Tuesday, March 21, 2023


Trailer folk: Jack the frame – not the axle

By Russ and Tiña De Maris

bigK of Justice on flickr.com

When we were new to the RVing-with-a-trailer set, we bought an older fifth wheel that had been sitting about on its tires for some time. Lots of tread left, sure, but the tires themselves had been exposed to plenty of UV radiation. Our RVing mentors “learned us” quickly that just because there’s plenty of tread left doesn’t mean it’s a safe tire. We soon took our “new” rig to what we thought was a reputable tire shop and got new treads all around.

More things to learn soon followed: The tire guy had us park the rig out back, and he set to work pulling the old tires off, replacing them with new. Some months later, and a few (emphasis on “few”) thousand miles later, those “new” tires weren’t looking so sharp. Odd tread-wear patterns began to appear on a couple of them, while the others looked pretty good. We replaced them, while head scratching.

Running into another season of snowbirding with our experienced friends, we got some seasoned advice: Best to take the trailer to an alignment shop experienced in RV work. It was a 90-mile tow to the shop, and they found our problem was a bent axle. Where did it come from? Road damage, possibly – hit a pothole, a big rock, what-have-you. But another bent axle possibility – improper jacking. Did the tire store flunky jack the trailer by the axle? Memory (though dulled by age) suggests that he might have.

Regardless of cause, ever after we’ve been extremely careful when tire work is done – hanging around and watching shop workers. More than once we’ve had to intervene when the tire guy has tried to set the jack under the axle.

So how does one safely jack a trailer?

First, do your utmost to do your lifting operations on solid, level ground. Thick gravel can cause a jack to slip, which could end up in injury or damage. If you’re stuck on a gravel road, see if you can “dig down” to solid ground to seat the jack.

Second, chock the wheels on the side opposite you’ll be raising up. This means a chock against the forward tire, and a chock against the rear tire. Don’t think about lifting your rig with it unchocked.

Finally, always set the jack under the trailer frame. In some instances this may mean you’ll need to block up the jack. Don’t try and throw blocking between the top of the jack and the frame: You’re asking for trouble. Rather, set solid “two-by” lumber under the jack, large enough the jack base will fit on a single board, not shoving two or more chunks together side-by-side.

While you have the trailer jacked up, it’s not a bad idea to spin the tire around through a rotation or two. Listen closely: Grinding noises or rough travel could indicate a wheel bearing in need of replacement. If you’re suspicious, don’t waste any time getting the bearing inspected – a trailer wheel rolling off into oncoming traffic is a sight you won’t soon forget.

Jack the frame, not the axle, and you’ll spend a lot less on alignments or tire replacements.




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3 years ago

Seems funny to me, too. But, the trailer manufacturer says don’t jack the axles… Use the frame. Now, who should know best?

Kathey Carr
5 years ago

? How would I identify the spring plate on my 2018 Salem 33ft TT?
Would that be the right place for me to add one of the secondary manual Jacks I just bought to supplement my automatic ones, so that hopefully I can get the trailer level?

5 years ago

Seems like jacking on the frame would have the possibility of causing a bent or twisted frame no? No single point on the frame is designed to carry the entire load of that side of the trailer. I think jacking at the spring attachment point as others have suggested is the best course of action.

5 years ago

Jack under the spring. Jacking under the frame is rarely a good idea.

5 years ago

I jack under the spring plate on the axle . MUCH safer and less likely to bend the frame. The axle is designed to carry the load on the spring plate. Bent axles most often caused by road damage or overloading.

Tommy Molnar
5 years ago

I agree with Mr. Reed. Trying to jack the trailer up by lifting by frame is a HUGE effort. Our Arctic Fox sits considerably higher than many other trailers, so this idea is problematic. And Like Barry mentions, I too put my bottle jack directly under the spring plate and gently lift the axle just enough to spin the wheel. I think this method closely resembles driving over a bump – it pushes up against the spring plate.

R Reed
5 years ago

Depends on where you jack it up on the axle just like a car. To the outside preferably under a spring plate. When you jack on the frame you must be able to raise the trailer enough to compensate for the droop as the spring lets the tire down. Even with blocks many, I do mean many trailers sit too high. I’ve been associated with the auto industry for over 40 years and being interested in this I checked with a few shops that I know who do a lot of trailer repair and maintenance. Only on very specific instances do they jack up the unit on the frame. The most common problem I’ve seen over the years with bent trailer axles is being overloaded.

5 years ago

I always place my bottle jack under the spring plate.
That way I can safely lift the tire without having to lift the entire trailer.

5 years ago

Always have trailer tires balanced.

Denise Wolff
5 years ago

Should the trailer tires have balance weights?

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