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Ask Dave: Having RV axle issues. Should I change my 6K axles to 7K?

Dear Dave,
My rig supposedly weighs right at 11,000 lbs. I have two 6K axles and continue to have RV axle issues such as the entire wheel and hub coming off and spun bearings, even though I completely disassemble and inspect and repack every few thousand miles. Will it help if I put 7K axles on instead of the 6K? —Doug, 2019 Crossroads Hampton

Dear Doug,
The first red flag that pops up to me is your statement “My rig supposedly weighs right at 11,000 lbs.” That tells me you are most likely getting weight information from either the brochure or the dealer, which in either case is probably the unloaded weight as they would not have any idea of how much cargo weight you are going to include. It is important to get your rig weighed with all the contents you have in it to determine the actual weight. You can do this at a CAT Scale at most truck stops, or get individual wheel position weights from the weighing teams at RV Safety & Education Foundation. You can find weighing locations here.

Since you did not specify the floor plan, I cannot tell what the unloaded weight is or the Gross Vehicle Weight Rating (GVWR) and how much cargo carrying capacity you have. I do see the 37-foot unit on the website is listed as 11,000 lbs. dry weight. It has a cargo carrying capacity of 2,300 lbs., so I doubt that unit has two 6K axles.

You can’t just replace axles with larger axles

You cannot just replace the 6,000 lb. axles with 7,000 lb. axles, as the brackets, frame, and other components are not rated for the heavier weight. I would recommend looking at the weight sticker that should be on the side of the rig and doing a little research on what your rig is actually rated for.

This will tell you the weight of the vehicle as it sits, with no fluids or cargo, and how much weight you can add to it, called cargo carrying capacity, to be at the Gross Vehicle Weight Rating (GVWR). Then when you weigh it, you can determine the proper weights.

What is puzzling is why you are having RV axle issues when you are inspecting and repacking bearings “every few thousand miles.” I think it has to do with weight. Understanding where your rig is at this aspect should help. One thing that I always recommend is to use a laser thermometer and check the temperature once a day when you are traveling. An extremely high temperature at the hub indicates the bearings are probably getting dry and need to be inspected. The high temperature at the brake drum indicates the brakes are probably set too high.


 You might also enjoy this from Dave 

Can I increase my RV’s axle capacity to haul more?

Dear Dave,
When we upgraded our axles at MORryde the shop manager told me that people who believe they can haul more if they increase the axle weight rating are mistaken.

Example: If you increase your axle capacity from 7K to 8K. The GVWR will not increase if a heavier duty axle is added. To quote him “The GVWR is the GVWR!” His additional comment was, “The frame’s capacity is fixed and it does not matter how big your axle is!” …

Continue reading the question and Dave’s answer.


Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here

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Don
1 month ago

One thing not mentioned, what grease are you using? Ask the axle manufacturer for a list of accepted greases and go with one of them. Some brands will do well for awhile but then just crash and you lose the whole works, this from a local utility trailer dealer I deal with.

Impavid
1 month ago

Using a laser thermometer is a great idea, however, you must do it properly. After driving down the highway you must find a long, straight stretch or preferably a pull-off where you’ll be safe. I like to put on about 20 miles first. Then downshift your vehicle, NOT USING YOUR BRAKES, to come an almost complete stop. To use your brakes for more than a few seconds to stop will heat up your hubs and give you a false temperature reading.

Thomas D
1 month ago

I don’t understand the need to constantly redo bearings.
I’ve driven cars into the ground and never greased wheel beatings. Most of the cars ive had were + 20 years old and had excess od 200,000 miles. Why do rv’s need constant attention? And yes, weigh the trailer.
Most CAT guys will work with you to properly get the axles weighed. Find a non busy time if possible!

Jeff Arthur
1 month ago

Found something I thought was interesting. When repacking my campers wheel bearing’s I found some small pits in one . I got a replacement bearing and found that my 4400# axle took the same bearing as a 1500# axle. Doesn’t make one feel very confident although the replacement has over 20,000 miles on it .

dale rose
1 month ago

The article from the man who has bearings going bad makes me wonder if he’s packing the bearings properly. I was taught in the military to put a big gob of grease in the palm of my hand and press the bearing down into the grease until it oozes out of the other side. Once you’ve gone around once, repeat the process to make sure that there are no voids with air. Then, in the hub, just put enough grease inside to keep it coated, to prevent rust. Putting too much grease causes it to hold the heat in and overheat the grease, which then can break down. He also needs to check the manufacturers specs on how to properly tighten the nut. There are different methods.

Snoopy
1 month ago
Reply to  dale rose

Hi Dale, I totally agree with the proper way to pack wheel bearings. learned that in the auto class in the vocational high school in the 50’s! In the years since I got tired of the mess, so being a machinist I designed & built a “press packer” worked great & they have them for sale on line! Your soooooo right about properly tightening the nut, thats very important to follow the manufactures directions, hey youtube can tell you!
Snoopy

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