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Topic ClosedBlack tank fell from r-pod - Event Date: 03 Nov 2016
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Happy Tripping View Drop Down
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Posts: 473 		Direct Link To This Post Calendar Event: Black tank fell from r-pod
    Posted: 17 Mar 2016 at 12:01pm
I looked at my 2 year old 171, bolts look secure and close-fitting. 

My guess is that changes in the basic design for additional things - slides, greater length, etc resulted in 'teething problems. I am sure FR will get this straight with time, but they have a clear responsibility to recall all of the defective trailers for appropriate correction, just like all car manufacturers are required to do now.
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Posts: 71 		Direct Link To This Post Posted: 17 Mar 2016 at 6:13pm
I've been reading this thread since it started.  It even prompted me to take a trip out to the storage lot I use and check on the brackets installed on my 2015 RP178.  I crawled under and found everything looked like it fit tightly and found no gaps.  However the screws do seem a little undersized (in my opinion).

But then I started doing the math, each tank is a 30 gallon tank.  Thats 250 Lbs.  Divided that in 2 because there are a front and rear bracket for each tank.  So thats 125 Lbs per bracket.  Now divided that in half again because the bracket is mounted on each end.  So now were down to 62.5 Lbs.  I had 2 screws on each end, so divide that in half again so each screw only has to support about 31 Lbs.  Maximum with a fully loaded tank.  

So looking at it like that I don't think there is any need to panic.  I feel each screw is more than capable of handling 31 Lbs.

Just my thoughts...
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CharlieM View Drop Down
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Posts: 1797 		Direct Link To This Post Posted: 17 Mar 2016 at 7:07pm
Originally posted by jstrenn



But then I started doing the math, each tank is a 30 gallon tank.  Thats 250 Lbs.  Divided that in 2 because there are a front and rear bracket for each tank.  So thats 125 Lbs per bracket.  Now divided that in half again because the bracket is mounted on each end.  So now were down to 62.5 Lbs.  I had 2 screws on each end, so divide that in half again so each screw only has to support about 31 Lbs.  Maximum with a fully loaded tank.  

So looking at it like that I don't think there is any need to panic.  I feel each screw is more than capable of handling 31 Lbs.

Just my thoughts...


You're probably correct if the screws are:

a) Present
b) Not twisted off or stripped
c) Installed without gaps between brackets and frame

These conditions are not always met, apparently. I believe #12 or #14 sheet metal screws would be adequate. I don't know what size is being used today. The worst cases are where there are gaps between the brackets and the frame. That puts a bending load on the screws, the weakest mode for a screw.



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StephenH View Drop Down
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Posts: 6289 		Direct Link To This Post Posted: 17 Mar 2016 at 8:08pm
Consider also these things:

1. RP-179 fresh water tank is 36 gallons, not 30. That is about 295 lbs. full.

2. The calculations posted are for static loads. While the screws might be adequate for static loads, we are discussing what are dynamic loads. When the R-Pod is going down the road and hits a bump, the frame is pushed up, but the liquid in the tank wants to keep traveling straight. It takes significant force to move that water up also. Conversely, when the trailer frame drops, it takes force to move the load down as well, perhaps not quite as much since gravity helps. All of these are dynamic loads that are significantly more than the static load from when the trailer is stationary. It has been a long time since I took physics or advanced math, but I do remember the concepts.

We took our R-Pod 179 to the dealer today to get the attachment of the brackets to the frame fixed. When we get it back, I still may end up modifying things myself to add at least one strong bolt through each bracket and the frame (at least 1/4") with appropriate washers and a nylock nut on each one. There are appropriate times to be a belt-and-suspender kind of guy.

Edit:  The service manager at the dealer said that all of the trailers on their lot use screws to attach the cross-members for the tanks. If this is so, then for the most part, it can be good enough, except when it isn't. Thus this message thread.
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Posts: 270 		Direct Link To This Post Posted: 17 Mar 2016 at 8:38pm
Another thing to consider is the stress put on the screws during assembly, there is a lot of potential to introduce damage to the screw when it is crushing into the frame going in. The type they are using now are self tapping an driven in with brute force. I am not trying to trash FR here, I think the Rpod is well thought out and a great value. It's just a fact that it is a questionable design for all the reasons mentioned in this thread. I am going into Rpod ownership with a mindset a little like owning any quirky American icon, a little wrench turning and upgrading is just par for course. They will be the first thing I inspect next week, if the bracket and screws look flush I will leave it be - and just put it in my log to check for loosening before each trip.
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Posts: 9059 		Direct Link To This Post Posted: 17 Mar 2016 at 8:55pm
Agree on the dynamic loading.  This has been a problem in the design since the start - my 2010 had this same design.
Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual
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Posts: 6289 		Direct Link To This Post Posted: 17 Mar 2016 at 9:14pm
Just a simple piece of strap iron welded just below the bracket on which the cross-member could rest and still be removable would have gone a long way toward fixing this, I think. It would provide enough redundant support that the screws would probably be adequate.
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Posts: 71 		Direct Link To This Post Posted: 17 Mar 2016 at 11:01pm
Originally posted by StephenH

Consider also these things:

1. RP-179 fresh water tank is 36 gallons, not 30. That is about 295 lbs. full.

2. The calculations posted are for static loads. While the screws might be adequate for static loads, we are discussing what are dynamic loads. When the R-Pod is going down the road and hits a bump, the frame is pushed up, but the liquid in the tank wants to keep traveling straight. It takes significant force to move that water up also. Conversely, when the trailer frame drops, it takes force to move the load down as well, perhaps not quite as much since gravity helps. All of these are dynamic loads that are significantly more than the static load from when the trailer is stationary. It has been a long time since I took physics or advanced math, but I do remember the concepts.

We took our R-Pod 179 to the dealer today to get the attachment of the brackets to the frame fixed. When we get it back, I still may end up modifying things myself to add at least one strong bolt through each bracket and the frame (at least 1/4") with appropriate washers and a nylock nut on each one. There are appropriate times to be a belt-and-suspender kind of guy.

Edit:  The service manager at the dealer said that all of the trailers on their lot use screws to attach the cross-members for the tanks. If this is so, then for the most part, it can be good enough, except when it isn't. Thus this message thread.


A few things you need to consider:

1.  Check your yellow weight sticker on your pod.  It lists your fresh water tank @ 250 pounds.  The other 6 gallons you are calculating are in your hot water heater.

2.  The shear strength of a #12 sheet metal screw is rated around 600 to 700 pounds in all the charts that I could find by googling.  Of course it varied by manufacturer.

I know that the strength is under ideal conditions.  But I feel if the brackets are installed correctly (no gaps) as was in my case.  I do not think there is a need to modify and go into a panic.

I'm an aircraft mechanic and I fully understand the difference of static and dynamic loads and was taking that into consideration on my first post.

You do what makes you feel better.  I'll inspect mine every now and then and not worry so much.
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Posts: 6289 		Direct Link To This Post Posted: 18 Mar 2016 at 9:32am
Originally posted by jstrenn

A few things you need to consider:

1.  Check your yellow weight sticker on your pod.  It lists your fresh water tank @ 250 pounds.  The other 6 gallons you are calculating are in your hot water heater.

2.  The shear strength of a #12 sheet metal screw is rated around 600 to 700 pounds in all the charts that I could find by googling.  Of course it varied by manufacturer.

I know that the strength is under ideal conditions.  But I feel if the brackets are installed correctly (no gaps) as was in my case.  I do not think there is a need to modify and go into a panic.

I'm an aircraft mechanic and I fully understand the difference of static and dynamic loads and was taking that into consideration on my first post.

You do what makes you feel better.  I'll inspect mine every now and then and not worry so much.


1. I  will check the sticker as soon as I get back. However, IIRC, the weight on the sticker was 295 lbs, not 250.

2. Thank you for providing the shear strength for the screws. I had not looked that up. In your case, the brackets are tight up against the frame, so the situation for the screws used in yours is ideal. In my case, the brackets are not tight and do have gaps, meaning that the strength of the assembly is compromised.

Nothing I wrote indicated panic. It is concern that this flaw still persists. Forest River's QA department is obviously not inspecting these R-Pods properly before they leave the plant or these flaws would not be present and we would not have read that the OP's black water tank had fallen off.

You could have mentioned your background. None of us are mind readers. I did not know your background, or that you had taken dynamic loads into consideration. I appreciate the expertise you are providing on this subject.

I will check when I get my R-Pod back next week. If things appear to be adequate, I will monitor to make sure things are not loosening. If I still have concerns, I will likely modify it once the factory warranty expires in December.
StephenH
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ouR escaPOD mods
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Posts: 270 		Direct Link To This Post Posted: 18 Mar 2016 at 10:25am
I think this is the point in the discussion where we all need to sit around the virtual campfire and have virtual beer.

At least arguing about the Rpods is a lot more productive than arguing about sports or politics!
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