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Author Topic: Suspension sagging, need new axle?  (Read 357 times)

cybertron

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Suspension sagging, need new axle?
« on: August 26, 2017, 01:06:04 PM »
I got back from my first trip on the new hub bearings thinking that everything had held up well and my hub temps were right in line with where they should be, even after 7 or 800 miles of towing at 65.  Then a couple days later I noticed that my TPMS was reading a few PSI low on one of the tires.  I checked it out and discovered that the suspension was sagging so much on that side that it was rubbing on the fender liner and had rounded off the shoulders on the tire.  >:(

I pulled everything back apart (and discovered I forgot to put the axle washer back on that side!  So, silver lining I guess? :-[) and it doesn't look like there's any sort of adjustment for the suspension.  Oh, and this is a torsion axle so I guess a new axle is my only option here?  I'm really surprised it's gone bad this quickly.  The trailer's only 7 years old and doesn't have that many miles on it.  :-\
2010 2011 Rockwood Mini Lite ETC 184
2015 Ram 1500 3.0L Diesel

SeilerBird

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Re: Suspension sagging, need new axle?
« Reply #1 on: August 26, 2017, 01:29:14 PM »
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The trailer's only 7 years old and doesn't have that many miles on it...of towing at 65...
I think you are towing way too fast. 55 would be the fastest I would tow it at.
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keymastr

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Re: Suspension sagging, need new axle?
« Reply #2 on: August 26, 2017, 02:56:08 PM »
Well, 65 is what the tires are usually rated for but most new tires are rated for 75 or higher now so 65 is fine in any case. I personally would not tow faster than that though.

As to your axle question,  at 7 years old it may indeed be time for a new axle. They are not that expensive. You should be able to go online to E-trailer, Northern trailer equip or similar site and find a direct replacement and possibly a repair. I am not familiar with the workings of torsion axles but search on youtube and see what comes up. Always amazed at what you can find on youtube.  EDIT: found tons of videos on youtube.

SeilerBird

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Re: Suspension sagging, need new axle?
« Reply #3 on: August 26, 2017, 03:03:35 PM »
Well, 65 is what the tires are usually rated for but most new tires are rated for 75 or higher now so 65 is fine in any case. I personally would not tow faster than that though.
65 might be good for the tires but the problem is the axle. Towing that fast is not a good idea.
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Telemark46

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Re: Suspension sagging, need new axle?
« Reply #4 on: August 27, 2017, 03:57:28 AM »
Yours may be the Dexter Torflex axle.  Eastern Marine stocks some, but others take at least 2 weeks to make up.
https://www.easternmarine.com/catalogsearch/result/?q=torflex

Our trailer developed a sag on one side, roughly 1.5" lower.  It is currently waiting for delivery of the new axle.  Search for "Torflex" on RV Forum for more details.

If you're healthy, handy, and have a place to work on it, you can probably do the work yourself.  I fit one of those criteria, so I'm having the work done by a tire shop that does suspension work also.
« Last Edit: August 27, 2017, 03:59:43 AM by Telemark46 »
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Gary RV_Wizard

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Re: Suspension sagging, need new axle?
« Reply #5 on: August 27, 2017, 10:41:02 AM »
I see multiple concerns here:

1. A "sagging suspension" could mean a bad torsion bar or a bent axle, but either of those suggest the trailer is or has been overloaded.   If so, replacing it is the immediate fix but eliminating the cause is equally important. A trip to the scales is recommended.

2. The tire that has been rubbing may need replacement as well.  Even if not worn through, it may have suffered heat damage that weakened it internally. Also, the shoulder is the weakest area of the tire due to the joint between sidewall and tread. Excessive wear there can be critical.

3. A rubbing tire won't make the air pressure go down unless it actually causes a tire failure (blowout).  If anything, the psi goes up due to increased heat. It seems likely the TPMS was  reporting either a normal few psi difference due to ambient temperature change or that it simply showed the difference between a cold tire and one that was recently driven upon.

4. If those are ST type tires, they are most probably rated for 65 mph max. It has nothing to do with old vs new tire technology - it's the type of tire construction. LT and P type tires are normally rated for at least 77 mph, but the usual for ST is 65 only. And those ratings assume a tire properly inflated for the load it is carrying. Even a bit too soft and a failure is highly likely, especially as speed increases.
Gary
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cybertron

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Re: Suspension sagging, need new axle?
« Reply #6 on: August 27, 2017, 09:05:34 PM »
One thing that's going to make replacement tricky is that my axles were made by Axis, who apparently were bought by Al-Ko and then Dexter in the subsequent years, so there isn't a 1:1 replacement part available.  My axles also seem to have a different bracket design from the Torflex axles I've been able to find, so although it looks pretty easy to bolt on new ones I'm not clear on whether I'll be able to find any that fit the existing mount, or if a Torflex one would work.  I'm going to do some calling around tomorrow to see what my options are.

I see multiple concerns here:

1. A "sagging suspension" could mean a bad torsion bar or a bent axle, but either of those suggest the trailer is or has been overloaded.   If so, replacing it is the immediate fix but eliminating the cause is equally important. A trip to the scales is recommended.
Yeah, that thought had occurred to me as well.  I don't feel like I carry that much in the trailer and I almost never tow with water in the tanks, but I've never actually scaled it.  Guess it's time to do so.

The other thing that may have been a factor is that I hit a very bad railroad crossing on the last trip.  I didn't notice that it was rubbing right after that, but then I was focused on the hubs on this trip and not the tires.  :-\

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2. The tire that has been rubbing may need replacement as well.  Even if not worn through, it may have suffered heat damage that weakened it internally. Also, the shoulder is the weakest area of the tire due to the joint between sidewall and tread. Excessive wear there can be critical.
Absolutely.  I'm actually going to replace both tires because they're about due anyway.  I had planned to keep them through this year and then replace them next year, but this has moved up the timetable.

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3. A rubbing tire won't make the air pressure go down unless it actually causes a tire failure (blowout).  If anything, the psi goes up due to increased heat. It seems likely the TPMS was  reporting either a normal few psi difference due to ambient temperature change or that it simply showed the difference between a cold tire and one that was recently driven upon.
I'm a little confused by what happened here.  It's stopped losing pressure over the past couple of days, but it definitely dropped about 6-8 PSI below what it was.  The other tire is still reading 52 cold like it should be, but the bad one is down to 44 PSI.  I guess it doesn't really matter though since I'm replacing them anyway.

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4. If those are ST type tires, they are most probably rated for 65 mph max. It has nothing to do with old vs new tire technology - it's the type of tire construction. LT and P type tires are normally rated for at least 77 mph, but the usual for ST is 65 only. And those ratings assume a tire properly inflated for the load it is carrying. Even a bit too soft and a failure is highly likely, especially as speed increases.
Yeah, I never tow over 65 and I have a TPMS on at all times to make sure the tires stay up to pressure.  With a single axle trailer I don't feel any need to mess around with the tires.
2010 2011 Rockwood Mini Lite ETC 184
2015 Ram 1500 3.0L Diesel

cybertron

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Re: Suspension sagging, need new axle?
« Reply #7 on: September 06, 2017, 05:19:16 PM »
Just got some really good news!  It's not the axle, it was the tire.  One of the belts broke and allowed the tire to expand larger than it's supposed to be.  Being a single axle trailer it wasn't obvious what had happened.  I just thought the tire was shaped funny because it had been rubbing on the fender.

I'm still going to look into replacing the axle at some point, because after spending an inordinate amount of time looking into this I discovered that the axle is supposed to be 22.5 degrees down, and with it up on jack stands (so no weight on the suspension) it was sitting at more like 10 degrees down.  However, since it turns out my trailer has some weird axle mount that the repair guy had never seen before, this will give us some leeway to find a mounting solution without having the trailer out of service for the rest of the season!  ;D

So, another lesson learned.  When they say you need to replace your tires at 7 years, they don't mean 7 years and a few months apparently.  At least not with cheap OEM trailer tires.
2010 2011 Rockwood Mini Lite ETC 184
2015 Ram 1500 3.0L Diesel

catblaster

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Re: Suspension sagging, need new axle?
« Reply #8 on: September 06, 2017, 06:28:08 PM »
  Have you looked into upgrades?
Will and Jane
95 Winnebago Luxor

cybertron

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Re: Suspension sagging, need new axle?
« Reply #9 on: September 06, 2017, 10:10:06 PM »
  Have you looked into upgrades?
The axle or the tires?  It's definitely getting different tires, whether they're any better will depend on what the trailer place has.  If they're too bad I figure I'll replace them with something better and keep the crappy ones as spares.
2010 2011 Rockwood Mini Lite ETC 184
2015 Ram 1500 3.0L Diesel

catblaster

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Re: Suspension sagging, need new axle?
« Reply #10 on: September 07, 2017, 01:00:27 PM »
  I was thinking you might want to upgrade both if you weight is close to maximum. It seems that manufacturers like to put just enough frame and suspension to do a minimal job.
Will and Jane
95 Winnebago Luxor

cybertron

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Re: Suspension sagging, need new axle?
« Reply #11 on: September 07, 2017, 01:59:34 PM »
  I was thinking you might want to upgrade both if you weight is close to maximum. It seems that manufacturers like to put just enough frame and suspension to do a minimal job.
Yeah, I need to get to a scale and see what kind of weight I've got on the axle when it's loaded for a trip.  I was concerned that maybe I was overweight when I thought I had trashed both the bearings and the suspension, but with it actually being bearings (totally my fault for not re-greasing as I should) and old tires (also my fault for pushing the replacement off one more year) I think it's less likely to be a weight problem.  Those two failures can be explained away by time and neglect.  I will still verify the weight too though since both problems could also be accelerated by too much weight on the axle.
2010 2011 Rockwood Mini Lite ETC 184
2015 Ram 1500 3.0L Diesel

 

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