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Old 11-28-2012, 10:06 PM   #1
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Rockwood 8315SS Axle Upgrade

A little history to begin with.

On our first trip with this trailer, a 2007 model Rockwood 8315SS, purchased in October of 2006, my first stop was at the scales. The weight on the 2 axles was 6640 pounds, which is 95% of the axle ratings, and does not account for side to side weight differences. This also represents a 92% loading factor on the tire ratings.

Early summer of 2009, I upgraded the tires to ST205/75R15 LRD. In doing this, I noticed cracks where the mounting brackets were welded to the axle tubes. These were Alko-Kober rubber torsion axles. I contacted Alko-Kober, they were very anxious to send me new axles, at thier expense. They did not want to work with me to upgrade to a heavier axle. I took the replacement axles and installed them in Sept of 2009.

Now 3 years and 25,000 highway miles later, summer of 2012, there were definete signs of tire wear on the insides of the tires.

At the time of the original axle failures, Alko-Kober gave me the complete specs on the existing axles.

I took these specs to Dexter Axle, and asked them to quote a 5200 pound axle, to replace the 3500 pound Alko-Kobers. Dexter sent me a very through and complete specification on a replacement axle.

The replacement 5200 pound axle has much larger spindles, and requires a 6 lug hub. So the upgrade involved not only replacing the axles, but the rims and tires as well.

I bit the bullet and ordered up the dexter axles, new rims and new MAXXIS ST225/75R15 LRD tires.

On Monday 11/26/12 I took the trailer to a friends shop and we swapped the axles. It was an easy swap, two mounting holes on the Dexters lined up with two of the mounting holes used by the Alko's. After getting the front axle in exact location, we drilled two new holes in the side mount flanges on the trailer to accommodate the Dexter mounting brackets. The entire process took 7 hours to accomplish.

We wired up the electric brakes and mounted the new rims and tires.

The result was that the trailer now sits 1 inch higher than it did before, clearance from the top of the tire to the wheel well top is greater than the recommended 3 inches.

The new limiiting factor on weight is now the tire rating of 2540 pounds per tire for a total of 10160 pound capacity. Now the 6640 load represents 65 percent of the tire rating and 64 percent of the axle ratings, a nice comfortable margin of safety!

I have only towed the trailer a short distance with the new setup, the trailer suspension did not seem overly stiff and it towed nicely as it always has.

Time will tell if this was money well spent, but for my personal peace of mind, knowing that I am no longer towing something that was loaded to the very max, it was worth the investment.

BTW we like this trailer a lot, or we would not have made this investment.

If anyone is interested in more details, PM me, I will share the Dexter spec and any other details you may be interested in.

John U
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Old 11-29-2012, 05:44 PM   #2
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Originally Posted by midnightpumpkin View Post
A little history to begin with.

On our first trip with this trailer, a 2007 model Rockwood 8315SS, purchased in October of 2006, my first stop was at the scales. The weight on the 2 axles was 6640 pounds, which is 95% of the axle ratings, and does not account for side to side weight differences. This also represents a 92% loading factor on the tire ratings.

Early summer of 2009, I upgraded the tires to ST205/75R15 LRD. In doing this, I noticed cracks where the mounting brackets were welded to the axle tubes. These were Alko-Kober rubber torsion axles. I contacted Alko-Kober, they were very anxious to send me new axles, at thier expense. They did not want to work with me to upgrade to a heavier axle. I took the replacement axles and installed them in Sept of 2009.

Now 3 years and 25,000 highway miles later, summer of 2012, there were definete signs of tire wear on the insides of the tires.

At the time of the original axle failures, Alko-Kober gave me the complete specs on the existing axles.

I took these specs to Dexter Axle, and asked them to quote a 5200 pound axle, to replace the 3500 pound Alko-Kobers. Dexter sent me a very through and complete specification on a replacement axle.

The replacement 5200 pound axle has much larger spindles, and requires a 6 lug hub. So the upgrade involved not only replacing the axles, but the rims and tires as well.

I bit the bullet and ordered up the dexter axles, new rims and new MAXXIS ST225/75R15 LRD tires.

On Monday 11/26/12 I took the trailer to a friends shop and we swapped the axles. It was an easy swap, two mounting holes on the Dexters lined up with two of the mounting holes used by the Alko's. After getting the front axle in exact location, we drilled two new holes in the side mount flanges on the trailer to accommodate the Dexter mounting brackets. The entire process took 7 hours to accomplish.

We wired up the electric brakes and mounted the new rims and tires.

The result was that the trailer now sits 1 inch higher than it did before, clearance from the top of the tire to the wheel well top is greater than the recommended 3 inches.

The new limiiting factor on weight is now the tire rating of 2540 pounds per tire for a total of 10160 pound capacity. Now the 6640 load represents 65 percent of the tire rating and 64 percent of the axle ratings, a nice comfortable margin of safety!

I have only towed the trailer a short distance with the new setup, the trailer suspension did not seem overly stiff and it towed nicely as it always has.

Time will tell if this was money well spent, but for my personal peace of mind, knowing that I am no longer towing something that was loaded to the very max, it was worth the investment.

BTW we like this trailer a lot, or we would not have made this investment.

If anyone is interested in more details, PM me, I will share the Dexter spec and any other details you may be interested in.

John U
I concur with your discussion. I posted a similar experience to the Forest River VIBE product line

I have learned a lot from my experience in purchasing a trailer & educating myself on understanding the GAWR & GVWR world. I made some mistakes in this purchase – but live and learn. Even though I feel the buyer should be responsible for doing the research, I do think the manufacturer has an obligation to provide a product that has an acceptable margin for safety.
The entire VIBE series are equipped with 3500 lb single axles. The “factory” shipped weight of these units range from 2900 lbs to 3300 lbs (depending on the model & options – we have the heavier model 6504 with the slide out bunks) and a GVWR around 3800lbs. When I purchased my unit I was of the expectation we would have a minimum of 511 lbs cargo carrying capacity (as per web site). I was not experienced enough to understand that this would include things like water in the holding tanks, full propane tank, and possible options installed outside of factory. When I received the unit I noted the “dry weight” of the trailer was stamped at over 3500 lbs and the Cargo Carrying Capacity restricted to 211 lbs. I was a bit shocked but realized I had not done enough research prior to purchasing the unit.
On closer examination the whole issue with the VIBE series seems to hinge on bringing it within the weight classification of a “mini van” for 3500 lb towing capacity (at least some would suggest that). I don’t buy that suggestion as I used to own a mini van (2006 Uplander), and there is no way it could tow a trailer in this weight class (even with the 3500 lb tow rating, you are pushing the limits of that class of vehicle with the VIBE series).
I have to assume Forest River is installing 3500 lb axles, hub, rim & tire combinations to meet the bare minimum requirements to support the trailer, unless they can suggest to me otherwise. It obviously results in some cost savings for them.
I really like the layout of the VIBE 6504 for our family of 4, and I have not seen anything else with an equivalent layout. I only wish they would have provided an option for an axle upgrade (especially for the heavier models). My unit was factory ordered, so an axle upgrade option would have been easy at the time (if it was available, but apparently not). It seems hilarious that the VIBE 6503 & VIBE 6504 models have these huge storage compartments that can only be used for a few pillows due to CCC restrictions. I am not sure how you pack a trailer for 4 people with such limited CCC.
I was not willing to negotiate with Forest River to make this right as I live in Canada and dealing with the factory would have resulted in major transportation costs, logistics and time so I bit the bullet myself to make it right. There was a local “reputable” trailer manufacturer that was willing to complete an axle upgrade. The limited CCC was not just linked to the axle, but the entire suspension (hubs, rims and tires were rated at the very minimum requirement around 3500 lbs). Yes if you factor out the tongue weight of 300 lbs you have slightly less load on the suspension, but it is way to close for comfort for me.
I replaced the 3500 lb Lippert axle with a 6000 lb Dexter unit (about $900.00 delivered to Canada). The axle was equipped with 3000 lb rated hubs. Upgraded the rims to a 6 bolt – 15 inch (2800 lb rating), and tires to 15 inch load range “E” (2800 lb rating) at a cost of just over $2000.00 (labor included). That is my story….which has a happy ending as I now have piece of mind when I travel down the road.
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Old 06-18-2013, 05:15 PM   #3
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I concur with your discussion. I posted a similar experience to the Forest River VIBE product line
Hi, I read your previous post about the 6504 axle upgrade with interest. After an exhaustive research process, we've concluded that the 6504 is the only camper that works for us I'm now in the process of having one factory ordered, since they are hard to find on the lot around here.

I was wondering if you'd be willing to share the details on your upgrade project : specifically the axle part number, hub face distance, and any modifications needed to get the 15" tires to fit. If you don't feel comfortable posting the details, feel free to send a PM instead.

Thanks!
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Old 06-21-2013, 06:16 PM   #4
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Originally Posted by dboreham View Post
Hi, I read your previous post about the 6504 axle upgrade with interest. After an exhaustive research process, we've concluded that the 6504 is the only camper that works for us I'm now in the process of having one factory ordered, since they are hard to find on the lot around here.

I was wondering if you'd be willing to share the details on your upgrade project : specifically the axle part number, hub face distance, and any modifications needed to get the 15" tires to fit. If you don't feel comfortable posting the details, feel free to send a PM instead.

Thanks!
I had previously posted the information of the VIBE Sway Control - Thread Page 3 if you want to have a look at that thread. Let me know what else I can tell you? Most of the work was done by a reputable trailer mfg.

Hi PA Paco.
Just got back home from an awesome trip to Disneyworld with the family.

Sorry it took me awhile to respond. I still have issues with posting messages from my work computer system, so I had to wait for an opportunity to reply to your post from home.
The conversion was quite simple for me as I had access to a local utility trailer manufacturer in my city. The do not manufacture travel trailers, but were quite familiar with trailer suspension systems. I am sure you could have any local trailer service representative complete the upgrade for you if you are determined to have the work done (as I was).
I opted to stay away from the original “Lippert” components as I was not too happy with the support I received from them in my initial research on completing an upgrade. The Dexter product seemed to also have better reviews from the research I did.
Dexter – Hub/Drum Kit (E/Z Lube) – for 6,000 lb axle (Part # K08-201-95)
Dexter – 12 x 2” Electric Brake Kit – (6,000 lb capacity per pair)
Dexter – 6,000 lb Torflex Axle
I locally sourced three – 15 inch rims and load range “E” tires locally (6 x 5.5 inch bolt pattern on the rims with a combined 5600 lb capacity for both rims & tires). Here is a link to the company website.
http://dexteraxle.com/home
You can likely source the axle, hubs & electric brakes for just under $1,000. Follow this link to a sample supplier of Dexter products.
http://www.theoempartsstore.com/product.php?productid=33340&cat=2297&page=1
The installation was almost straight forward with the exception that the Dexter mounting bracket bolt pattern did not perfectly match up with the existing mounting bracket on the VIBE trailer. I believe the trailer manufacturer had to take a measurement of the existing Lippert axle width from hub to hub to & trailer frame mounting bracket spacing to determine the correct Dexter axle requirements. The trailer manufacturer simply welded a custom bracket to the trailer that mated (bolted) easily to the factory installed Dexter bracket on the axle. ***The key here was that the custom bracket was welded to the trailer & NOT TO THE TORSION AXLE , as any welding to the torsion axle could damage the cords inside.***
The bonus of completing the upgrade was the trailer now also has better clearance from the ground with the beefier axle & larger tires. The axles/hubs/brakes/rims & tires (including spare) came out to about $2,000 for me (however that included freight for delivery of parts to Canada, depending where you are you could probably get the work done for less).
I could take a photo of the axle upgrade from under the trailer if you think it would help. The trailer is sitting in a bit of snow , but it probably would not be to hard to clear enough away to take a few pics.
Hope this info helps you.

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Old 06-24-2013, 11:10 PM   #5
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Hi thanks, that's really helpful. I hadn't found that other thread yet.

My big problem is likely going to be finding a shop competent to modify trailers in Montana. Also want to look into how to re-register with the new GVWR and if there are any insurance implications from modifying the trailer. I won't ask for your advice on those issues since the Canada situation is I'm sure different.

Thanks again.
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Old 07-16-2013, 11:28 PM   #6
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Originally Posted by pdchristensen View Post
I had previously posted ......_________________
PD,

We just bought a 2012 Vibe 6502. Used but not used. Fellow bought it and decided they did not want to travel....go figure. Said they bought it on impulse. Regardless. Fellow pulled it from his home to ours (total 100 miles on trailer including dealer to his home then a year later to our home) as I did not have electric brake controller yet. This was a week ago. I had a new set of Goodyear Marathon tires installed yesterday as I had read of all the woes with the china tires. I did not get one mile from the tire store when I discovered the new left tire smoking. Got back to the tire store and found the rear of the left tire rubbing heavily against the trailer body. Put the never used spare (china tire) on and got it home although it rubs but not as bad as the Goodyear. I called Forest River and they blew me off by shuttling the blame to Lippert. Lippert is acting like they are willing to help me out.

I am sending them pictures of the damage and ruined new tire. But your post has changed my mind. I am certain the Vibe has lacking suspension and want to go to the 6000 pound rating. I will be asking Lippert if they will upgrade that axle and I will not press them to replace the $120US tire that has 3 miles on it. A friend of mine with a Scamp 5th wheel also went with a 5000# +/- axle with 15 inch wheels and Load Range D tires. Also, my sister-in-law had a Forest River trailer similar to ours that had a very similar axle failure. Forest River was more than happy to help her plus it appears she got an upgraded axle assembly installed by FR dealer.

Please send me a few pix of the mounting bracket changes you made to the trailer axle mount. I am capable of doing the swap but need to see the brackets your installer made to match the bolt pattern of the Lippert.
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Old 07-21-2013, 02:52 PM   #7
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Hi thanks, that's really helpful. I hadn't found that other thread yet.

My big problem is likely going to be finding a shop competent to modify trailers in Montana. Also want to look into how to re-register with the new GVWR and if there are any insurance implications from modifying the trailer. I won't ask for your advice on those issues since the Canada situation is I'm sure different.

Thanks again.
Well...I've now found a trailer workshop in the valley here that is willing and able to do the axle upgrade.

It appears that at least in Montana, the authorities are not too concerned about paperwork relating to the modification. The local DMV seemed mostly worried about collecting the correct amount of tax, and told me that I don't need a new VIN (it goes with the frame, not the axle), and they don't care about the GVWR sticker as long as I register it with a GVWR less than I plan to load.

So now we need to go buy a Vibe 6504. Since the nearest one available on a dealer's lot is 950 miles to the east...road trip!
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