1. Trailer Leaf Spring Suspension
  2. Universal Group
  3. Leaf Springs
  4. Springs
  5. Slipper Springs - 1-3/4 Inch
  6. 30 Inch Long
4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long

4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long

Item # SP-040275
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Trailer Leaf Spring Suspension
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Universal Group Springs - SP-040275
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Slipper leaf spring acts as part of a trailer's suspension system by providing an attachment point for a 3,700-lb axle. Spring flexes to resist shock and also ensures a smooth ride. Includes bushing with 9/16" inner diameter. Lowest Prices for the best trailer leaf spring suspension from Universal Group. 4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long part number SP-040275 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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  • Reviews (73)
  • Q & A (24)
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  • Why etrailer?

Universal Group Trailer Leaf Spring Suspension - SP-040275

  • Leaf Springs
  • Springs
  • Slipper Springs - 1-3/4 Inch
  • 30 Inch Long
  • 3700 lbs
  • Universal Group

Slipper leaf spring acts as part of a trailer's suspension system by providing an attachment point for a 3,700-lb axle. Spring flexes to resist shock and also ensures a smooth ride. Includes bushing with 9/16" inner diameter.


Features:

  • Leaf spring acts as part of your trailer's suspension system
    • Provides attachment point for your trailer's axle
  • Multiple leaves allow flexibility to absorb road shock
    • Allows for a smooth ride
    • Reduces wear and tear on trailer
    • Ensures level ride on bumpy and uneven surfaces
  • Sturdy steel construction
  • Nylon bushing included
  • Pre-mounted hangers or aftermarket hanger kit (sold separately) required for installation
    • Eye of spring attaches to hanger mounted on trailer frame
    • Slipper end slides into hanger or equalizer


Specs:

  • Quantity: 1 leaf spring
  • Spring capacity: 1,850 lbs
  • Axle capacity: 3,700 lbs
  • Length from center of spring eye to end of spring: 30"
  • Spring width: 1-3/4"
  • Eye diameter with bushing: 9/16"
    • Eye diameter without bushing: 7/8"
  • Leaf thickness: 3/8"
  • Number of leaves: 4
  • Additional dimensions: see table


Flat End Slipper Spring

Part NumberABCDE
SP-04027513-3/4"30"15"17-3/4"4-7/8"


Note: To ensure proper axle alignment and suspension performance, leaf springs should always be replaced in pairs.


Leaf springs are an integral part of your trailer suspension system. The leaf springs provide the attachment points for your trailer's axle, suspending it from the frame of your trailer. Each spring flexes to absorb road shock as you travel, allowing the axle to move somewhat independently of the rest of your trailer. This helps to reduce wear and tear on the trailer and also ensures a smooth ride.


Slipper leaf springs attach to hangers that are welded onto your trailer. The eye of this spring will attach to the front hanger with a suspension bolt. The flat slipper end of the spring will slide into the rear hanger. If you have a tandem- or triple-axle trailer, the slipper end will slide into the equalizer that connects multiple springs. The shape of the slipper end of a leaf spring may vary slightly due to differences among trailer manufacturers. Because of this, it's important to check your leaf spring's slipper end before purchasing a replacement spring.


To mount this spring, you will need hangers, a suspension bolt, and possibly a spring keeper bolt, depending on the design of the rear hanger. If you are simply replacing a spring, you may still have hangers welded onto your trailer, but it would be wise to replace the bolts as they can experience wear. It is also recommended that you replace the other leaf spring in your setup at the same time. Because springs can sag and elongate as they wear, this new spring may not exactly match the old one, and the alignment of your trailer could be affected.


If you are fabricating a trailer, you will need to purchase a hanger kit for installation. To determine the type of hanger kit that you need, you must know the specific type of leaf spring that you have, as well as your axle capacity. Depending on the hanger kits used with them, springs can be configured to work for single-, tandem- or triple-axle applications. Hangers and other suspension components can also be purchased separately if there isn't a complete kit that works for your setup.



UNA-040 Universal Group Slipper Trailer Leaf Spring - 4 Leaf - 1,850-lb Capacity

Replaces WIG4






Customer Reviews

4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long - SP-040275

Average Customer Rating:  5.0 out of 5 stars   (73 Customer Reviews)

Slipper leaf spring acts as part of a trailer's suspension system by providing an attachment point for a 3,700-lb axle. Spring flexes to resist shock and also ensures a smooth ride. Includes bushing with 9/16" inner diameter.

- SP-040275
by:

Good part came on time 914231



- SP-040275
by:

Easy ordering. Arrived quickly. Absolutely no problems with the parts. etrailer.com will be my go to for my trailer parts from here on out. 899020



- SP-040275
by: 09/04/2020

873985



- SP-040275
by:

Replaced rusty springs thanks for the great product 833801



- SP-040275
by:

I was searching for a replacement on an out dated boat trailer. The spring had two broken leaves. It was an unusual slipper spring that mounted crosswise. While I did not find one with the exact configuration, I was able to find a similar one with adequate load capacity and had the correct dimensions for proper mounting. It is working fine. 830767



- SP-040275
by:

easy to install fits perfectly. 823065



- SP-040275
by:

The springs work just fine. They are a little over kill for my boat. It has raised the trailer more than I would like. That's my fault. They are exactly what I ordered. Also I like that you can grease them. 820929



- SP-040275
by:

I have a 20+ year old flat bed trailer. One of the leaf springs [finally] broke. This replacement set was a drop in fit! Perfect for my flat bed trailer. Replacing the springs was made easier by having the right parts and etrailer had them. Thanks, etrailer! Great price, right fit and fast shipping. Can't ask for more. 820174



- SP-040275
by:

Receive items as ordered and on the date . Thank you 782882



- SP-040275
by:

The only minor issue was that the springs were sticking through the box. The springs went on quickly, and fit properly. My only wish is that the product be made in America. I would be glad to pay a bit more. 771000



- SP-040275
by:

Works great hasn't had any problems 748748



- SP-040275
by:

product delivered early all goo, box was ripped in transit but all ok Great survice and follow up support1 723335



- SP-040275
by:

I just cant say enough good things about my experience. Along with a great product, the service and support are unbelievable. Thanks from a first time but multiple future customer. 708476



- SP-040275
by:

Great product.Fits perfect 698222



- SP-040275
by:

price was good, shipping was fast and installing the springs was easy. What more can I say. 693728



- SP-040275
by:

Very good product. My mechanic told me to go get the same thing I had on my trailer, only more leafs. Knowing very little about these, I couldn't find what I thought I needed...then etrailer came up on Google search. I got what I thought would be needed and all the mechanic had to get were ubolts etc to connect to axle. These leaf springs should be strong enough to help me save fuel when hauling wood and mulch no matter what vehicle I am using. Thanks for helping me get what I needed. Emily 682988



- SP-040275
by:

We initially ordered the wrong size spring leaf and Rebecca made the exchange easy. The correct ones came very fast! Thank you! 682211



- SP-040275
by:

You Da Man!!! Perfect fit, boat and trailer has never pulled that smooth before.. thank you for the speedy shipping also. 673726



- SP-040275
by:

Very good , help full, and fast shipping. Thank you. 664630



- SP-040275
by:

I ordered a fender, springs,8 and misc parts for my magic tilt boat trailer to get it back in good condition. Everything was exactly what I ordered and worked great. The order was delivered in two days with free shipping The customer service was also very helpful (thanks Taylor ) Only place to go for your trailer needs. 656436



- SP-040275
by:

Just installed it, not driven with it yet, but no problems. 602439



- SP-040275
by:

Really happy with product 600138



- SP-040275
by:

Great service product and price........nuf said 585398



- SP-040275
by:

Holding up just fine 584260



- SP-040275
by:

Product was exactly as described and arrived in a timely manner. Customer service was great too. Web page was easy to navigate and I would recommend etrailer to anyone looking for trailer parts. They have it all. 571298


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Show More Reviews

Ask the Experts about this Universal Group Trailer Leaf Spring Suspension

  • Replacement Slipper Springs to Replace 32 Inch Long Springs
    The 30 inch slipper springs we carry don't have a measured radius but the 28 inches you're looking for will work just fine. Your 32 inch springs were likely a little shorter than that originally and have flattened over time. Although probably not the full 2 inch difference but enough that our 30 inch springs will work on your trailer. We carry three different weight capacities that are 30 inches: 4-Leaf for 3,700 pound axles # SP-040275 3-Leaf for 2,900 pound axles # SP-039275 2-Leaf...
    view full answer...
  • How to Find Axle capacity of a Trailer to Choose the Right Replacement Slipper Springs
    The leaf springs on a trailer will need to meet or slightly exceed the axle capacity. So if you know the axle capacity then each spring should be rated for at least 1/2 of that capacity on a single axle trailer. The axle capacity may be listed somewhere on the trailer frame near the front of the trailer. Another option is to pull off a hub and retrieve the inner and outer bearing numbers stamped into the sides of the bearings. With that information I can determine the likely hubs that...
    view full answer...
  • Recommended Spring Seat for a Square Axle Tube
    Correct, you will need to have a spring set installed on the axle tube to hold the leaf springs in place and prevent them from sliding back and forth. That said, although we do not have any spring seats specifically for a square tube axle you can use the Spring Seat part # TRSS300 by grinding the ends down and then welding it to the axle tube.
    view full answer...
  • Looking for Spring for Model R1828 Yacht Club Boat Trailer With 1-3/4 x 30 Leaf Slipper Springs
    As long as a spring is of the correct weight rating, size and type (slipper or double-eye), the number of leaves in a spring isn't important. This is especially true since springs should always be replaced in pairs. If you are confident that your trailer has a 3500 lb axle, the # SP-040275 slipper spring should work just fine for you.
    view full answer...
  • Replacement 32 Inch Leaf Springs for Trailer
    The closest leaf springs we have available to the specifications you mentioned is the Universal Group 4-Leaf Slipper Spring # SP-040275. These slipper springs have a 30 inch length from the center of the spring eye to the end of the spring. Leaf springs will stretch over time, so it's possible that the leaf springs on your trailer originally had a length closer to 30 inches. These are designed for axle capacities of 3,700 pounds and have a width of 1-3/4 inches. The eye diameter with...
    view full answer...
  • 30 inch Long Slipper Spring Recommendation for Boat Trailer
    We have a few options for 30 inch long slipper spring that is 1-3/4 inches wide. For a 3,700 lb axle option we have the part # SP-040275. For a 2,900 lb axle option we have the part # SP-039275. For an 1,800 lb axle you would want the part # SP-038275.
    view full answer...
  • Replacement Leaf Springs for 1989 TeeNee Boat Trailer
    As leaf springs become worn, they tend to flatten out, which would explain the slightly longer dimensions of your existing slipper spring. The correct replacement spring you need will depend on the capacity of your axle. If your TeeNee boat trailer uses a 3500 lb axle, then the # SP-040275 is the correct replacement. For a 3000 lb axle, use # SP-040275. Leaf springs should be replaced in pairs.
    view full answer...
  • Replacement Leaf Springs and U-Bolts for a 1987 Shore Line Boat Trailer
    Thank you for submitting the photo of your setup. Considering the height of your axle and the amount of clearance you currently have from the axle to the frame of your trailer you wouldn't have enough room to put your axle above the leaf spring. You would barely have a couple of inches of suspension travel. For U-bolts you would want the part # SP01-160 and then for plates you would want the # 117594. Based on the dimensions of your current slipper springs the # SP-040275 that you...
    view full answer...
  • Can Bottom Leaf be Removed When Replacing 3-Leaf Slipper Spring with 4-Leaf Slipper Spring
    You can easily replace a 3-leaf slipper spring with a 4-leaf option like the Universal Group Slipper Spring # SP-040275 that you referenced. You should definitely not remove the bottom leaf from this as that would lower the weight capacity plus the center bolt that holds all of the leaf springs together would need to be modified. All the extra leaf spring will affect is the height of your trailer but that will be very minimal. Just be sure that the leaf spring is rated properly, has the...
    view full answer...
  • Are Trailer Spring Seats Needed for Square Axles with Leaf Springs?
    Square axles normally don't have spring seats like a round axle but do have a hole for the leaf spring bolt to fit into. Take a look at the CE SMITH # CE33201GA-HUB for a visual. The U-bolt mounting kits will have a hole in the center for the other side of that leaf spring bolt to keep everything in line. If you have a 1-1/2 inch square axle use # CE23102. If you have a 2 inch axle use # CE23103.
    view full answer...
  • 4-Leaf Slipper Spring Recommendation for a 3,500 lb Axle Boat Trailer
    As long as the capacity of the spring matches what the trailer needs it won't matter at all if there are a different number of leaves on the spring. Based on the weight of your trailer and the fact the # SP-040275 matches up dimensionally this spring would be the perfect spring to use. I attached a review video for you to check out as well.
    view full answer...
  • Are 5-3/4 Inch U-Bolts Long Enough for a 3 Inch Tall Axle and Slipper Spring # SP-040275
    The internal length of u-bolts # SP01-160 is 5-3/4 inches so you would not subtract 9/16 inches from that length. The u-bolt plate # 117594-G is 3/16 inches thick. The spring stack for # SP-040275 I just measured and it is 1-7/16 inches thick. Adding in the 3 inch height of the axle and the total comes to 4-5/8 inches. So all of these parts will fit your trailer axle.
    view full answer...
  • 4-Leaf Slipper Spring Recommendation that is 1-3/4 inches Wide and 30 inches Long
    I believe the closest spring we carry to what you are looking for is the 4-Leaf Slipper Spring part # SP-040275. This is a 4-leaf spring that is 1-3/4 inches wide that is 30-1/4 inches long. This spring is designed for a 3.500 lb axle. If the axles you have on your trailer are 3,500 lb capacity this spring would work well for you. I attached an FAQ article on slipper springs for you to check out also.
    view full answer...
  • Thickness of the 4-Leaf Slipper Spring SP-040275
    I went and grabbed a 4-Leaf Slipper Spring # SP-040275 from our warehouse to measure it and found that it is 1-7/8 inches thick if you only look at the leafs. If you add in the bolt that runs down the center you would add 1/2 an inch to the overall thickness.
    view full answer...
  • Trailer Leaf Slipper Spring Hardware
    The Trailer Leaf Slipper Spring, part number SP-040275, is not galvanized or coated it is a solid steel leaf spring. The leaf springs are shipped with a light coat of paint for rust protection but are not rust proof. Coating or treating the springs would not work because of the flexing and rubbing the springs are subject to under the trailer. The leaf springs can be painted but the paint will not last long with the constant flexing and road debris hitting them. The mounting hardware...
    view full answer...
  • What Size Bolt Is Needed for the 4-Leaf Slipper Spring 3,700 Lb with Flat End
    The 4-Leaf Slipper Spring w/ Flat End part # SP-040275 is designed for 9/16" bolts only, the Spring-Eye Bolt with Locknut for Slipper Springs part # 166079. There isn't any way to use a 3/4" bolt with this leaf spring nor do we have an option that will in this size.
    view full answer...
  • How To Choose Correct 3,500 Lb Axle for Slipper Spring Setup
    In order to determine which axle is correct for your trailer we need to find out what your hub face (HF) and spring center (SC) measurements are. If you take a look at the photo I have attached for you that should then help with obtaining the above two measurements. The most important thing we need to look for is the hub face as the spring center can then be moved (within a range) if we need to. I have attached a list of the 3,500 lb axles we offer in the varying hub face and spring center...
    view full answer...
  • Replacement Slipper Springs for 1985 Harding Boat Trailer
    I do have options for you but exact replacements for old boat trailers are hard to come by. In the majority of cases, items will need to be altered for an exact fit which I assume is what is going to need to be done on your trailer as well. We don't have a slipper spring that is 1-3/4" wide x 28" long (center of eye to end of spring) with a 2,500, 3,000, or 3,500 lb capacity. However, leaf springs will fatten out over time which means the leaf spring that was originally installed on the...
    view full answer...
  • Replacement Slipper Style Leaf Spring for 1984 Tee Nee Trailer
    For your 1984 Tee Nee trailer, the number of leaf springs is not the determining factor but rather the length and the capacity rating. The 3-Leaf Slipper Spring w/ Flat End for 2,900-lb Trailer Axles - 30" Long # SP-039275 is a great replacement option based on your photo as long as your axle capacity is 2900 lbs because each spring is rated for 1450 lbs. If you have a 3,500 lb axle then instead you would want # SP-040275 because it is a higher weight rated spring. If the trailer...
    view full answer...
  • How to Select the Correct Leaf Spring Size for a Tandem Axle Trailer with Slipper Springs
    To determine the correct slipper springs for your tandem axle trailer, the axle capacity will need to be determined. Selecting a spring by length alone could cause the selection to be under or over capacity substantially. If your spring is shaped like the 4-Leaf Slipper Spring for 4,100-lb Trailer Axles, # SP-264275, and each axle capacity is 4,100 lbs or just below that, then this spring should work for you. This is the only spring we have with the slipper end shaped this way. If...
    view full answer...
  • Recommended Bolt On Hangers For Aluminum Frame Trailer
    Since you've got an aluminum frame trailer, I understand why you're looking for a bolt on solution. The only available bolt on hangers we have available would be the # CE14017G and # CE14016G but they are designed for slipper springs and not double-eye springs like # SP-124275 you were looking at. If you went this route you would want to use something like the # SP-040275 as your springs, which have a 3700-lbs capacity. This would be the best solution available for your new aluminum...
    view full answer...
  • Replacement Slipper Springs for a 2,100 lb Trailer
    The most important factor in picking out a new leaf spring for a trailer is to match the capacity needed. Going with a 3,500 lb spring for a 2,100 lb trailer is going to give you a very harsh ride. For a spring similar to the # WIG4 that is better rated for your trailer we have the # SP-039275 which is for a 3,000 lb axle or part # SP-038275 for a 2,000 lb axle. If you need all 2,100 lbs of your trailer's capacity you would have to go with the # SP-039275. If you have a 2 inch square...
    view full answer...
  • 1-3/4 Inch Slipper Spring That is 30 Inches Long and Over 2,500 lb Capacity
    We have a couple of slipper springs that may work for you, as they are 1-3/4 inches wide, measure a total of 30 inches, and have the capacity you need. Springs do elongate over time, but you may have to have your brackets re-positioned if the 30 inch length isn't enough (this is the longest available for 1-3/4 inch or 2 inch springs). You will want to get a spring that is as close to your axle capacity as possible without going under it's capacity. - 2,900 lb Axle: 3-Leaf Slipper Spring...
    view full answer...
  • Replacement Leaf Spring for 1987 Shoreline Boat Trailer 3000 lb
    The most important thing to match when replacing trailer leaf springs is the weight capacity. Which for a trailer that weighs 3,000 lbs I'd recommend going with 3,700 lb axle springs like # SP-040275 which are 30 inches long. This means you'll need to move out your old hangers wider which we have replacements with # 115706S.
    view full answer...

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Info for this part was:

Expert Research:
Michael H
Expert Research:
Jameson C
Installed by:
Cole B
Updated by:
Sarah W
Written by:
Alexander C

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