Coilover spring rate for a cushy ride

[Artificer]

I'm putting together a Rimple style trailer to move rabbits on a 12,000 mile trip. They need as soft of a ride as possible. If you have a 400lb trailer, and up to 400lbs of bunnies/gear, what would you select as a spring rate for the coilover shocks?

I picked up a pair of LTR450 rear shocks off of Ebay for $78. I thought they were going to have either 160lb or 300lb spring rate. Turns out the ones I've got have 500lb/inch rate.

Since they only have about 3" of travel, I'll probably mount them in front of the wheel. That should give me 4" of travel at 75% pivot distance, and an effective rate of 375lbs/in. Since I can preload the springs to take the weight of the trailer, it still seems high to me.

Any thoughts? What would be your perfect spring rate, since I can get springs in 25lb increments.

Thanks

Michael

[Artificer]

Never mind. Its off on its first trip. After backing off the pretension adjusters all the way, you could get spring compression by just pulling down on the side of the trailer. Not really soft, but better than the 2,000 lb capacity utility trailer I use the most.

The trailers not done, but... done enough. Its made at least 750 miles of the 900 miles scheduled for the first leg of the trip today. Tows well at 70 I've heard.

Michael

[jeprovo]

Nice suspension setup. It's really interesting! Please jeep us posted on how it performs.

[Artificer]

In Memphis, trying to get around some flooding, she hit two low curbs. The trailer stayed level and didn't bounce when she felt/heard the thud(s). It seems to ride better than the jetta.

The main problem with the trailer is that it is so light, when a semi passes in the opposite direction, it really gets blown around.

The water crocks in the rabbit cages have water still in them when she stops. Some sloshed out due to cornering, apparently, but still... not too shabby. She's up to 1,700 miles so far on the test run.

Michael

[Jiminsav]

are you the first known Artificer in teadrop suspension?

[Artificer]

with a gas shock and just leaf srping sucpesion I can get a well smooth ride and I am still heavy enough that the passing semis do not move me around one idota!

...
SLowcowboy.

Are you saying the coilovers are not needed?

I didn't say I wanted a smooth ride, but a cushy ride. There's quite a difference between "it doesn't bounce things around" and "soft as a mattress." Sort of like the difference in ride comfort of a sports car and a Cadilac. Since the trailer was designed to haul animals around, and they would spend days/week/1,000's of miles in it at a time, the softest ride possible was important.

I have no doubt your trailer rides smoothly. I've mentioned the piece of farm equipment I built that is maxing out the springs. It has a very smooth ride, but it weighs 3500#'s. "still heavy enough" did I mention I was building it as light as possible? A passing semi is only an occasional situation. 12,000 miles of travel and fuel economy is a major concern.

I don't believe just adding shocks to a leaf spring suspension will make it ride smoothly. If you have rock hard tires and a massively over-capacity spring, you will never get suspension travel. If the suspension doesn't travel, shocks are useless. HOWEVER, if you have a properly rated spring, you get the longest spring possible, and tire pressure is set appropriately, then a shock can help.

The setup I used isn't for everyone. If someone only goes on smooth to mildly rough roads, a traditional suspension will be fine. If you want a really smooth ride, or go over really rough roads, my suspension will perform better. As it is, my spring rate is too high. If I wanted to minimize bouncing, I should have 300lb or less springs for a fully loaded weight of 600lbs. The goal is to maximize the suspension travel, while still not bottoming out. With 4" of travel, I can go awfully soft without worrying about bottoming out. Being an independent suspension is just icing on the cake.

Michael

[Mikka]

Ok I give up!
Michael, I have to ask; what's the reason to take rabbits on these trips?

Like your set up! will use it for an ATV trailer.

[Artificer]

Ok I give up!
Michael, I have to ask; what's the reason to take rabbits on these trips?

See post: http://tnttt.com/viewtopic.php?t=44095

Exchanging rabbits across the US to mix the genetics in a rare breed.

Michael

[dh]

Slow, a traditional teardrop has 48'' tall walls. Lets do a little math on your's, 5' tall with 20'' ground clearance, that implies your walls are only 40'' tall. I have to say, either your teardrop is 5' 8'' tall, or you don't really have 20'' ground clearance, or you can't sit up in your teardrop.

It looks like the wheels are centered on the trailer. I bet if you moved them back a bit your sway problems would be reduced.

[Trackstriper]

It looks like the wheels are centered on the trailer. I bet if you moved them back a bit your sway problems would be reduced.

Atificer,

Check to see what percentage tongue weight you have per dh's comment. A little more tongue weight might help. Another factor that may come into play is that, unlike most small cargo trailers or teardrops, you have a fairly soft, compliant suspension with little roll control. Standard trailer springs get that job done by being generally stiff....so they are stiff as far as bounce goes, but also stiff in roll.

Years ago I bought a whole rear axle assembly from....no joke here...a VW Rabbit. It was a trailing arm suspension functioning much like yours, however, the two trailing arms were connected by a cross beam near the swing pivots. This cross beam was in the shape of a "T" set on it's side and was made of steel plate, it was not tubular. It had strength in the vertical and horizontal planes, but could twist to allow the swing arms to interact with one another.



This only shows half of the axle, and you have to use your imagination for the rest of the coil-over shocks. But you can see how the beam plates provide some torsional resistance.

I never used the whole assembly after looking at how complex the mounts would be and how much space the spring towers would consume....a Rabbit had a fairly narrow track. I pirated the spindles and drums, used standard Rabbit rims....made an axle beam to bolt the spindles to and used conventional trailer springs. NEVER had any problems with bearings after that....many, many miles. Remember the last time you had a rear wheel bearing problem with a FWD car?

You might be able to incorporate a light sway bar from a small car.

Rabbit food for thought.

[Artificer]

Trackstriper,

The comment you referenced is about slowcowboy's trailer/comments.

The bunny hauler really doesn't have a problem with roll. I believe its more a matter of a really light trailer being blow about. In the other post, I mentioned the stationary trailer being moved by the 56mph winds in Texas. The trailer actually handled the 30-45mph quartering/side winds during the 1,000 mile run across the northern plains fairly well. Might be the cause of the unusual tire wear, but the trailer still tracked well. Driving 55mph on a two lane road and meeting an oncoming semi can be interesting. As long as you know its coming, its fine. Sort of like when I drove a Honda 125 around the state. Brace for it, counter steer, and continue on your way.

When I saw the drawing, I thought to myself that it looked an awful like a Rabbits rear... then read your message to find out it was. I'm driving a 1984 Rabbit diesel, and totally redid the rear end when I bought it last year. $350 for the car, $75 for all the brake parts, cables, some brake lines. I love that car. I splurged when I was rebuilding it... I spent the $3.49 for the brand new brake cylinders. $7.50 for the drums...

I like the fully independent suspension. I don't think I really need to tie both side together. If I do, I'll bend up a torsion bar to get a controllable amount of roll prevention.

Michael

[dh]

Just a thought, some bigger (wider) ruber may give a better grip on the road.

[anntann]

Helloooo from the driver of this rig!

woooHOOOO!! Do I love my new trailer. When Artificer mentioned my being blown by the semis, it wasn't much...the problem was that the thing pulls so easily, that I'd forget it was there..and a semi on a 2lane highway would blow by me the opposite direction and WHOOOSH I'd get a blast of wind. Didn't blow it off the road, but enough to wake me up.

I'm trying to get Artificer to do a whole "build" thread for it because this thing is amazing. I can move it around with one hand when it's unhooked because of the way the tires work (and it's lightweight..my guess 500lbs empty).

The coil over spring spindle things work beautifully. One thing about rabbit hauling...if the rabbits bounce, they get stressed. Also, heat or sun is BAD. What we found with this build is that I could put an already stressed rabbit into the trailer and when I checked on him after a few hours, he would have calmed down and be quietly munching on hay and drinking water. I attribute that to 2 things...the coolness of the trailer, and the smooth ride. Water simply didn't slosh around out of the "cups"

There was a ton of interest in the trailer every time I stopped to fuel up, or for the night. One trucker got his camera out and crawled around underneath to take pictures.

The other thing that happened....after 12,200 miles, the tires are really not worn much. I know Artificer posted elsewhere about the strange wear...but if you look at them now...it's evenly worn and amazingly, still a lot of tread. I put some of that down to the coilover spring spindle thing. No axle causing the opposite tire to move when something happened to one of the tires.