How to Determine Weight Capacity of Trailer Axle

Question

Question:

I know I have a 4 leaf spring on my utility trailer. Is there a way to find out which load capacity my axle is? I snapped the spring on my last trip. I have yet to remove it was trying to understand what I should be looking for before talking it apart. Thank you for any help.

asked by: Cecillia L

0

Expert Reply:

To find the load capacity for your axle you should look on the trailer VIN plate or sticker that lists the VIN number. The weight rating of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that will list the weight capacity.

You can also tell the weight capacity of the axle by measuring the diameter of the axle. Here is a list that will show the axle weight capacity based on the axle diameter:

Typical Axle Diameters Based on Axle Capacity:
- 1,000-lb - 2,000-lb Axles: 1-1/2 inch diameter - 1-3/4 inch diameter - 2-3/8 inch diameter
- 3,500-lb Axles: 2-3/8 inch diameter - 3 inch diameter
- 6,000-lb - 7,200-lb Axles: 3 inch diameter
- 8,000-lb Axles: 3-1/2 inch diameter
- 9,000-lb Axles: 4 inch diameter
- 10,000-lb Or more axles: 5 inch diameter

If you cannot determine the weight capacity using the above suggestions the next step would be to measure bolt pattern on the hub, size of brakes, and bearing part numbers, to narrow down the capacity of your axle.

The more information you can provide the better we can find you a solution.

expert reply by: Chris O

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John

7/3/2020

The above axle diameter don't include 5200lb axles?

Reply

Chris R.

7/8/2020

A 5,200 pound axle likely has a 3" diameter, although it's good to keep in mind that diameter alone isn't the best way to determine its rating. You'll want to go by the info sticker/tag on the axle itself or by checking with the trailer manufacturer if there isn't one.

Reply

Steve

10/1/2020

@ChrisR Need some information on a square tube axle w/12 brakes. The seller I bought them from had acquired them by themselves and had no info regarding their capacity or what they came off of. Specs" 2" square tube, appear to be .250 or thicker tube, and springs were over axle. 5 bolt backing brake backing plate with 12" brakes and 5 on 5.25 lug bolt pattern Outer bearing number is LM67048(Koyo brand) Using the spindle diagram featured in other answers, the measurements for mine are A-1.753" B/C Section-tapers from 1.64" to 1.435" and is " in lentgh D-1.248" E-0.982" F-1.23" Info needed, is What are your bearing replacement numbers? What is the capacity range? Then based on their capacity range, could they be used with a trailer that has 83" hub face to hub face axles w/65.5" center to center spring perch, and these axles are 90" hub face to hub face. I understand that there is a limit on how far the spring perches cam be from the hub face, is the 65.5" of the current frame within the safe range, and if not, could I reinforce the outer ends, to negate the stress/force applied to the bearings due to the narrower perches? Thanks

Reply

Jon G.

10/2/2020

@Steve We definitely have the replacement bearing # LM67048 that you need, but I'm having trouble finding anything that matches the dimensions you recorded for the B/C measurements. Did you remove that bearing as well so that we have a part number? Trailer 12" brakes usually fall in the 5.2K - 7K range for the axle but I would confirm this on your end by looking on the axle itself for a plate that says what the weight capacity is. This can generally be found in the middle of the axle. Spring seats can be cut off and then new ones welded on to accommodate differences in trailer designs but this axle that you're talking about is pretty different than the ones that you're currently using. I recommend going with an axle that has the same hub face measurement and then you can adjust the spring seats a little if needed.

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See All (5) Replies to John ∨

Answer 1

Often an axle's weight rating will appear on a sticker or plate on the axle beam itself, or sometimes the trailer's main identification sticker will include axle ratings. This is helpful unless of course the axles have been replaced…

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Answer 2

The standard diameter for trailer leaf spring bolts is 9/16 inch which is why the part #E4139 and all similar options have this hole size. We don't have anything with a smaller diameter but my guess is what you have is actually 9/16 inch.

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Answer 3

Yes, the Roadmaster Comfort Ride system part #RM-2460-2570 would fit your 2019 Fuel 335 Toy Hauler. It would do a great job improving the ride quality.

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Answer 4

Yes you certainly can go from a 4 leaf to a 6 leaf spring on your 2020 Open Range 5th Wheel. It will add slightly to your ride height, but there should not be any other components that will be compromised or need to be swapped out. You will want to…

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Answer 5

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose #8-258-5UC1. If the inner bearings are marked…

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Answer 6

We can help but we don't have wheel cylinders for the brake assemblies you have. Best solution would be all new assemblies like the part #AKUBRK-35-D which are 10 inch assemblies for a 3,500 lb axle. If you had a 5k axles the assemblies would be…

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Answer 7

Thank you for the photo and dimensions of your 368 equalizer! You can upgrade your leaf springs from 4K to 6K but just keep in mind that it will make the ride quality of your trailer a bit more stiff and the springs need to have the same length as…

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Answer 8

Hey Rob, the bolts that come with the equalizer kit part #AP233 that you referenced are Grade 5.

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Answer 9

Your 5th wheel is equipped with a Venture CJ13517 pin box, and I'm sorry to say that there is not a compatible Gen-Y Goose Box model. So your best bet will be to continue to use your B&W Companion hitch. If you want to replace your pin box,…

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Answer 10

We do recommend switching over to an 8 on 6-1/2" bolt pattern when adding disc brakes to a 7K axle. All of the 6 lug disc brake kits are going to be rated for 6K and under. For a full disc brake conversion I recommend the Hydrastar Conversion…

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Answer 11

Trailer wheel bearings are specific to the spindle that is installed on the axle that is on your trailer. You will need to safely support the trailer, remove the wheel and tire, remove the grease cap, remove the cotter pin and washer that secures the…

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Answer 12

The Roadmaster Comfort Ride Leaf Spring Suspension Kit w/ Shock Absorbers - Tandem 7K Trailer Axles #RM-2460-2570 is a new system for 7,000 lb axles that isolates each axle. It uses both slipper springs and shock absorbers to accomplish this and give…

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How to Determine Weight Capacity of Trailer Axle

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