Update 2006 Rockwood Frame Bending

[thomasbr]

I am finally getting around to these repairs:

The frame on my 33 foot rockwood bent because:
1) It is built light; 9/64 inch thick x 2.5 inches wide x 6.5 inches tall.
2) It overhangs the rear axle by 11.5 feet.
3) This area holds a rear bedroom with a slideout and a bathroom.
4) Both 60 gallon waste water holding tanks are mounted underneath.

I earlier posted that I put two 8000 lb axles under this trailer (16 inch tires 8 bolt lugs) because I was burning out bearings and blowing tires. This trailer weighs over 7000 lbs empty and had 15 inch tires 5 bolt lugs on 3500 lb. axles. Some people speculated the bending was caused by too heavy of axles. However after checking with Dexter these 8 bolt Dexter rubber torsion axles #58632 with ST235/80R/16 tires, larger spindles, brakes, hubs, bearings, and heavier axle tube are also only rated at 3500 lbs/axle. So other than larger bearings, (no bearing failure since) larger tires, (no tire failure since and tires are E rated at 3500 lbs. each) and heavier axles I guess I didn't gain anything as far a suspension goes. I find this hard to believe but this is what the Dexter factory told me after looking up the part number.

I am not able to box in the frame or strengthen it in any substantial manner as the driver's side slide out supports come across the underside of the trailer and attach to the passenger side frame right in front of the forward rear tire. In order to continue using the trailer I purchased another #58632 axle and will be mounting just behind the second axle making the trailer a triaxle. I can extend the 8" x 3/16" x 2.5" axle support beam 5 ft behind the one mounted under the trailer frame in the same way and weld it to the frame and the existing axle carrier 8" box. This will leave only 5.5 ft of trailer overhanging the rear third axle support. The frame had bent right at the original rearmost axle support and by blocking the front of the trailer up and jacking the rear frame just in front of the rear bumper on both sides, with the axles hanging in thin air the frame now appears straight again. I will box the existing area on both sides where the frame had bulged out with some 1/4 inch plates also. Granted the trailer will weight a little more and the tires will skid when making extremely sharp turns but overall I think this is my best option and I will gain extra carrying capacity and another set of brakes. I will post some pictures as this project develops.

As far as the sagging floors go, I have removed belly cover as I thought I would have to shore the floors up from underneath as well work on the top side. When I opened up the top side under the vinyl I found that the deck is a prefabricated floor system of 1/4 inch luan plywood on top, glued to 1.5 inches of styrofoam with 1/6 inch fiberglass cloth glued to the bottom. There are however (good news for me) 1.5 inch square aluminum tubing sandwiched in this system 16 inches on center extending to both sides of the trailer and also of course sitting on the frame. Over time the area between the aluminum supports sags down about 1 inch as you step there because the bonding has broke between the luan and the styrofoam.
I have ripped out all of the vinyl, carpeting, and luan plywood in a couple of areas where it had been wet. (floor area in kitchen by closet that holds water pump had leaked for a while at one time) Also the front bedroom had rotten floors from water coming in where the front corner broke loose, water coming in the baggage compartment doors that have been left open in the rain at times, and from who knows where else. I was able to remove the luan in this area right down to the aluminum and styrofoam. I will sheet this floor with 3/4 inch treated t&g plywood and cover the rest of the floor where the 1/4 inch luan is still good with 1/2 inch treated plywood screwing to the aluminum supports. I am going to install a floating locking vinyl waterproof plank flooring system throughout the trailer including the floor of the larger kitchen slideout. I appears that the slideout will come up over the 1/2 inch plywood and new flooring. I will also post some pictures of this as it develops.

To Be Continued Later. Thanks for your interest.

[TURBS]

how will you fab the new "fender" needed to cover all 6 tires ?
or isnt that an issue ?

[thomasbr]

I don't know. Maybe I can buy some triples and cut the one with the slideout? May not be an issue as the tire is below the bottom of the trailer but you are right inferring that it may look funny.

[TURBS]

No problem I was just thinking out loud!

Good luck!
Can't wait to see pics

[trudinator]

What model do you have?

[thomasbr]

8318 SS model with a living room slideout and rear bedroom slideout. I am just getting back on it. I have the third axle installed. the new floors installed, and the front bedroom remodeled to a center aisle with two twin beds instead of the queen bed. I just need to lay the vinyl plank flooring and install the aluminum side panels to the underbelly. Should be done in a couple of weeks.

[thomasbr]

Found some tri-axle fender skirts that should work perfect on the internet for $120 from rv surplus in Indiana. These are new and will be in about the first of June. I will post some pictures when finished.

[TURBS]

saweet !

[Driftfishing1]

I have the exact same issue with my trailer. Here is how I fixed it - and it wasn't cheap.

The issue:

The driver side factory frame rail was cut just behind the second axle and extended outward about 10 inches and then continues to the rear bumper to allow the toilet access to the holding tank below. Also located behind the second axle are both the black and grey water tanks. This design coupled with the location of the holding tanks and the light weight frame caused our frame to sag almost 2" over approximately 10 ft and made the operation of the passenger side slide out difficult.

What I did:

I had a local frame shop straighten the frame and weld in a 6" x 2.5" x 3/16" wall tube that extends 6 feet in front of the axles and 8 feet behind the axles on both sides. This is the same size tube that existed in the axle truck assembly so it was simply cut out and the new tube/axles welded in their place. I'll post some images of the repair and the factory frame issue.

This, of course, created issues with the lower aluminum skirting and the plastic belly pan but a few hours with an aluminum brake and some self tapping screws and it looks as good as new.

The trailer is a bit heavier now than it was before, but it is infinitely stronger.

[thomasbr]

Thanks for the information. I had looked at beefing up the existing frame by adding steel plate to the sides but with the slide out rails and other items I could not get enough ahead and behind the axles to do the job. I never thought of cutting out the center of the existing I beam and replacing it with box tubing but I think this is a great way to solve the problem with the inherent design of this model. I had replaced the two 5 bolt axles with 8 bolt axles with heavier bearings and tires to solve a problem I was having with bearing failure which solved that problem and then the frame gave way. I thought that 5 bolt axles were rated at 3500 lbs. , 6 bolt axles at 5400 lbs, and 8 bolt axles at 8000 lbs. After the frame bent I decided the easiest way to fix this was to add extra frame underneath the existing frame behind the rear most axle and add a third axle. I found another axle identical to the two I had previously purchased from the same surplus rv supplier and decided to call dexter to see exactly what these are rated at. (someone speculated that the 8000 lb axles I thought I had added created too stiff of a suspension and caused the frame to bend.) It turned out that the rubber torsion axles I bought with the 8 bolt wheels are also rated at 3500 lbs, so I only gained the heavier bearings and tires and not any increase in weight rating. Now with three 3500 lb axles, I feel comfortable carring the extra weight of the third axle, the 1/2 inch plywood floors above I added, and the weight of the extra frame and steel behind the second axle. I now have a frame cantilever of 5.5 feet instead of 11 feet behind the last axle and do not anticipate any problems in the back again. ( I hope the front doesn't bend now between the tongue and the first axle) My 1x2 wood also came off the bottom of the frame which holds the underbelly plastic as the self taping screws broke. I replaced all of that with 2x2's on 24" centers and installed 1/2 inch foil faced foam to the bottom of this before putting the plastic underbelly back on. The aluminum was long enough to make it but I had to fabricate 10 new steel end caps to replace the plastic ones as it now is 1.25 inches below what it was with the 3/4 inch 1x2. The floors broke down because they are a 1/4 inch plywood glued on top glued to 1.5 inch styrofoam glued to 1/8 inch plywood with a black plastic filmed glued to this on the bottom. This whole floor system has 1.5 inch aluminum square tubing with a hardwood core sandwiched at 16" centers throughout. It is laid on the frame and everything is built off of this. When eventually the glue bond breaks down the floor begins to give between the aluminum joists. I was able to laminate 1/2 inch plywood throughout the camper except I had to stay 10 inches back from the big slideout since it had to come in about 10 inches before it would clear the 1/2 inch plywood and the 1/4 inch vinyl plank floor. I just feathered the vinyl plank from the new plywood to the existing floor at the slideout joint. I did not add plywood to the slideout as it is 3/4 inch solid plywood. I no longer have any carpet in the camper. I also reconfigured the master bedroom since I had to remove the bed and cabinets to replace the floor. I opened up the sliding door opening to the size of the sliding door and jambed it to swing into the kitchen which can now only be accessed if the main slider is out about 8 inches. I put two twin beds on each side of a center aisle with a long storage area under the drivers side bed accessible from the front left compartment door and a short storage space under the right bed accessible from the outside compartment door, and the rest of the space under the right bed accessible from the center aisle for suitcases and such. All in all it turned out really nice and does not seem much heavier to tow. It stops better with the three axles with brakes but will tear up the ground more with very sharp turns when parking and you need more room when turning to clear the curbs. I will try to post some pictures in the near future. It was interesting adding the third axle well on the left side as I had to cut and extend the existing frame farther back from where it had originally jogged to clear the toilet drain. I also added a 60 gallon fresh water tank to the existing 34 gallon tank and mounted both over and between the axles and replaced the holding tank dump cables in the back with solid pull rods.

[thomasbr]

The vinyl planking is about 1/4 inch thick and not 1/2 inch adding a total of 3/4 inch to the existing floors.

[SkyQuake]

I noticed this post is about 10 years old, but I'm wondering if the original members are still around and responding to the comments here. Let me know. Thanks, James.

[bikendan]

Originally Posted by SkyQuake

I noticed this post is about 10 years old, but I'm wondering if the original members are still around and responding to the comments here. Let me know. Thanks, James.

As I said in your other post, in a 3 year old thread, you might be better off sending the OP a PM. They haven't posted in almost 10 years.

[krazyk]

This might be a strange thing to ask but why didnt you trade this in on a new one? Your wasting alot of time and money.

[wmtire]

Originally Posted by krazyk

This might be a strange thing to ask but why didnt you trade this in on a new one? Your wasting alot of time and money.

What is even stranger is that this question is being asked in a 9 year old thread from 2012 that was resurrected. Going to go ahead and close it to put it to rest.