Firestone Air Bags... will they increase payload?
09-04-2012, 11:15 AM
#21
Have not been able to find any info on their site or the web, but im wondering if the bags have any kind of built in bump stop? You would think that that would have some way of protecting the bag and shocks in a bottom out situation.
09-04-2012, 12:30 PM
#23
For example, my trailer has a tongue weight of 602# and my truck weighs exactly 6200#. With the bars on my WDH disconnected and the trailer just sitting on the hitch, my axles register 6802#. With the bars hooked up it registers 6560#. Point being, if you only have 600# of payload left after you have your truck loaded with people and gear you could technically have a tongue weight over 600# since the WDH will transfer some of it back to the trailer. If you are right at the limit, you should go to a scale and have it weighed. It's something you want to guesstimate.
I hope that's not too confusing.
09-06-2012, 12:56 AM
#24
Just to clarify, this is technically correct but a bit misleading. A WDH does not increase GVWR but it does put some of the tongue weight back on the trailer axle.
For example, my trailer has a tongue weight of 602# and my truck weighs exactly 6200#. With the bars on my WDH disconnected and the trailer just sitting on the hitch, my axles register 6802#. With the bars hooked up it registers 6560#. Point being, if you only have 600# of payload left after you have your truck loaded with people and gear you could technically have a tongue weight over 600# since the WDH will transfer some of it back to the trailer. If you are right at the limit, you should go to a scale and have it weighed. It's something you want to guesstimate.
I hope that's not too confusing.
For example, my trailer has a tongue weight of 602# and my truck weighs exactly 6200#. With the bars on my WDH disconnected and the trailer just sitting on the hitch, my axles register 6802#. With the bars hooked up it registers 6560#. Point being, if you only have 600# of payload left after you have your truck loaded with people and gear you could technically have a tongue weight over 600# since the WDH will transfer some of it back to the trailer. If you are right at the limit, you should go to a scale and have it weighed. It's something you want to guesstimate.
I hope that's not too confusing.
Also, you are forgetting the weight of the WDH itself, most are around 100-150 lbs. That would make it about a wash with a 600 lbs tongue weight trailer as in your example. So no, if you have 600# of payload left after you have your truck loaded with people and gear, you can't really have a tongue weight over 600 lbs and still be within the limits - unless that weight measurement was taken with the WDH attached.
Last edited by flixden; 09-06-2012 at 01:09 AM.
09-06-2012, 01:06 AM
#25
242 lbs of a 602 lbs tongue weight transferred back to the trailer sounds like you have your WDH too tight, it should only be around 150 lbs.
Also, you are forgetting the weight of the WDH itself, most are around 100-150 lbs. That would make it about a wash with a 600 lbs tongue weight trailer as in your example. So no, if you have 600# of payload left after you have your truck loaded with people and gear, you can't really have a tongue weight over 600 lbs and still be within the limits.
Also, you are forgetting the weight of the WDH itself, most are around 100-150 lbs. That would make it about a wash with a 600 lbs tongue weight trailer as in your example. So no, if you have 600# of payload left after you have your truck loaded with people and gear, you can't really have a tongue weight over 600 lbs and still be within the limits.
09-06-2012, 01:15 AM
#26
If you really have a tongue weight of 600#, and really transfer 240# back to the trailer axles, then you are probably transferring somewhere around 300 lbs back to the front, and your rear axle is nearly unchanged from having no trailer at all. That would mean that you are increasing the load on the front axle to more than unhitched - which should not be done (increased risk of jack-knifing the rig). What wheel base is your truck? 157" or 145"?
09-06-2012, 01:21 AM
#27
If you really have a tongue weight of 600#, and really transfer 240# back to the trailer axles, then you are probably transferring somewhere around 300 lbs back to the front, and your rear axle is nearly unchanged from having no trailer at all. That would mean that you are increasing the load on the front axle to more than unhitched - which should not be done (increased risk of jack-knifing the rig). What wheel base is your truck? 157" or 145"?
You are incorrect. I weighed it on a 3 section cat scale both coupled with WD and the truck alone. I had one axle on each scale. The front axle was identical (cat scales round to the nearest twentieth I believe) and the rear increased by roughly 360 pounds with the trailer hooked up. According to my tongue scale, it is a dead weight of 602. Tomorrow I can scan in the print outs and post them if you want to take a look.
BTW, it's a screw 145
09-06-2012, 01:35 AM
#28
Yeah, the numbers would be interesting. There could be some rounding errors, too, and tongue weight scale inaccuracy. I am assuming you use a Sherline (I have one, too, they are good, but not overly accurate).
With a 145" wheel base, you are unloading the front by 244 lbs without WD with a 600# tongue, assuming a ~60" ball overhang (measured on my Equalizer - what hitch are you using?). So if the front axle was identical, and the rear axle increased by 360 lbs after WD was applied, that means you took 484 lbs off the rear axle with the WD. If 244 lbs of that was added to the front to bring it back, then 240 lbs (= 484 - 244) were transferred to the trailer.
So you are right. That is the difference between a 145 and 157 WB truck, I guess, at least partially. Hmmm, interesting! 360lbs added to the rear axle sounds low, but again, the different wheel bases. My trailer has a tongue of 600 lbs also, and I am adding 525 lbs to the rear axle, transferring 225 lbs to the front.
With a 145" wheel base, you are unloading the front by 244 lbs without WD with a 600# tongue, assuming a ~60" ball overhang (measured on my Equalizer - what hitch are you using?). So if the front axle was identical, and the rear axle increased by 360 lbs after WD was applied, that means you took 484 lbs off the rear axle with the WD. If 244 lbs of that was added to the front to bring it back, then 240 lbs (= 484 - 244) were transferred to the trailer.
So you are right. That is the difference between a 145 and 157 WB truck, I guess, at least partially. Hmmm, interesting! 360lbs added to the rear axle sounds low, but again, the different wheel bases. My trailer has a tongue of 600 lbs also, and I am adding 525 lbs to the rear axle, transferring 225 lbs to the front.
Last edited by flixden; 09-06-2012 at 01:42 AM.
09-06-2012, 01:58 AM
#29
MDX, something still does not add up right.
Download this spreadsheet and play with the numbers (post #69):
http://www.airforums.com/forums/f464...s-19236-5.html
While there are still a few opens, your numbers indicate a very short trailer, only around 7.5' from ball coupling to midpoint of axle system. What kind of trailer do you have?
Download this spreadsheet and play with the numbers (post #69):
http://www.airforums.com/forums/f464...s-19236-5.html
While there are still a few opens, your numbers indicate a very short trailer, only around 7.5' from ball coupling to midpoint of axle system. What kind of trailer do you have?
09-06-2012, 02:00 AM
#30
Yeah, the numbers would be interesting. There could be some rounding errors, too, and tongue weight scale inaccuracy. I am assuming you use a Sherline (I have one, too, they are good, but not overly accurate).
With a 145" wheel base, you are unloading the front by 244 lbs without WD with a 600# tongue, assuming a ~60" ball overhang (measured on my Equalizer - what hitch are you using?). So if the front axle was identical, and the rear axle increased by 360 lbs after WD was applied, that means you took 484 lbs off the rear axle with the WD. If 244 lbs of that was added to the front to bring it back, then 240 lbs (= 484 - 244) were transferred to the trailer.
So you are right. That is the difference between a 145 and 157 WB truck, I guess, at least partially. Hmmm, interesting! 360lbs added to the rear axle sounds low, but again, the different wheel bases. My trailer has a tongue of 600 lbs also, and I am adding 525 lbs to the rear axle, transferring 225 lbs to the front.
With a 145" wheel base, you are unloading the front by 244 lbs without WD with a 600# tongue, assuming a ~60" ball overhang (measured on my Equalizer - what hitch are you using?). So if the front axle was identical, and the rear axle increased by 360 lbs after WD was applied, that means you took 484 lbs off the rear axle with the WD. If 244 lbs of that was added to the front to bring it back, then 240 lbs (= 484 - 244) were transferred to the trailer.
So you are right. That is the difference between a 145 and 157 WB truck, I guess, at least partially. Hmmm, interesting! 360lbs added to the rear axle sounds low, but again, the different wheel bases. My trailer has a tongue of 600 lbs also, and I am adding 525 lbs to the rear axle, transferring 225 lbs to the front.
The truck without the trailer but with the hitch and bars still in the receiver
Front axle - 3340
Rear axle - 2900
The truck and trailer weighed with WDH
Front axle - 3340
Rear axle - 3260
To me, it looks like the front is unchanged and the 240 pounds was transferred back to the trailer axles.