Jayco RV Owners Forum

Thread Tools Display Modes
Old 11-13-2019, 02:16 PM   #1
Junior Member
Join Date: Oct 2015
Location: Yorktown
Posts: 17
Thinking about adding Sumosprings to my SRW F350

I have a 2014 F350 SRW that I tow a 321RSTS fifth wheel. My CAT scaled rear axle weight is 6500lbs. The truck handles the load quite well but it is riding on the overload springs. I am thinking about adding a set of 1500lb Sumosprings to the rear of the truck to help carry the load and reduce fatique on the truck springs. I would like to hear if anyone has done the same and what your experience with the Sumosprings has been. Including the effect on the unloaded ride.


2018 Eagle 321RSTS
2014 F350 SRW 6.7l
Yorktown, VA
bwbarnes is offline   Reply With Quote
Old 11-13-2019, 02:35 PM   #2
Senior Member
Vicr's Avatar
Join Date: Apr 2016
Location: Snohomish
Posts: 850
Sumo Springs will lessen the symptoms but the forces of physics are still there. To counteract the forces of physics I would add another leaf spring or two and a really stout swaybar to the rear axle. Shocks may need to be addressed also. I've been getting my Mustang ready for racing road courses so I've done a lot of suspension research this last year.

Vicr is offline   Reply With Quote
Old 11-13-2019, 08:49 PM   #3
Senior Member
Join Date: Aug 2011
Location: Missouri City, The Republic of Texas
Posts: 3,974
Our 350 has 6240# on the rear axle which is similar to your weight tho a bit lighter. I added Timbrens last year to reduce the squat a bit and have been pleased with the results. Was originally wanting air bags but started getting $$$ when I priced all the “extras” I knew I’d want. Haven’t noticed the ride being any different tho some folks have. When loaded my overload springs are engaged too.

We’ve logged a touch over 30k miles (Timbrens were recent additions) with this combination. My 350 is 2WD.

2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks
RedHorse1 is offline   Reply With Quote
Old 11-14-2019, 08:49 AM   #4
Senior Member
DonaandDon's Avatar
Join Date: Aug 2017
Location: Kingston
Posts: 1,062
Not an expert on this subject but what I'm understand about the F-350 SRW, is they have what's called a "Top mounted over load spring(s).

When LOADED, doesn't the top mounted over load spring come into play?

Will it stiffen your "unloaded" ride if you add Sumospring(s)?

Have you talked to your Ford parts department or your local "Truck Spring shop" for better overload springs?

I pull a fully loaded F-250. Mt local truck spring shop installed extra leaf and Timbrens. Yes I knew it would stiffened my ride. I now have over 12,000 on my NP381 and its working. I might consider a conversion to the top mounted over load next year.

Attached Thumbnails
Don & Donna Stout

E-9 Anchor Clanker
Full timers since 2010
2017 North Point 381 DLQS
2015 F-250 6.7 w/Timbrens
DonaandDon is offline   Reply With Quote
Old 11-14-2019, 11:26 AM   #5
AmericanBiker's Avatar
Join Date: Jun 2019
Location: Kerrville, Texas
Posts: 66
Air bags

2016 F150 2.7 4X4 CrewCab ShortBed 6Speed 3:55's
2019 Jayco Octane 222 SL
2016 HD Dyna S and 2019 HD Softail Slim
AmericanBiker is offline   Reply With Quote
Old 11-14-2019, 01:51 PM   #6
Senior Member
TxLoser's Avatar
Join Date: Feb 2017
Location: DFW
Posts: 875
Thinking about adding Sumosprings to my SRW F350

Iíve got a 321RSTS as well. Had a 3/4 ton without top overloads and installed Sumo springs. They worked great loaded and unloaded. Didnít know they were there unloaded.

Now, like you Iíve got a 1 ton with the top overloads(only difference with GM). Mine rests on the top overloads as well, which is ok by me as thatís the point of the overloads. Iíll be curious to hear how the ride improves if you add something.
2019 Eagle 321RSTS
2019 Chevy 3500HD SRW Dmax
TxLoser is offline   Reply With Quote
Old 11-22-2019, 07:08 AM   #7
Senior Member
ShawnR's Avatar
Join Date: Jul 2012
Posts: 220
I have SumoSprings on my half ton. The unloaded ride is not affected because I have a 1Ē gap between the axle and spring. I chose these springs for 2 reasons. Lower maintenance than airbags and softer ride than timbrens. Iím satisfied.
ShawnR is offline   Reply With Quote
Old 12-09-2019, 08:46 PM   #8
Junior Member
Join Date: Jun 2019
Location: Perris
Posts: 6
another vote for air bags here. i tried the sumo springs and pulled them off shortly after and went with air bags. 2017 f350 srw with 3200 on the pin, 6700 on rear axle. i had to set the sumo springs where they were almost touching the axle when unloaded to be somewhat effective when loaded. they probably work better on a 1/2 or 3/4 ton truck with less pin weight. i also like the adjustability the air bags offer.
SocalSeismic is offline   Reply With Quote
Old 12-10-2019, 11:23 AM   #9
Junior Member
Join Date: Oct 2015
Location: Yorktown
Posts: 17
I found a great deal on the SumoSprings on Amazon so I went ahead and bought them and installed them on my truck. They haven't changed the unloaded ride noticeably. Unfortunately, my camper is taking the long winter nap. I'm looking forward to the first tow of the season to see how the SumoSprings work with the load.
2018 Eagle 321RSTS
2014 F350 SRW 6.7l
Yorktown, VA
bwbarnes is offline   Reply With Quote
Old 12-11-2019, 03:13 AM   #10
Senior Member
Big1's Avatar
Join Date: Nov 2015
Location: Lakewood, WA.
Posts: 2,031
Great, can't wait to hear about the outcome when you do hook it up.

2018 Dodge Ram 3500 6.7L CTD
2019 Jayco Eagle 321RSTS 5th Wheel
Retired Army MSG
Big1 is offline   Reply With Quote

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

Powered by vBadvanced CMPS v3.2.3

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

All times are GMT -6. The time now is 07:06 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright 2002-2016 Social Knowledge, LLC All Rights Reserved.