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  1. Trailer Leaf Spring Suspension
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1-1/2" Square Trailer U-Bolts (Qty 2)

1-1/2" Square Trailer U-Bolts (Qty 2)

Our Price: $23.81
Trailer Leaf Spring Suspension
Shipping Weight: 1.48 lbs
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Great Prices for the best trailer leaf spring suspension from Redline. 1-1/2" Square Trailer U-Bolts (Qty 2) part number SP01-120 can be ordered online at or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (136)
  • Q & A (0)
  • Videos (1)
  • Photos

Redline Trailer Leaf Spring Suspension

  • U-Bolts
  • Camper
  • Car Hauler
  • Utility Trailer
  • Square Axle - 1-1/2 Inch
  • 5 Inch Long
  • 3500 lbs
  • 1/2 Inch Diameter
  • Redline

Square Trailer U-Bolt

  • Width: 1-1/2"
  • Diameter: 1/2"
  • Length: 5"
    • Threaded portion measures 2"
  • For 3,500-lb axles only
  • Includes Lock Nuts

071090 Redline Square Trailer U-Bolts with Nuts and Washers

Item # SP01-120

Video of 1-1/2" Square Trailer U-Bolts (Qty 2)

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Redline Trailer Suspension SP01-120 Review

Today we'll be reviewing part number SP01-120. This is Red Line's 1 1/2 inch Square Trailer U-bolts. You're going to get two U-Bolts and you're going to get four nuts. The width of the U-bolts. We're measuring the distance between the two bolt posts. Is going to measure an inch and a half.

Each bolt is going to give us a diameter of a half inch. The length that we have from the bottom of the cross member to the bottom of the mounting post or the bolt post is going to be 5 inches. The threaded portion going to measure right at 2 inches. This is for 3500 pound axles 00:43 only. Again, you're going to get two U-bolts, measure a half inch in diameter, and you're going to get four nuts.

That's going to do it for our review of part number SP01-120. This is Red Line's 1 1/2 inch Square Trailer U-bolts. .

Customer Satisfaction Score:

Customer Reviews

1-1/2" Square Trailer U-Bolts (Qty 2) - SP01-120

Average Customer Rating:  4.8 out of 5 stars   (136 Customer Reviews)


I'm working on a 12 ft long 1957 Corvette trailer. Easy install, and perfect fit. I dropped the axle to gain 3".


I purchased these U bolts to upgrade the suspension on my trailer. I would get a a lot of trailer sway when I was towing my jet ski trailer. I bought the trailer used and never really looked at the springs. Unfortunately for me, There was nothing but one U bolt strapped diagonally across the spring. I'm no suspension expert but I knew this could NOT be safe. I did extensive research on trailer suspension. It was difficult to find parts for a 11/2 inch square axle. It was until I came across etrailer webpage. They had everything I required to upgrade and make my trailer safe to operate on the road. It was actually criminal what the person did to attach the original spring. I am greatful nothing ever happened while towing. Now with the new parts installed, I feel a lot better and my trailer does not sway anymore.

I will definitely purchase my trailer needs from etrailer from now on. The pictures and videos make finding what I needed so much easier. The complete transaction from order to delivery was extremely efficient and the customer service is absolutely outstanding.


These U-Bolts were exactly what I needed to replace the 1 1/2" wide ones on my 1966 Silver Streak travel trailer. When I started this project I had no idea how hard parts were going to be to find. When I brought the original U-Bolts in to my local (Anchorage, AK) trailer supply place and also a custom spring shop they all looked at them like they had dropped in from outer space. etrailer had exactly what I needed to get our vintage trailer back on the road. This will be my first stop the next time I need parts for my not so standard trailer. Thanks!


I purchased the 3000# axle springs and all mounting hardware to replace the old ones on my 1963 travel trailer. My trailer no longer leans to the left and goes down the road better than new. I should have done it many year ago. I received my package on time and installation was easy and fit perfect. Thanks Bridget


Good quality parts! Would buy again.


I was very impressed with the quality of these square U bolts. The bends were smooth with no stress cracking. The legs of the bolts were parallel and the nuts were a very high quality.


Not threaded far enough. I had to add spacers.


Exactly what I needed. Installed without any issues and have had no problems.


U-Bolts fit my trailer perfectly.


Excellent product, bolted right on, great fit. Several orders through have yet to be disappointed


I ordered these bolts to use on my '63 Shasta (Canned-Ham ) Compact camper. The old girl had developed a squat worse than factory and that sat low. I removed the axle and springs and moved the axle below the springs and added a new plate with a tab to mount shocks that this trailer never had. The ubolts arrived in about 1 week and worked perfectly. The camper is a joy to tow now.

Don M.


Al, how did you deal with the nub on the bottom of the spring stack? I have 1 1962 Compact.



There is a square plate top and bottom .There is a hole I drilled in one for the rivet that hold the springs together.


etrailer has gotten terrible with shipping. They didn’t include these in my order which already took a long time to arrive. They did reship but the shipping was slow, their mistake they should priority ship to you and not waste your time because they messed up!


Perfect fit. Everything went together very smoothly.

Michael M.


great, no problems with about 1000 miles on the new parts now.


These U-bolts were hard to find any where else. As always, etrailer came thru. The U-bolts went perfect with the plate that I also ordered from etrailer. The part went on with ease on my old Gamefisher trailer. Road tested it today and its holding good and no problems. Everything that I have ordered from etrailer has a very good price and great inventory that no one can match.



Its been a year since I put this on my trailer and its working great. No problems at all. Thanks etrailer for having hard to find parts and great service.


Well I can't believe it's really been a year since I purchased all the parts from Etrailer to rebuild my jon boat trailer. I bought this tilt trailer on craigslist and well let's just say needed some MAJOR TLC. From the roller brackets, fenders, tires/wheels, hitch coupler, winch, etc.. All the parts have held up extremely well and I am VERY happy with not only the quality of the parts but the customer service as well. This is my "GOTO" place to buy parts for all 3 of my trailers!!


Worked great


Was just barely able to use to the min thread. 1 1/2" thick axle and 4 leaf 3500lbs springs. Had to add standard Split Lock washers under nuts to get enough thread available. Torqued to 50 Ft Lbs and there was less than 1/2 of a thread available if I need to retorque. These are nice and heavy. 1/2" x20 Nuts that come with U-Bolts are Non Locking and you will need to add Lock washers and the thread should be higher up the U-Bolts like another 1/2 to 1 inch if a person uses a 3 leaf 3000lbs spring or less thickness in my opinion.


The U bolts and spring plates were of good quality, but the price was much higher than it should be. I needed them so I bought them, even though the price was way too high.





The U bolts were the perfect size as listed on the site, after we had such a hard time finding these specific ones. We ordered them and they were quickly delivered and of great quality compared to some others. We will definitely be ordering from this site whenever we need anything else.


I used these u bolts on a harbor freight folding trailer. I wanted to lift the trailer to put larger tires. After welding blocks on, these u bolts fit perfect.


very good products and excellent customer support.


Products arrived very quickly and in good shape. had to do some
modification on installation as its an odd ball trailer but happy with the results . Jim.

Jim R.




Used these after moving axle from inside spring to under. Worked great. It is hard to find 1 1/2 inch u bolts that are 1/2inch. Thanks. Shipping was great.


The u-bolts did not include lock nuts, just standard nuts. I had trouble getting one of the sides to tighten up and used a bit of force--it stripped the nut with no warning. I would say these bolts are too soft to use on an axle, and you need to come up with your own lock nuts.


100% impressed with etrailer. My customer rep, Diana, was very courteous, knowledgeable, and friendly. I placed my order on Monday and was told that my shipment would arrive on Thursday. About ten minutes later, I received an email stating that my order had shipped! I just received another email that my package has been delivered - a day early. I was able to track the package from the etrailer website. I just want to say thank you for the unexpected, exceptional service from everyone at etrailer. I look forward to placing more orders in the near future. Thanks again

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Info for this part was:

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Employee Jameson C
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Employee Adam R
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Employee Kathleen M
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