Twin Axle Trailers

Silverfox · 23 July 2012, 13:21

I'd rather be safe than sorry.

I have a twin axle trailer, and at some point the wheels are going to have to come off, either to change to a spare or bearing change.

So, I am think of what kit I might need to change a wheel and how to do it.

Would I be correct to think that the best option is to jack up the trailer using the axle where the "flat" is, and then axle stand both axles, or do I jack the "good" axle, axle stand that, then jack and axle stand the one I want to change.

Or is simply jacking one axle OK, which would be my preference, but as I say, I'd rather be safe than sorry.

9D280 · 23 July 2012, 14:22

Is your concern that as it's a twin axle, the axle with thre jack under it is taking more load?

I suspect the dynamic load of driving along the road will be loads more than you'll see from the jack under one axle - remember the springs on the other axle will keep pushing that other wheel down, granted to a lesser extent the higher you go..... Otherwise it would fail on the first sign of a big hole as the forward wheel drops in!

Apoloigies if I misinterpreted your question.

Silverfox · 23 July 2012, 14:35

Quote:

Originally Posted by 9D280

Is your concern that as it's a twin axle, the axle with thre jack under it is taking more load?

I suspect the dynamic load of driving along the road will be loads more than you'll see from the jack under one axle - remember the springs on the other axle will keep pushing that other wheel down, granted to a lesser extent the higher you go..... Otherwise it would fail on the first sign of a big hole as the forward wheel drops in!

Apoloigies if I misinterpreted your question.

No need to apologies.

My concern is I have no idea of the travel of each axle, so wasn't sure which to jack up.

Maybe I am being overly cautious, but there is no issue on a car or single axle trailer, but as I have never had to change the wheel of a twin axle I guess my question is, what to do I need to be careful of, if anything.

jyasaki · 23 July 2012, 16:30

If you're that worried about overloading one suspension piece, you could always place the jack under the frame and raise both wheels clear. You'll need a taller jack than if raising the axles, but a single jackstand under the frame will support the whole thing.

From what I've seen boat trailers don't have a lot of suspension swing; 2 or 3 inches or so, depending on load (that's for leaf spring; don't know how much swing on torsion axles.)

jky

captnjack · 23 July 2012, 16:54

Just jack the one axle where the flat is. You won't damage the jacked axle just because its taking "all" of the boat load on that side. There should be ample capacity between the rated axle load and its yield load (ie they are built with a safety factor of about 3x).

Chock the wheels on the opposite, side although the hitch will probably do most of the work keeping the trailer from shifting.

Silverfox · 23 July 2012, 17:46

All good advice. Thanks

Pikey Dave · 24 July 2012, 11:13

I don't jack under the axle, I jack under the chassis close to where the axle bolts on. If I'm working at home changing bearings etc, I jack the trailer up & place axle stands under the chassis fore & aft of the axles. There's a photo somewhere on here, I'll try & dig it out.

Try this

Silverfox · 24 July 2012, 15:56

Thanks Dave - perfect.

captnjack · 24 July 2012, 18:46

Quote:

Originally Posted by Pikey Dave

I don't jack under the axle

Why not? I put my jack right under the pad where the axle bolts to the leaf spring. If I jack the frame there's a chance the road surface/angle will prevent the frame from getting high enough to compensate for the sag in the spring so the wheel won't get all the way off the ground.

Pikey Dave · 24 July 2012, 19:46

Quote:

Originally Posted by captnjack

Why not? I put my jack right under the pad where the axle bolts to the leaf spring. If I jack the frame there's a chance the road surface/angle will prevent the frame from getting high enough to compensate for the sag in the spring so the wheel won't get all the way off the ground.

Leaf spring!!

You'll be telling us you still buy petrol.. sorry gas, in gallons next

Most of our trailers have solid beam axles fixed directly to the chassis (you can see this in the photos) the independant suspension units are in the end of the axles, so lifting the chassis lifts the axles & wheels in one go. It's easier to lift under the chassis rather than scrabbling about under the trailer trying to get a jack under the axle(s) IMHO it's also more stable.

captnjack · 24 July 2012, 21:53

Quote:

Originally Posted by Pikey Dave

Leaf spring!!

You'll be telling us you still buy petrol.. sorry gas, in gallons next

Most of our trailers have solid beam axles fixed directly to the chassis (you can see this in the photos) the independant suspension units are in the end of the axles, so lifting the chassis lifts the axles & wheels in one go. It's easier to lift under the chassis rather than scrabbling about under the trailer trying to get a jack under the axle(s) IMHO it's also more stable.

Uhuh and I've seen a few pics of your torsion axles with the bushing all worn out

Most boat trailers over here are using leaf springs, cheap and easy to replace. And you can see their condition easily. You can buy the torsion axles, but they are more expensive and its a boat trailer afterall. Their added cost is not worth it to most.

And besides you still have the problem when you jack the frame that the wheel drops on the suspension and drags on the ground. Maybe not on your perfectly flat driveway. But along the side of the road its easier and perfectly adequate to jack the axle so you know exactly how high the wheel will get and stay that way.

Pikey Dave · 25 July 2012, 06:25

Quote:

Originally Posted by captnjack

And besides you still have the problem when you jack the frame that the wheel drops on the suspension and drags on the ground.

Jack (pun intended), that's the point, in effect there is no axle. The chassis & axle are effectively one unit. Jacking the chassis, jacks the axle. If you look at the photos, there isn't anywhere to jack up the wheel. When you lift the trailer, the wheel sag is minimal, due to the nature of the suspension. The only bit that moves in relation to the chassis is the small swinging arm between the end of the axle & the hub. With a wheel mounted, its virtually impossible to get a jack under there & if you could it would be very unstable. If you lower the jockey wheel (or vehicle suspension

) block up under the rear of the chassis, raise the jockey wheel/suspension, you can virtually get the wheels off the ground without using a jack, be it on a drive, roadside, or field.