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Replacement U-Bolt for 2" Wide, Square Axles - 1/2" Diameter - Zinc Plated

Replacement U-Bolt for 2" Wide, Square Axles - 1/2" Diameter - Zinc Plated

Part Number: UBZC12X212X525
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Trailer Suspension Parts
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This 5-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2" wide, square trailer axle to its leaf springs. Sturdy, zinc-plated steel resists corrosion. Great Prices for the best trailer suspension parts from Redline. Replacement U-Bolt for 2" Wide, Square Axles - 1/2" Diameter - Zinc Plated part number UBZC12X212X525 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (153)
  • Q & A (0)
  • Videos (1)
  • Photos

Redline Trailer Suspension Parts - UBZC12X212X525

  • U-Bolts
  • Boat Trailer
  • Snowmobile Trailer
  • Square Axle - 2 Inch
  • 5-1/4 Inch Long
  • 3500 lbs
  • 1/2 Inch Diameter
  • Redline

This 5-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2" wide, square trailer axle to its leaf springs. Sturdy, zinc-plated steel resists corrosion.


  • Replacement U-bolt acts as part of a trailer suspension system
    • Used with another U-bolt (sold separately) and a U-bolt plate (not included) to secure one side of your axle to a leaf spring, which is mounted to your trailer's frame
  • Square bolt fits square axle beams
  • Zinc-plated steel construction is heavy duty and corrosion resistant
    • Ideal for use on boat or snowmobile trailers
  • 1 U-bolt included


  • Application: 2" wide axles
  • Inner width: 2-1/8"
  • Length: 5-1/4"
  • Bolt size: 1/2"-13

U-Bolt Diagram

UBZC12X212X525 Redline Square Zinc Plated U-Bolt for 2" Trailer Axles - 2-1/8" Inner Width - 1/2" Diameter - 5-1/4" Long

Video of Replacement U-Bolt for 2" Wide, Square Axles - 1/2" Diameter - Zinc Plated

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

Video Transcript for Redline Trailer Suspension UBZC12X212X525 Review

Today we'll be reviewing part number UBZC12X212X525. This is Red Line's replacement U-bolt for 2-inch wide square trailer axles. It's going to act as part of a trailer suspension system. It's going to be used with another U-bolt. It's going to be sold separately as well as the U-bolt Plate, also sold separately, to secure one side of your axle to a leaf spring which is mounted to your trailer's frame. The square bolt is designed to fit square axle beams. Has a really nice zinc plated steel construction so it's going to be very heavy duty and corrosion resistant. It's going to be ideal for use on boat or snowmobile trailers.

One bolt is included with this part number. Again, it's designed for 2-inch wide axles. The inner width between the bolt posts is going to measure 2 1/8 of an inch. The length that we have from the bottom of the cross member to the bottom of the bolt post is going to measure 5 1/4. Then the bolts are going to give us a diameter of a half inch. The threaded portion on each bolt is going to measure right at 2 inches in length. That's going to do it for our review of part number UBZC12X212X525.

This is Red Line's replacement U-bolt for 2-inch wide square trailer axles.

Customer Satisfaction Score:

Customer Reviews

Replacement U-Bolt for 2" Wide, Square Axles - 1/2" Diameter - Zinc Plated - UBZC12X212X525

Average Customer Rating:  4.8 out of 5 stars   (153 Customer Reviews)

This 5-1/4" long U-bolt works with a U-bolt plate and another U-bolt to help secure your 2" wide, square trailer axle to its leaf springs. Sturdy, zinc-plated steel resists corrosion.


I ordered the ubolt kit for 2” square axle when i bought my new leaf springs. My old ubolts were 5 1/2”, the new ubolts were only 4 1/2”. Not long enough to use lock washer and thread bolt sufficiently. I had to order longer ubolts to make it work, only to find out 2 things.
1- the new longer ubolts do not include washers or nuts.
2- the 4 1/2” ubolts were fine thread while the new 5 1/4” are coarse thread, so i had to make the 6 mile trip to home depot to buy new coarse thread nuts.

Why do you suggest a ubolt kit that doesn’t work with a 2” square axle and a 4 layer leaf spring

Etrailer Expert

Jenny N.


I am sorry as I did check and the only all in one u bolt kit we have is the one that you had ordered part # CE23103. It is a good idea to have more options when it comes to the u bolt kits.


Good quality


Very good and very strong U-bolt. Fits and works exactly as expected.


Product was adequate for my needs. Expected delivery was Thursday. ???? 2 1 1/2 mile trips on foot to the mailbox 2 days later and it arrived late today. Won’t be ordering items from you again. Your choice of transportation is horrible. UPS item will be delivered as scheduled. Saved a buck on the first shipment. Lost a customer! Pass this on to the idiot that decided to save a buck. Good bye!


Quick delivery and exactly what i ordered. Thank you.


etrailer has always had what I needed when no one else did. They are my #1 source for any of my trailer needs.


Make sure you get course thread nuts for these u bolts


I ordered 8 but only got 4. The explanation that was given to me was that they only had 4 and that I could not get the other 4 until July. It seems to be a no brainer to sell only what you have and maybe list the amount that you have in stock on the website.


I bought springs, shackle bolts, and u-bolts and plates. Everything was great and fit perfectly. Only issue were the u bolts which were not galvanized. However, at a local trailer store, I bought galvanized U bolts for $4.50 each.
For the DYIers, taking the old ones off took more than 4 hours for each side. My existing shackle bolts were so heavily rusted that I had to cut three off with a hack saw. Difficulty was confined space to operate hack saw with boat still on trailer. However, reassembling the new springs was less than 45 minutes each side.
Must have tools are large diameter 3/4-13/16-7/8 deep sockets (6 point), 2 2 foot long breaker bars and a can of PB blaster.
For safety: Good quality jack stands, minimum of 3--don't rely on the front trailer jack as it may roll.
By the way, I did these myself and I am 64 years old.


Excellent products. All were very well made. Very fast delivery. Extremely happy dealing with etrailer. Will definitely order from etrailer in the future. Also hard to find galvanized parts. Would refer friends to etrailer.

Johnny B.


Everything I have purchased from trailer has been of the highest quality and after a years use, still performs excellently.


Great price, quality product!


I ordered several items for my boat trailer to replace the springs and renew the related hardware. There was a little glitch, as the springs were sold out in inventory. The etrailer staff quickly advised me of this issue and offered alternatives. However, my order was shipped was shipped within a few days and arrived as ordered. I will definitely use etrailer again.


This shipped with USPS but came late. We would have liked it to ship with UPS.


After a long search, etrailer had exactly what I needed. Delivered when promised.



It has held up wonderfully.


Perfect replacement part fit and function no alterations were necessary and fast shipping. I replaced the worn out springs on my 1987 Skeeter boat trailer and was mad that I had not done it sooner. All the replacement parts fit perfect.


Quick delivery, well packaged.

what I wanted to use on my tractor ROPS bar.

Will be back for more components for my next project.

John M.


High quality, no issues holding light bars on tractor


These products are very difficult to find except at
They had the exact product: Square U-Bolts to fit a 4 inch x 2 inch framed trailer.
It's impossible to find these locally, (for me), but one stop at took care of my needs.


I ordered parts from before and this time the service was as good as the last time. Parts were identified very well and they fit perfect. Thanks again for the great service. I also found out that my son ordered his trailer hitch for his new Ford van from you and he says he'd do it again.

Thank you ,


Rebuilt trailer suspension, should be good for another 20 years. One of my old springs snapped.


High quality U bolts to mount a trailer tongue toolbox on my main beam of my trailer. Etrailer has many hard to find products & fast shipping & always great customer service. I use them fairly often. When searching for anything for trailers.....start here.


I ordered these a few weeks ago. Unfortunately the package was damaged in transit and the contents were lost. etrailer reached out and informed me they would send a new set. Arrived in a timely fashion but the second package was also damaged in transit but fortunately none of the U bolts fell out. Might package better for shipping but other than that, Excellent customer service!!!


Products are great and for a fair price. Be aware that the square u bolts have course threads and the nuts they sell for boat trailer u bolts have fine threads. I had to use some from a local store. Super fast shipping got me back fishing in no time!


One year later and no signs of rust. Used on a boat trailer. Fully submerged in salt water multiple times. Great product!!!


Matched what came off the trailer. Don't forget nuts and anti-seize. Suprised how fast it was delivered considering it was by ground transport.


So far so good.Right size and fit.I would buy this /these products again from

Show More Reviews

See what our Experts say about this Redline Trailer Suspension Parts

  • Need for Additional U-Bolts to Install CE Smith Roller-Style Guide-Ons CE27610
    The CE Smith Roller-Style Guide-Ons # CE27610 will fit your 2 x 2-inch trailer frame. The standard included brackets work with frame members up to 3-inches wide and 4-1/4-inches tall. It is a good idea to add another u-bolt to each guide-on in your application. I linked our main page for trailer u-bolts where you can see items like CE Smith U-Bolt Kit # CE23103 and # UBZC12X212X525.
    view full answer...
  • 5 Inch Long U-Bolt Recommendation for Square Trailer Axles
    The closest thing we have that would potentially work for you would be the # UBZC716X212X400 but it's an inch too short. A better option would be the part # UBZC12X212X525 but it has a 1/2 inch diameter. See picture. I am assuming you are looking for axle u-bolts.
    view full answer...
    Image 1 for
  • Zinc Platted U-Bolt or Square 2” Wide x 3 Tall Trailer Axles
    I looked up your order and the 6-Leaf Double-Eye Spring part # e27SR you have is about 1-1/2" thick. Since you axle is 3" tall you would need a u-bolt that is at least 4-1/2" tall. Therefore, I recommend taking a look at the Replacement U-Bolt part # UBZC12X212X525 which is 5-1/4" long x 2-1/8" wide. This u-bolt is zinc plated and for the correct lock-nut you will want to use part # 12ZLN.
    view full answer...
  • U-Bolt Recommendation for 2 inch Square Axles
    Is your square axle a 2 inch square axle? I believe it most likely is and you would want the # UBZC12X212X525 for a replacement u-bolt as this is 5-1/4 inches long and fits a 2 inch square axle. For nuts you would want the # 12ZLN and then for a bottom plate # 117594-G.
    view full answer...
  • Availability of 3/8-Inch Diameter Square U-Bolts 3-1/8-Inch Wide by 5-1/4-Inch Long
    We do offer a range of u-bolts and u-bolt kits and all can be seen on the link provided. I was not able to find a 3/8-inch diameter 3-1/8-inch wide by 5-1/4-inch long square u-bolt. All the u-bolts that have 3/8-inch diameter are round. The one square u-bolt we have that is 5-1/4-inches long is only 2-1/8-inches wide (part # UBZC12X212X525). You can use the filters at the left-hand margin to sort the products; perhaps you can find a suitable substitute.
    view full answer...

Do you have a question about this Trailer Suspension Part?

Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jameson C
Expert Research:
Jameson C
Employee Adam R
Expert Research:
Adam R
Employee Adele M
Updated by:
Adele M
Employee Wilson B
Updated by:
Wilson B
Employee Kathleen M
Video by:
Kathleen M
Employee Cole B
Installed by:
Cole B
Employee Lisa S
Written by:
Lisa S

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