Free 7 Day Trial RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Free 7 Day Trial ×
 

Go Back   Thor Forums > Thor Tech Forums > Motorhome Tech Topics
Click Here to Login
Reply
 
Thread Tools Display Modes
 
Old 07-07-2018, 06:03 AM   #1
Senior Member
 
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
Attached Thumbnails
Click image for larger version

Name:	SUMO1.JPEG
Views:	769
Size:	369.1 KB
ID:	11261   Click image for larger version

Name:	SUMO2.JPEG
Views:	272
Size:	281.2 KB
ID:	11262  

Click image for larger version

Name:	SUMO3.jpg
Views:	329
Size:	195.0 KB
ID:	11263  

__________________
captmetal is offline   Reply With Quote
Old 07-07-2018, 02:29 PM   #2
Senior Member
 
ArrrV's Avatar
 
Brand: Thor Motor Coach
Model: 2015 ACE 30.2
State: Florida
Posts: 258
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.
__________________
ArrrV is offline   Reply With Quote
Old 07-07-2018, 04:25 PM   #3
Senior Member
 
Brand: Still Looking
State: Texas
Posts: 5,413
THOR #2121
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.
__________________
Chance is offline   Reply With Quote
Old 07-07-2018, 04:51 PM   #4
Senior Member
 
Brand: Thor Motor Coach
Model: Hurricane 31S
State: Texas
Posts: 3,104
THOR #6411
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....
__________________
Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow
Beau388 is online now   Reply With Quote
Old 07-20-2018, 04:30 AM   #5
Senior Member
 
Brand: Thor Motor Coach
State: Nevada
Posts: 575
THOR #12329
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..
__________________
vegasruv24.1 is offline   Reply With Quote
Old 07-20-2018, 04:36 AM   #6
Senior Member
 
Brand: Thor Motor Coach
State: Nevada
Posts: 575
THOR #12329
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???
__________________
vegasruv24.1 is offline   Reply With Quote
Old 07-20-2018, 05:14 AM   #7
Kev
Senior Member
 
Kev's Avatar
 
Brand: Thor Motor Coach
Model: Windsport
State: Florida
Posts: 745
THOR #3918
I have them on all my coaches with good results. Never had a problem.
__________________
Kev is offline   Reply With Quote
Old 07-20-2018, 05:18 AM   #8
Senior Member
 
Brand: Thor Motor Coach
State: Nevada
Posts: 575
THOR #12329
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..
__________________
vegasruv24.1 is offline   Reply With Quote
Old 10-09-2021, 11:20 PM   #9
Junior Member
 
Brand: Thor Motor Coach
State: Missouri
Posts: 18
THOR #24505
Have a 24.1 Vegas with a steering stabilizer, but it does roll on uneven highways, so wondering what I can do to reduce it. Other than that, we love this coach!!
__________________
Winnie is offline   Reply With Quote
Old 10-10-2021, 02:15 AM   #10
Senior Member
 
Brand: Thor Motor Coach
Model: Hurricane 31S
State: Texas
Posts: 3,104
THOR #6411
Quote:
Originally Posted by Winnie View Post
Have a 24.1 Vegas with a steering stabilizer, but it does roll on uneven highways, so wondering what I can do to reduce it. Other than that, we love this coach!!
This movement is known as "sway". The only way to reduce sway is stiffen (increase) the spring rate. Selectively this done by an sway bar or anti-roll bar between the springs. This bar can be installed in the front, rear or in both places. This bar effectively increases the spring rate on the spring on the outside of a turn and decreases the spring rate on the inside spring. This does effect the ride quality, but not usually to a noticeable amount. Sumo springs do the same by increasing the spring rate. The Sumo Springs are longer and softer then the bump stops they replace, so the contact the springs earlier limiting spring travel. Sumo Maxims are longer and stiffer and come with special brackets that allow the springs to stay in contact with the springs at all times. This means they reduce sway by compressing when the coach leans to the outside of a turn and stretches resisting the lean on the inside of a turn.

The problem is basically your body is not used to being 5 ft above the roll center of the vehicle, so you are not used to the 5 times greater movement than in a car or small truck.
__________________
Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow
Beau388 is online now   Reply With Quote
Old 10-18-2021, 10:27 PM   #11
Junior Member
 
State: Arizona
Posts: 11
THOR #16549
2019 hurricane 29m. What model/make of Sumos are recomended ??? Tx in advance.
__________________
Rich1339 is offline   Reply With Quote
Old 10-18-2021, 11:18 PM   #12
Member
 
electric's Avatar
 
Brand: Thor Motor Coach
Model: 2022 Vegas 25.6
State: California
Posts: 38
THOR #24413
Quote:
Originally Posted by Beau388 View Post
The problem is basically your body is not used to being 5 ft above the roll center of the vehicle, so you are not used to the 5 times greater movement than in a car or small truck.
This is a great explanation and advise. I'm new to driving a huge box, so my initial experience is not pleasant, causing me to believe I need suspension upgrades, especially with forum full of such solutions. But maybe the problem is lack of proper experience and adjustment is needed between my ears rather than suspension. I think I'll hold off any suspension upgrades for now.
__________________
electric is offline   Reply With Quote
Old 10-19-2021, 02:05 AM   #13
Site Team
 
16ACE27's Avatar
 
Brand: Thor Motor Coach
Model: ACE 27.1
State: Florida
Posts: 7,528
THOR #7035
Quote:
Originally Posted by electric View Post
This is a great explanation and advise. I'm new to driving a huge box, so my initial experience is not pleasant, causing me to believe I need suspension upgrades, especially with forum full of such solutions. But maybe the problem is lack of proper experience and adjustment is needed between my ears rather than suspension. I think I'll hold off any suspension upgrades for now.

Excellent analysis! Body roll will always exist on a MH. The new MH driver is not used to it and is terrified of the feel of a rolling coach and seeks to stop it, hence the market for all the after market suspension upgrades.

I was just thinking about this today as I was driving the Blue Ridge Parkway up and down the mountains, around the curves, and occasionally through some wrinkled roadway sections. It's quite a workout on the MH and driver and although I have quite a few miles under my belt on interstates and lower altitude roads this was a new experience for me. Yet here I was a week into driving these mountain roads and my comfort level was so much higher than when I started because i was used to the way the MH handled the direction and road changes. It doesn't roll any less but I am used to it and know what to expect, so my reflection was; how little of an anxiety raiser it had become.

The only "suspension" upgrade I have is the Roadmaster steering stabilizer.
__________________
Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad
2020 Chevy Colorado Z71 Trail Runner Alternate Toad
16ACE27 is offline   Reply With Quote
Old 10-19-2021, 03:44 PM   #14
Senior Member
 
Brand: Thor Motor Coach
Model: Hurricane 31S
State: Texas
Posts: 3,104
THOR #6411
Quote:
Originally Posted by 16ACE27 View Post
Excellent analysis! Body roll will always exist on a MH. The new MH driver is not used to it and is terrified of the feel of a rolling coach and seeks to stop it, hence the market for all the after market suspension upgrades.
The only "suspension" upgrade I have is the Roadmaster steering stabilizer.
I remember watching a sports car race in 1963 in Fort Sumner AP, NM; it was the under 1500 cc race. The were Porsche 356 Supers, Alfa Romeo Giulias and one Isuzu Bellel sedan. The Porsches corner almost flat, The Alfas leaned a little more but not any more than my Fiat Abarth 750. The Isuzu leaned so far in the right hand turns I thought the drivers side door handle would touch the pavement. When the Isuzu passed the Porsche on the outside of a right hand 120 degree turn, I was blown away. It was later I learned the Isuzu had Bosch direct cylinder fuel injection (same system as the Mercedes 1956 300 SL), so there was no fuel cutout on the hard cornering. The lean allowed a more compliant suspension to cope with the bumpy, AP's concrete surface (built in 1942);thus much better traction. Body roll is not all that bad if you want a smooth ride and better cornering on a rough road.
__________________
Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow
Beau388 is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Thor Industries or any of its affiliates. This is an independent, unofficial site.




All times are GMT. The time now is 03:55 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0 PL2