All About Leaf Spring Centerbolts

[@kocherpm]

Great video for a wannabe trailer fixer like me. Thanks!

[@noahriding5780]

Are trailer leaf springs supposed to be more flatter than bow shaped compared to truck leaf springs? Thanks.

[@EatonDetroitSpring]

A leaf does not care which way it bows. the final shape, smiling or frowning, depends on the design of the spring. However, most trailer springs are designed to be smiling.

[@noahriding5780]

@@EatonDetroitSpring Thank you for the reply.

[@ChuddleBuggy]

I see many trucks especially from Ford and Toyota have springs flexed the opposite way (concave instead of convex). Do they still work in this inverted state? I always thought leaf springs elongate as they are compressed, hence the shackle that allows for them to change in effective length. But when they get inverted they would only shorten as more load or flex is applied! I worry they break this way but apparently they don't. I'm confused.

[@EatonDetroitSpring]

GREAT question and one we will have to do a 1MM on. The shape/direction a spring is bent while under load is determined by it's design. It can be bent upward (smiling) or downward (frowning), it does not matter for it will still support it's load and flex as it should. Many, many springs are designed to have a reversed arch when on the vehicle. The length of a leaf spring does change as it flexes. The purpose of the shackle is to allow for this length change.

[@Meche697]

With the center bolt being off center, how can you tell which side of the spring goes towards the front?

[@EatonDetroitSpring]

999 times out of a thousand, the short end of the spring goes to the front of the vehicle. But to be sure, tell me what the vehicle is.

[@Meche697]

@@EatonDetroitSpring 67 Mustang. Restarting a project car that dog tracked when "new" springs were installed. Looking to align the axle and doing easy item checklist first. Not sure if bushings would have an effect, but I think the one of the springs was installed backwards. Getting to the car shortly.

[@EatonDetroitSpring]

@@Meche697 I doubt very much that one of the springs have been installed backwards, for there is a 9.25 inch difference between the short end and long end of the spring. I would bet the center bolt head has not been located correctly.

[@blairjosephbernard2011]

What’s the torque specs on the centre bolt for 3/8 bolt

[@EatonDetroitSpring]

30 foot lbs. should be enough.

[@JacobWinkle]

My center bolt was installed the wrong way and I had to flip the center bolt because on a 2000 Chevy S10, the axle sits on top. Dorman by the way. So keep that in mind, someone, somewhere in a factory making minimum wage or less not putting it together correctly. Was on both brand new leaf springs and I'm not going to flip my axle.

[@happygear]

Do you called this bolt a center bolt?

[@CoastalAutoReactionCAR]

More great info!!!

[@baylor3769]

how strong dose the bolt have to be aka grade cuz when i look up new OEM bolts theres no grade and it just says snug it up

[@EatonDetroitSpring]

Most center bolts are grade 5, but grade 2 will do just fine.

[@baylor3769]

@@EatonDetroitSpring ok and how tight should it be

[@EatonDetroitSpring]

@@baylor3769 35 to 45 foot lbs would be fine.

[@baylor3769]

@@EatonDetroitSpring ok thx u

[@abelrivera4629]

Both of my bolts on my 88 chevy silverado c1500 are missing just recently checked because I noticed that my rearend keeps moving from left to right, right to left so by me putting in the new screws it should stop the rearend from swinging back and forth right ???

[@joedirt5098]

Great how the hell do I get the bolt lined back up in a new leaf spring

[@joshfixall7938]

Use ratchet straps

[@chevelle5021]

is there a front and back to a leaf spring when installing it if the center bolt is not in the center?

[@EatonDetroitSpring]

999 times out of one thousand, the short end goes to the front of the vehicle. But to be sure, check the position of the old ones before taking them off.

[@nobroko]

Great info , why are the centerbolts actually off centre ?

[@EatonDetroitSpring]

Length wise some are but most are not. The front half of the leaf springs almost acts as a trailing arm, while the back half provides the support. An off set spring can be a better design depending on the application.