Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.
Error submitting comment. Please try again momentarily.
A secure axle mount is key to safe towing. This kit locks your axle to the springs with four 9/16"-diameter, Grade 5 steel U-bolts. Each one provides a strong clamp for 3" round axles rated from 5,200 lbs to 7,000 lbs. When torqued between 65 and 95 ft-lbs, they hold firm without bending the plates, keeping your suspension tight and steady mile after mile.
Getting the geometry right matters for ride height and handling. These 7-1/16" long U-bolts are made for 3" diameter round axles and work with 2" wide springs. The plates are drilled for a clean fit, with 3-3/4" center-to-center spacing between holes and 2-5/8" between the spring bolt locations, so everything lines up just the way it should.
You don’t have to chase down missing pieces. The kit includes four U-bolts, two heavy plates for 2" springs, and eight 9/16"-18 hex nuts. Everything threads together cleanly with 3" of usable thread length per bolt, giving plenty of bite for reliable torque and even pressure across the assembly.
If you’re raising your trailer with lift blocks or taller spring hangers, these U-bolts have the 7-1/16" length to handle the extra space. They give you the reach needed to tighten down securely without running short on threads, making them a versatile choice for upgrades or maintenance on high-capacity setups.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Today we'll be reviewing Part Number APUBR-9. This is Red Line U-Bolt Kit for mounting 5200 lbs to 7000 lbs round trailer axles. It's going to attach the trailer axle to your leaf springs, it's going to include four 7 1/4 U-bolts, 2 U-bolt plates for 1 3/4 inch or 2 inch springs, and then it's going to include eight 9/16 inch hex nuts. Spring seats are required for mounting the axle to the leaf springs and that's all going to be sold separately. It's going to fix axle diameters of 3 inches, typically 5200 lb to 7000 lb trailer axles. The spring width that this would fit is going to be 1 3/4 inch or 2 inch and we'll just take a few moments to go over some dimensions. We take a measurement of the length of the u-bolt, again we're measuring from the bottom of the cross member, to the base of the bolt post.
It's going to give us a measurement of 7 1/4. The threaded portion on each bolt is going to measure 3 inches. It's that portion there and then the width that we have in between is going to measure right at 3 inches and that's just a measurement between the bolt posts. Taking a look at one of the plates, it's going to measure 5 1/4 by 3 3/4. We measure the distance, center on center between the holes going this direction, it's going to measure 3 3/4 of an inch and then center on center going this direction is going to give us a measurement of 2 5/8 of an inch. That's going to do it for our look at Part Number APUBR-9, this is Red Line U-Bolt Kit for mounting round trailer axles and again the bolts are going to measure 7 1/4 of an inch in length.
.
Customer Satisfaction Score:
98% were satisfied with this product
2% of customers were not satisfied
Ratings & Reviews
Fast shipping good product
Nice upgrade from 1/2 inch
Good quality item, and it fit perfect.
Excellent parts for the project I was working on. I installed a 1997 Chevy axle on a 1950 International box trailer. With a few “adjustments”, I made it work!
Product is good but shipping was terrible, box was ripped and all 4 leaf springs weee scratched up.
The parts where just what we needed and mounted perfectly.
Totally satisfied with my purchase. Thanks to the great help from Tegan who was both polite and professional. He steered me in the right direction, and I received my parts super fast. Great quality and fitment. ETrailer made the job easy. Everything about ETrailer from customer service to shipping has been above and beyond satisfaction. I'll always go to Etrailer when needed. Thankyou
The order will be shipped to my summer home in Nome Alaska. I can send the review after it arrives.
These fit great. Only thing is they rust really quickly so I had to paint them with a clear coat to help stop the rust.
Delivered as promised and installed as required.
No problems with service and the product.
Excellent company to do business with. Always glad to have etrailer available for go to supplies at lowest cost.
This kit was sent with cheap lock washers, they all pealed open. Last time they came with flange nuts. I had to go buy them to correct this project.
The parts in the U-Bolt kits (I had two of them) fit perfectly, and I am very pleased with everything about them.
I had rusted old bolts and leaf springs, these were great replacements. No issues look great work well and fast shipping.
Couldn’t be happier!
Everything fit perfectly!
I chose this particular kit mainly for the 9/16" u-bolts. I could have easily used the 1/2" kit but it was a nice upgrade and not much difference in cost. These u-bolts and plates fit my car trailer perfectly without any modifications. Everything in product description was just what it said when I received them. Shipping was faster than I expected!
Works good.
Joshua B was great help and all the parts showed up as promised
The kit was missing a nut but I had one so I kept the kit. It took two weeks to get a kit that should have arrived in two days, and when I called after 4 days requesting they send out another so I could have it for the weekend they told me they thought it was in Tulsa and would still be delivered that night. When I called back the next day they said they could not get it to me in time for the weekend and I should wait. Very poor customer service considering it should have been included in my original order which totalled nearly $2,500.00 but the CSR only put one on the order knowing I had two axles and would therefore need 2 sets. I have the ubolt kit 2 stars for missing a nut... I would give ETrailer 0 stars if asked. We watch several ETrailer sponsored influencers and thought they were honestly singing your praises... now we know we can't trust what they say.
The u bolts themselves are just fine but the plates and hardware are junk. The plate bends at 70ftlbs when I torque them. The lock washer fails at the same time. Torque spec is 65 to 90ftlbs. Wish these came with better hardware. But what else can I expect from a Chinese kit.
Kayleigh who helped me out was fantastic and would definitely use etrailer again if not just for their products but also for the customer service.
Mike L.
6/25/2026
Thanks David, we appreciate the kind words!!
Usually the etrailer items I order are good quality, but I was highly disappointed in this product. I replaced the U-bolts on a trailer we were rebuilding and when I torqued the nuts to 69 ft lbs the lock washers spread open . When I took the nuts off they were distorted also. U-bolts seemed OK so I bought new nuts and washers.
The U-Bolt kit came with lock washers which should not have been included. With the assumption that this was an upgrade, to the U-Bolt kit, I installed them on several locations until I recognized that I had a failure. The lock washer actually squished out from under the nut in the location that I was working on. I contacted e-Trailer about this since my previous U-Bolt kit didn’t have any lock washers and found out that they weren’t an upgrade and shouldn’t have been included or used. If you purchase the APUBR-9 U-Bolt kit do not use the lock washers. In order to torque the nuts to the required ld/ft and hold there shouldn’t be any lock washers involved. Regretfully, I should have caught this before installing any of them. Otherwise the top plates fitted better that the previous kit I received. Time will tell if it is actually a quality product.
My 2019 Coachman Freedom Express Liberty 320BHDS was chewing the inside treads of tires regardless of rotations. Thanks to Kyle B and Daylon H, your team quickly diagnosed the issue and recommended this suspension upgrade including new 6000lb leaf springs, u-bolts, equalizer and the MORyde wetbolt hardware kit. Installation took the better part of a weekend, but was a complete success. Be mindful of the torque specs and ensuring your RV is properly supported (including axles). Thanks to some recently cut stumps, I was able to support boths sides of the axles to safely torque bolts to 80lbs. RV rides about 1.5 inches higher, but nice and smooth. No noticeable camber with the tires now. Time will tell, but sincere thanks to Kyle and Daylon for taking their time to view my photos and answer questions.
Gwendolyn Y.
5/20/2026
Thanks for the awesome detailed review, Kevin! Really glad Kyle and Daylon were able to help track down the issue and get you pointed toward the right setup. It sounds like you put a lot of care into the install, and it definitely paid off. Making use of those stumps was pretty genius too. Safe travels ahead!
Do you have a question about this Trailer Suspension Part?
Info for this part was:
At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.
Brooke M.
2/17/2025
The photo looks great! Thanks for sending it in. So glad youre happy with it! :)