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Spring-Eye Bolt with Locknut for Slipper Springs - 3-1/2" Long

Spring-Eye Bolt with Locknut for Slipper Springs - 3-1/2" Long

Item # 166079
Our Price: $14.29
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166079 - 3-1/2 Inch Long ABS Fasteners Suspension Bolts
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9/16" Diameter spring-retainer bolt is used to mount slipper spring inside front hanger. Includes locknut. Great Prices for the best trailer suspension parts from ABS Fasteners. Spring-Eye Bolt with Locknut for Slipper Springs - 3-1/2" Long part number 166079 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (462)
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ABS Fasteners Trailer Suspension Parts - 166079

  • Suspension Bolts
  • Camper
  • Car Hauler
  • Utility Trailer
  • 3-1/2 Inch Long
  • 9/16 Inch Diameter
  • ABS Fasteners

9/16" Diameter spring-retainer bolt is used to mount slipper spring inside front hanger. Includes locknut.


  • Suspension bolt attaches leaf spring to front hanger
  • Included locknut secures in place on bolt


  • Diameter: 9/16"
  • Length: 3-1/2"

166079 Spring Eye Bolt with Nut - 3-1/2" Long


Video of Spring-Eye Bolt with Locknut for Slipper Springs - 3-1/2" Long

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

Video Transcript for Review of Trailer Leaf Spring Suspension - Spring Mounting Hardware - 166079

Jeff: Hello, everybody. This is Jeff at Today, we're going to take a look at the 9/16th diameter, 3 1/2 inch long spring eye bolt with the lock nut for slipper springs. Now this 9/16th diameter spring retainer bolt is used to secure the slipper spring to the front hanger of your slipper spring trailer suspension. The 3 1/2 inch long bolt is common on trailers that have a 6,000 pound or 7,000 pound axle and uses 2 inch wide leaf springs.Now, the bolt itself is a grade five bolt. The way we can tell that is, if you look at the head, you'll see three lines on it.

That'll indicate that that meets the grade five designation. The length on this is 3 1/2 inches, and that's measured from under the head to the end of the bolt, so there's your 3 1/2 inch length. Diameter of this bolt is 9/16th of an inch. The thread size on the end here that the lug nut or the block nut attaches to is 9/16th by 18 threads per inch. Now the bolt head size is a 13/16th of an inch, and let's show you here's a 13/16 socket.

Oops, wrong one. Here's the 13/16 size socket. You can see it fits securely on there.And the lug nut size uses the 7/8th inch size socket, and that's the first one here I pulled. And you can see that fits exactly on there. And this included lock nut is what will secure this bolt to the spring eye.

But that should do it for the review on the 9/16th diameter, 3 1/2 inch long spring eye bolt with the lock nut for slipper springs.

Customer Satisfaction Score:

Customer Reviews

Spring-Eye Bolt with Locknut for Slipper Springs - 3-1/2" Long - 166079

Average Customer Rating:  4.8 out of 5 stars   (462 Customer Reviews)

9/16" Diameter spring-retainer bolt is used to mount slipper spring inside front hanger. Includes locknut.


Just what needed for my trailer. My old leaf springs were so rusted that I was one pot hole away from being broken down on the side of the road. These new ones are perfect.


When I asked questions about my order they answered back quickly. Everything fit like it should. Yes time will tell if the springs are good.


Great Experience!

When I noticed
that the leaf springs on my 44 year old boat
trailer had cracked I thought I would never find replacements.
I fully expected to have to have something custom built.

I was amazed when I found the fantastic diagrams/descriptions
dimensions for replacement springs on

The phone support person was wonderfully helpful in confirming
if items were in stock and ready to ship. The replacement springs
arrived on time and everything bolted up perfectly!

Thanks for such a great site!


I will be disassembling and do a further visual coming up. But what I did see while on the trip is that it definitely looks as the rollers (gold colored like a grade 5 - 8 bolt, I'm assuming they are hardened) that are in the system to roll on the slipper springs are showing wear.


I have bought many different products from Etrailer and the staff have been more than helpful and I would recommend this company.



It’s been a year already! How time flies. Every things still working great thanks again.


Perfect size great fit


Bolts where a exact fit.


I have purchased a number of items from such ans leaf springs, axle and hub assembly, and other items as well, I recently finished the trailer and it is now on a cross country trip. The trailer has just finished a 3,000 mile leg of this trip and I am told it was so smooth that it could not be felt by the towing vehicle.

Every product I have ordered from has been top quality and has worked extremely well. I would come back again for any of my future trailer needs.

Robert H.


The trailer has since been on a second cross country trip and it is still working just like it was the day I finished it.


Everything was as expected! Products are as described and the shipping was fast! Thanks! I will buy from them again


Great products from e trailer. They work as expected and hassle free. Even better prices.



The trailer springs and brackets have been great no issues at all. Very pleased with etrailer products.


Bolt was a great replacement


Two of the bolts were sent as the wrong size...they were properly labeled, but were 9/16 instead on 1/2. Kylie requested photos of the bolts to "prove" they were incorrect which kind of frustrated me further. She is sending new ones to me soon. One of the hub kits arrived with the seal broken and the contents were scattered in the shipping box, but all the parts from the kit were there, so no harm done.


Awesome product and fast shipping!


It's 4 in long and no shoulder.


Great company to do business with and very knowledgeable assistants! Recommended


Super service getting all the right parts. I received the parts in just two days it took about one hour to change both springs .everything fit grate back on the road.thanks


Quick delivery and product as described


Customer Service was / is excellent. Timely delivery easy ordering process. Correct parts and easy to install Great Company and would use again when I need to


Very good service and very good parts as usual!


Right size


I get the correct hardware every time!


I received the order to late to use before my road trip.In total, it took 27 days to receive my order. I placed my order on September 1st and received the package on the 8th. Whomever packaged the order used a very larger box and three sheets of packaging paper. By the time I received the order it was missing half of the items I ordered. I emailed etrailer immediately and received a response quickly. I was told that a replacement order was sent to their warehouse or shipping department and they would send the replacement parts. However, this is where things started to brake down. I asked for a projected delivery date and i was told that it usually takes 3 to 5 days once it ships and they would send me an update once it shipped. On the 14th I still had not received an email stating the order had shipped so I emailed etrailer again. I left on my road trip on the 15th so did not have the time to check my emails until the 19th, and found I had not receive a reply yet so i sent another email. The response I received stated that they had sent me an email on the 14th to notify me that one of the missing items from my original order is now back ordered. I reviewed my email inbox and junk mail on three devices that receive all mail sent to my email address. I did not receive an email from etrailer as stated. Bottom line, i didn't receive the replacement items until the 27th. This put me on the road without the trailer parts I was counting on for my trip. I'm not a satisfied customer.


worked as advertised.


The original spring bolts were 1/2" these are 9/16" and I had to enlarge mounting bracket holes but satisfied with these stronger bolts. The springs and all other hardware high quality at a very good price.

Patrick M.


Great. Quiet, firm ride. Handles great.


Melissa @ eTrailer was simply the best. She took the time to confirm the leaf springs were the correct size for a trailer I am rebuilding. Received the parts on time. Could not have done better with any other company.

Show More Reviews

See what our Experts say about this ABS Fasteners Trailer Suspension Parts

  • How to Determine Correct Slipper Spring Replacement for 1,500 lb Axle
    What happens to slipper springs is that over time they elongate and flatten out, particularly if your springs are considerably older. The most important measurement you mentioned was the 26 inches from the center of the spring eye to the end of the spring. Based on that the closest slipper spring we have that could work is the 3-Leaf Slipper Spring w/ Radius End for 1,500-lb Trailer Axles - 24-5/8" Long # SP-178275, which would work if you had a tandem-axle trailer. There are no slipper...
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  • How to Determine the Correct Slipper Spring for 6,000 lb Axle
    The slipper spring we carry for 6,000 lb axles is the 5-Leaf Slipper Spring w/ Hook End # e67SR. To figure out if this spring is going to work for you there is a measurement you will need to take. If you look at the accompanying diagram you can see that "C" is 27 inches. This is the length from the center of the eye to the end of the spring with the slipper; you can measure your current slipper spring to see if you have a similar measurement, keeping in mind that the current spring may...
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  • Can You Get etrailer Suspension Kit E99ZR without Hangers?
    No problem! It's not all going to be as a kit but you'll need the following part's and quantities: (2) Equalizers # TREQE1 (8) Shackle Straps # TRSL313 (14) Bolts # 166079
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  • Replacement Suspension Components for 6,000 Lb Axles with 25-1/4 Inch Long Leaf Springs
    Thanks for the photo! I have everything you need to get your trailer back on the road. I have attached my recommendations on the following parts for you trailer as well as the quantities needed. Leaf Springs: part # e34SR (4) Equalizers: part # TREQ310 (2) Shackle Straps: part # 115208GALV (8) U-Bolts: part # APUBR-8 (2) Eye Bolts: part # 166079 (12) I have also attached a few review videos on the above products for you as well.
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  • Recommended Slipper Spring for Custom Kayak Trailer
    Thanks for the photos with measurements. The 2-Leaf Slipper Spring w/ Radius End for 1,000-lb Trailer Axles - 24-5/8" Long # SP-177275 are rated for 500lbs each for use with a 1000K axle. This will work with the inside to inside measurement you are seeking. You will simply need the 9/16 inch bolt # 166079. If there is any extra space in the hanger it won't be an issue with the bolt and bushing.
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  • What Are the Dimensions of the Spring-Eye Bolt with Locknut for Slipper Springs
    The Spring-Eye Bolt with Locknut for Slipper Springs # 166079 is a total of 3-1/2" long. The measurement from the back of the head to the start of the threads is 2-3/4" and the length of the threads are 3/4".
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  • Are there Bolt-On Hangers for Trailer Leaf Spring Suspension
    We do have a couple of bolt-on spring hangers # CE14017G and # CE14016G but they are designed for slipper springs and not double-eye springs like # e77SR. Its not likely that professional welder would charge that much. You might be able to find one locally via an iron workers union near you. For u-bolts for your 1-1/2 inch square axle you can use # SP01-120 for 2 u-bolts and 4 nuts. For a u-bolt plate you can use # 115983. For a hanger kit you could use # APS1. Now what you could do is...
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  • Recommended Shackle Bolt For Escort Trailer
    The shackle bolt we offer that measures 3-1/2 inches is part # 166079. This is a 9/16 inch diameter bolt and includes the locknut. We do not offer a shackle bolt that measures 9/16 inch x 4 inches.
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  • Replacement Springs for Fulton Boat Trailer
    Your 32 inch springs were likely a little shorter than that originally and have flattened over time. It sounds like what you are looking at, the 4-Leaf Slipper Spring w/ Flat End part # SP-040275, a 30" long x 1-3/4" wide will work. If you need it, there's a U-Bolt Kit # CE23103 and for suspension bolts, the Spring-Eye Bolt with Locknut for Slipper Springs, # 166079.
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  • Replacement Slipper Spring for Boat Trailer 1000-lb Axle
    Well-worn leaf springs can become elongated and actually measure longer than their length when new. It is not uncommon for a leaf spring to get as much as 3/4-inch to 1-inch longer from years of use. If your spring measures 25-1/4-inches long then chances are that when new it was indeed the 24-5/8-inch length of the Redline # SP-177275. This 2-leaf spring is rated for 1000-lb trailer axles; you can check the sticker on your axle to confirm it's weight rating. This spring does indeed use...
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  • Where is the Length of the Bolt part # 166079 Measured
    The 3-1/2 inch length of the bolt part # 166079 is measure from below the head of the bolt to the end of it. Based on what you mentioned this should work well for you.
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  • Replacement Slipper Leaf Spring for Triton PWC Trailer
    The best slipper spring option for your Triton PWC trailer is going to be the Slipper Spring part # SP-039275 as it's for up to a 2,900 lb axle, is a 3-leaf setup, and is 1-3/4 inches wide. It does have a flat end though and not a radiused end but that shouldn't be an issue.
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  • Bushings, Shackle Straps, and Wet Bolts for Tandem Axle Trailer
    The bronze bushings with 9/16 inner diameter come as a single, # D014-077-00, or in a pack of four, # K71-291-00. The closest shackle strap we have to that length is 3-1/8 inches. I've linked our selection for you. We do carry a heavy-duty strap that's 3-3/4 inches long, part # 018-026-05. We have wet bolts that are 3 inch, # 126B2, but the 3-1/2 inch long bolt that will fit the 9/16 inch bushing is not a wet bolt, # 166079. All of the prices can be seen on the linked product pages.
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  • Replacement Trailer Suspension Parts for Trailer with 2 Square Axle
    It looks like you've got a pretty good grasp on all of this and thank you for the detailed information; it looks like most of the parts you've mentioned will work for you. For the leaf springs, the 26" long # e27SR will be the best option for you since springs stretch out over time and they're right around the capacity of what the axles likely is. The next closest size would be the 25-1/8" # e54SR, but I would be hard pressed to believe that your old ones have stretched out over a full...
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  • Bushings for Slipper Spring with 1/2-Inch Inner Diameter
    The nylon bushing is included with Slipper Spring # SP-178275. The bushing has an inside diameter intended for a 9/16-inch bolt like # 166079. I linked a page showing all suspension bolts in this diameter. For a bushing with a 1/2-inch inner diameter and the 11/16-inch outer diameter required for this spring you can use # TRBU11506.
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  • Axle Spacing When Using Slipper Spring Equalizer Kit # APT6SE with 26 inch Long Leaf Springs
    Based on your leaf spring length the axle spacing you'd have with the hanger kit part # APT6SE would be right at 33 inches. This kit is designed for use with 9/16 inch bolts like the # 166079 and we would not recommend drilling out the kit to fit a wider bolt.
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  • 9/16 inch Diameter Shackle Bolt Longer than 3 inches Availability
    We have the # 166079 which is a 9/16 inch diameter shackle bolt like you need that measures 3-1/2 inches in length.
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  • Comparing Lippert Never-Fail Bushings to the Bronze Bushings and Wet Bolt Option for Tandem Axles
    The bronze bushings and wet bolts are a great option but they still do require maintenance especially under the conditions you referenced. There really isn't any new information in comparing it is basically the difference between maintenance required and zero maintenance. The Never-Fail bushings # LC279685 are maintenance free and self-lubricating so they will be a better fit for you. This kit comes with the bushings for 4 springs and two equalizers for a complete tandem axle trailer....
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  • 11 Inch Long Equalizer For 2 Inch Slipper Springs & 7/8 Inch Wet Bolt
    Hi Ryan, Really appreciate that detailed info, and we can get you the equalizer you're looking for, as well as the bolt. The parts you're looking for are the following: - Equalizer for 2" Wide Slipper Springs - 11" Long - 7/8" Center Hole # TREQ1304 - Wet Equalizer Bolt with Castle Nut and Grease Zerk - 4-11/16" Long - 7/8" Diameter # TRFA71063 Just note the equalizer and bolt come individually so because you need both sides you'll want to make sure you get a quantity of 2 of each.
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  • Replacement 30" Long Slipper Spring for Boat Trailer
    It sounds like you're looking for the 4-Leaf Slipper Spring w/ Flat End part # SP-040275 which is a slipper spring, 30" long x 1-3/4" wide, with four leaves. It can then be mounted on a 2" square axle with the CE Smith U-Bolt Kit part # CE23103. For the suspension bolts, we have the Spring-Eye Bolt with Locknut for Slipper Springs part # 166079.
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  • 12 Inch Slipper Spring Equalizer Kit Recommendation
    The only 12 inch slipper spring equalizer we offer is the part # E4541-Z. For shackle bolts you would need the part # 166079, for equalizer bolts you would need # TRFA71063, cotter pin part # 165649, and for spring keeper bolts part # 7-7. We do not have all of this in a kit though.
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  • Recommended Bolt On Hangers For Aluminum Frame Trailer
    Since you've got an aluminum frame trailer, I understand why you're looking for a bolt on solution. The only available bolt on hangers we have available would be the # CE14017G and # CE14016G but they are designed for slipper springs and not double-eye springs like # e77SR you were looking at. If you went this route you would want to use something like the # SP-040275 as your springs, which have a 3700-lbs capacity. This would be the best solution available for your new aluminum trailer,...
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  • What Type of Bushing Comes with 4-Leaf Slipper Spring w/ Radius End for 2,000-lb Trailer Axles
    The bushing that comes with the 4-Leaf Slipper Spring # SP-179275 is a nylon bushing like part # TRBU11566 so you need a standard non-grease bolt like part # 166079 for the installation. The nylon bushings are pressed in there by themselves without any specific type of sleeve.
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  • Hanger Bolt Recommendation for a 3-Leaf Slipper Spring # WIE3
    You need to use a 9/16 inch bolt for the front eye of the 3-Leaf Slipper Spring that your referenced part # SP-178275. For that I would recommend the Spring Eye Bolt with Lock Nut part # 166079. The correct rear hanger is part # 115706S if it's a single axle trailer. Since the spring does not have an eye on the back of it you do not need to match a 9/16 inch bolt to anything.
    view full answer...

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