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  1. Trailer Leaf Spring Suspension
  2. Redline
  3. U-Bolts
  4. Camper
  5. Car Hauler
  6. Utility Trailer
Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter

Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter

Item # 175643
Our Price: $5.34
Trailer Leaf Spring Suspension
Shipping Weight: 0.31 lbs
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Trailer Leaf Spring Suspension 175643 - 4-1/4 Inch Long - Redline
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This 4-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2,000-lb round trailer axle to its leaf springs. Bolt has an inner width of 1-3/4". 2 Nuts included. Great Prices for the best trailer leaf spring suspension from Redline. Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter part number 175643 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (19)
  • Q & A (0)
  • Videos (2)
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Redline Trailer Leaf Spring Suspension - 175643

  • U-Bolts
  • Camper
  • Car Hauler
  • Utility Trailer
  • Round Axle - 1-3/4 Inch
  • 4-1/4 Inch Long
  • 2000 lbs
  • 3/8 Inch Diameter
  • Redline

This 4-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2,000-lb round trailer axle to its leaf springs. Bolt has an inner width of 1-3/4". 2 Nuts included.


  • Replacement U-bolt acts as part of a trailer suspension system
    • Used with another U-bolt (sold separately) and a U-bolt plate to secure one side of your axle to a leaf spring, which is mounted to your trailer's frame
  • Round bolt fits round trailer axles
  • 1 U-bolt and 2 nuts included


  • Application: 1-3/4" diameter axles
  • Inner width: 1-3/4"
  • Length: 4-1/4"
  • Diameter: 3/8"

U-Bolt Diagram

175643 U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter - 4-1/4" Long

Video of Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" 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 with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter - 175643

Average Customer Rating:  5.0 out of 5 stars   (19 Customer Reviews)

This 4-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2,000-lb round trailer axle to its leaf springs. Bolt has an inner width of 1-3/4". 2 Nuts included.


Look great didn't get to use them yet.


Springs for my tow behind my bike trailer arrived on time, all hardware included. They were easy to install once I broke the 1981 hardware loose. It is like having a new trailer, not really it is clearly a oldie. Past purchases from etrailer have all been just fine, will order what I need from them anytime.


The customer service was outstanding. Thru the process of identifying what I needed to ordering and delivering the products I dealt with multiple Customer Service Representatives (CSR). Everyone of them were helpful and courteous. I really appreciated the follow up after my initial contact with CSR. Once the product was ordered I was kept up to date on the status of the order thru regular emails from an etrailer CSR. The parts arrived as they promised, and a CSR even followed up with me after that. Great service, keep it up!


Product was perfect for my application. It arrived well packed, (protected), and on time.


just right. thanks

J. S.


just right, still. should last forever.


I ordered these u bolts online. The web sight was user friendly, with the right information to get the right part. The price was very reasonable for both the part and the shipping cost. I will definitely be ordering in the future as the need arises.
Keep the faith!


Every thing was just as I ordered. Great friendly super fast service. Thank you !!!!


They’re exactly what I needed and arrived as fast as could be expected.


Was what was order and good quality and all fit well


Just what the doctor ordered.


It was the perfect fit


Just what the dr. ordered. Fast deliver y.



fit perfectly fast shipping


Great customer service. Very much appre ciated


Perfect fit. Just what I .





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

  • Center to Center Distance Between Threaded Parts of U-Bolt 175643
    For u-bolt # 175643 it is 2-1/8 inches on center. All of the 1-3/4 inch, 3/8 suspension u-bolts will be the same. Since it is only 1/8 of an inch off you can probably bend them a little to fit your application.
    view full answer...
  • Parts Needed To Flip A 1-3/4 Inch Axle On A 1990 Coleman Pop-Up Camper
    We don't have an over under kit for your application, but, you can make one. U-Bolt Plate - 1-3/4" Diameter Trailer Axle - 1-3/4" Wide Spring - 3/8" Bolts # TRTP175173 Spring seats welded to the axle like the Spring Seat for Typical 2,000-lb, Round Trailer Axles with 1-3/4" Diameter # TRSS175 For U-bolts we have the Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles - 3/8" Diameter # 175643 but you will most likely need to find longer u-bolts with the other dimensions being...
    view full answer...
  • What U-Bolts Fit A 1-3/4" Round Trailer Axle And Are Over 4" Long
    I do have u-bolts with very similar measurements to the one's you have provided, however, we currently do not have a u-bolt that matches your exact dimensions of 5" long X 1-3/4" wide X 1/2" thick. Instead we have a very similar u-bolt like the 1-3/4" Round Trailer U-Bolt part # SP01-020 which is 4-1/4" long X 1-3/4" wide X 3/8" thick.
    view full answer...
  • Hole Dimensions in U-Bolt Plates 117535-G and TRTP175173
    The four holes in the U-Bolt Plate parts # 117535-G and # TRTP175173 are sized to accept 3/8-inch u-bolts like # 175643-Z. I went to our warehouse and measured these plates' thickness and hole diameters and found them to be 1/4-inch and 0.4-inches respectively. Note that since these items are die-formed there can be slight variances between samples.
    view full answer...
  • Replacing Harbor Freight Trailer Axle and Mounting on Underside of Leaf Springs
    I recommend getting the correct parts for the axle that you have and not trying to use the parts in the Over-Under Conversion Kit # K71-384-00. The correct Spring Seat # TRSS175 will need to be welded onto your new axle. This will allow you to mount the axle on the underside of your leaf springs. The Replacement U-Bolt with Nuts for 1-3/4" Round Trailer Axles # 175643-Z are the correct diameter for the Dexter Axle # 20440I-EZ-60. The U-Bolt Plate # CE20023G has the bolt hole pattern...
    view full answer...

Do you have a question about this Trailer Leaf Spring Suspension?

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 Lisa S
Updated by:
Lisa S
Employee Chris R
Video Edited:
Chris R

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