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U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts

U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts

Item # APUBR-35
Our Price: $58.92
You Save: 13%
Trailer Leaf Spring Suspension
This item qualifies for Free Shipping
Shipping Weight: 11 lbs
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Mount your round, 3-1/2" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included. Great Prices for the best trailer leaf spring suspension from Redline. U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts part number APUBR-35 can be ordered online at or call 1-800-496-5010 for expert service.
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Redline Trailer Leaf Spring Suspension - APUBR-35

  • Camper
  • Car Hauler
  • Utility Trailer
  • U-Bolt Kits
  • Round Axle - 3-1/2 Inch
  • 8 Inch Long
  • 8000 lbs
  • 9/16 Inch Diameter
  • Redline

Mount your round, 3-1/2" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included.


  • Attaches trailer axle to leaf springs
  • Includes:
    • (4) 8" Long U-bolts (11-65)
    • (2) U-Bolt plates for 1-3/4" or 2" springs (117581)
    • (8) 9/16"-18 Hex nuts (916N)
  • Spring seats required for mounting axle to leaf spring sold separately


  • Axle diameter: 3-1/2"
    • Typical 8,000-lb axle
  • Spring width: 1-3/4" & 2"
  • Dimensions: see below

U-Bolt Diagram

APUBR-35 U-Bolt Kit for 8,000-lb Round Trailer Axles

Video of U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts

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

Video Transcript for Redline Trailer Suspension - Leaf Spring Suspension - APUBR-35 Review

Speaker 1: Today, we're taking a look at U bolt kit for mounting 8000 pound round trailer axles. This kit attaches a trailer axle to the loose springs. It includes four eight inch long U bolts. That measurement's taken from the bottom of the U portion here out to the end of the threads. Comes with two U bolt plates for 1 and 3/4 inch, or 2 inch springs, and it comes with eight 9/16th inch by 18 hex nuts.Now, spring seats, they're required for mounting the axle to the loose springs. Ours sold separately.

If you need spring seats, you can check some options out at This kit is designed for a typical 8000 pound axle that has a diameter of 3 and 1/2 inches. We're looking at nice, durable steel construction on this kit. And again, it fits springs that have a width of 1 and 3/4 inches and 2 inches. That's going to do it for today's look at the U bolt kit for mounting 8000 pound round trailer axles..

Customer Satisfaction Score:

Customer Reviews

U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts - APUBR-35

Average Customer Rating:  4.9 out of 5 stars   (48 Customer Reviews)

Mount your round, 3-1/2" diameter axle to your trailer's leaf springs with this U-bolt kit. U-bolts, plates and nuts included.


Worked well .


Nice job "e-Trailer"; received this "heavy" order very promptly; did not expect it so quickly in view of how other retailers/ manufacturers/ on-line businesses are behind in fulfilling orders. Packages (3) came all intact, well packed and product received in great condition. The order included:
> 5-Leaf Slipper Spring w/ Hook End for 6,000-lb Trailer Axles (2)
> U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles - 8" Long U-Bolts (2)
> Tandem-Axle Trailer Equalizer Kit for 2" Slipper Springs - 10-1/8" Long Equalizers (2)
> Dexter Nev-R-Adjust Electric Trailer Brake Kit - 12" - Left and Right Hand Assemblies - 6K (2)
> Mounting Bolts and Hardware for 12" Brake Assemblies (2)
> Bearing Buddy Bearing Protectors - Model 2441SS - Stainless Steel (Pair) (2)
> Bearing Kit, 15123/25580 Bearings, GS-2125DL Seal (4)
> Optronics LED Combination Trailer Tail Lights - Submersible - 40 Diodes - Driver and Passenger Side.
These items are being utilized in the total suspension replacement of a 10,000 gvwr tandem axle trailer. Good sized job for a DIY'er. I expect that it will give my JD 2038 tractor a smooth and safe ride as it is towed/ hauled down the highway.
Thank you.
I would/will strongly recommend to a friend/relative or associate.
( I'd take a picture of the "project", but there is a vicious rain storm occurring outside; perhaps one or two pics to follow at a later time).


Worked well


Samatha was very helpful in helping with an alternative of leaf springs i needed. Reached out to me right away with the others i could use, and purchased. Now i can get my trailer back together.


Great product! The steel is of very high quality, not the cheap gold colored stuff that'll snap off as soon as you try to tighten it. The backing plates are good and thick, and after wrenching on them pretty hard with the impact and then a breaker bar, there is no deformation. I'm confident that these will stand up to whatever the road throws at them. As always, very fast shipping and great customer service! Thanks!


Good products, fair prices and decent delivery with sturdy packaging.


worked great


It was exactly what I was looking for at a good price thank you


Installed on 25’ gooseneck trailer. I’ve had no issues and have put thousands of miles and lots of heavy loads since.


The specialist at etrailer walked me through the options and helped me select the perfect fit for my trailer. My trailer went from serious danger on the road to a 10 minute fix! Thanks for your help!


I am very happy with this product. everything fit as if the trailer was new. product is Excellent.
Thank you etrailer.


People were great


Exactly as I ordered i will be ordering more products from etrailer great service and fast shipping.


Awesome parts, prices, and service. I highly recommend etrailer.


Direct replacement perfect fit.

by: 07/21/2021


Fit as they should, quality parts at and affordable price.


Heavy duty product. Love it!!


Very fast shipping! even quicker than expected. Heavy duty product. Great communication. Thank you!


They worked and fit great

Still doing great
Nathan P - 04/15/2020


Awesome products and super fast shipping a+++++


Excellent quality and fast shipping. < br>Thanks


REally did the job..


Fast shipping, good product, excellent customer service


Show More Reviews

See what our Experts say about this Redline Trailer Leaf Spring Suspension

  • Torque for U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles
    The U-bolts on the U-Bolt Kit for Mounting 8,000 lb Round Trailer Axles # APUBR-35 are 9/16". The torque specs for 9/16" bolts on trailer suspension 65 ft/lbs - 95 ft/lbs. Torque specs depend 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
    view full answer...
    For the large 8000 lb. springs you want to use U-Bolt Kit for Mounting 8,000-lb, Round Trailer Axles part # APUBR-35 and for the smaller 3500 lb. springs use the U-Bolt Kit for Mounting 3,500-lb, Round Trailer Axles part # APUBR-1. Thes will give you the u bolts, nuts and the new plates so you will be set.
    view full answer...
  • Replacement Springs for 2020 Grand Design Momentum 351M
    Since you're looking for 4,000 lb springs I am assuming you have tandem 8,000 lb axles on your 2020 Grand Design Momentum 351M. I recommend verifying this information since the diameter of your axle and capacity plays a role in choosing the correct U-bolt kit and leaf spring. In order to find the correct replacement springs you will need to take some measurements. If you have double-eye springs you need to measure the distance from one eye to the other. If you have slipper springs, you...
    view full answer...
  • Trouble Shooting Furrion Camera That Is Flickering
    It sounds like your running light pin is not providing enough power for the three cameras. I would recommend using The 7-Way Vehicle Power Adapter w/ Power Switch for Furrion RV Observation Camera # FR87PR. This harness will connect the trailer wiring from your tow vehicle's 7-way trailer connector. It will provide your camera extra power. If this doesn't help I would reach out to where you purchased the cameras from. It could be an internal problem. I attached a review video link below.
    view full answer...
  • Options For Replacing Broken 7-Leaf Slipper Spring
    For a 2" wide by 29-1/2" slipper spring we have two options. The 6-Leaf Slipper Spring w/ Hook End, # SP-161275 rated for 8,000 lbs. (spring capacity of 4,000 lbs., axle capacity of 8,000 lbs.) And the 8-Leaf Slipper Spring w/ Radius End, # SP-284275 rated for 10,000 lbs. (spring capacity of 5,000 lbs., axle capacity of 10,000 lbs.) The quantity of leaf springs is not the point to focus on, the weight rating is. What we have available does not support adding an additional leaf. My suggestion...
    view full answer...
  • Spacing Between Hangers With Slipper Springs for 8,000 lb Axles and Hanger Kit
    I checked for you and when installing the 7-Leaf Slipper Spring w/ Hook End for 8,000-lb Trailer Axles # SP-285275 with the Tandem-Axle Trailer Hanger Kit for 2" Slipper Springs - 12" Long Equalizers # APT6SE the distance between the front and center hangers will be 28-1/2", the distance between the center and rear hangers will be 29-1/2", the distance between the U-bolts will be 33" and distance between the center of the axle and trailer frame will be 4-1/2". I made a diagram for you...
    view full answer...
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  • Raising the Height of a Trailer that has a 3-1/2 Inch Diameter Round Axle
    There are no over/under conversion kits for a 3-1/2 inch diameter axle but I can tell you the parts you will need to make one. You will need spring seats for 3-1/2 inch diameter axles, # TRSS350 and a new u-bolt kit # APUBR-35. The new springs will have to be welded onto the axle.
    view full answer...
  • Hanger Kit, U-Bolt Kit and Spring Seats for Tandem Axle Trailer with 3-1/2 Inch Diameter Round Axles
    A 3-1/2 inch diameter round axle is usually rated at 8,000 pounds but could also be a 3,500 pound axle though this is rare. You can get a more accurate determination of the capacity by getting the inner and outer bearing numbers stamped into the sides of the bearings. For a hanger kit # APT3 will keep the distance from the deck to the axles at a minimum and still have room for suspension travel. You will also need a u-bolt kit, # APUBR-35, for one axle. And you will likely need new spring...
    view full answer...
  • Hanger, U-Bolt, and Slipper Spring Kit for 8k Trailer Axles
    If you use the Dexter Tandem-Axle Trailer Hanger Kit for 2" Slipper Springs # HAP-105-205-01 that you referenced you'd end up with a height of 4-7/8 inches between the axle center and the frame of the trailer and 8 inches between the tires for most tire sizes. How that relates to your fender to tire clearance really depends on the location you install the fenders. For an 8k slipper spring that is 2 inches wide we have the etrailer # e37SR that would work really well. The hanger kit part...
    view full answer...
  • Parts Needed For Reducing 7,000LB Leaf Springs On a 2021 Keystone Carbon From Flattening
    I do have a recommendation for you as switching out all your leaf springs on your 2021 Keystone Carbon 358 is a big undertaking. The SumoSprings Trailer Helper Springs # SS26MV are designed to work on 5,000lb to 8,000lb trailer axles and each set provides 900lbs or capacity at 50% compression. These springs are also progressive so they will help to absorb road shock while also providing support to your leaf springs giving a smoother ride inside your trailer to reduce the odds of damage...
    view full answer...
  • How to Determine Correct Replacement Slipper Springs for Triple Axle Trailer With 8,000 lb Axles
    I can help you determine exactly what you need to replace the suspension in your triple axle trailer, although we don't have any type of database which has each part for each year, make and model of trailer that would tell us exactly what you have on your trailer, which means you'll need to do a bit of pretty simple measuring. Since you have a triple axle trailer, with three 8,000 lb axles you will need slipper springs for that axle capacity, for which we have two of that capacity. To...
    view full answer...
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Info for this part was:

Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Updated by:
Alexander C

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