suspension problems

[smsage999]

Okay, so I will try to make this as short and to the point as I possibly can.
I recently purchased a used 2013 Forest River XLR Thunderbolt fifth wheel toy hauler. I must say it is a massive upgrade from my previous keystone Cougar 320 SRX.

Went on my first trip a month or so ago, and noticed the coach leaning significantly to the curbside. Not so much that I felt unsafe so i pushed on to the house (3 hours), and immediately got my creeper out and went under the unit. All I can say is WOW, the leaf springs on the curbside were a straight line and the roadside were not much better. Counting the leafs, I determined through lots of research on this forum and others, that these springs were only rated to a max f 2250 lbs, which is not enough to carry the empty weight of the coach, much less the GVWR of 18,000 lbs. So I immediately ordered springs rated for 3400 lbs each and replaced the springs and all bolts. This raised the coach almost 7 inches!!! I was happy for that, now I tow more level which eases my mind on tire wear.

Fast forward to this past weekend. the DW and I went on a trip to north-central Texas (6 hrs away) and I noticed about the halfway point (also when daylight was good), when the coach hit a bump in the road, I would see a puff of smoke come out from under the wheels. So I pulled over and noticed the spacing between the middle and rear axle was only about 1/4 inch, while the spacing between the front and middle axle was 2 inches minimum. Again, I pushed through stopping regularly to check wear and temperature. Fortunately no tire damage as the tires only made contact with each other a handful of times, but I began the "kicking myself" wondering how I missed this issue before I changed the springs, then tonight it hit me. with the flattened springs, the axles were pushed further apart, and now with proper springs, they are pulled together.
So moments ago, I went and took some measurements, and cannot believe what I am seeing.

The axle spacing from front to middle axle is 34 inches on center, with the equalizer measuring 7 inches eye-to-eye.

The axle spacing from the middle axle to the rear is only 31 inches on center, with the equalizer only measuring 5-3/4 inches eye-to-eye.


can someone help me figure out why this is? Was looking to get the ez-flex equalizers, with wet bolts, but hell, the measurements are so funky, I don't know which size I need to buy.

Please help, I have a very long trip to Tennessee coming up soon.

[twodownzero]

I can't help but think that just adding 1-2 leaves to the original springs could have done the job. It actually gets me to thinking that rather than flipping mine, which is a ton of work and would involve reengineering a bunch of stuff (like the shock mounts) that perhaps I should just add a few leaves to my spring under 5er and see if I can get a few inches out of that.

I wish I could get another few inches of axle spacing so I could run the 255/85R16 Goodyear Endurance tire to get another ~3/4 in of bedrail clearance and gain the capacity, but I suspect I'd have to cut the mounts off the frame and move them, which I lack the patience for even though I do have the means and ability.

[leibin]

Well, a bit late on this thread, but I'm looking at upgrading my axles and suspension on my 395 AMP to 7k axles and 3500 lb springs. What size spring did you end up with (OP)? with mine under load of the camper and some personal items inside, my springs are measuring between 25.5 and 26" eye to eye. I'm thinking they're 25.25" inch springs when not under load. Would love to know how everything worked out as I'm about to head down a similar road!

[mapguy]

Got a chance to review some of your measurements. Looks like an Alko set up at 29.5 - 33 - 29.5 hanger spacing. Alko calls out a 26" spring but it is actually 26.25. the spring length assumes use of equalizers and shackle links that are the same dimension as Alko shows in their attaching hardware kits.
Found a PDF brochure of your year trailer - it says 6k axles are standard. The heaviest spring I would use is a 3200.
Have you weighted the trailer to ensure it isn't overloaded? Might be a good item to verify axle size. Alko axles have a metal id band, around axle, near right hand brake mount flange. Dexter axles have decal stuck on the axle.

[Bob_E_]

I was only using the 2" as an example. But I think you are headed in the right direction. I'd probably jack up the trailer to get the load off the springs and measure their unloaded length. Your loaded length is 1/2" too long so just buy springs that are about 1/2" shorter than what you have. Of course, if you re-order springs with a different load rating and/or arch, this will screw up your calculations.

Also, check to see if they are bound up under load. If your shackles are pushed to their max, they may actually be restricting the growth of the springs a bit. So you might need to subtract a little more than 1/2" to account for that.

The last thing to check (if you pull the springs off) is the location of the center locating pin for the axle. I've seen leaf springs where this pin is not exactly centered. When I did the lift kit on my Bronco, the leaf springs did have a front and rear with the locating pin offset to account for shackle movement. I don't know if trailer springs have this or not, but its worth checking.

[tinner12002]

Did you actually measure your stock springs and then measure your new ones? They do have different lengths. With more arch in your new springs, it should have actually made your tires further apart, as they flatten out they will get closer together. Not sure why you would have different lengths of equalizer though. Are your tires oversized possibly, maybe 85 series when stock was 80 series, just a thought.

[mapguy]

Your spring hanger dimensions dictate what combination of shackle link, equalizer, and spring are needed for your suspension. Forest River, using the trailer VIN, should be able to provide information on what combination of parts are installed. Upgrades are possible but they need to be of the right dimension or combination of dimensions to work properly.

Also, need to remember that the original suspension was probably not specified to carry the full GVWR of the trailer. Springs installed were probably specified to carry the Gross Axle Weight Rating (GAWR) as found on the Federal Certification Tag on the trailer left front side.

You are correct about the limited selection of springs available from Axle Manufacturers. They pre-engineer suspension/axle packages -carrying only the parts necessary to make these pre-engineered packages work.

A much larger selection of springs is available in the aftermarket. Check out Stengel Brothers webpage for many more options. There are places like Stengel Brothers all over the US....

http://www.stengelbros.com/trailer-suspension-parts/trailer-leaf-springs/

The generalities spoken about axle spacing are that -just general in nature - the devil is in the actual details. Be careful putting to much spring on the trailer as the axles will not carry more weight than their rating.

[smsage999]

Bob E. wrote:
Since the rear equalizer has shackles front and rear, this would result in the center and rear tires moving towards each other as the springs flatten under load. Maybe this is your problem??

Actually, the more I think about it, the more I think this is your problem. Your springs are too long. You had stated that you believed you were supposed to have 35" axle spacings because it is a triple axle trailer. However, according to Dexter, you can have a triple axle setup with 33" spacing, and your measurements from hanger to hanger match Dexter's spec for 33" spacing. Did you order springs for a 35" axle spacing? Think about it. The front and rear spring hangers are fixed. If all three springs are 2" too long to start, that would push the front and center axles back 1" and the rear axle forward 1". This would be why your total distance from your front axle to rear axle is less than 66 total inches (2 spaces at 33"). You are measuring 65 total inches (34"+31"). Plus, now that you have taken a trip, your new springs have relaxed and settled a little flatter making the problem worse. I'd wager a bet that your shackles are leaning way more towards the spring hangers than the originals. They may even be bound up.

Measure your spring length from eye to eye under load and see what it is.

Okay, so I have measured the springs under load (it finally stopped raining), and the measurements under load are 26-1/2" eye to eye, so I believe you have the answer to my problem. Dang springs are too long. With that being said, I find the solution is not that simple. You mentioned 2 inches shorter, however I cannot locate a 24 inch spring (unloaded measurement) that meets the weight rating of my trailer. The closest I can get is either 24-7/8 inch or 25-1/8 inch. The loaded measurement should be 26 inch according to the specs I have read from Dexter and Axis. So I am leaning towards the 25-1/8 inch that when loaded will be closer to 26 inches.

[mapguy]

check out page 4 of the pdf at the link. This shows the various sping hanger/spring length combinations available from AlKo Axis. The same kind of info is available from Dexter Axle. You need to match up dimensions of the original parts installed to resolve the spacing problem. Your frame manufacturer and or the trailer manufacturer should be able to tell you what exact running gear was installed at factory using the VIN.

go to page 4

[Passin_Thru]

Put Airlift on it and pull it.

[fj12ryder]

OP's suspension

[Bob_E_]

fj12ryder wrote:

Bob E. wrote:
The other thing I thought of, just looking at your photo of the springs. The new springs have a lot more arch built in than the old ones. And, it could just be the way the photo is taken, but it appears the new springs are at least as long as the old ones or even slightly longer. With that much arch, when the new springs are loaded and flatten out, they will lengthen as the eyes spread apart. Since the rear equalizer has shackles front and rear, this would result in the center and rear tires moving towards each other as the springs flatten under load. Maybe this is your problem??

Where did you see a photo of the springs? I looked through this thread several times and still couldn't find it.

In his original post, he attempted to attach an image but did it wrong and it doesn't show. But if you right click on it and check the properties, the path is there. I just copied and pasted that into my web browser.

https://photos.google.com/share/AF1QipO8E8t0o2YkpLCQj3c0RJ2MnA0resALZ4OzpXlRF1td0vlksux1F0JTRungwqY0MA?key=eGozQXdsenF0bk12VTAyLVVrS2QtUTVwZV9sWTRn

[fj12ryder]

Bob E. wrote:
The other thing I thought of, just looking at your photo of the springs. The new springs have a lot more arch built in than the old ones. And, it could just be the way the photo is taken, but it appears the new springs are at least as long as the old ones or even slightly longer. With that much arch, when the new springs are loaded and flatten out, they will lengthen as the eyes spread apart. Since the rear equalizer has shackles front and rear, this would result in the center and rear tires moving towards each other as the springs flatten under load. Maybe this is your problem??

Where did you see a photo of the springs? I looked through this thread several times and still couldn't find it.

[Bob_E_]

The other thing I thought of, just looking at your photo of the springs. The new springs have a lot more arch built in than the old ones. And, it could just be the way the photo is taken, but it appears the new springs are at least as long as the old ones or even slightly longer. With that much arch, when the new springs are loaded and flatten out, they will lengthen as the eyes spread apart. Since the rear equalizer has shackles front and rear, this would result in the center and rear tires moving towards each other as the springs flatten under load. Maybe this is your problem??

Actually, the more I think about it, the more I think this is your problem. Your springs are too long. You had stated that you believed you were supposed to have 35" axle spacings because it is a triple axle trailer. However, according to Dexter, you can have a triple axle setup with 33" spacing, and your measurements from hanger to hanger match Dexter's spec for 33" spacing. Did you order springs for a 35" axle spacing? Think about it. The front and rear spring hangers are fixed. If all three springs are 2" too long to start, that would push the front and center axles back 1" and the rear axle forward 1". This would be why your total distance from your front axle to rear axle is less than 66 total inches (2 spaces at 33"). You are measuring 65 total inches (34"+31"). Plus, now that you have taken a trip, your new springs have relaxed and settled a little flatter making the problem worse. I'd wager a bet that your shackles are leaning way more towards the spring hangers than the originals. They may even be bound up.

Measure your spring length from eye to eye under load and see what it is.

[Bob_E_]

The equalizers are different length because they attach to the springs differently. The rear equalizer attaches to the center and rear springs with shackles front and rear. The front equalizer should have a shackle on the front, but bolts directly to the spring on the rear (front of center spring). You can see the difference in Joebedford's photo. Where there are shackles, the eyes of the springs should be above the eyes of the equalizers.

According to your spring hanger measurements, your axles should be 33" spacing center to center. This could vary a little once everything settles. The spring length should be 26" eye to eye.

For whatever reason, it seems that your center axle has moved back by about an inch or so. With only 1/4" between the center and rear tires, I'm guessing that you would have noticed this condition when you had reassembled it. So that leads me to believe something has shifted during your trip.

Is it possible that the u-bolts aren't tight on the center axle?