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RV Shocks. Who is using them and how do you like them?

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  • MidwestCamper
    replied
    Spoke with Sonny who mentioned he was aware a single failure of the upper brackets. In this particular case, the customer did not use the correct size pilot drill bit where the self tapping bolts did not have the necessary grip at the thread and as a result, they pulled out. He also re-confirmed he uses a 60/40 damping ratio for jounce/rebound.

    He also confirmed his 3" axle kit would work well for the 3500lb axles where from our discussion he has allowed for damping that covers a wide range of loads where the theory is, some damping while not being optimized is better than nothing. I may still take some other measures on the 0.2" thick upper brackets on my Imagine where Sonny mentioning of no known failures with proper installation buys me some confidence.

    Below are a couple articles on the installation of the joyrider system where one is a review where two fellows are riding inside the rig for a subjective evaluation. Funny stuff but in engineering subjective evaluations using ones Buttometer is commonly done as well as with data. However never heard of tests with a cat as part of the evaluation. The first article bases the results on the contents being moved about inside the rig where at a minimum some of us ( I plan to) can gather some video.

    http://rvimprovementsystems.com/arti..._Joy_Rider.pdf

    https://www.youtube.com/watch?v=u0aizlG4c68&sns=em

    Jim
    Last edited by MidwestCamper; 02-13-2020, 11:54 AM.

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  • MidwestCamper
    replied
    Rob,

    Thinking each rig may respond differently and also do not prefer how the joyriders mount close to the center hanger. I'm confident in my X factor bracket in removing most if not all lateral motion in the center hanger so if the channel can handle loads in the Z direction, I would be ok. There are no failures that I can find on the internet.

    Looking back to my video, it appears shocks may help in my case since the dirt section of my drive was not rough at all on the TV. But the rig does appear to be underdamped at the 2 minute point. In my case, the older Lippert chassis uses 3 inch axles but they are 3500lb with 1750lb springs. So this rig may not fit within the one size fits all category for a 3 inch axle, and may end up being overdamped with shocks.

    We have some feedback from EMetz582 on the 2017 2800BH where the results were deemed as excellent. This rig would have had the same chassis as my 2017 Imagine. Not sure how much clearance he had but my Imagine does not have the necessary 4 inch tire/frame clearance for the Lippert shocks. Also not liking my thin wall square tubing on my rig, but believe I have a few solutions in mounting the joyriders should I go this route. I also spoke with Sonny who is confident in the upper mounts on the 0.20" channel where the damping rate from his shocks, the spring rate and other factors would be needed to calculate these loads on the channel while using the self tapping bolts. He tells me he uses a 60/40 damping rate with his shocks for jounce/rebound.

    Glad I could spark your interest Rob.

    Jim
    Last edited by MidwestCamper; 02-12-2020, 10:56 AM.

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  • Cate&Rob
    replied
    Great graph of under-damped vs critically damped vs over-damped . . . this is what we are discussing! (I think I remember this graph from a first year engineering text book )

    This is usually measured in the fore-aft direction (I will get back to this). When I began to consider adding dampers ("shocks" is a really confusing name for these things) I watched the side of the trailer in the mirror. I could not see under-damped motion. The trailer settles after jounce impact very much like critically damped. So, I got Cate to video the trailer in her mirror so that I could study the trailer motion more closely. Essentially "critically damped" with the control element seeming to be the damping in the center spring "equalizer" connection.

    In my discussions with Sonny Dismuke (Joyrider designer) he led me to believe that all systems use the same damper regardless of axle diameter. As I have said before . . .this doesn't make sense to me . . . based on several years of automotive damper tuning experience.

    Back to fore-aft vs side-to-side . . . Jim MidwestCamper brought this into the discussion. I added stronger springs to the left side of my 303RLS to carry the 800 lb heavier weight on that side. (a whole other story). Before this, the trailer would always fall to the left (heavy) side on every road impact. With the springs matched to the load being carried, the trailer now "bobbles" from side to side on road impact. I can see where damping could be an asset in controlling this. (Thanks Jim ) ​​​

    So, I am thinking that the damper sales guys sell their product because the trailer never needed fore-aft damping in the first place. What they damp is side-to-side oscillation which does give the trailer a smoother ride.​​​​

    I still don't like how the main two brands of dampers require two sets of relatively large diameter mounting holes close together near the centre hanger attachment to the frame. This is a critical load area for the frame rails and most of the frame rail strength is in the lower flange.

    In the cost/benefit analysis . . . I'm still not convinced that this would be (a significant amount of) money well spent.

    Rob

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  • MidwestCamper
    replied
    JeffC,

    Great feedback. Take a look at the video I posted on #38 and you will see my Imagine is underdamped at 2 minutes into the video. This input was not severe at all but the underdamped oscillation and the undamped compression (jounce) and rebound can be seen.

    Jim

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  • JeffC
    replied
    There is a lot to agree with in the last few posts.

    If you can't obtain theoretical perfect, underdamped on the compression stroke is probably better for a trailer but rebound is what makes the ride smooth. The springs themselves do a fine job of compression dampening but the total lack of rebound control is what makes the trailer bounce.

    Properly designed suspension systems balance all the componentry to operate in a specific load and speed range. That range is designed to work within the empty and total weight range of the vehicles they support. You should not have to change shocks based on load although the most sophisticated shock and suspension systems do exactly that through a variety of mechanical and electrical means.

    However, a perfectly designed shock absorber that will support a 7K axle and a 12-14K trailer is not the same set of specs required for an 8K axle and a 20K + trailer.

    OTOH, it is almost certainly better than nothing. I just wish there was a bit more specificity in application.

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  • MidwestCamper
    replied
    I ran across this old video I took of the underside of my 2600RB Imagine. Was looking at several different scenarios back then such as simulated sway and aggressive sharp turns on pavement and the effects on the hangers. But for this discussion an interesting observation can me seen at time 2.0 minutes. The drive moves from pavement to dirt and back to pavement where the drive overall was reasonably smooth.

    https://www.youtube.com/watch?v=6RhEKItnjCY

    Jim

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  • MidwestCamper
    replied
    Howard,

    Funny I see this example from the internet states " Underdumped" Its supposed to be underdamped but the idea can be seen on the plot.

    Thank you,

    Jim

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  • howson
    replied
    MidwestCamper -- only thing I can do to add to this thread is post your chart for ya! I don't know a thing about what you guys are writing about, other than I know when it works and when it doesn't.

    Click image for larger version

Name:	Jim's chart for posting.JPG
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Size:	29.2 KB
ID:	12414

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  • MidwestCamper
    replied
    Suspension systems are designed to be critically damped with normal inputs. The graph (if it posts correctly) shows three graphs. Underdamped, critically damped and overdamped. In a passenger car it seems a critically damped system would be ideal where on the heavy truck or heavy trailer I suspect there is a compromise between being critically damped when lightly loaded and slightly underdamped when fully loaded. Taking a shot and thinking this may be a best case compromise. Not trying to talk folks into the shocks but rather I believe, or hope there was some engineering on the best choice of damping for a reasonable compromise.

    https://www.bing.com/images/search?v...x=4&ajaxhist=0

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  • MidwestCamper
    replied
    Originally posted by JeffC View Post
    All of the above makes sense to me.

    A shock absorber has a single function, to dampen oscillation. All shocks are designed to work within specific weight and performance (dampening, rebound, travel, etc) parameters. An empty 450 would still not be optimal using the same shock as a loaded 150. (pick any other analogy that you like, it is the difference in load and travel that I'm talking about)

    Using the same shock on a 10K TT and a 20K 5th wheel still does not make sense to me. Is it better than running without? Maybe. Over dampened is not a good thing anymore than under dampened.

    I would be much happier if there were two or three different shocks available depending on load.
    What about an empty F450 and the same F450 that is fully loaded? Doesn't this imply that the shock is the best all around fit for both load cases? For the TT and 5th wheel, the shock kits are sized by axle diameter. Would having the same shock for a 3 inch 5000lb axle and a 8000 lb axle also be a compromise to cover both load cases? I agree with having a custom tune on the suspension but this is not currently found even on the F450 between being unloaded and fully loaded where the shock handles both cases reasonably well.
    Last edited by MidwestCamper; 02-11-2020, 04:07 PM.

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  • EMetz582
    replied
    I made edits to my original post for clarity.

    Dexter frames with more standard slides are compatible with Roadmaster and Joyride shock kit...but may require mild mods.

    Lipperts kits will NOT work on Grand Design trailers with Dexter frames.

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  • EMetz582
    replied
    Originally posted by JeffC View Post

    My understanding from the posts in this thread was that there was a single shock part number for all the kits. Is that not correct?
    You're right. Each kit shares the same shock among brand kit.

    You might be over thinking this whole thing. None of the shocks in these kits are Heavy Duty that would have an adverse affect on the trailer.

    We're talking about a total weight range delta among kits of 3000-4000. For a generic shock on a trailer, I feel that's a non-issue.

    Compression on these shocks is low. Its rebound dampening that really slows the oscillation and results in a smooth riding trailer.

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  • MidwestCamper
    replied
    Originally posted by EMetz582 View Post
    Take a look at other trailers going down the road, watch the axles, not the wheels. Look how much vibration exists. Then look how much bounce is allowed. Shocks dampen all of this, and get the trailer tracking solid as a rock. If you have the time and money, shocks are a significant update for your trailer that will not improve towing from a drivers perspective, but from a trailer and tire life perspective.

    I have installed Lippert shock kits on two TT's, one being a 2017 2800bh, with excellent results.

    The "older" GD trailers with Lippert frames and Schwintek slides are compatible with the LIppert shock kit.

    Dexter frames with more standard slides are 100% compatible with ANY shock kit.

    With some mild mods, Roadmaster and JoyRide can be installed, both of which are practically the same design FYI.

    I have a Roadmaster 2460 system on hand right now, ready for installation on my 2020 2800bh in Spring. It will not be a quick job like the Lippert kits were.
    EMets582,

    Great feedback! Thank you,

    Jim

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  • JeffC
    replied
    Originally posted by EMetz582 View Post

    Again, the shocks in each shock kit are selected by the axle size and thus weight range among brands.

    If you feel you can better select shock dampening yourself, there are an infinite number of shocks that fit each kit. Esp the Roadmaster and Joyride.

    You can also vary the angle to increase and (more so) decrease the amount of dampening. Using your F-450 example, if you felt the provided shocks were too stiff for your trailers weight, simply increase the angle.
    My understanding from the posts in this thread was that there was a single shock part number for all the kits. Is that not correct?

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  • EMetz582
    replied
    Originally posted by JeffC View Post

    I would be much happier if there were two or three different shocks available depending on load.
    Again, the shocks in each shock kit are selected by the axle size and thus weight range among brands.

    If you feel you can better select shock dampening yourself, there are an infinite number of shocks that fit each kit. Esp the Roadmaster and Joyride.

    You can also vary the angle to increase and (more so) decrease the amount of dampening. Using your F-450 example, if you felt the provided shocks were too stiff for your trailers weight, simply increase the angle.

    Leave a comment:

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