_z_flex_equalizers

 

[GOTTOYS]

30,000 miles could be enough to cause stress on the shackles to stress fracture, its not something people think about on their annual check list. There was also one company that had some issues with the springs and shackles right around the time yours was built, not sure who Heart Land uses for those so it could be a couple of things combined that caused it. You may want to take pictures and email them to Heart Land tomorrow and see if they have any explanation or other reports of the same happening with other rigs built round the same time just in case and what they would recommend on a new spring, shackles and bolts though as Jon mentioned, wet bolts are much easier to maintain overall.

One thing you may want to also check is your tow rig. You'd be surprised at torque transfer when a bearing (left side in your situation) is worn out and needs to be replaced.

Just curious, What should the tow rig be checked for? I can't see any correlation between a broken shackle on the trailer and "torque transfer???" ...Just asking...Don

 

[ParkIt]

Don
What most people aren't told is the transfer at the axle while towing aka torque ratio when buying a truck to haul. It always trips me up trying to explain it with words...the engine produces the power, it travels to the axle and what comes from the rear tires is torque or 'pull/push' threshold. When that is strained the energy at the axle is transferred anywhere it can - the bearings being the easiest place first. That can wear down the bearings so the torque power transfers to the next path of least resistance which is usually an axle behind it - which would be on the trailer. Since that torque disperses out it can put undue pressure on the weakest spot - the shackles causing wear at that point as well. (I need crayons to draw a picture right now).

Lets say you were on a flat track and going to race with the trailer hooked up. The tires are locked but the engine is revving and that power is transferred to the back, what you would see is the truck twisting slightly (torque transfer) then the trailer would also absorb the energy and have an even slighter twisting as well. Not that we do this to our trucks and trailers but its the same principal only at a lower threshold done over and over while being towed.
If I can find it there is a video of a consumer truck built for hauling, a school bus and the cab of an 18 wheeler that did a track test in Vancouver B.C. just to see what would happen. You can see how torque transfer works in an amplified way.

btw, the semi had the best time in the quarter mile.
(I feel totally nerdy right now)

 

[Thenomads]

ParkIt,

Love your explanation of transferred torque. By any chance are you an engineer. Our son is an Aerospace Engineer and when he is trying to explain something to us it usually ends with "I sound a little nerdy" followed by,"you probably won't understand anyway". LOL!! We appreciate your insight and explanation. We had a couple shackles break on our old trailer a 27' SOB, Hmmm, I wonder...

Corey & M'Lissa

 

[Willym]

I'm sorry but after reading this several times, it makes absolutely no sense to me.

Don
What most people aren't told is the transfer at the axle while towing aka torque ratio when buying a truck to haul. It always trips me up trying to explain it with words...the engine produces the power, it travels to the axle and what comes from the rear tires is torque or 'pull/push' threshold. When that is strained the energy at the axle is transferred anywhere it can - the bearings being the easiest place first. That can wear down the bearings so the torque power transfers to the next path of least resistance which is usually an axle behind it - which would be on the trailer. Since that torque disperses out it can put undue pressure on the weakest spot - the shackles causing wear at that point as well. (I need crayons to draw a picture right now).

Lets say you were on a flat track and going to race with the trailer hooked up. The tires are locked but the engine is revving and that power is transferred to the back, what you would see is the truck twisting slightly (torque transfer) then the trailer would also absorb the energy and have an even slighter twisting as well. Not that we do this to our trucks and trailers but its the same principal only at a lower threshold done over and over while being towed.
If I can find it there is a video of a consumer truck built for hauling, a school bus and the cab of an 18 wheeler that did a track test in Vancouver B.C. just to see what would happen. You can see how torque transfer works in an amplified way.

btw, the semi had the best time in the quarter mile.
(I feel totally nerdy right now)

 

[wdk450]

BTW, both Dexter and Lippert sell shackles much thicker (and thus wear longer) than the standard OEM shackles.

 

[caissiel]

I balanced my tires when we bought our unit and after 20k miles there is absolutely no wear to the bushings and shackles. One bad tire can wear a whole side.

Sent from my U8666-51 using Tapatalk 2

 

[TedS]

With the common 5th wheel hitch that can tilt side to side, I don't expect truck chassis twist transferring through to the trailer.

 

[labarn]

We had a broken shackle in April on our trailair center point suspension so to make a point I have our frame or anything under the fifth inspection every other year and same with the roof. It seems to be a good idea but we all know stuff happens. Lippert didn't seem to understand what broke to sell us a new longer than a normal shackle for their product. Be safe labarn