RV, Broken Spring Hanger Bolt... with picture

Good Morning Gentlemen, my parents have a tandem axle fifth wheel RV that is just a little over a year old. It's about 43' feet long and weighs about 18,000 lbs. We've had it on the CAT scale and he is within his axle weights and overall capacity. He has broken the bolts that fasten the rear most leaf spring eye to the hanger that is welded to the frame. The bolts that have broken are the greaseable wet style bolt that ride in a bronze bushing. We put new bushings in it this summer as the factory ones seemed quite worn. The breakage of the bolt seems to be right at the cross drilled grease cavity. (see attached picture) The two bolts that did break did not break at the same time, about 5 months apart. And both times they broke we were out on the road and not in the comforts of our garage.

To get a little more life out of these bolts should I replace with a similar stye non greaseble bolt (lubed up on assembly)?
or
A grade 8 bolt double nutted?
Is there a better solution?

Thanks
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Overtightened on assembly.I've seen it,and done it on my own trailers.The trailer supply place warned me,but I didn't listen.Tighten by hand,with a ratchet,not with an impact like they did at the factory.They only need to be tight enough to stay in place,not pull two parts together.
 
Have you checked the spacing and alignment of the hangers where they are welded to the frame? Especially if the same one breaks every time.

You can get the specs from the website of the spring manufacturer or by the length of the spring and center pivot.
 
Is the trailer possibly putting more stress on the back axle?as in not level when hooked to the tow vehicle
 
You can replace it with a non greasable bolt if you grease it with good grease on assembly. Buying a different bolt will be Hader than most think as they are an odd size and need the knurling to keep them from turning. Without them knurled part the hanger holes wi wear quickly. They should be tightened til the hanger is just shy if touching the spring. A gap or too tight will cause problems. Make sure you hold the bolt with a wrench when installing so the bolt doesn't spin in the hanger and make the hole too big.
 
that is a poor design! you are inviting the crack by drilling it. if they were going to have a hole drilled then it needs to be a bigger bolt engineered for the load. use a non drilled bolt with some never seize. what size is that bolt? darn near looks like 1/2 inch which is way too small anyhow. looks like it has splines on the one end to fit tight into the hangar also. and just so you know when drilling those holes they need a chamfer with a bigger bit after the main hole is drilled.
 
(quoted from post at 06:40:26 09/26/22) Overtightened on assembly.I've seen it,and done it on my own trailers.The trailer supply place warned me,but I didn't listen.Tighten by hand,with a ratchet,not with an impact like they did at the factory.They only need to be tight enough to stay in place,not pull two parts together.

Given the trailer is only about 1 year old, I would say those are the factory bolts and you're 100% right, overtightened, because they use the impact gun at the factory.

One too many ugga-duggas, or maybe 100 too many...

RV manufacturing is about cranking out as many units as possible, not producing a quality unit. My brother-in-law bought a brand new trailer this year, and it was UNUSABLE it was so poorly put together.
 
(quoted from post at 06:32:59 09/26/22) The bolts that have broken are the greaseable wet style bolt that ride in a bronze bushing. We put new bushings in it this summer as the factory ones seemed quite worn. The breakage of the bolt seems to be right at the cross drilled grease cavity. (see attached picture) The two bolts that did break did not break at the same time, about 5 months apart. And both times they broke we were out on the road and not in the comforts of our garage.
Is there a better solution?
Thanks

The grease hole in that bolt is the weakest point. Bolt probably made in land of almost right. I would replace it with a solid bolt and accept that the bushings are going to have to be checked and probably replaced every year. Buy a US made bolt. You can get one stronger than Grade 8, but you don't know the unintended consequence yet. The stronger you make that point, the more likely you'll find the next failure point. The suspension is probably undersized for that trailer. Are the axles rated for 10K, or less.
 
43 footer, 18k actual loaded trip weight on tandem axles?

Are they single wheel 10k axles??

Your first post sounds like you have tandem axles on double eye leaf springs.

Which generally top out at 8k capacity per axle.

Generally, any leaf spring of higher capacity is a one eyed slipper spring.

This post was edited by DoubleO7 on 09/26/2022 at 08:01 am.
 
You said trailer is just over a year old and 1 broke 5 months ago. Just for for my reference, what brand RV doesn't warranty it for at least a year?
 
I use nylon bushings on my tractor trailer, they seem to hold up ok. My trailer is only 1/2 the weight of your trailer though. Stan
 
To answer some of the additional comments:

The trailer has (2) 8,000 lb dexter axles. It runs 17.5 load range H tires. Double 07 was correct, they are double eye leaf springs. Not the slipper setup.
I included the two cat scale tickets: 45,020 lbs total rig on the scale minus the truck of 26,500 lbs = trailer total weight of 18,520.
The trailer is made by Forest River, first broken bolt was covered under warranty.
This may not be the best picture but the rig is pretty level overall when hitched.


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505



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Quite the nice setup!

Why was the second bolt failure under warranty?

Is the failure in the same location, on the right hand side rear most bolt?

After looking at new 5th wheel RV's, it appears to be the industry standard to use tandem 8k axles under them and advertise as 18k gross weight.

But that 18k not being the weight on the trailer axles.

I would weld a plate longitudinal to the frame on center and up against the center of spring eye. I would notch it so that the plate extended forward over the top of the spring eye a few inches as well.
So as to keep the spring eye from moving rearward or up or down if the bolt breaks.
or maybe just add some steel to existing hanger to box in the spring eye top, bottom and behind.

At least then you can limp to a repair facility.

This post was edited by DoubleO7 on 09/26/2022 at 09:10 am.
 
All spring eye bolts are 9/16. Someone mentioned that that may be a 1/2 inch bolt. WRONG. Another mentioned double nuts. WRONG, Use only spring eye bolts as the bolts are knurled right under the head and the nuts are self locking and not to be used again after removal. The one who suggested replacing with solid sounds right since two broke. I would contact the builder. Apparently some posters know nothing about trailers.
 
I really doubt that the cause is overtightening. Those bolts have shoulders that the flange nut hits so over torque would only stretch the threaded portion. It seems more likely to me that there is a design issue. Or rather an installation error at the factory. Maybe the hangers are too close together and don't allow enough flex room for the springs grow in length when they compress. Does either the spring maker or Dexter provide engineering info on mounting? If so it would be worth a look.

It also seems to me that the axles are being loaded beyond their rating. 8K each but an 18K trailer? Even a 16K trailer would be pushing it IMO.
 
A solid bolt with a 1/16 groove milled down one side so grease can get to the bushing, drilled through the head for a fitting, then positioned so the groove is down would keep it lubed and on the compression side of the force. Polishing the groove and using a ball end mill would keep the groove strong. Jim
 
(quoted from post at 08:35:19 09/26/22) To answer some of the additional comments:

The trailer has (2) 8,000 lb dexter axles. It runs 17.5 load range H tires. ... I included the two cat scale tickets: 45,020 lbs total rig on the scale minus the truck of 26,500 lbs = trailer total weight of 18,520.

You're overloaded. I have two trailers running 8K axles in oil and 17.5/H tires. Axles are Rockwell and Dexter, same as yours. The max GVW with 17.5-s is 17,500lbs. That's a very nice rig but the factory didn't do you any favors when they built it with axles they knew would be used at their extreme load limit.
 
The way I understood it, the CAT scale slip shows he has 14,880 lbs on the trailer axle grouping. If the equalizer splits the weight equally thats only 7,440 lbs per axle. This seems to be pretty on par for
the RV industry.
 
Did you see on the weight tickets that he is running at 14,880 on the trailer axles??

Every fifth wheel rv builder is using two 8k axle and rating the trailer at 18k gtw.
He is 1,120 below the 16k for his axles.

This post was edited by DoubleO7 on 09/26/2022 at 11:04 am.
 
My triple axle 5th RV toy hauler has been from north to south and east to west in the USA carrying a full load. After heavy use for work for 3 years. I replaced all the shackles, equalizers, bolts and bushings with non grease able solid bolts. After seeming your broken bolt, Im glad I went solid.
 
Without seeing the rest of the system I would guess that the fault was in the tempering. I first saw those bolts in all sorts of trailers built in the late 60s.... they (and everything else) usually wore down to practically nothing before failure...the side links often failed first. I suppose the logical thing to do would be to go with solid bolts, since nobody greases them anyway... just squirt some oil on them once a month.
 
I'm going to go a different route. While the axles and pins seem to be at their limit for capacity. I'm going with the truck pulling it. The truck is to big for the trailer. With a typical pickup the trailer is on a more even par with the truck. the old semi tractor is able to pull that railer up and down hil without knowing it is there thus causing excessive strain on suspension parts when it hits holes in the road and such along with the bounces along the way on the roads. Sort of like putting a 500HP tractor on a 3 bottom plow the tractor will not even know when the plow hits a stone buried in the ground or a big root along a fence line with a few trees. However the little 30-60 HP tractor will give some if it hits the stone or root. I would also put it on an air suspension since you have air supply on the truck it would cushion the springs a lot if you had air bags under it. I believe they make an air bag kit that can be put under them for this. Though I also think you will then find the axles are not enough for the weight you have.
 
Huh broke where the grease port is. Maybe need rotate it so flexing is in different locations . Check the rest of them , replace all of them
 
(quoted from post at 10:40:19 09/26/22)
(quoted from post at 08:35:19 09/26/22) To answer some of the additional comments:

The trailer has (2) 8,000 lb dexter axles. It runs 17.5 load range H tires. ... I included the two cat scale tickets: 45,020 lbs total rig on the scale minus the truck of 26,500 lbs = trailer total weight of 18,520.

You're overloaded. I have two trailers running 8K axles in oil and 17.5/H tires. Axles are Rockwell and Dexter, same as yours. The max GVW with 17.5-s is 17,500lbs. That's a very nice rig but the factory didn't do you any favors when they built it with axles they knew would be used at their extreme load limit.

I didn't read your weight cert-s before making this comment. As much as I'd like to say it's a bad idea to run 14,500 continuous on a 17,500 suspension, that's what the engineers designed it for.

Next, I'd tell you to check with Dexter and ask their engineers if your suspension components are sufficient. I just looked at my 17,500 suspensions, Big Tex and Great Northern. To my surprise, they are both using solid Grade 5 bolts. If they don't know what they're doing, no one does. Call Dexter. There's an engineering principal re when G5 is better than G8 that I've long forgotten. It may pertain to side loading and shock like you're dealing with here. All I remember is there are situations when G8 will crack and G5 will not.
 
That's not true. He has 16,000 on the axles
and 6,000 on the hitch legally, so with
what's on the truck he is well within the
load capacity for the axles.
 
They don't break from the stretch,they break from the twist.A lot of times if I want to remove the bolt I will just crank on it with the air wrench until it breaks in the middle.After it breaks I spin it until I can pull the loose half out with pliers.Then I can stick a drift in the hole and drive the piece with the splines,or knurling,out the other side.I really think the problem starts with quality,I've seen some of these older pins worn almost in half that won't twist in half.
 
I can't believe how many are saying the axles are over loaded. His scale ticket says he's fine. And most figure trailer capacity without adding the hitch capacity. He has 16,000 on the wheels and 6,000 on the hitch legally, for a total of 22,000 pounds Nand he is well under that. Manufacturers keep them as close to max as possible to get the best ride possible and also to keep costs down. I would just replace with solid bolts and see what happens.
 
(quoted from post at 11:50:15 09/27/22)
Someone said over torquing the bolt will give first at the threads. Not always the case. Weakest point in the bolt will break first.

The broken bolt is what they call a step bolt.
9/16 body
7/16 threaded end
1/4+/- steel hanger leg inbetween.
The nut is gonna come to a dead stop.
With too much torgue, is it gonna break within the plate hole or down the 9/16 body??
 
With a regular bolt you will not have the nerling to o keep it from spinning. Make sure you put a flat washer on next to bolt head then pound one flap up against hex head and the other down around hanger. You can also do this on the nut end instead of double nut.
 
I have a JD 265 loader that came originally with pins for the boom drilled for grease like the spring bolts you have. They would break like your bolts. When new ones were ordered from JD, they were solid and came with a grease fitting and pipe and instructions to drill and tap the boom for greasing. Just sayin..........Ron
 

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