What Torque Should Be Used For U-Bolt Nuts On Trailer Suspension

Question

Question:

Hello, I am changing the leaf springs on my boat trailer. When I tighten down the u-bolts, is there a foot pound number I should tighten them down to?

asked by: Lenny B

1

Helpful Expert Reply:

If the U-bolts are 9/16 inch diameter, the torque specs should be between 65 to 95 foot lbs.

If the U-bolts are 3/8 inch diameter, the torque should be between 30 and 50 foot lbs.

expert reply by: Jeffrey L

1

Dave

9/27/2024

Jeffery Hi, I need to re-align the bunks on our boat trailer and need to know if this also applies to the U-bolts for bunk brackets? Mine as 3/8" U-bolts with a nut and washer on each end of the bunk U-shaped bunk bracket bolt. Given bolt diameter I assume the correct approximate torque is 30 - 50 or around 40 foot pounds of torque. Though I'm uncertain of the threads per inch on this bolt and it appears they are zinc plated galvanized bolts not stainless steel. Thanks Dave

Reply

Kyle S.

9/27/2024

@Dave Yep, you assumed correctly, it is 30-50 ft. lb of torque and 40 would be just fine.

Reply

Dave

9/27/2024

@KyleS Thanks! I appreciate the info and the very prompt response!

Reply

Anthony

2/4/2025

I have a 10000 dual axles i realigned the axles put new hangers and equalizer im wound what are the inch pounds they get torqued down too

Reply

Jameson C.

2/4/2025

@Anthony What diameter u-bolts are they?

Reply

3/4 B.

2/6/2025

@JamesonC they are 3/4 U bolts

Reply

Jameson C.

2/6/2025

@3/4B For 3/4 inch diameter U-bolts the correct torque spec would be 160 ft lbs.

Reply

Answer 1

For 1/2 inch trailer u-bolts that attach to axle the recommended torque value is between 45 and 70 ft lbs of torque.

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Answer 2

The torque requirements for leaf spring u-bolts depend on the diameter of the u-bolts that are being used. If the gross weight of your tandem axle trailer is 7,000 lbs, then you likely have two 3,500 lb axles. Typically 1/2 inch diameter u-bolts are…

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Answer 3

Hey Jon; I was actually just talking to Furrion about heat options for the Chill Cube yesterday (1/21/2025). At this time, the only way to have heat with this unit is through a furnace on a ducted setup. The Furrion Chill Cube RV AC w/ Air…

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Answer 4

It's not common for the spindle number to be printed anywhere on the axle. That said, if you're looking for new bearings/races and seals all you need to do is note the capacity or measure. The easiest method would be to crawl under the…

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Answer 5

The only difference between a 4 leaf spring and a 5 leaf spring like the #e34SR is that the 4 leaf spring will use slightly thicker leaves and is 1/8 of an inch shorter. To get the best measurement of your existing springs, measure the center eye to…

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Answer 6

According to our FAQ on slipper springs, linked for referenced, the torque specs are as follows: Torque Ratings 1/2 inch Bolts: 45 ft/lbs - 70 ft/lbs 9/16 inch Bolts: 65 ft/lbs - 95 ft/lbs 5/8 inch Bolts: 100 ft/lbs - 120 ft/lbs The Replacement…

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Answer 7

The 5 means that the wheel is 5 inches wide from bead to bead (not overall width). The J indicates the design of the wheel bead seat but it is nothing you need to be concerned with as this is the most common shape for all trailer tires. To measure…

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Answer 8

Hi Leo; I would start by checking to see if there are axle tags on the axles. They will probably have the capacity on them or at least a serial number the axle manufacturer could use to identify the axle. If the trailer manufacturer is still in…

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Answer 9

When picking out an axle you really just need to go by the capacity and dimensions you need. The adjective used before "trailer" really doesn't amount to much. The numbers you listed are bolt patterns for the hubs that the axle comes…

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Answer 10

Hey Darrel, we actually have exactly what you are looking for with the part #TRU52FR which is for a 7k axle and is 25-1/4 inch from eye to eye. This is also a 6 leaf spring as well. The spring you referenced would be too short.

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Answer 11

We do have a more robust option to replace your 072-078-00 double-eye springs, which are for 4,400 lb axles and have a 2,200 lb capacity, like you mentioned. So for a higher capacity option, I do not recommend going any higher than a 5,000 lb spring.…

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Answer 12

There is no specific torque rating for shackle bolts. You'll want to ensure that the bolts you use are long enough so that when installed you will have at least 2 threads protruding from the nut. Make sure that the bolt you're using has a…

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What Torque Should Be Used For U-Bolt Nuts On Trailer Suspension

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