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 800-298-1624 for expert service.
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  • Reviews (95)
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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:  4.9 out of 5 stars   (95 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:

easy to install fits perfectly.


Comments
Fantastic product. still functioning perfectly.
Dennis - 06/29/2021


- SP-040275
by:

Everything 100% correct anything I need to concern with a trailer will definitely be to you thank you very much



- 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.



- SP-040275
by:

Product is what I wanted exact meaurment I'm just trying to get my old one off rusted pretty good then we got rain ugh but great product I will take pic of it installed soon as it's on send ya a pic



- 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.



- SP-040275
by:

Replaced rusty springs thanks for the great product



- 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.



- SP-040275
by:

Springs are here, look good but will not be installing for another week



- SP-040275
by:

great service; Greg made sure that my delivery was expedited which was very much appreciated



- SP-040275
by:

On time delivery as promised and excellent quality part. 5 star service.



- 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.



- SP-040275
by:

nice heavy duty



- 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.



- SP-040275
by:

Got the springs yesterday 2/26 , put them on today 2/27. They fit and worked great. Thank y’all Mark D.



- 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



- 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.



- SP-040275
by:

Bolted right in once I got the old ones out.



- SP-040275
by:

Great looking quality, fast fast shipping ??, gives my trailer a higher tire clearance from the deck which is what I needed. My only recommendation to etrailer is seeing if their supplier can start making this same spring in a 32" version due to that's what this 30" spring is replacing. I made some modifications to make this spring work. Overall this is a nice spring pack assembly.



- 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.



- SP-040275
by:

I was restoring my boat trailer and ordered these springs along with hangers and etc. All items were excellent and price was the best I found. Etrailer shipped all my items together in one box which makes it cheaper for shipping. They box items up excellent and delivered by UPS



- SP-040275
by:

The leaf springs came early morning on the third, I've looked over the springs and they are in excellent shape just waiting for paint to dry to install and try them out.Overall great service and product.



- SP-040275
by:

Quality product, perfect fit, great price and fast, reasonable shipping that would have been free if Id ordered all my parts from etrailer. I couldnt be more pleased.



- SP-040275
by:

Very helpful taking my order and great pricing . Also free shipping at $100.00 is a great money saver based on the weight of trailer leaf springs and all the hardware i received shipping would have been a killer . I will be using this place again for sure !!



- SP-040275
by:

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



- SP-040275
by:

Needed new spring sets in a hurry for an older trailer which had broken springs. The etrailer organization provided the right parts at a good price, with quick shipping. Just what was needed.


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Show More Reviews

Ask the Experts about this Universal Group Trailer Leaf Spring Suspension

  • 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...
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  • Replacement 30" Long Slipper Spring for Boat Trailer
    It sounds like you're looking for the 4-Leaf Slipper Spring w/ Flat End part # SP-040275 which is a slipper spring, 30" long x 1-3/4" wide, with four leaves. It can then be mounted on a 2" square axle with the CE Smith U-Bolt Kit part # CE23103. For the suspension bolts, we have the Spring-Eye Bolt with Locknut for Slipper Springs part # 166079.
    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...
    Image 1 for
  • 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...
  • 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...
  • 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...
  • 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...
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  • 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...
  • 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...
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  • 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...
  • 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...
  • 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...
  • Can 3700lb 4-Leaf Slipper Spring SP-040275 Be Used On Trailer W/ 3500lb Axle?
    Yes, the 4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long # SP-040275 would work on a 3500lb axle, they are just ever so slightly stiffer. Now to make sure they will fit your trailer you will need to measure from the center of the spring eye to the end of the spring of your current leaf springs, and the width of the spring. You will need to make sure the axle is off the ground with no weight on spring, as weight on the spring will cause it to stretch and give you...
    view full answer...
    Image 1 for
  • 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...
  • 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...
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  • 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...
  • 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...
    Image 1 for
  • 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...
    Image 1 for
  • Replacing Old Slipper Springs and U-Bolts
    Though the leaf springs are rusty, they do not seem to look pitted, so they should still be fine. It wouldn't hurt to clean them off with WD-40 or a rust remover to make sure they don't get worse. If you did want to replace them though, you could go with something like the Universal Group # SP-040275. As I couldn't tell 100% how wide the leaf spring is, this is a 1 3/4 wide one. It is also much longer with the overall length of 30 inches, so the rear hanger would most likely need to be...
    view full answer...
    Image 1 for Image 2 for Image 3 for Image 4 for Image 5 for
  • 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...
  • 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...
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  • 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...
  • Slipper Springs and Slipper Bracket for a 28.5" Bolt to Bolt Trailer Mount
    I recommend using the 4-Leaf Slipper Spring w/ Flat End for 3,700-lb Trailer Axles - 30" Long Item # SP-040275, for your trailer leaf springs that are 28.5 from center of bolt to center of bolt with 3,000 lbs trailer. You will need a slipper spring hanger bracket # CE14017G. This bracket is a simple bolt on adapter that changes the rear mounting style for the leaf spring. I have linked a video to show you how the brackets work.
    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:

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Expert Research:
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Employee Cole B
Installed by:
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Updated by:
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