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  1. Trailer Leaf Spring Suspension
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Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter

Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter

Item # 175666
Our Price: $18.06
Trailer Leaf Spring Suspension
Shipping Weight: 1.41 lbs
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Trailer Leaf Spring Suspension 175666 - Camper,Car Hauler,Utility Trailer - Redline
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This U-bolt, in conjunction with a U-bolt plate and an additional U-bolt, attaches your round, 8,000-lb axle to your 10-leaf springs. Bolt is 9" long and has an inner width of 3-1/2". Great Prices for the best trailer leaf spring suspension from Redline. Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter part number 175666 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (12)
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  • Videos (2)
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Redline Trailer Leaf Spring Suspension - 175666

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

This U-bolt, in conjunction with a U-bolt plate and an additional U-bolt, attaches your round, 8,000-lb axle to your 10-leaf springs. Bolt is 9" long and has an inner width of 3-1/2".


  • Used with U-bolt plate to secure axle to leaf springs, which are mounted to the trailer frame
  • Attaches with a U-bolt plate (sold separately) and an additional U-bolt with same dimensions (sold separately)
  • Fits 8,000-lb, round trailer axles with 3-1/2" diameter and 10-leaf springs
  • Includes 2 nuts


  • Bolt diameter: 9/16"
  • Length: 9"
  • Width: 3-1/2"

U-Bolt Diagram

175666 U-Bolt for 8,000-lb Round Trailer Axles

Video of Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter

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

Video Transcript for 3 Inch Round Trailer U-Bolts Installation

Hi there trailer owners. Today we're gonna be taking a look at red lines line of replacement U bolts. Round U bolts are commonly used to hold your leaf spring stack onto your axle. And if you're making any repairs to your trailer it's possible that the threads can get damaged where you can't reuse the U bolt. You might have to replace them in that instance, or if you had some sort of blowout or any other kind of damage where you might've had some damage that caused some issues with your U bolts here you may need to replace those as well. Over time if you've constantly taken these off they do stretch out over time.

So it is a good idea to replace them. If you've had several repairs done and remove them. The ones that redline have, offer slightly longer length. So that way you can ensure it's going to be a fit for your trailer. We also recommend these.

If you're gonna be adding accessories to your trailer and you need the additional length if that accessory goes under a U bolt we can see our factory U bolt here on the trailer We we're just working on if we wrap it around and we can see it only goes up about that high. This is about six inches in length. The new one here that we put on is about seven inches in length and it gives us the extra length that we needed to be able to install the mounting plate for the shock absorbers that we just installed on here. With our factory U bolt we'd have almost no threads here sticking out. So our nut would be able to go on but it wouldn't be able to be properly torqued with enough threads to ensure that it's gonna stay torqued in that position.

Today, we're showing off the three inch wide U bolts with a half inch diameter. These have a seven inch length, and we're gonna use those to get our comfort ride system installed but we have them available on all the various sizes. So that way you can ensure you got a replacement for your trailer. We have them down as small as an axle diameter of one and three quarters of an inch. That's going to be your 2000 pound axles all the way up to an axle that is five inches in diameter.

And that's gonna be your larger axles that are around 12 to 15,000 pounds. Now the diameter of the U bolts do change as the sizes go up.Your smaller ones that only are for the one and three quarter inch axles typically have a size of three eights and of diameter while your large ones, with that five inch wide axle length is going to have a diameter of a U bolt of about three quarters of an inch to ensure that it can handle that weight rating of that. Now there are a couple of different U bolts that do have an overlap. The three inch ones that we're using here also have another three inch version available. That's in a nine 16th diameter. So you want to just check your trailer and your old U bolt to make sure you're replacing it with one that's going to be accepted acceptable with the hardware that you have on here. Cause we wouldn't be able to take a nine 16th and slide it through these brackets because the bracket on here was designed for a half inch. Replacing your U bolt is pretty easy. The smaller your trailer is usually the easier it is. Those larger U bolts. You are going to need to have a little bit more strength required to remove and torque down the nuts ' cause they are typically a higher torque value for the larger the U bolt. When taking them off you wanna make sure your axle is properly supported. If you follow along with us, we'll show you an example of how to remove and swap out the U bolts. We'll begin our installation by parking our trailer onto level ground. Your driveway in most cases is a great spot and lifting it up and removing our wheels. You'll wanna Jack it up and support the frame with Jack stands. You have to get it high enough off the ground where your wheels are off the ground so you can get those pulled off. And once you've got those pulled off here you are set up to begin working. We're using a lift here on ours to hold ours up. But again, it's gonna be very similar at home. You're just not gonna have the cross beam with the lift. You'll have just these Jack stands here underneath your frame. Now the Jack stands that I've got here. These are just precautionary Jack stands that are underneath the axles because we're going to be taking the U bolts loose. And once we take those loose, the axle can drop down. But I also have my Jack here underneath the axle and I'm gonna be moving this Jack around and keeping it under the axle that I'm working on this 'cause the Jack stands are really just supplementary in case something happens. My Jack, where two something we're to happen to the Jack with a fluid leak out we got a Jack stand here to support it. So we're going to remove the nuts here on top to take these U bolts off, the U bolts that are on your trailer. Aren't gonna be long enough to accept the brackets for the comfort ride system. So we are going to be replacing these U bolts. You can get new U bolts here at etrailer. Once we get these off, we'll show you the new U bolts. We're using a three quarter inch socket to remove the nuts, they are gonna be on there little snugs if I have to start it by hand, and then your tool can zip it off easily the rest of the way. Now we've got these all zip loose. We can pull our U bolts out of there. They just pull down. They're usually a little bit stiff. So just kind of working back and forth and just pull downward, come out of there. You can also kind of rock the top piece here. sometimes that helps . If you pull it over like this you can kind of get a little bit of a bang motion on it. To help persuade it off of there. So now we've got our factory bracket out of the way. This is your comfort ride. Your shock bracket. You'll have four of these in the kit and they are gonna be specific to a certain location. So we've got them set out here for the axle. So this is going to be for the front axle towards the front. We want this bracket to be angled down towards our equalizer here. And we also want to make sure that the holes are flat facing towards the center of our trailer like that. And the one for the axle behind this is gonna face like this. So these brackets are gonna be angled like this, on the opposite side of our trailer we want the same story to be mimicked over there. So we'll take our bracket now we'll set it on top of our leaf spring you see there's alignment pin there that does line up with the hole in the bracket. We can then set our factory bracket right back on top grab our new U bolts. We'll go up through the bottom through our shock bracket and our factory one. And then we'll secure it with the new nuts that came included with the U bolts. We'll do the same thing with the other two sets of holes right over on the other side of our leaf spring stack. Once we got them all started we can go back and tighten them down. You do wanna kind of go back and forth to try and tighten them down evenly. So you have roughly the same amount of U bolts sticking up above each night. So now we'll torque our hardware to the specifications found in your instructions. And that completes our look at red lines line of replacement, U bolts..

Customer Satisfaction Score:

Customer Reviews

Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter - 175666

Average Customer Rating:  4.5 out of 5 stars   (12 Customer Reviews)

This U-bolt, in conjunction with a U-bolt plate and an additional U-bolt, attaches your round, 8,000-lb axle to your 10-leaf springs. Bolt is 9" long and has an inner width of 3-1/2".


These were used to replace the existing Dexter ubolts on 8K axle. I added the Roadmaster Slipper spring system, which we love. I am very unhappy with this product. The Dexter ubolts were on the RV for a year and showed zero signs of rusting. These replacement bolts have barely been on 9 months and as the photos show are rusted. I know steel will rust however it appears they added nothing to protect them, had I known I would have dipped them myself. I believe the description should indicate this will happen so as a consumer you can take preventative measures.


It's doing exactly what it was made for .!!



These fit my application perfectly


As shown and quick delivery







Perfect fit.



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

  • What is the Difference Between U-Bolts 176500 and SP01-080
    At first glance, I was puzzled as well. But upon closer inspection, I have an answer for you. The difference is that Suspension U-bolt, # 176500, is just one bolt. SP01-080 is the same shape, size, and used for the same application (5.2K, 6K and 7K Axles) but it comes with two bolts. And part number 175666 that you reference is 1/2 inch wider, 1-3/4 inches longer, and is used on 8K Axles.
    view full answer...
  • How to Prevent Leaf Springs from Wearing Out on Grand Design with 7K Axles
    It's possible that the leaf springs from the factory are underrated. It's also possible that you may be adding more weight to the trailer than you think. That said, either way it would not do any harm to replace the springs with a higher rated set, the Roadmaster Comfort Ride Leaf Spring Suspension Kit part # RM-2470-2580 if you have the budget is really the best trailer suspension option out there, better than cushioned equalizers or anything else really. This system will not only provide...
    view full answer...
  • Availability of 3-1/2 Diameter Axle U-Bolt
    We do have 3-1/2 inch u-bolts with the part # 175666 for axle attachment. The diameter of the stud is 9/16 inch.
    view full answer...
  • Hardware for Over-Under Conversion on 3-1/2 Inch Axle
    I have a solution for you but there is not a conversion kit for your 3.5 inch diameter axle. You will need to weld on the Spring Seat for Typical 8,000-lb, Round Trailer Axles with 3-1/2" Diameter # TRSS350. Then for the axle hardware you will use the Replacement U-Bolt w/Nuts for 8,000-lb, Round Trailer Axles - 9/16" Diameter # 175666 and the U-Bolt Plate for 3-1/2" Diameter, Round Trailer Axles with 1-3/4" or 2" Wide Springs # 117581.
    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...

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Info for this part was:

Employee Michael H
Expert Research:
Michael H
Employee Dustin K
Video by:
Dustin K
Employee Cole B
Installed by:
Cole B
Employee David F
Installed by:
David F
Employee Chris R
Video Edited:
Chris R

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