Hub failure - question about possibly mismatched wheel hub and weight ratings
Hello All,
I hope you are all having a great season and are enjoying great times and making memories in your campers!
I have a 2012 Heartland North Trail 32 Buds.
I recently had a hub failure that also damaged my axle. In fact, the trailer is still 5 hours away in a public parking lot abandoned and unable to be moved.
While we are trying to find replacement parts and get things squared away with the aftermarket warranty people, we found something odd…
While trying to find the replacement hub/brake and axle we found something that I would like the forum’s opinion on…
Immediately and initially the axle/wheel repair people looked at the hub and quickly said it looked too small for the application.
When looking up the replacement brake/hub assembly it was samped with part number Axletek BD-65535-17
The description on this brake/hub assembly shows it as being a 6 lug - 5.5 bolt pattern -3500# capacity per axle – 1750# capacity per wheel – that tends to make sense based on the part number. We found where these hubs are made and imported from China and they are listed with a maximum capacity rating of 3500# per axle (2 wheels) and 1750# per individual hub/wheel.
I know the following facts:
The trailer had a dry weight of 6995#
It has a GVWR of 8600#
It has a GAWR of 4400#
It weighed at 8300# loaded
Research from authoritative sources provides the following info:
The wheel hub is the section that bears the entire weight of the vehicle, includingthose of its passengers and cargo and connect the vehicle and its wheels.That's why car manufacturers warn owners not to overload their vehicles becausethe wheel hub has only a finite capacity. If that capacity is greatly exceeded,especially when it happens frequently, the wheel assembly could break and youcould lose control of the vehicle.
Overloading a hub creates similar conditions as over-tightening the hub. The excessive weight forces the lubricant from between the bearing rollers and bearing raceson the loaded side of the bearing causing localized heat and fatigue.
Do not exceed the capacity of yourtrailer's running gear. Overloading can seriously degrade the life of thevarious components, result in unsafe braking and may lead to catastrophic failure.
The Gross Axle Weight Rating (GAWR) of your running gear is determined by the lowest rated component in the assembly.The capacity of the wheel, tire, axle, brake, springs/rubber and hub are all considered.
The axle is rated at 4400# and per LCI Lippert the bearings areproperly rated to support the listed weights on the 4400# per axle. However, this brake/hub assembly seems tohave a maximum weight capacity of 3500# PER AXLE and only 1750# PER WHEEL. To be properly rated to conform with the GAWR,it seems these hubs should have a minimum rating of 2200# per hub assembly for a minimum total of 4400# per axle.
Assuming all weights are distributed equal, the camper has 4 tires with each hub assembly seemingly rated for a max of 1750#. Take the max rating of 1750# per wheel and multiply it by 2 and it adds up to a max axle weight GAWR of only 3500#, but the camper is stamped with a 4400# max axle rating. Now multiply that times 2 axles witth the same 3500# rated hubs and that only gives me a 7000# max GVWR on a camper that was 6995# when it left production and was 8300# in use and stamped with a GVWR of 8600#
I spoke with Heartland and Lippert and they insist the parts used are correct and would not recommend any other suitable replacements. The person I spoke with from Lippert also seemed to be initially mislead by the hub rating thinking that the individual hub was rated for 3500# and not actually for #1750. As I tried to clarify, they proceeded to argue,insist it was the right part and even asked if I was an engineer – which I am. They are supposed to get me the technical specs on the hub, but I have not received response. If they did misunderstand the maximum rated capacity for a pair of hubs and thought it was for an individual hub, I would think that could be a serious problem.
I’ve been towing campers for 10+ years and have never experienced a hub failure. I am very careful with my tow weights and maintenance for hubs and bearings. I do not think there is anything that I have not done or have done incorrectly to cause this, but am concerned that I am going to continue to have failures due to these hubs being overloaded for this camper -and seemingly not being incompliance with the GVWR and GAWR listed values.
Am I missing something, or does it seem that these hubs are not sized correctly for this application? I can watch the wheels flex in and out a significant amount when turning in a parking lot and the amount they bend does not seem normal - wheel flex can also be an indication that the hubs are not rated correctly.
Thnoughts?
Thanks,