Where to Jack your Mac-trailer

[Wind Chime]

We have a 2000 factory steel trailer with standard leaf springs.

After having it completely rebuilt a few years ago I'm trying to keep up with the annual brake/bearing maintenance etc, and every time I go to jack the trailer up - I wonder if I am putting the jack in the right spot under the trailer?

Thoughts on best place to put the jack? Just using the standard "x" type vehicle jack.

[Tomfoolery]

Right under the spring stack takes the least cranking, and is the lowest spot. But that axle is relatively robust, so anywhere near the springs would be fine, too.

When I service the bearings on mine, which is every spring after launch, I use a shop crane and lift the whole trailer side high enough that I don't have to bend over.

[Wind Chime]

Under the springs huh ? ... ya, that's why I asked - a guy at the marina says it's best under the frame because it doesn't cause any stress to the spring attach brackets?

Is this also incorrect as well? - lift the tries off the ground over the winter, to take stress off the tires and springs and allow you to rotate the wheels/brakes/bearings. I've got a set of trailer stands, is it worth it to block it up, or can being on jacks stress the steel trailer frame?

[NiceAft]

I have been wondering for awhile now, whether or not I should protect the tires by raising the boat and trailer up on four jack stands over the winter?

Ray

[grady]

Under the springs huh ? ... ya, that's why I asked - a guy at the marina says it's best under the frame because it doesn't cause any stress to the spring attach brackets?

Jacking on the axle will not change any stress on the spring hangers!!!!! They take a lot more when you are running down the road hitting pot holes.

[Tomfoolery]

Under the springs huh ? ... ya, that's why I asked - a guy at the marina says it's best under the frame because it doesn't cause any stress to the spring attach brackets?

Jacking on the axle will not change any stress on the spring hangers!!!!! They take a lot more when you are running down the road hitting pot holes.

Second that. And metal fatigue is not caused by time under load (bending stress in the springs themselves in this case, mainly). It's caused by changes in load, over many cycles. The greater the load, the fewer the cycles to fatigue, as a general rule. So rollin' down the highway with the springs flexing constantly will do more damage over time (number of cycles and magnitude of stress variation) than just sitting on them, which causes no fatigue.

And steel has the property known as the endurance limit (and other similar names) which refers to the stress below which the material will never fatigue. Aluminium and other non-ferrous materials don't have such a limit, and can experience fatigue (and fatigue failure) with enough stress cycles of any magnitude.

Which is why I support the middle of my mast when trailering, as it already experiences cyclic bending stresses while sailing, and fatigue failure is hardly uncommon in the area of the spreader connection. Don't need to add to it by letting the mast bounce around while doing nothing useful.

[paul I]

I have been wondering for awhile now, whether or not I should protect the tires by raising the boat and trailer up on four jack stands over the winter?

Ray

I bought a new pair of jack stands this year for this specific reason. It cant be good to let those tires sit in one position under load all off season long. You wouldn't want to do that with a car for an extended layup either.

By the way... why would you need 4 jack stands? I was planning on using only 2, one under each side of the axel with the bow supported by the trailer jack.

Any other thoughts on this?