1. Trailer Leaf Spring Suspension
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  5. Round Axle - 2-3/8 Inch
  6. 5-1/2 Inch Long
U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts

U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts

Item # APUBR-1
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Trailer Leaf Spring Suspension
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Redline Axle Mounting Hardware - APUBR-1
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Mount your round, 2-3/8" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included. Lowest Prices for the best trailer leaf spring suspension from Redline. U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts part number APUBR-1 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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  • Reviews (533)
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Redline Trailer Leaf Spring Suspension - APUBR-1

  • U-Bolt Kits
  • Axle Mounting Hardware
  • Round Axle - 2-3/8 Inch
  • 5-1/2 Inch Long
  • 3500 lbs
  • 1/2 Inch Diameter
  • Redline

Mount your round, 2-3/8" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included.


Features:

  • Attaches trailer axle to leaf springs
  • Includes:
    • (4) 5-1/2" Long U-bolts (176400)
    • (2) U-Bolt plates for 1-3/4" springs (117595)
    • (8) 1/2"-20 Hex nuts (12N)
  • Spring seats required for mounting axle to leaf spring sold separately


Specs:

  • Axle diameter: 2-3/8"
    • Typical 3,500-lb axle
  • Spring width: 1-3/4"
  • Dimensions: see below


U-Bolt Diagram



APUBR-1 U-Bolt Kit for 3,500-lb Round Trailer Axles





Video of U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts

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




Video Transcript for Trailer Axle Long U-Bolt Mounting Kit Review

Speaker 1: Today we're going to be taking a look at the Redline U-bolt kit for mounting 3500 pound round trailer axles. These are 5 1/2 inch long U-bolts. The part number is APUBR-1.Now, when replacing your axle, it's a really good idea to also replace the U-bolts. These are a pretty cost effective item you can get and ensure that you're going to have excellent, excellent hold with your axle to your springs. You can see this is going on a floor spring pack. The opening on them is going to be 2 3/8 inch, so it's going to fit the outer tube diameter of our axle here.

It comes with the new lower plate, and also four new flange nuts that allows you to secure that end, keep everything locked tight, so you don't have any issues for a very long time.Now we're going to remove the four nuts on the bottom here that hold our axle down, and they hold the U-bolts here. When replacing an axle, generally you're going to replace these as well, just because these can kind of stretch over time. So, if these nuts won't come off, you can also just cut your U-bolts on each side.Now we're going to grab our new U-bolt kit and place these down and around, just like our old U-bolts were, and when we we'll replace the bottom bracket up on the U-bolts we'll see the hole here in the middle. That's meant for that nut to come down through, and then in each position we'll install one of the flange nuts.Now we'll go through and you're evenly going to tighten down our bolt. We'll get them snugged up first and then we can torque them.

For these nuts you'll want to use a 19 millimeter 3/4 inch socket. Notice we're tightening them evenly, but in a crossing pattern.That's going to compete our look at the U-bolt mounting kit for 3500 pound round trailer axles, part number APUBR-1.


Customer Reviews

U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts - APUBR-1

Average Customer Rating:  4.9 out of 5 stars   (533 Customer Reviews)

Mount your round, 2-3/8" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included.

- APUBR-1
by:

I replaced the rusted out U bolts on my 5x8 utility trailer with this kit, APUBR-1 from Redline. The kit fit great, no problems. Good quality parts. Great price. Would buy from etrailer again. 521171



- APUBR-1
by:

I recently replaced my 1/2 ton truck with a 3/4 ton truck. In order to hook up to my existing fifth wheel camper, I had to raise my camper. To do this, my brother and I moved the axles from the top of the leaf springs and attached them under the springs. This kit made it very easy to do this. We torched off the old u bolts and used this set as a replacement. The quality of this kit was very good. Hard to get too excited about u bolts but I would purchase this again if I had to do it all over again. I was able to gain about 5 1/2 inches by flipping the axles. Here is a before and after. 135541



- APUBR-1
by:

Fit was exact. Took longer to cut old ones off than to install and torque new ones. Shipping was fast - everything as promised. Thanks!! 898414



- APUBR-1
by:

great price 897655



- APUBR-1
by: 09/26/2020

Work great! They were essy to install, especially by reviewing the provided videos. 892941



- APUBR-1
by:

easy, fast and good price 898470



- APUBR-1
by: 09/17/2020

It was what I needed 882252



- APUBR-1
by:

Top quality parts that worked perfectly on my trailer to correct my old sagging springs. 892919



- APUBR-1
by:

Product looks good it off box. As always very fast shipping and even bear their own timeline 874361



- APUBR-1
by: 09/03/2020

873408



- APUBR-1
by: 08/31/2020

872224



- APUBR-1
by: 08/24/2020

Its exactly what is pictured. 867535



- APUBR-1
by: 08/17/2020

863477



- APUBR-1
by:

Same parts I bought locally but since I was buying the new axle from E-trailer it saved me a separate trip. All installed easily and trailer is ready for service again. 860914



- APUBR-1
by:

Worked great 858908



- APUBR-1
by:

Nice heavy duty parts. Fit perfectly. 858700



- APUBR-1
by:

Good product 856490



- APUBR-1
by:

Excellent product and simple self installation. Extremely pleased with purchase. 855920



- APUBR-1
by:

Perfect fit and happy with the service and the price 854256



- APUBR-1
by:

very good quality of material 857090



- APUBR-1
by:

Great service!! 852343



- APUBR-1
by:

I am very pleased with my order and how quickly it was delivered and all complete. Thank you 852317



- APUBR-1
by:

Would give a 5 star rating, but it was very hard to find a tie plate and u-bolts that would fit... I was worried that 5 1/2 " u-bolts wouldn't fit. But everything worked out ok, without any modifications.... 850113



- APUBR-1
by:

All parts that were ordered were delivered and fit perfectly. The delivery was made sooner than we expected and we had no issues installing. The website was easy to use and each part listed had all the dimensions and specs which made it easy to find what we needed. 845468



- APUBR-1
by:

Great website, quick shipping 837261


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Show More Reviews

Ask the Experts about this Redline Trailer Leaf Spring Suspension

  • Installation of the U-Bolt Kit for Mounting 3500 lb Round Trailer Axles
    The U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts # APUBR-1 do not have a specified torque from the manufacturer. I did some research online and it appears that about 72 ft lbs would be appropriate for the 1/2 inch diameter nuts on the U-bolts.
    view full answer...
  • Torque Specs for U-Bolts on 3,500 Pound Axles
    For 3,500 pound axle U-bolt kits like the Redline # APUBR-1 that use 1/2 inch hex nuts you will want to torque them down somewhere between 45 and 70 foot pounds. I have attached a great article on trailer suspension that includes this info along with details on all the other necessary components that you can look through.
    view full answer...
  • Torque Specs for U-Bolts on LoadRite Boat Trailer
    The correct torque spec for trailer suspension u-bolts will depend on the the diameter of the bolt. You will want to use the following depending on bolt size: 1/2" bolts: 45 ft/lbs - 70 ft/lbs 9/16" bolts: 65 ft/lbs - 95 ft/lbs 5/8" bolts: 100 ft/lbs - 120 ft/lbs 3/4" bolts: 140 ft/lbs - 160 ft/lbs The U-Bolt Kit part # APUBR-1 that you were referencing will need to be torqued to 45 ft/lbs - 70 ft/lbs as they are 1/2" diameter bolts. There should not be any space between the u-bolt...
    view full answer...
  • Should I Replace the U-bolts When Replacing the Leaf Springs
    I would not recommend reusing your existing u-bolts because the nuts are designed to mis-align the threads as they are tightened down to prevent the u-bolts from coming loose. You should choose the u-bolt kit that will fit the diameter of your axle. The u-bolt kit # APUBR-1 that you referenced is designed for one 3,500 lb trailer axle with a diameter of 2-3/8 inches. The kit includes 4 u-bolts, 2 u-bolt plates and 8 hex nuts 1/2 inch.
    view full answer...
  • Torque Specifications for Redline U-Bolt Kit APUBR-1
    The torque rating for the 1/2 inch diameter u-bolts in the U-Bolt Kit # APUBR-1 is a minimum of 45 ft lbs and a maximum of 70 ft lbs. These are designed to mount your trailer's leaf springs to round, 2-3/8 inch diameter axles. The U-bolts, plates and nuts are all included in this kit. I have attached a couple of videos on this product so you can look at the installation process and see exactly what all is included in the kit.
    view full answer...
  • U-Bolts and U-Bolt Plate Recommendation for Installing Leaf Springs on a 1-1/2 in Square Axle
    If what you really need is a new axle you can go to a local trailer shop to you and have them custom order you the exact specs you need for a trailer axle. But to attach springs to your 1-1/2 inch square axle you would want the mount plate part # 115983 and then for U-bolts part # Sp01-120. I attached review videos for both products.
    view full answer...
  • Grade of U-Bolt in the U-Bolt Kit APUBR-1
    The U-bolts of the U-Bolt Kit part # APUBR-1 are Grade 5. I attached an install and review video for this kit for you to check out as well.
    view full answer...
  • What is the Torque Rating for 1/2 Inch U-Bolts for Leaf Spring Trailer Suspension
    The torque rating for 1/2 inch u-bolts in U-Bolt Kit, # APUBR-1, is a minimum of 45 ft lbs and a maximum of 70 ft lbs.
    view full answer...
  • Should I Paint U-Bolts to Protect Finish
    If you are concerned about rust and corrosion, an excellent option for you is the CE Smith U-Bolt Kit for Mounting # CE23002 which comes with galvanized plates and zinc-plated hardware. The u-bolts included are also 5-1/2 inches long and 1/2 in diameter just like in the APUBR-1 kit. You can apply a coat of rust-resistant paint to the U-Bolt Kit # APUBR-1 if you want to but it's not required. In fact, most people don't because these components, while susceptible to rust, are not directly...
    view full answer...
  • U-Bolt Kit for Smaller Round Axle on Jet Ski Trailer
    It could just be the angle but looking at the picture you attached it appears that you have a 1-3/4 inch diameter axle. This would be consistent too with the smaller 2,000 pound axles that are typically on jet ski trailers like what you have. I do recommend verifying this measurement once more but if this is indeed the case then you can use the CE Smith U-Bolt Kit # CE23000 which features U-Bolts with an inner width of 1-7/8 inches and galvanized plates to resist any rust or corrosion....
    view full answer...
  • Troubleshooting U-Bolt Kit for Unique Trailer Axle and Leaf Spring Combination
    For the plate and U-bolt for the dimensions you gave, you simply need the U-Bolt Kit for Mounting 5,200-lb to 7,000-lb, Round Trailer Axles - 7" Long U-Bolts # APUBR-8. This will give you the plates and the length of U-bolts you need. The issue is your axle diameter won't be a fit so you would need to fabricate something for stability. Instead I recommend you either change your leaf springs because 3 inches wide is not standard for trailer applications, or you can use the Dexter Trailer...
    view full answer...
  • Longest U-Bolt Kit for Trailer Axles that are 2-3/8 inches in Diameter
    The inner width of the U-bolt needs to match the diameter of the axle that you have. The longest kit we have that has a 1/2 inch diameter studs is the part # APUBR-1 which has U-bolts that are 5-1/2 inches long.
    view full answer...
  • Recommended U Bolt Kit and Shackles for 3500-lbs Axle
    For a 3500-lb axle, it's most likely a 2-3/8" diameter so you can use the U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles - 5-1/2" Long U-Bolts # APUBR-1. If this is a boat trailer or utility trailer that might be sitting outside a lot you may want to consider upgrading to the CE Smith U-Bolt Kit # CE23002 since they're zinc plated and will help fight off corrosion a bit better. For shackles, the most popular size shackle is 2-1/4" like the part # TRSL225, but you'll want to measure...
    view full answer...
  • What Grade is the U-Bolt of the U-Bolt Kit part # APUBR-1
    The U-bolts of the U-Bolt Kit part # APUBR-1 are Grade 5. The torque range is minimum of 45 ft lbs and a maximum of 70 ft lbs. I attached an install and review video for this kit for you to check out as well.
    view full answer...
  • Can a Three Leaf Spring Stack Be Used To Replace a Two Leaf Spring Stack
    Yes, you can replace a two leaf spring stack with a three leaf spring stack so long as your center to center (double eye springs only) measurement matches but please note the loaded and unloaded as well as the new and used center to center measurements will be different. There is a correlation between the numbers of leaves in a stack and the weight capacity of that stack but there are also two leaf spring stacks with the same weight capacity as three leaf spring stacks so going by the rated...
    view full answer...
  • Kit Needed to Move Trailer Leaf Springs Back Under Axle
    If the leaf springs for your trailer are currently installed so that they are sitting on top of the axle, you can just use a standard U-Bolt Kit to move the leaf springs back under the axle. For a 2-3/8 inch, 3,500 pound axle, you will need the Redline U-Bolt Kit # APUBR-1 and for 3 inch axles with 5,200-7,000 pound capacities, you will use # APUBR-8. I have also attached a helpful installation video for you to check out.
    view full answer...
  • Raising the Height of a Trailer with a 2-3/8 Inch Diameter Round Axle
    The longest u-bolts we have for a 2-3/8 inch diameter round axle are going to be 5-1/2 inches long, # APUBR-1. But I have another solution that may work for you to be able to raise the height of the trailer. You may be able to use an over/under conversion kit if: The trailer leaf spring stack is currently mounted under the axles The trailer uses double-eye springs And the trailer has 2-3/8 inch diameter round axle For a 2-3/8 inch round axle use # K71-384-00. If you cannot...
    view full answer...
  • Replacement Axle for 1993 Western World Tandem Axle Trailer
    We do sell some replacement trailer axles. To see if what we have would work for you, I'd need some information from you. I'll need the following: Hub face to hub face dimension Spring center to spring center dimension Axle capacity Reference numbers from inner and outer wheel bearings With this information, I'd be able to check to see if one of our axles would work for you.
    view full answer...
  • U-Bolt Kit Recommendation for 3,500 lb Trailer Axle that is 2-3/8 inch In Diameter
    The part # APUBR-1 is available through us. It is a U-bolt kit for 3,500 lb axles like what you have which are rated for 3,500 lbs.
    view full answer...
  • What is the Diameter of 3,500 lb Dexter Axle 35545I-EZ-89?
    The diameter of Dexter Axle # 35545I-EZ-89 is 2-3/8". For this axle the correct U-Bolt mounting kit would be # APUBR-1. I've added a link to a video review of this product for you to check out.
    view full answer...
  • Compatibility of Replacement Trailer Suspension Components
    The parts you referenced are compatible with each other. Hanger Kit # APS1 works with 1-3/4-inch wide leaf springs like # SP-210275. U-Bolt kit # APUBR-1 fits your 2-3/8-inch axle as does Spring Seat # TRSS238. For reference I linked you to an article on trailer suspensions and to our main page for all trailer suspension components.
    view full answer...
  • Finish of Redline U-Bolt Kit # APUBR-1
    The # APUBR-1 U-bolts are constructed of steel, and the parts have a raw finish. They are coated with a light film of oil to help inhibit corrosion during storage.
    view full answer...
  • Can the U-Bolts of the U-Bolt Kit # APUBR-1 be Cut 1/2 inch Shorter
    We can't cut the U-bolts of the U-Bolt Kit # APUBR-1 1/2 inch shorter. But you certainly can if you have a grinder or know someone who does. It would be pretty easy to do, especially if you have a cutting wheel.
    view full answer...
  • Parts Needed to Add Replacement Axles to Tandem Axle Trailer
    We do sell replacement trailer axles. To see if what we have would work for you, I'd need some information from you. I'll need the following: - Hub face to hub face dimension -Spring center to spring center dimension - Axle capacity - Reference numbers from inner and outer wheel bearings With this information, I'd be able to check to see if one of our axles would work for you.
    view full answer...
  • Are U-Bolts Includes with Trailer Axle
    The trailer axles we currently have available do not include the U-bolts necessary to mount the axle to the leaf springs on your trailer. The U-bolts you need will depend on the size of axle you are purchasing, along with its capacity. I have attached a couple links that will take you to our available selection of trailer axles and U-bolt kits that you can look through. If you can tell me what type of axle you are getting, I will be happy to recommend a kit that should work nicely.
    view full answer...
  • U-Bolt Plate Width For Leaf Spring Mounting on APUBR-1
    The width dimension of the U-Bolt Kit for Mounting 3500-lb Axles # APUBR-1 is 2-3/8", which is the typical diameter of a 3500-lb axle. These can be used to mount leaf springs 1-3/4" wide to an axle when used with with the included plates and Spring Seat for Typical 3500-lb Round Trailer Axles # TRSS238 . I've attached a picture for reference on these measurements.
    view full answer...
  • Correct Leaf Spring for Trailer with Lippert 3,500 lb Axle
    Thank you for the photo! I was able to use the serial number on your axle to determine which is the correct replacement leaf spring for your trailer. For this, you are going to want to use the 3-Leaf Double-Eye Spring part # SP-220275 which is a double eye leaf spring that is 1-3/4" wide, has a 4,000 lb total weight capacity, and a 25-1/4" eye to eye measurement. The measurement you provided of 26" long is correct but the leaf spring needs to be measured while unloaded as it will lengthen...
    view full answer...

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Info for this part was:

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Video by:
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