Springs way too bouncy - how to fix?

[Walt Burville]

I've got a 1800 lbs Harbor Freight frame, and my nearly finished trailer is scaling at 640 lbs., probably 800-900 lbs when done and the water tank filled.

I'm wanting to take out two of the three spring leaves to reduce the bounce on the road. Good idea? or bad?

What makes a smooth gliding ride? Like a limo. I need the correct relation of mass to spring strength, I think. How do I get the right combo? Do I need shocks too, and how do I determine/specify the shocks I need. I don't weld, so bolt-in shocks would be best. Can I get those -- at an auto store?

Any help?

Walt B

[Chip]

Walt, there is a couple things ya can try,,,, first are you running stock HF trailer tires,, if so drop the air pressure down by a quarter or a third and take it for a spin with a little more weight to simulate finished loaded trailer,,, I dropped my first trailer in half to calm it down,,, If ya still need a bit of softness try one spring leaf only,, along with the reduced tire pressure, it might get ya smoother,,, as a limo,,, probably not but smoother

chipper

[angib]

Someone will doubtless say that Chip is all wrong about reducing tyre pressures and every tyre should be pumped up to the maximum pressure written on its sidewall.

I don't think this and I've looked at any data I can find on the load rating of trailer tyres at less-than-max pressure. There are differences but one thing they all show is that the load capacity doesn't drop as fast as the pressure - what this means is that, for example, at half the maximum tyre pressure, the tyres can carry at least half the maximum load (and often quite a bit more).

So for your particular situation, Walt, you could take the tyre pressures as far down as half the maximum to see if that gives the improvement you want.

Are you planning on locking some part-drunk prom-nighters inside the trailer and then illegally towing it to see if you achieve a 'limo' ride?

Andrew

[madjack]

Walt, the first thing I would try is reducing tire(tyre) pressure to around 30#s and see how that affects the limo like ride you are wanting...next would be removing one spring from each side...if still too bouncy you can add shocks...I believe Monroe sells a kit for that purpose... http://www.shockwarehouse.com/site/mon_retrokit.cfm
madjack

[Walt Burville]

Good ideas, thanks. I hadn't thought of softening the tire by letting off some pressure.

The shock absorber kit I'll see if I can get it at a parts dealer. Otherwise online at a later time.

Running on the single main leaf doesn't seem to be a safety problem, then. It's rated at 1800 and I won't put more than 1/2 that on it.

Maybe I should try the other stuff first.

walt b

[madjack]

Walt, one thing to remember is that for safety and longevities sake you want your spring capacity to be at around 50% over what ever your loaded weight will be....
madjack

[Jiminsav]

Walt, if'n I were you, I'd write my governor and demand he spend some of your tax dollars on smoother roads....if'n I were you.

[BobR]

The problem with reducing tire pressure is two fold. One, the reduction in stiffness of the sidewall reduces the load capacity of the tire. Two, it makes the tire run hotter from increased friction at the footprint and the flexing of the sidewall. If you want to know what this can cause, just search for Ford Explorer and Firestone tire roll-over accidents. Tires that are run at highway speeds need to be properly inflated, period.

The best way to address the bounce issue is to make sure that the sring rate is appropriate for the weight of the trailer and to add shock absorbers to reduce spring rebound.

Just my two cents worth...

[Sonetpro]

Just what I did.
3000 lb Axle, 2000 lb springs, Jeep Gas shocks, 235 70R15 tires.
It rides so smooth that the stuff in the galley doesn't move. The remote for the TV rode on the front shelf all the way to the beach without moving.

[Nitetimes]

The problem with reducing tire pressure is two fold. One, the reduction in stiffness of the sidewall reduces the load capacity of the tire. Two, it makes the tire run hotter from increased friction at the footprint and the flexing of the sidewall.

The best way to address the bounce issue is to make sure that the sring rate is appropriate for the weight of the trailer and to add shock absorbers to reduce spring rebound.

Just my two cents worth...

If you read the side of the tire it tells you what the maximum tire pressure is at full load, nowhere does it say what the minimum pressure is. If your tire is getting hot you have the pressure way too low. A little experimenting will get you to where your pressure gives you a good ride and doesn't over heat the tire.
The load capacity of the average tire is well over 1500lbs each so unless your trailer is extremely heavy you can afford to loose quite a bit of it.
The whole idea is to get the tire to flex.

The best way to address the bounce issue is to make sure that the spring rate is appropriate for the weight of the trailer and to add shock absorbers to reduce spring rebound.

Lot of extra work and expense for a simple fix IMO

[Artificer]

The problem with reducing tire pressure is two fold. One, the reduction in stiffness of the sidewall reduces the load capacity of the tire. Two, it makes the tire run hotter from increased friction at the footprint and the flexing of the sidewall. If you want to know what this can cause, just search for Ford Explorer and Firestone tire roll-over accidents. Tires that are run at highway speeds need to be properly inflated, period.

The best way to address the bounce issue is to make sure that the sring rate is appropriate for the weight of the trailer and to add shock absorbers to reduce spring rebound.

Just my two cents worth...

I finally checked at work on our Suburban, since I knew it had load dependant tire pressures. For max load it wants 44/80 psi (front/rear), but for 3 people and 200lbs load it goes to 44/50 psi. So there's an example of lowering pressure to get a better ride. It actually mentions the ride comfort on the tire inflation sticker. Since the trailer doesn't need all of the tire load capacity, I don't think a reduction in capacity will be a problem.

If I remember correctly, the Explorer rollover problem was that with higher pressures, the Explorer would tend to roll over during cornering. Ford lowered the pressure (26psi?) to increase road adhesion, but that brought to light manufacturing problems with the tires resulting in blowouts. Jacked up tall vehicles being driven like cars is a bad design.

The increase in heating from tire flex might also be debateable. I don't think there will be much difference in sidewall flex between full pressure/highly loaded tires and lowered pressure/lightly loaded tires. If you compare the sidewall flex for a lightly loaded trailer, then lower psi will result in more flex, but I don't think it will be excesive. (as Nitetimes said, it they're hot, you let out too much air)

Shocks are nice, but they only stop the second bounce. I'll probably add some to my trailer when I'm completely finished, but I'm in the same boat as far as too strong of springs. I have 2 leaf 1250# springs, and I've been thinking of taking out the 2nd leaf. (950lbs trailer weight)

Hope this isn't beating a dead horse, but I finally remembered to check the Suburban...

[Melvin]

If I remember correctly, the Explorer rollover problem was that with higher pressures, the Explorer would tend to roll over during cornering. Ford lowered the pressure (26psi?) to increase road adhesion, but that brought to light manufacturing problems with the tires resulting in blowouts. Jacked up tall vehicles being driven like cars is a bad design.

The Ford/Firestone Fiasco had several root causes.

1) The propensity for tall narrow vehicles to roll (physics is a bitch) especially when driven by minimally skilled drivers surprised by a blowout.
2) the tendency for a swing arm suspension to aggravate that (Twin I beam in the front pre '95). Also a rear tire blow out changes an Explorer from an understeering vehicle (like 99.999% of those on the road) to an oversteering vehicle (common on competition vehicles)
3) Tire pressures specified for good ride aggravating 1 & 2 (a stiff tire equipped vehicle is less likely to roll than a soft tired vehicle)
3a) marginal tire pressure specifications leaving no margin before dangerous underinflation leading to tread separation (Firestone's take).
3b) Poor quality control by manufacturer leading to tread separation (Ford's take).
4) Vehicles loaded past tire load limits (user error). Also the Explorer's suspension design understeers less the heavier it is loaded.
5) Media hype. Lots of SUVs roll every year but it was much more likely to make the news at the time if the roll over was an Explorer.

[asianflava]

I wonder if they used their 8D program to figure those out.

[JIML1943]

I don't know about lowering tire pressure to get a better ride unless it's for a 6 or 8 ply tire or a small tire. I'm running 195/205/14 on my TD on our last trip my daughter was behind us for 2 hrs. she said the curb side tire was bouncing the whole trip, these are new tires with less than 300 miles. I checked the tire pressures drivers side had 32 lb. curb side had 25 lb. My TD weighs 1420lb. on 2000lb. springs. I decided to go with shocks. Thanks for the link Madjack, $91.00 for retro kit with shocks (free shipping)ordered fri. had in my hands tue.

[Finntec]

I am certainly no expert, but from my experience I found that lowered the pressure a little did smooth out the ride. Our TD weights 580. We had 200 lbs of gear in it. The trailer is rated to 990lbs. We lowered the air pressure 10 psi under max. It reduced the bounce. I thought of doing more, but I didnt want to chance it.

I know that my TD can "Get two feet of Air" when you hit a 10" frost heave at 60mph. The car missed it, TD didnt. I said, "Who put that basketball under the pavement?"

I am not saying I went over the speed limit, but I know the TD pulls well up to 83 mph. I did drive for hours at the posted limit of 75. Well above the recomended limit of many trailers. Mostly we traveled at 65mph or 35 mph. It just worked out that way.

Our tires and hubs never got hot. I checked every two hours.

I was told once to keep in mind that many of the trailers we use for TDs are used everyday in construction and farming in situations we might never attempt to go with a TD and they work fine. Be safe and experiment carefully and you'll find out what works well for you.

11,000+ TD (original tires). So far this year. -Ray & Debby