The problems seem to be mounting! While under the coach and doing the final piece of the engine rear main seal, replacing the drive shaft, I looked forward and spotted a crack in the frame. It is a crack where the panhard rod attaches from the top of the diff to the frame.



I have long been suspicious that the way the rod was attached to the frame it was not really doing a good job of steadying the diff. It is pushing and pulling in the wrong plane of strength of the frame rail.

I had my son push rhythmically on the back of the coach while I was watching an sure enough, the frame was moving and also rolling as the rear of the coach was moved back and forth. It is obvious that compression forces were exerted on the frame rail as the ripple in the lower web near the crack is visible. The extension forces is what cracked the lower web of the frame.

I was going to add a rod to the other side of the chassis to the opposite frame rail but attach it forward to where the frame had a lateral cross brace.

NOW I WILL DO THIS.

I first have to talk with Spartan about the material of the frame. That will determine what I do to weld and re-enforce the cracked area.

So much for the over hang hall of fame! (WEIGHT and MOMENT)

O M G
good thing you found that!!!
I'm sure Spartan wants to know more about it.
They ought to pay for beefing it up. I don't think I have seen this issue ever before on the forum.

I think I remember seeing some body misalignment on your coach a coupla years ago. Is that related?

Not a good sign, being in the flange,where the greatest stress is. Certainly Spartan should cooperate, as that failure mode is unacceptable.

quote:

"I think I remember seeing some body misalignment on your coach a coupla years ago. Is that related?"

No I don't think so. That ripple that you saw is almost fully dependent on whether or not the sun is shining directly on the side. The hotter it gets the more pronounced the ripple is.

I have laid a straight edge along the frame and it does not appear bent around the fracture. The frame only moves laterally. I am going to take a video of the area when pushing and pulling on the coach, it is really obvious what is going on here.

I may employ a truck frame specialist to beef the area up and add the cross structure, these guys do this all day long and should be better at it that I am.

It appears that the crack is fairly old. so I think that the area isn't super critical but certainly needs a really good fix.

I am kinda bummed about this but will take more pictures in the AM of what is there and what needs repairing.

Well, would you look at that. Congrats on the find Ed... And, sorry you found it.

I've always been amazed at the stuff I've found on just cursory inspections. It seems that most owners of big rigs are oblivious to stuff like this.

If you're into it, I'd like to see what it looks like with the wheels off.

quote:

I am going to take a video of the area when pushing and pulling on the coach, it is really obvious what is going on here.

I'd like to see that too, if you don't mind.

Wow.
Ed, glad you found that crack.

Guess I better crawl under and look. Find it a little strange that the crack appears to be 90 degrees. Looks more like a cut.

Just speculating, but the chassis was designed for the 542 box and then the much heavier 3000 transmission was used. Lots of extra momemtum back there.

Just curious, but did they move the axle ahead to acomadate the longer transmission.

quote:

Just curious, but did they move the axle ahead to acomadate the longer transmission.

No I think the axle is in the same location but there is a difference between the Dana axle panhard bar and the Eaton Panhard bar. What is your wheelbase?

I seem to remember that with the Dana axle the panhard bar goes from the frame, clear across the diff to the other side of the axle for attachment. This would be a much longer radius and would not work against the frame so hard with up and down movement of the axle as compared to the shorter bar on my coach.

I think the engine and trans were moved back. My drive shaft is about 18 inches long (45 Lbs), As I recall yours is much shorter and lighter but maybe the 542 is longer and certainly is much lighter.

I have a question DO you live. Under the coach or is your coach on the the second floor of your house.?
lenny

Going VERY slowly, I am about ready to weld up the crack from the top side and have the fish plate all cut and ready to weld to the bottom of the "C" channel across the crack.

Still have not addressed the additional cross bracing I believe will be required to prevent this from happening again.

Now that I will have the bottom adding extra strength, I was hoping to add a fish plate to the top above the same area. Alas, there is a gas line (pipe) there and may not be possible. I don't want to transfer the loads to another area, particularly the top flange as if that breaks, could really be bad.

Pictures and more later

I love it when people say fish plate instead of scab.

quote:

Originally posted by MWrench:

I seem to remember that with the Dana axle the panhard bar goes from the frame, clear across the diff to the other side of the axle for attachment. This would be a much longer radius and would not work against the frame so hard with up and down movement of the axle as compared to the shorter bar on my coach.

Do you think the Panhard bar did it? Certainly the location makes it a suspect.

I wonder if the axle vertical travel is enough for there to be much difference. I have noticed a difference in off road vehicles with a lot of axle travel, but not sure if it would be a factor on a MH.

Your failure makes me think I might have to rethink this.

BTW, does your Panhard bar slip on and off easily at rest? Is it horizontal at rest? These things can really ramp up the stress.

quote:

Originally posted by MWrench:


I first have to talk with Spartan about the material of the frame. That will determine what I do to weld and re-enforce the cracked area.

What did they say?