I was recently thinking about adding carrying capacity to a travel trailer by replacing the factory axles with higher rated ones, but I got to thinking (a dangerous thing I know) how about simply adding a third axle of equal size and capacity in front of the other two (as most of my added weight such as batteries, mini-split AC and solar goodies would be in the front of the trailer), like I've seen on Airstreams, toyhaulers, boat trailers, etc.. It would seem that adding a 5,000 lb axle assy. would be cheaper and easier than replacing the 2 existing ones, not to mention being capable of carrying more weight. This would spread the trailer load on a larger area of the frame, for greater frame support (less flexing). It would make for a more stable ride too, with less front to rear weight shifting and tongue bounce. Plus I would add an extra pair of brakes for improved stopping ability too. Now, I don't think it would support the full 5,000 lb axle load rating, (as the frame would now be the weakest link) nor do I have any intention of adding even 1/2 that weight, just another 1,000 - 1,500 lbs of boondocking equipment.
My question is, has anyone added an extra axle to a TT or 5er, or known of anyone who has? If so, how did it work out.
Thanks for your replies,
Chip
TRAILERKING said
09:35 PM Aug 17, 2014
Not necessarily that simple.............A lot more to the whole picture. Just by adding an axle in front or behind the existing, you will change the "axle to pin(ball or fifth wheel pin)" ratio. Also the build and structure of the existing frame will make a huge difference on what may need to be done in the modification. Usually if adding another axle and not changing overall "Ball to Bumper" length, then would usually move the existing axles back slightly then add the new axle in front.
Sushidog said
11:01 PM Aug 17, 2014
Thanks for your reply, Trailerking.
Yes I agree, if I wanted to equally distribute the added weight on the trailer, then I would need to move the existing axles back a foot or so to balance the load. But what if all the added weight, were to be placed on the tongue, in the front storage compartment, and on the roof as far forward as possible? Wouldn't the weight be better balanced if the fulcrum or balance point were relocated forward a tad? Remember, like a tag axle that extra axle doesn't have to equally distribute it's rated 5,000 lb load, just support an extra 1,500 or so lbs added to the front, as the factory engineered axle placement is correct to support the existing travel trailer load, which would not change. True the frame would have to be of consistent width, strength and design to allow the placement of an additional axle, springs and hangars. This would need to be researched before the trailer is purchased. I think it would be better to take my trailer to a shop that builds trailers (there are a couple near where I live) to get their opinion on feasibility and axle placement as well as to actually do the fabrication.
Another question: Will the added rolling resistance of the extra axle materially affect mileage? Or will the reduced load and tire flex on the others offset most of the added rolling resistance of the extra set of bearings and tires? In other words do 3 axle trailers take much more power to pull than an equal weighted and designed 2 axle ones? And what would this translate to in real world fuel mileage numbers? .5 mpg? 1 mpg? More? Less?
I was recently thinking about adding carrying capacity to a travel trailer by replacing the factory axles with higher rated ones, but I got to thinking (a dangerous thing I know) how about simply adding a third axle of equal size and capacity in front of the other two (as most of my added weight such as batteries, mini-split AC and solar goodies would be in the front of the trailer), like I've seen on Airstreams, toyhaulers, boat trailers, etc.. It would seem that adding a 5,000 lb axle assy. would be cheaper and easier than replacing the 2 existing ones, not to mention being capable of carrying more weight. This would spread the trailer load on a larger area of the frame, for greater frame support (less flexing). It would make for a more stable ride too, with less front to rear weight shifting and tongue bounce. Plus I would add an extra pair of brakes for improved stopping ability too. Now, I don't think it would support the full 5,000 lb axle load rating, (as the frame would now be the weakest link) nor do I have any intention of adding even 1/2 that weight, just another 1,000 - 1,500 lbs of boondocking equipment.
My question is, has anyone added an extra axle to a TT or 5er, or known of anyone who has? If so, how did it work out.
Thanks for your replies,
Chip
Yes I agree, if I wanted to equally distribute the added weight on the trailer, then I would need to move the existing axles back a foot or so to balance the load. But what if all the added weight, were to be placed on the tongue, in the front storage compartment, and on the roof as far forward as possible? Wouldn't the weight be better balanced if the fulcrum or balance point were relocated forward a tad? Remember, like a tag axle that extra axle doesn't have to equally distribute it's rated 5,000 lb load, just support an extra 1,500 or so lbs added to the front, as the factory engineered axle placement is correct to support the existing travel trailer load, which would not change. True the frame would have to be of consistent width, strength and design to allow the placement of an additional axle, springs and hangars. This would need to be researched before the trailer is purchased. I think it would be better to take my trailer to a shop that builds trailers (there are a couple near where I live) to get their opinion on feasibility and axle placement as well as to actually do the fabrication.
Another question: Will the added rolling resistance of the extra axle materially affect mileage? Or will the reduced load and tire flex on the others offset most of the added rolling resistance of the extra set of bearings and tires? In other words do 3 axle trailers take much more power to pull than an equal weighted and designed 2 axle ones? And what would this translate to in real world fuel mileage numbers? .5 mpg? 1 mpg? More? Less?
Chip