HF 1720lb Suspension Set Up

[Cantputt]

I'm thinking I missed the boat completely in regards to my suspension. I started out with a new 1720lb 4'x8' HF trailer and built a simple 3/4" plywood box. You can see my Silver Sword in the build journals. Back home after my first trip up north I found that my box was coming apart at the rear hatch. I put things back together and added more braces. On subsequent trips everything in the trailer is getting bounced around terribly. Today when I was putzing around I pulled out my Coleman lantern and as I expected both mantles were laying in the bottom. I never added the stabilizing jacks that I planned because I had found I didn't need them. Ya, right, I didn't need them because my suspension is so stiff there isn't a bit of movement. I have maybe 500lb on a 1720lb suspension. I stood my 220lb in the door and bounced up and down, nothing. I looked underneath where the spring is supposed to slide back and forth as it compresses, no indication that it has ever moved. Over the next couple of weeks I'm going to pull the suspension and take out leaves until it feels right. Any suggestions or tips?

[les45]

It's not just the springs. The stiff trailer tires and high tire pressures are half the problem. I had a similar problem with my weekender bouncing like that and it weighed 1,100 lbs on a 2,000 lb GVW NT 5X8. I dropped the tire pressure from 60 lbs to 40 lbs and no improvement. I finally changed out the 5.30X12 Chinese trailer tires for some 175-70R13 passenger car tires and it made a world of difference. The softer tires virtually eliminated the bounce without changing springs or adding shocks. There have been several posts on this subject on the forum and, if I recall, the conclusion was that eliminating leaves from the springs didn't really help that much.

[Dale M.]

60PSI in tires....... That is way to much!.......

And removing leaves will reduce weight capacity but will also soften up spring rates....

Dale

[Cantputt]

It's not just the springs. The stiff trailer tires and high tire pressures are half the problem. I had a similar problem with my weekender bouncing like that and it weighed 1,100 lbs on a 2,000 lb GVW NT 5X8. I dropped the tire pressure from 60 lbs to 40 lbs and no improvement. I finally changed out the 5.30X12 Chinese trailer tires for some 175-70R13 passenger car tires and it made a world of difference. The softer tires virtually eliminated the bounce without changing springs or adding shocks. There have been several posts on this subject on the forum and, if I recall, the conclusion was that eliminating leaves from the springs didn't really help that much.

Don't your tires get hot? That has been my experience with underinflated tires. Swapping out the wheels/tires for full size is in the long range plan.

[Cantputt]

60PSI in tires....... That is way to much!.......

And removing leaves will reduce weight capacity but will also soften up spring rates....

Dale

60psi is what the tire is designed to run at.

Yes, removing leaves will reduce capacity. That is the point, I have a 1720lb capacity trailer only hauling 500lb.

[absolutsnwbrdr]

60psi is what the tire is designed to run at.

Yes, removing leaves will reduce capacity. That is the point, I have a 1720lb capacity trailer only hauling 500lb.

Someone around here pulled a leaf from their HF trailer. Can't remember who it was though.

I'd agree that 60 is way to much. 60psi (max) is for a fully-loaded trailer. Just like 3-leaf springs are for a fully loaded trailer. Dropping the tires to 40psi will improve the feel a lot, as will dropping a leaf. Since your trailer is so light, the tires won't think that they're under-inflated.

[les45]

I made several trips with 40 psi in the tires and did not notice any heat (and I do check tires and bearings often on trips). That was because I was only running about one half of the rated load. 60 psi is the recommended pressure for a maximum loading (1,750 lbs) of the trailer. My main point was that the stiff sidewalls on trailer tires contribute to the rough ride at any loading and any tire pressure. With the trailer tires at 40 psi, I could try to bounce my trailer by hand and it wouldn't budge. With the passenger car tires it will bounce up and down and sway a little from side to side. On the road, that give in the tire smooths out the ride considerably. I definitely need my stabilizer jacks on the rear with the softer tires.

[Dale M.]

This tire pressure thing embossed on tire sidewall is a running argument in many forums, not just trailers.... Tire pressure stamped on side of tires is "maximum" cold inflation pressure not to be exceeded..... Tire pressure is determined by wear pattern across tread face.......... IF you will look at the tires on your tow vehicle, it will probably have a maximum pressure to inflate to, BUT there is a sticker usually in glove box or on door jam giving recommended tire pressures for loading of vehicle.....

If you find excessive tire wear in center of tread pattern, your tires are over inflated...

If you find excessive tire wear on outer edges of tread pattern your tires are under inflated....

The new tires I just put on my tow vehicle ($800 worth) says inflate to recommended pressure in owners manual....

Suggested reading, third paragraph in this article...

http://www.tirerack.com/tires/tiretech/ ... p?techid=8

I think you might want to do some independent research on this subject....

Dale

[Woodbutcher]

Jeep guys use the chalk method for proper tire pressure.Load the trailer as it would be for a trip. Draw a chalk line across the tread. Pull the trailer forward on a flat concrete or asphalt drive about 2-3 tire revolutions. Look at the chalk line. If it is worn evenly across the tire, you have proper tire pressure. Missing on the outer edges, to little pressure, center worn, to much pressure.

[Cantputt]

Well, finally had some decent weather so I pulled the suspension apart and took out the bottom spring. I dunno, the trailer is sitting lower which is not a great thing, should have taken some measurements before I pulled the spring, feels like it's down about a 1/2" to an 1". Still feels pretty stiff though I thought it would be soft like my big trailer. My tow vehicle went back in the shop today so I could not pull it to see any difference. It pulled fine before from that perspective. The problem was everything in it was thrown all around.

[working on it]

Tire pressure is a constant discussion point among trailer people and dragracers alike. Everyone develops their own theory about what's right or what's wrong, eventually. Even tire dealers and manufacturers differ on many points. The points made here are all valid. But, the main things in my experience are to monitor the wear patterns and the heat build-up in the tires. I like my street driven tires a little on the firm side, to resist roll in cornering, sacrificing some wear in the tread middle (more firm on the rear, softer on front). Just the opposite on my drag car, as soft as possible on the drag slicks (until the sidewalls begin to ball up-screws prevent them from rotating on the wheels) and as firm as possible, on the narrow "pizza-cutter" tires on front (decreased rolling resistance). And on my trailer(s): full inflation based on loading percentage. Max loading (my usual scenario with the car-hauler) calls for max pressure recommendations given on the sidewall. Empty trailer means reducing it by up to 25% (I found that my car-hauler will wander, empty, with less pressure). As for my 4x8 trailer: given that the original suspension was most likely a 1000 lb max rating, having added 14" tires where 8" tires were before, and loaded to 1475 lbs for its' only trip, I assumed that the safest way to travel was at the tire max pressure rating (1475 lbs trailer on a 1760 lb x 2 tire suspension), just in case. It didn't bounce, nor did I expect it to, and didn't sway around (my WD hitch and spring bar made it hunker down), and the tires at max precluded any tire sidewall-induced wandering. But one thing common to all my experimentation on very different wheeled projects is that I check for tire wear patterns and heat build-up. They tell me when to change my direction in loading-pressure-even equipment. I check for heat build-up at every stop when towing (I use my hand, and experience, to judge...others use infrared heat guns for more accuracy). http://www.harborfreight.com/infrared-thermometer-93984.html

[Socal Tom]

Search for a thread I started called "suspension secrets" . Check that you haven't over tightened the leaf springs and shackles. Tires can be used at less than the max on the side, manufacturers provide a chart that shows the weight rating at each pressure. I've provided a couple of them in that thread.
Tom

[Cantputt]

Hauled the trailer up north this weekend. I didn't think my suspension change made that big a difference. I was wrong, everything was still in it's proper place both on the way up and the way back. The taking out the leaf spring worked great. Sweet, no more jumbled up mess and tipped over cooler.

[professor.smith]

I have same problem with rough ride. but I am more conserned about my toung. the welds on both sides have broken where the remobable pin attach. I just returned from a 2500 mile trip to the Smokeys when I found the cracks. they are so bad you can see light through the welds. Check yours.