Hi. I am not an expert by any means but this is what I know to be true about independent suspension (I'm a hobbyist and have rebuilt suspensions on vehicles and am a geek when it comes to things I am interested in).
Unequal weight distribution is not an inherent characteristic of independent suspension. If the suspension is properly engineered and aligned, and the load is distributed correctly, then weight imbalance issues are minimal. The load distribution element generally refers to the vehicle design itself. However if you add 1K pounds over only one wheel of a trailer with independent suspension it would also come into play. Think of a motorcycle doing a wheelie; the rear suspension is carrying an unequal amount of mass (100% of mass on the rear suspension/ 0% on the front suspension).
Leaf spring suspension is inherently better at equalizing load across axles. This becomes particularly noticeable on uneven terrain. If you think about pitch and roll caused by terrain characteristics, there is a possibility that a majority of mass can be transferred to one wheel with an independent suspension but really difficult with a leaf spring setup. However, if the independent suspension is designed correctly, and the transfer is momentary, it's not a big deal. If this unequal weigh distribution was constant, yes, the wear to that axle would almost necessarily be greater than the other less loaded axles. In this context of an RV, towing ability would also be reduced with weigh concentrated over one axle.
Independent suspension is better at high speed hits (impact that compresses the suspension). Leaf springs are generally better at most significant square hits (dropping into a pothole, coming off of a curb). However, independent suspension is always better at side hits (think yaw or twisting, torsion) and is superior at maintaining control when turning. You can look up the data on scrub forces comparing independent vs. leaf suspension...you'll see that forces applied to the sidewall of the tire, frame twisting, etc. are fractional compared to the same vehicle with leaf spring suspension...especially with dual axles.
I have not found any objectively qualified data that proves independent suspension reduces structural wear on an RV. However, there is a lot of subjective data indicating this is the case and it much more than just anecdotal. My opinion, there are too many variables in RV construction to suggest reduced structural wear is an absolute beyond wear caused by yaw forces. But, we could look at similar rigs used in similar ways to draw some pretty good inferences.
I added IS and DBs to my 340RL that is being built. Here is a chart to consider. I had it labeled with what I thought were pros and cons but will leave that up to you all to decide as the "wins" were for my wife and me and the way we are going to use the rig.
Feature / Factor | Leaf Spring with Equalizer | Independent Suspension |
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Weight Equalization | Good at equalizing load between axles due to mechanical linkage using the equalizer | No physical load sharing; each axle bears its own load independently |
Ride Quality | Rougher ride, more vibration transmitted to the frame and contents | Smoother ride, less shock transferred to RV and cargo |
Handling on Uneven Roads
(not applicable offroad) | May bounce or transfer impact between axles | Each wheel reacts independently, providing better stability and control |
Component Wear | Bushings, shackles, and equalizer parts wear out and need maintenance | Fewer moving parts (in some designs), generally lower wear if properly loaded |
Maintenance | Higher; requires frequent inspection of bushings, bolts, and equalizers | Lower for high-quality systems, but some may still require lubrication or inspection |
Cost | Lower upfront cost | Higher initial cost |
Installation Complexity | Easier, especially for standard trailers | More complex; may require welding or modification in aftermarket installs |
Load Sensitivity | More forgiving to slight loading imbalances | Sensitive to uneven loading; overloaded axle can wear faster |
Aftermarket Support | Widespread support, easy to find parts | Limited to specific manufacturers and installers (e.g., MORryde IS, Timbren) |
Ground Clearance & Travel | Limited vertical travel; potential for “hopping” over bumps | More vertical travel, better ground handling, will not hop when used within operating limits |
Alignment Options | Fixed geometry, limited adjustability | Some, i think all new systems, allow for alignment tuning and adjustments |