shock absorbers

Tundra57

Any thoughts on if adding shock absorbers to the axle would help the stability of the trailer and vibration passed inside of the tab?

Very few travel trailers have then fitted.

rfuss928

Shocks are a popular add on accessory for the Alko chassis used on the DM T@Bs.
https://www.alko-tech.com/en/shock-absorbers

Tundra57

I just have to see how I can fabricate brackets for my tab.

mreric

that would a great accessory.    someone created a bolt-on kit for Casita trailer.   no welding needed,  there is a few video on youtube.   check them out 

tabiphile

On a fixed axle trailer, how does that actually do any damping? The movement must be minute and the force vector is direct forward? @rfuss928, do you have this installed and what does it actually do?

falcon1970

I have also been wondering about the utility of this concept.  The rubber in the axle acts as a shock absorber so there wouldn't be anything for the additional shock absorber to do.  I doubt there is enough wheel travel for there to be any movement of the piston in the shock absorber.

ScottG

The rubber in the torsion axle seems more similar to a spring than a shock absorber--the spring allows the wheel to move up and down, but the shock dampens that motion to prevent excessive bouncing. I question whether that is a problem that really needs solving on a typical trailer, so maybe that is why you rarely see shocks fitted.

Mouseketab

tabiphile said:

On a fixed axle trailer, how does that actually do any damping? The movement must be minute and the force vector is direct forward? @rfuss928, do you have this installed and what does it actually do?

Bob Fuss, like myself has a Dutchmen T@B on an Al-Ko frame. The shocks are an available item made by Al-Ko, and we located and installed them on our trailers. It does make a difference, but our frames are decidedly different from the frames on nuCamp T@Bs.

mreric

https://youtu.be/qIiXFw--j4M

tabiphile

The Casita mounting makes sense. The shock is set up so that it can actually dampen motion. The installation that Bob Fuss shows looks like it would not do much of anything. If the lower bracket projected forward to allow a more vertical shock mounting then it might do some dampening but the way it is currently installed it does not look like it could do much. It almost begs for another shock to be mounted towards the back to pick up the rest of the load. The piston is side loaded and only a fraction of the vertical movement of the wheel is translated to the shock.  That's not to say that it doesn't do something..

Tundra57

I agree that the purpose of the shock is to damp out oscillating bounce. This is different to resisting the force on it like a spring. Without on a car you can see on a heavy auto rear wheel drive with worn out shocks, you see it bouncing along for ages after hitting a bump sometimes swaying from side to side.

I also am not sure on a shock's effectiveness on my tab as the travel is not very much.

However on a pot-holey road my tab does dance a lot at the back of my Tundra, wondered if shocks would help. Doesn't seem a big job to fit them as long as they don't stiffen the ride excessively.

I was just wondering if anyone had tried is and got a real world feel for the result.

TabberJohn

The Dexter torsional axle has 2" play from what I have read.
As @tabiphile notes you'd have to mount the shock vertically to benefit. 
Watch the Casita video again carefully staring at the frame and horizon, not the wheel.
The shock definitely stabilizes the wheel but the effect on frame movement is minimal.
Yes, there would be less bouncing in the cabin but similar results could be obtained by lowering tire psi.
I'm not sure how much this mod costs, but IMO it would only make sense if you spend lots of time on rough forest roads with ruts, potholes, and washboard.

rfuss928

Maybe this photo will help some folks better understand how torsion axle shocks work.  As the wheel moves up and down the arm that it is mounted on rotates back and forth around the axle center (grey dot near center of photo).  The shock arm moves similarly as the wheel compressing and extending the shock absorbers.



Dampening wheel motion vastly improves tire contact with undulating pavement and noticeably improves trailer tracking behind the TV.  The narrator in the Casita video above does a good job of describing the many benefits the improved control shock absorbers provide.  Bouncing over speed bumps and pot holes is not really the point.  Our little trailer tracks flawlessly behind our very capable TV on all types of roads and speeds with total stability and confidence.  A great accessory IMO.

TabberJohn

rfuss928 said:

Shocks are a popular add on accessory for the Alko chassis used on the DM T@Bs.

What do the rest of us have that is different from a Dutchman's frame and axle?
I get your point I but haven't noticed any tracking issues with our setup.
Is the issue more pronounced with a lighter trailer?

N7SHG_Ham

@TabberJohn does the Dutchman use a torsion axle or is it a spring axle? That might be a difference? FWIW I have a Wells Cargo trailer with a similar Dexter axle as the Tabs and exactly same with no shock. I am most convinced a shock would justify the effort on either application?

atlasb

The Dutchman is the same type as used on our T@B's. They use the AL KO which was the same brand used here until Dexter took over Al Ko here in the US.  The torsion arms in the Al Ko appear to be stamped VS what is used on our Dexter arms  which are cast Iron. 

Tundra57

Awesome comments thanks. I'm just leaving thro the summit racing catalog for brackets and shocks.

mdomb529

I ended up installing the Al-Ko shocks on my T@b.  Here's my semi-in-depth discussion:  https://tab-rv.vanillacommunity.com/discussion/11122/dm-t-b-i-installed-al-ko-shocks/p1?new=1