What Are The Longest 3,500 lb Axle U-Bolts Available?

Updated 03/25/2026 | Published 03/20/2026

Question:

My travel trailer has two dexter d35 3500lb axles and Im planning to replace the leaf springs because mine are flattening out. I have the upgraded leaf springs 3-Leaf Double-Eye Spring for 4,000-lb Trailer Axles - 25-1/4inch Long Part Number: e57SR but someone suggested i change out the ubolts too. I found u bolts on your site with a 5.5inch depth but my current setup measures closer to 6inch depth which leaves some thread sticking out past the nut. Do you carry longer u bolts? Or will the 5.5inch stretch that much when torqing?

asked by: Ryan

U-Bolt Measurement
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U-Bolts
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Axle Tag
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Expert Reply:

Hello Ryan, thanks for reaching out. Yes axle U-bolts are not meant to be re used so you will definitely want to replace them. For a 3,500 lb 2-3/8" diameter axle, the longest we carry are the 5-1/2" U-bolts like what come with the # APUBR-1 kit you were looking at. They aren't going to stretch any significant amount when you torque them.

That said, the 5-1/2" length is measured from the inside of the bolt, not the outside. Looking at your picture it looks like you are measuring the 6" from the outside of the bolt, so I am thinking the 5-1/2" bolts will definitely work for you. Its a very common/standard size so this very well could be what you have now.

Can you retake that measurement from the inside of the bolt and confirm?

Any other suspension parts are needing?

expert reply by: Jesse M

U-Bolt Dimensions
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Ryan

3/20/2026

It's hard to show in the photo with the angles but as close as i can tell 5.5" would be flush with the nut or slight recessed. I did re measure to verify.

Earl M.

3/21/2026

@Ryan Hi Ryan, I had the same issue/thought. Old u-bolts had extra threads. I changed out leaf springs as mine were also almost flat and tires rubbed a hole through underbelly and wore a hole in the water line(pectubing). So I had more to repair than expected. The new u-bolts had barely a threads after tightening. I've checked it periodically just out of caution. Hope this helps. Happy Camping. Earl.

Jesse M.

3/24/2026

@EarlM Hey Earl, thanks for sharing your thoughts! That definitely helps!

Jesse M.

3/24/2026

@Ryan I gotcha. Sounds like the 5.5" should still work. Especially if you are having a hard time finding a 6" version.

Woodchucks G.

3/21/2026

It was long past due and lost an axle pack destroying a steel fender on a 35 year old trailer. E Trailer had what we needed. E Trailer provides detailed measurement information as well as seasoned experts ready to help. Don't guess, Use they're site Info and compare it to yours & remeasure & remeasure. Make sure you order the correct Lb & style spring your already using. The U bolt kits are perfect - just measure your own to determine width and length. We filmed the install on FB reels on our own FB page. We filmed everything with E trailer kits prominently displayed.

Jesse M.

3/25/2026

@WoodchucksG Thanks for sharing your experience! Glad the kit worked out and that our measurements and fit info helped make the install go smoothly. Appreciate the tip on double-checking spring style too, that’s huge.