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Old 07-07-2018, 06:03 AM   #1
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Brand: Thor Motor Coach
Model: outlaw 37ls
State: Europe
Posts: 230
THOR #6831
failure of sumo springs

Failure of sumo springs

thor outlaw 2013 37ls

this is the accounting of the failure of sumo springs under normal use.

I had installed sumo spring in the summer of 2017 to reduce body like many have done before me. Having driven about 7000 miles with them, they seemed to do the job, also installed the 2nd rear sway bar from roadmaster and the trac bar from blue ox.,

this year the big trip to yellowstone and mt rushmore all went fine until the end of the yellowstone trip, i do not pull a car i drive the coach everywhere.

I donít drive fast over bumps or do crazy abusive stuff, this was the first trip with the garage loaded to max 2500 lbs, it was noted that the rear of the coach dropped 1 inch in height with the load. .

In yellowstone there was some construction and driving on dirt roads nothing any worse the normal pot holes we find in the city. (driven at slow speed) there was one area that was very rough i drove it at 3 mph through the 200 feet or so of bad roads, the coach did sway from side to side in a extreme manner, 2 or 3 sways (but within range of a evasive highway maneuver.)

during a brake check stop ( yes the brakes got hot ) on the steep pass, it notice the sumo springs had moved out of there normal vertical position and where bulging out of position.

It was obvious that the sumo springs needed to be removed and i really did not want to do it on the side of the road unless there was no other way.

I was able to get the coach to cody, wy where i had a local truck shop remove the sumo springs.

As can be seen in the photos on driver side the super heavy frame bracket was bent out of shape, the frame bolts holding one side on was sheared off and the frame bracket was hanging and got bent out of shape.

The passenger side the lower spring bracket was smashed and bent massively out of shape and
the huge amount of grinding marks on the lower bracket, this rubbing was done by the oem sway bar link and it needs to be replaced also.

The tires seemed to make it with out any damage .

The lesson learned here is that maybe the sumoís work and reduce sway, but under some type of maximum movement the sumoís will fail.

The sumoís may fit the f53 frame but failure of the mounting system will result in other damage as there is no extra room for the sumoís to move out of position. The rear tires could have easily been damaged for a later down the road nasty tire failure.

Since i drove the coach for 2000 miles after removal of the sumoís i am not sure anymore if they are really needed, there seems to be a bit more body movement, semiís passing mostly does nothing, crosswinds can be tricky i had some severe crosswinds during a eastern colorado route on my return.

It would be wise to check your coach for the condition of the sumoís, i am amazed at the very heavy brackets being bent and the mounting bolts being sheared off, the forces here are incredible
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Old 07-07-2018, 02:29 PM   #2
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Model: 2015 ACE 30.2
State: Florida
Posts: 251
THOR #1287
and Sumo said....

Wow!!! What was Sumo's response? I found them to be very responsive and helpful when I needed their guidance before installing front and rear on my ACE last year. My first reaction is that your rear axle was overloaded--max capacity is still limited by the max load per axle. Did you weigh the coach before the trip to make sure you were within the weight allowances? Glad you made it back safely. We did that trip summer of 2016 with the grandkids and it was spectacular.
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Old 07-07-2018, 04:25 PM   #3
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Quote:
Originally Posted by captmetal View Post

....cut.....

In yellowstone there was some construction and driving on dirt roads nothing any worse the normal pot holes we find in the city. (driven at slow speed) there was one area that was very rough i drove it at 3 mph through the 200 feet or so of bad roads, the coach did sway from side to side in a extreme manner, 2 or 3 sways (but within range of a evasive highway maneuver.)

.....cut....
Apples and oranges. With all due respect, this is exactly what Iíve warned against many times when ďupgradesĒ are made to reduce body roll without considering what happens when the suspensionsí ability to articulate is reduced significantly.

When a motorhome leans or rolls side to side during a highway maneuver on relatively flat surface, the front and rear suspensions are not fighting each other, so all that extra roll stiffness added by stiffer sway bars and Sumo Springs isnít that bad. However, when the road surface isnít flat, like what you experienced in Yellowstone driving off-road, the front suspension may want to pivot (articulate) in one direction and the rear in the other direction, and if prevented from doing so by excessive suspension stiffness, something has to give.

Having said that, this failure should not have occurred solely because of stiffer sway bars since that in itself should spread load on Sumos even if it meant motorhome wheels lifted off road. My biggest concern with these types of ďupgradesĒ is that while they reduce roll, and improve crosswind handling, they also add loads (forces) throughout the motorhome that few of us can predict or understand.

Driving off-road isnít the only limitation. The same can happen when smooth pavement isnít flat. The front wants to roll one way, the rear the other way, and add-ons are there to prevent it.
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Old 07-07-2018, 04:51 PM   #4
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It appears the brackets are the same by coach manufacturer, and year but not chassis weight. For the front Sumos, that difference is not significant at 1,250 lbs per wheel for the lightest to the heaviest F-53 chassis. The rear difference, however, is 3,250 lbs per wheel. I know how easily my 18,000 lb coach is to overload the rear axle, especially when going out for a week of dry camping. Just saying....
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Old 07-20-2018, 04:30 AM   #5
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State: Nevada
Posts: 575
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Quote:
Originally Posted by captmetal View Post
Failure of sumo springs

thor outlaw 2013 37ls

this is the accounting of the failure of sumo springs under normal use.

I had installed sumo spring in the summer of 2017 to reduce body like many have done before me. Having driven about 7000 miles with them, they seemed to do the job, also installed the 2nd rear sway bar from roadmaster and the trac bar from blue ox.,

this year the big trip to yellowstone and mt rushmore all went fine until the end of the yellowstone trip, i do not pull a car i drive the coach everywhere.

I donít drive fast over bumps or do crazy abusive stuff, this was the first trip with the garage loaded to max 2500 lbs, it was noted that the rear of the coach dropped 1 inch in height with the load. .

In yellowstone there was some construction and driving on dirt roads nothing any worse the normal pot holes we find in the city. (driven at slow speed) there was one area that was very rough i drove it at 3 mph through the 200 feet or so of bad roads, the coach did sway from side to side in a extreme manner, 2 or 3 sways (but within range of a evasive highway maneuver.)

during a brake check stop ( yes the brakes got hot ) on the steep pass, it notice the sumo springs had moved out of there normal vertical position and where bulging out of position.

It was obvious that the sumo springs needed to be removed and i really did not want to do it on the side of the road unless there was no other way.

I was able to get the coach to cody, wy where i had a local truck shop remove the sumo springs.

As can be seen in the photos on driver side the super heavy frame bracket was bent out of shape, the frame bolts holding one side on was sheared off and the frame bracket was hanging and got bent out of shape.

The passenger side the lower spring bracket was smashed and bent massively out of shape and
the huge amount of grinding marks on the lower bracket, this rubbing was done by the oem sway bar link and it needs to be replaced also.

The tires seemed to make it with out any damage .

The lesson learned here is that maybe the sumoís work and reduce sway, but under some type of maximum movement the sumoís will fail.

The sumoís may fit the f53 frame but failure of the mounting system will result in other damage as there is no extra room for the sumoís to move out of position. The rear tires could have easily been damaged for a later down the road nasty tire failure.

Since i drove the coach for 2000 miles after removal of the sumoís i am not sure anymore if they are really needed, there seems to be a bit more body movement, semiís passing mostly does nothing, crosswinds can be tricky i had some severe crosswinds during a eastern colorado route on my return.

It would be wise to check your coach for the condition of the sumoís, i am amazed at the very heavy brackets being bent and the mounting bolts being sheared off, the forces here are incredible
I can see from the pic these were not installed correct, have who ever installed these fix it..
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Old 07-20-2018, 04:36 AM   #6
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also, you stated this.;

"I had installed sumo spring in the summer of 2017 to reduce body like many have done before me. Having driven about 7000 miles with them, they seemed to do the job, also installed the 2nd rear sway bar from roadmaster and the trac bar from blue ox.,"


but then you say damage was done by the stock oem sway bar???
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Old 07-20-2018, 05:14 AM   #7
Kev
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I have them on all my coaches with good results. Never had a problem.
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Old 07-20-2018, 05:18 AM   #8
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I wanted to add, I'm in vegas, and if anyone has a problem with a sumo product,.. hit me up and I'll get you back on the road..
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