Weight Distribution Bar Size

03-01-2012, 06:43 PM

I just bought a used 2720SD and am looking at weight distribution hitches. I have searched the forum but can't find a discussion related to using 1000 lb bars when hitch weight could range from 600 to 900 depending on trip. So the question is if anyone uses 1000lb bars with light tongue weights.

rvcycleguy · 03-01-2012, 08:23 PM

Please explain why your hitch weight ( tongue weight) would fluctuate from 600-900 lbs? The tongue weight should not vary that much? depending on trips. What are you adding to the tongue to increase the weight that much? Propane, battery, tool box, ?

what am I missing from this inquiry? Typically the tongue weight is 10-15% of the tow weight.

ThePair · 03-01-2012, 08:37 PM

I recall a line of thought that pegged the "target" weight for spring bars that would offer WDH without being too stiff at 750-800#. 1000 seems like a little too much, some have reported that the lack of flex was less than ideal over bumps/dips, etc.

03-01-2012, 09:05 PM

My tongue weight can vary as some trips include 2 or 3 dirt bikes in the bed of my Tacoma. This adds about 300lbs behind the rear axle of the truck. It seems that the smaller bars would be overloaded in this case. I have seen some 800lb bars which may be adequate but could be at the limit. 1000lb would cover both cases if they are ok at 600lb tongue weight.

**mjlaupp** · 03-02-2012, 06:34 AM

I towed my 2720's with a 1000# WDH on my F150. I had no problem with the bars having "no flex" at lighter loads. My dealer recommended the 1000# bars for this combination.

I don't agree with using bars that are right at their rated load. I think that the bars should be rated at 120% to 150% of the anticipated load.

rvcycleguy · 03-02-2012, 07:00 AM

thanks for clearing that up for me jdaniel. Makes sense. I carry my cruiser motorcycle in the Tundra bed and I'm using the 1000lb bars. When I don't have the bike, I don't use the WDH.

03-02-2012, 08:00 AM

Although the WDH works well at getting weight off your rear axle and back onto the front, it also transfers a lot of weight to the trailer's axle.

You might want to check that you're not exceeding the trailer's GAWR if your 1000# spring bars are hooked up tight.

Mr. Adventure · 03-03-2012, 10:19 PM

My scale numbers show that 86# on the trailer axle is enough to take all but 320# of the 506# tongue off of the rear axle of my tow vehicle (with no WDH, the 506# tongue would add 733# to the rear axle of the TV). You can calculate the actual trailer axle loads as well as the loads you'll have on your spring bars with a spreadsheet you'll find here: http://www.trailmanorowners.com/foru...ad.php?t=12552

I don't see any virtue in undersizing the WDH spring bars, and I think adjusting the hitch head is probably easier if you have more capacity to work with.

03-04-2012, 08:38 AM

Quote:

Originally Posted by Mr. Adventure

My scale numbers show that 86# on the trailer axle is enough to take all but 320# of the 506# tongue off of the rear axle of my tow vehicle (with no WDH, the 506# tongue would add 733# to the rear axle of the TV).

If I'm interpreting these numbers right, your WDH removes 733 - 320 = 413# off the drive axle and only puts 86# of that on the trailer axle? And moving the remaining 413 - 86 = 327# to the steer axle? Don't think I have that right.

Anyway, my last CAT scale #'s are quite different.
http://www.trailmanorowners.com/foru...ad.php?t=12684
The WDH removed 440# from the drive axle and put 160# of that on the trailer axle, with the remaining 280# on to the steer axle.

But my main point was that when you're using a WDH to move a lot of weight off your drive axle, as these guys carrying motorcycles (as well as tongue weight) are trying to do, it's perhaps a good idea to check your trailer's GAW.

Mr. Adventure · 03-04-2012, 10:05 PM

Quote:

Originally Posted by brulaz

If I'm interpreting these numbers right, your WDH removes 733 - 320 = 413# off the drive axle and only puts 86# of that on the trailer axle? And moving the remaining 413 - 86 = 327# to the steer axle? Don't think I have that right.

Anyway, my last CAT scale #'s are quite different.
http://www.trailmanorowners.com/foru...ad.php?t=12684
The WDH removed 440# from the drive axle and put 160# of that on the trailer axle, with the remaining 280# on to the steer axle.

But my main point was that when you're using a WDH to move a lot of weight off your drive axle, as these guys carrying motorcycles (as well as tongue weight) are trying to do, it's perhaps a good idea to check your trailer's GAW.

What's happening to my 506# tongue weight is that my WDH is moving 100# to the front axle and 86# to the trailer axle, leaving 320 # on the rear axle. But yes, this has the effect of avoiding the 733# I'd otherwise have on the rear axle. yielding a net rear axle improvement of 413#, all with only 86# additional on the trailer axle. But weight "improvement" isn't the same as weight "movement" (we may need to get an accountant to help us here so that we don't add our debits and credits).

Your trailer has a long distance from the hitch ball to the trailer axle vs the distance from the hitch ball to the front axle. So whatever load you add to the trailer axle, you'll move more than that to the front axle. I haven't looked closely at your scale numbers yet, but I'll take a look and get back to you in a day or two.