To Lower the HF Frame or not

[Toytaco2]

It seems a lot of people mount the HF axle above the springs instead of beneath them where the assembly instructions say that they should go. I understand that this is to lower the trailer body. I'm no engineer so I'm only guessing, but doesn't that cause the trailer to essentially hang by the u-bolts from the axle instead of sit "perched" on the top of it? And, wouldn't this compromise the load capacity of the trailer?

Also, do most people use this "lowering the axle" approach and am I just worrying about nothing? I am considering a 5 foot hight for my trailer body so I would really like to have the lower overall height I could get from mounting the axle above the springs.

[Jim540]

I wouldn't worry about weakening the axle assembly by placing it on top of the springs. If you look at the way rearwheel drive cars ( the ones with leaf springs ) and smaller pickups ( like an S-10 ) do their rear ends it is this method. I don't think I have ever seen a broken U-bolt in a light duty capacity like you are talking about.

Jim

[Alphacarina]

It seems a lot of people mount the HF axle above the springs instead of beneath them where the assembly instructions say that they should go. I understand that this is to lower the trailer body. I'm no engineer so I'm only guessing, but doesn't that cause the trailer to essentially hang by the u-bolts from the axle instead of sit "perched" on the top of it? And, wouldn't this compromise the load capacity of the trailer?

Also, do most people use this "lowering the axle" approach and am I just worrying about nothing? I am considering a 5 foot hight for my trailer body so I would really like to have the lower overall height I could get from mounting the axle above the springs.

Yup - The trailer weight hangs from the U-bolts . . . . just as my brother's 12,500 pound 5th wheel RV does and just as many other well designed trailers do - Probably as many or more axles are mounted above the springs as below them

Do you need to do it? Probably not . . . . but if you're towing with a smallish tow vehicle (like a 4 cylinder car) then lowering the trailer about 5 inches (which is about what you'll get) will present you with less wind drag, better gas mileage and a more stable (lower center of gravity) trailer. I'm lowering the HF trailer I'm building . . . . for all the above reasons

Don

[boardhead]

The goal is to keep the trailer chassis level while towing, not tilted forward or backward. In my case, towing with a full size pickup, using a hitch with a 2" drop, it worked out best to mount the axle below the springs as shown in the Harbor Freight assembly instructions.

[Alphacarina]

I got my 'upside down' axle installed on the Harbor Freight trailer today and made an interesting observation

Initially, I was worried about wheel camber, as most trailer axles have a slight bend in them to put a little positive camber in the wheels so that when the loaded trailer stresses the axle, the wheels will both be about perpendicular to the ground . . . . because most axles flex a little when you load them. I was worried that the Harbor Freight axle might have a little camber in it and reversing it (putting it above the springs) would give me the opposite camber from what I need

Careful examination of the axle (and testimonials from many folks here) convinced me that the axle is essentially straight, so no need to worry about camber when flipping the axle . . . . but in my case, with the axle installed upside down, I actually have some positive camber on my wheels now (which is a GOOD thing) but it really makes me wonder what I would have had if I had installed it in the recommended manner

I suspect (but can't confirm) that maybe the Harbor Freight axle was designed for some trailer were it mounts above the springs and was possibly adapted to this trailer at a later time - I suppose it could be just crummy production tolerances, but on my axle, the positive camber on both wheels is exactly the same amount . . . . which would be a heck of a coincidence - With the trailer frame level, each wheel is tilted out at the top by 1/8th of a bubble or so on my level (plumb)

Anyway . . . . . It's certainly possible to reverse the axle with great results and I also easily took out the shortest leaf from the springs too, since my trailer final weight will be in the 1,000 pound range and I figured it would ride better on a softer spring

Don

[toypusher]

Somthing that I don't think has been mentioned here yet. The lower the frame sits to the ground, the more likely it is to drag when going thru dips and going in and out of lots of driveways. My curb (even into the driveway) is about 6" high and my drivewany slopes down a bit. The bottom of the tongue drags when I go in and out. That is with the axle mounted under the spings.

[Darren]

In my opinion the best reason to flip the axle is so your feet don't dangle when you sit in the doorway.

Kerry - When the trailer is attached to the tv wouldn't the height of your tongue be the same with the axle in either position?

[Steve_Cox]

Kerry,

Doesn't the tongue drag due to it's height at the hitch ball and the proximity of the rear wheels of the tow vehicle? I would think axle height placement would only be a consideration if the rear of the trailer frame drags, and on tear drops that is difficult since the axle is so close to the rear of the frame.

[toypusher]

OK, the tongue dragging on my sidewalk in my driveway is not a good example, but the back of the teardrop also just barely misses the same sidwalk when going out of my driveway and again when backing into it. The rear dragging is what I meant to emphasis about lowering the height of the frame. But, with that said, it would drag even more if my axle was mounted above the spings because I would then have to lower the height of my receiver hitch and that would lower the overall ground clearance.

[Alphacarina]

You guys must be talking about trailers with 8 inch tires

The top of my car hitch ball is 16 inches above the ground

Even with the axle flipped (on top of the springs) the trailer sat lower in the front than it did in the rear using the stock 5.30 X 12 tires supplied with the HF 1740 trailer - I really wanted to use 14 inch tires, but it would look like a 4 X 4 if I did and I'd never get it level

To cure the 'altitude problem' (and get the trailer level) I lowered the coupler on the HF 1740 trailer about 2 1/2 inches. Instead of it being just above the 'Vee' of the tongue, I now have it even with it. The trailer frame is still more than a foot off the ground (close to the 16 inches that the top of the hitch ball is from the ground) . . . . I really can't imagine either end of it dragging anywhere. I wish I could get it a little lower still

Pictures tomorrow

Don