Adjusting the hitch for a new set of axles

[Tom Bray]

We just got back from a our vacation over Thanksgiving, a little over 1300 miles round trip. Just before we left we put new axles and brakes on our 1972 23' Safari with tandem axles. We finished putting the axles on last Friday afternoon and left Saturday morning. The truck is a 2007 1500 GMC Sierra which we bought to tow the Safari.

The first thing I noticed when I hooked it the Safari to the truck was that the trailer is now towing a little nose down compared to being perfectly level prior to changing the axles (the new axles raised up the camper an inch or two). I commented that it was different to my mechanic friend and his response was that it should get better gas mileage when towed a little nose down, otherwise it shouldn't make any difference.

The first thing I notices is that I think the truck and camper being blown around more; by the wind, other trucks, and cars driving a lot faster than I was. In the past the truck seemed to be more stable with the camper on than with it off. For this trip, that wasn't the case.

Last year when we took the Safari from Central Alabama down to South Florida, the truck recorded in excess of 11 MPG, about 11.5 or so which included running fairly fast (70+) on the way home. This trip the truck registered almost 10 MPG with significant portions of the trip being in the low 9 MPG which I have never seen before except when crawling up a small mountain. In addition to the towing angle, these are brand new brakes but I would thing that after 650 miles on the first leg, of which a significant portion consists of country and small town roads, they should be pretty well broken in. So much for better gas mileage.

Can all this be attributed to improper towing angle?

The hitch is a Reese weight distribution variety that I got from the local Airstream dealer in Michigan. Since it worked so well in the past, I assume that they picked the right one and set it up correctly. Of course, since the dealer did the installation and setup, I didn't get any of the documentation with the hitch.

Suggestion? Comments?

Tom

[ROBERT CROSS]

Tom,

A little down...how little. Photo on level ground would help.

Do you have weight tickets from the original set-up?

First... I would get some weights from the CAT scales.

ITMT...more tension to bring the nose up...trailer must be level to distribute the weight equally on your new axles. Ck all tire pressures.

BTW...get the install/owner manual for the Reese. Probably available on-line.

Bob

[Inland RV Center, In]

Tom.

Your axles and trailer are designed to work together, as equally as possible.

When the trailer is not level while being towed, one axle is carrying more weight than it should and the other is carrying less weight than it should.

The tires will wear unevenly because of that.

A sway will be set up.

Your suggestion guy might be right, but for a single axle only.

Torsion axles work very differently from leaf sprung axles.

Get the trailer and tow vehicle level with respect to itself, and then your ease of towing will return.

Yes, when you replace axles, the front end will always be down, because you raised the trailer.

If the tow vehicle is level, then raise the ball so that it properly accomodates the new trailer ball height. That is a MUST.

Don't be mislead.

Andy

[Dan and Liz]

We had to raise ball height 1-1/2" after installing new axles. Then hitch worked fine just as before. "Nose down" probably means more weight on the front trailer axle; I agree with the need to get to scales and check tire pressure.

I guess your friend thinks you'll get better mileage because the trailer is going downhill all the time?

[Wazbro]

With the nose down on with torsion axles you will also have less tongue weight which will hurt towing performance.

[Tom Bray]

The truck is level, the trailer indicates about 1.5 ticks from level on the bubble level, which is probably close to 1.5 inches based on eyeballing it. I set the weight distribution bars the same as they always have been, they cinched up the same as they did before changing the axles.

There hasn't been a weight distribution change. I was pretty sure when I looked at it after it was on the truck, the tongue was down and the rear was up in the air, that things weren't right.

I was a little surprised by the difference in handling by it being just a small amount off.

I'll pull the Reese information before I start moving things.

The current rush is over, the trip was good, no real problems. Now I get to go and finish the things that had to be ignored to get on the road on schedule.

Tom

[overlander63]

The lower the nose, the lower the tongue weight. The lower the tongue weight, the more squirrely the trailer will tow.
I wouldn't think raising the trailer a couple of inches would increase drag enough to effect gas mileage.

[Tom Bray]

I was looking over the Reese manual and setting up the hitch is fairly involved and the directions are a bit confusing. By raising the hitch up an inch or so, should it be necessary to also adjust the angle for the leveling bars or should this setting stay relatively constant?

Tom

[KYAirstream]

Is there a general rule for the amount of hitch height required to be raised per the amount of lift achieved by new axles?



With 32 degree axles and going from 15" to 16" rims, my trailer went from 23.5" to 27.25" at the bottom of the passenger side wheel well and from 24.5" to just shy of 28" on the drivers. Raising the hitch 3.5" seems logical. My driveway isn't level, so it'd be nice to dial in the hitch height of the propride in advance.