Adding big deck/ extra axle to a 5er. Carry 4 motorcycles.
I have a 355 Chaparral that we love. Sleeps 10. Great loft, layout, etc. I pull it about 2500 miles every summer.
The stock 355 has a ULVW was 10,200 pounds. GVWR is 14,000. I upgraded the stock axles and tires from 6,000 pounds to 8,000 pound torsion units with hydraulic disk brakes. This all works great.
I also added a 40 inch HD rack and raised bicycle rack to the back and put on a roof rack. We presently haul 3 adult kayaks on the roof as well as 3 to 5 bicycles and and 2 dirt bikes on the back racks. The trailer presently weighs 13,500 pounds loaded up. We generally travel with empty tanks.
I've used the trailer like this for 8 years with no problems.
I'd like to upgrade it further. I want to haul 2 full size road motorcycles as well as 2 dirt bikes on a large rack on the back. Total bike weight will be 1700 pounds, plus the weight of the rack.
The trailer has a 10" drop frame in the back for the back bedroom. Currently it runs under the main 12" frame beam by about 6 feet.
I'm thinking of doing the following:
- remove the current running gear
- adding 10 feet of 10" beam to each side under the existing 12" frame in front of the drop frame. This will put a double frame (10" and 12") under the entire running gear, plus a few feet forward.
- adding 2x6 x 1/4" square tubing under the entire new length of the 10" frame and back under the 10" drop frame.
- bolting 3 8,000 pound torsion axles to the 2x6 beam. This raises the trailer about 6", which would be perfect as it sits a bit low right now. The trailer will now be a triple axle, with the extra axle to the rear of the existing axles.
- running the 2x6 past the trailer by a couple feet. This will be the base for the folding rear deck. I think it will be about 10 feet long.
So the frame will be:
- stock from a couple feet in front of the running gear to the front of the trailer.
- 2x12 stacked on top of 2x10 stacked on top of 2x6 from a couple feet in front of the running gear to the drop frame for the back bedroom
- 2x10 stacked on top of 2x6 under the back bedroom back to the rack itself.
The axles will go from 2 x 8,000 pound torsion hydraulic brakes to 3 axles.
Current loaded weight is 13,500 pounds. The new loaded weight will be about 15,000 pounds. The pin box is rated for 16,000 pounds.
I've run some calculations on frame bending moments and trailer hitch balance with this setup and it seems like a reasonable thing to do.
Current hitch weight is about 2,000 pounds without the dirt bikes, about 1800 with the dirt bikes. If my calculations are correct the new hitch weight will be 2400 pounds without the 4 bikes and 1800 pounds with the 4 bikes.
Adding the extra rear axle really decreases the frame bending moments. Adding the 2x6 under the entire rear portion of the frame really strengthens up the frame back there.
Has anyone done anything like this ?
The stock 355 has a ULVW was 10,200 pounds. GVWR is 14,000. I upgraded the stock axles and tires from 6,000 pounds to 8,000 pound torsion units with hydraulic disk brakes. This all works great.
I also added a 40 inch HD rack and raised bicycle rack to the back and put on a roof rack. We presently haul 3 adult kayaks on the roof as well as 3 to 5 bicycles and and 2 dirt bikes on the back racks. The trailer presently weighs 13,500 pounds loaded up. We generally travel with empty tanks.
I've used the trailer like this for 8 years with no problems.
I'd like to upgrade it further. I want to haul 2 full size road motorcycles as well as 2 dirt bikes on a large rack on the back. Total bike weight will be 1700 pounds, plus the weight of the rack.
The trailer has a 10" drop frame in the back for the back bedroom. Currently it runs under the main 12" frame beam by about 6 feet.
I'm thinking of doing the following:
- remove the current running gear
- adding 10 feet of 10" beam to each side under the existing 12" frame in front of the drop frame. This will put a double frame (10" and 12") under the entire running gear, plus a few feet forward.
- adding 2x6 x 1/4" square tubing under the entire new length of the 10" frame and back under the 10" drop frame.
- bolting 3 8,000 pound torsion axles to the 2x6 beam. This raises the trailer about 6", which would be perfect as it sits a bit low right now. The trailer will now be a triple axle, with the extra axle to the rear of the existing axles.
- running the 2x6 past the trailer by a couple feet. This will be the base for the folding rear deck. I think it will be about 10 feet long.
So the frame will be:
- stock from a couple feet in front of the running gear to the front of the trailer.
- 2x12 stacked on top of 2x10 stacked on top of 2x6 from a couple feet in front of the running gear to the drop frame for the back bedroom
- 2x10 stacked on top of 2x6 under the back bedroom back to the rack itself.
The axles will go from 2 x 8,000 pound torsion hydraulic brakes to 3 axles.
Current loaded weight is 13,500 pounds. The new loaded weight will be about 15,000 pounds. The pin box is rated for 16,000 pounds.
I've run some calculations on frame bending moments and trailer hitch balance with this setup and it seems like a reasonable thing to do.
Current hitch weight is about 2,000 pounds without the dirt bikes, about 1800 with the dirt bikes. If my calculations are correct the new hitch weight will be 2400 pounds without the 4 bikes and 1800 pounds with the 4 bikes.
Adding the extra rear axle really decreases the frame bending moments. Adding the 2x6 under the entire rear portion of the frame really strengthens up the frame back there.
Has anyone done anything like this ?
