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“How to Determine the Proper Rise or Drop of a Ball Mount - CURT”


At 38 seconds into the video the person talking to the camera starts to describe how to find the trailer’s coupler height using a bubble level.

That only works if the trailer is setting on a level surface.

It is difficult to eyeball a level surface, and outdoor hard surfaces are not level by design to allow water to run off. The method might work IF the hard surface is ‘close’ to level, but most aren’t.

A better method is to measure known points at the same height position on the trailer near the front and rear of the trailer and adjust the tongue jack so that they are equal distance from the hard surface.

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In the photo, the trailer has been leveled with a bubble level. The photo shows hard ground that is obviously not level under the trailer. This would not be the ideal place to measure coupler height, but it could be done. It is obvious that the bottom of the coupler is closer to the ground than the same point would be at the rear of the trailer.

In the video, he describes the most typical way to find the drop, or rise, required for the hitch; subtract the receiver height from the coupler height.

He is demonstrating what is called a bumper pull, or weight carrying hitch, with a trailer that will be pulled by a pickup truck. That means no weight distributing hitch.

If that trailer is relatively light, it will have little effect on the rear suspension compression and that method for finding the drop, or rise, will work fairly well.

The pickup could have a Class III hitch. If it is a Class III hitch with a 2” square receiver, then “Class III hitches used as weight carrying are rated up to 6000 lbs. gross trailer weight (GTW) with a maximum trailer tongue weight (TW) of 600 lbs.”

If the tongue weight is approaching its maximum, the suspension will be compressed some, even on the pickup. How much? There is really know way of knowing.

When the suspension is compressed, the receiver height is changed. It may, or may not, be changed enough to affect the resulting drop or rise number.

The receiver height changes from about 24” for an unloaded Ascent to about 21.5” with a tongue weight of between 400 lb. and 500 lb. That’s significant and has a significant affect on the correct drop, or rise, required.

“How To Determine the Rise or Drop For Your Ball Mount - Draw•Tite®”


At 1:18 in this video the voice-over person notes, “Make sure that both the tow vehicle and trailer are parked on level ground.”

It shows leveling the trailer with a bubble level.

The method for determining the drop, or rise, is the same as in the Curt video.

The same comments apply as for the Curt video.

How to Select the Correct Ball Mount for your Hitch


At 31 seconds into the video, the spokesperson says to “level your trailer”, but gives not hint as to how.

All of the comments from the previous two videos apply.

Reese-Hitches Website:


The methodology is slightly different. The measurement for the receiver height is the same as previously mentioned.

Step 2: Level trailer, then measure from the ground to the top of the trailer coupler.

Step 3: Subtract the height of the hitch ball (most are 2-1/2" to 3" high) from Step 2. The example would be 18" minus 3" = 15”.

Step 4: The difference between Step 1 and Step 3 would be the "Drop" or "Rise" that is needed for your Towing System. The example would be a result of 8" (23" minus 15") Drop is required.

The term level is not qualified, and the result, again, does not allow for the compression of the suspension.

Based on the above, I believe that the best way to measure for the ball mount drop, or rise, for the Ascent is to use a receiver height of 21.5” and then to set “level” for trailer using the measuring method and NOT the bubble level method to determine the bottom of the coupler height and then finding the difference between 21.5” and the measured coupler height. The resulting number will have to be rounded to the closest inch.

The measuring method is demonstrated here.

 
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