1. Trailer Leaf Spring Suspension
  2. Redline
  3. U-Bolt Kits
  4. Axle Mounting Hardware
  5. Round Axle - 3-1/2 Inch
  6. 8 Inch Long
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
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Trailer Leaf Spring Suspension
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Shipping Weight: 11 lbs
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APUBR-35 - 8 Inch Long Redline Axle Mounting Hardware
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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. Lowest 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 etrailer.com or call 800-298-8924 for expert service.
  • All Info
  • Reviews (18)
  • Q & A (5)
  • Videos (1)
  • Photos
  • Why etrailer?

Redline Trailer Leaf Spring Suspension - APUBR-35

  • U-Bolt Kits
  • Axle Mounting Hardware
  • Round Axle - 3-1/2 Inch
  • 8 Inch Long
  • 8000 lbs
  • Redline
  • 9/16 Inch Diameter

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 etrailer.com. 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 Reviews

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

Average Customer Rating:  5.0 out of 5 stars   (18 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.

- APUBR-35

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! 735426

- APUBR-35

Awesome products and super fast shipping a+++++ 700204

- APUBR-35

Excellent quality and fast shipping. Thanks 677306

- APUBR-35

Fit as they should, quality parts at and affordable price. 652026

- APUBR-35

They worked and fit great 619723

- APUBR-35

Everything fit as described. Shipping was fast. 563708

- APUBR-35

Fast shipping, good quality and price. 561829

- APUBR-35

Everything I wanted and delivered quick ly 505822

- APUBR-35

Very fast shipping! even quicker than expected. Heavy duty product. Great communication. Thank you! 457915

- APUBR-35

Delivered on time and packaged well. Good prices too. 421389

- APUBR-35

Just what I needed and the price was great shipping was free and came very quickly 420007

- APUBR-35

Just what I ordered, I plan to install soon... The shipping was really quick!! 398805

- APUBR-35

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! 398760

- APUBR-35

Perfect and delivered quickly. 297861

- APUBR-35

I am very happy with this product. everything fit as if the trailer was new. product is Excellent. Thank you etrailer. 245704

- APUBR-35

Exactly as I ordered i will be ordering more products from etrailer great service and fast shipping. 215368

- APUBR-35

Fast shipping, good product, excellent customer service 192446

- APUBR-35

good price, fast shipping, good product 192442


Ask the Experts about this Redline Trailer Leaf Spring Suspension

  • 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...
  • 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...
  • 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...
  • 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...
  • 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...

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Info for this part was:

Installed by:
Cole B
Updated by:
Sarah W
Updated by:
Alexander C

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