What Would Cause Keystone Carbon 358 Suspension to Sag

Updated 02/09/2025 | Published 01/24/2025

Products Featured in This Question

Correct Track Trailer Alignment and Lift Kit - Tandem Axle

(51)

$501.96

Timbren Trailer Suspension Enhancement System Medium-Duty Trailers 7,000 lbs

(4)

$398.07

Question:

axle over under kit question I have a 2022 keystone carbon 358 and Ive noticed rear axle tires are rubbing underside of floor. it started on the driverside when loaded with a golf cart in the garage. then on the passenger side hauling empty. since my trailer has MORryde CRE3000 correct track is out . flipping the axle giving the trailer 5-6 inches of lift, seams to be to much to me and just looks unstable . my question is can I use and over under kit and change from 7000lb springs to the 8000lb springs?the 7000lb springs 24 7/8 have a D demention of 3 1/2 inches. the 8000lb spring has a D demention of 1 3//4. thoughts if this setup will work on my rig and will that dimension soften the 5-6 inch lift by an 1 3/4 im open to any other suggestions just looking for more clearance from floor and a little lift in the rear to soften the Angle of the hauler in tow. Im assuming the majority of the load is sitting on the rear axle with the slight nose up and added weight in the garage thats causing the rubbing problem. thanks for any suggestions.

asked by: Shawn

Keystone Carbon 358
(click to enlarge)

Expert Reply:

Hey Shawn, is it possible your leaf springs are just worn out and due to that your suspension is sagging and causing the tires to rub? Doing and over under kit and then trying to go with softer springs to offset the additional height would not be recommended and it certainly wouldn't change the height by 1-3/4 inches.

We also have Timbren kits for trailer suspension like with the part # TTRA1032 which will give you additional support too to prevent the rubbing. Did you by chance increase tire diameter at any point?

What is current length of your leaf springs.

expert reply by: Jameson C

Shawn

1/24/2025

I haven’t increased tire size. The tires have been on for 2 seasons now and just recently they have started to rub. Just is disappointing that the springs on a 3 year old unit would be worn out already, when it’s used empty 90% of the time.

Jameson C.

1/27/2025

@Shawn If it's a recent problem either the springs are worn out or maybe additional weight was added to the trailer to cause it to sag more? I am sure you checked already but is there anything damaged in the suspension?

Shawn

2/1/2025

@JamesonC The springs measure 26.5 with the weight of the trailer on them empty.