Replacing Leaf Springs And U-Bolts On A 2021 Grand Design 31MB

Updated 04/17/2024 | Published 02/01/2024

Products Featured in This Question

5-Leaf Double-Eye Spring for 6,000-lb Trailer Axles - 25-1/4" Long

(2173)

$79.21

MORryde U-Bolts for 5,200-lb to 7,000-lb Round Trailer Axles - Qty 4

(104)

$119.73

U-Bolt Plate - 3" Diameter, Round Trailer Axle - 2" Wide Spring - 1/2" Bolts

(152)

$13.83

Question:

Hello, I have 2021 Grand Design 31mb looking to upgrade my leaf springs. I have a Dexter 5200 axle. Originals have 4 leafs. Would like to have additional support with an extra leaf. Will these work below? And do I need longer ubolts? Thanks. 5-Leaf Double-Eye Spring for 6,000-lb Trailer Axles - 25-1/4inch Long MORryde U-Bolts for 5,200-lb to 7,000-lb Round Trailer Axles - Qty 4

asked by: Larry

Expert Reply:

The 5-Leaf Double-Eye Spring # e34SR will be a good replacement for your 2021 Grand Design 31MB, provided the stock leaf spring is also 25-1/4" long. The suspension is all designed based on a specific length of spring, so it is critical that the replacement springs are identical in size to the stock springs. A 5-leaf 6,000 rated spring will definitely give you more support than the 4-leaf 5,200 lb springs.

It is possible that you will need longer U-bolts, but it really depends on how long the current U-bolts are. The # e34SR leaf spring has 3/8" thick leaves, so if you still have an extra 1/2" or so on the current U-bolts you should be good. Otherwise, the MORryde U-Bolts # MR66ZR will be plenty long to accommodate a thicker spring. We also have new U-bolt Plates # TRTP300200 if you want to replace those while you are at it.

expert reply by: Jesse M

Larry B.

4/16/2024

Hi Jesse, I went ahead and purchased the e34SR springs for my RV. My question is about the center pin. My springs are installed above the axle so the bolt and nut are on top through the spring plate with head facing down. These springs have the center bolt head on top. Does orientation of the center bolt matter? Can these still be installed?

Jesse M.

4/17/2024

@LarryB We call that an "overslung" axle. Some trailers will do this to raise the deck height .To answer your question, yes, the # e34SR leaf springs can still be installed. They will work with both overslung and underslung axles.