Cracked MJ Frames; I Need Info.

[89 Manche]

I've seen here, and on other sites, that some MJs have developed cracked frames that couldn't be fixed.

Subsequently, the trucks had to be parted-out or scrapped. :eek:

 

Is this more common for the MJ frames than other for truck frames?

Is it more common in other parts of the country/continent than in others due to the environment? :dunce:

 

Where is the most common place for the cracks to start or be?

Finally, can you see the frame cracks easily with your eyes by crawling around underneath of it or does it have to be on a lift to be able to be detected?

Pics would be helpful if any are available.

 

As always, thanks in advance for and advice you are able to give!

[SoloCamo]

I would assume it would be more in climates with extreme variations in temperature, especially if the thing is already rusting out. I know my old 87' I had up in NY was rusted under there to hell, but it showed no signs of cracking. Never heard of this as being a major problem for the comanche frame though.

[Bacon]

rust has nothing to do with temperature, and everything to do with salt and moisture. salt on the roads- here in the northeast, our roads are sanded/salted in the winter hence the older vehicles in this area of the continent are usually much more rusty than in say alberta, where it gets colder during the winter, but they don't use salt, they only sand the roads. salt in the water- any vehicle which has been used to tow a boat/jetski and has backed into the ocean (salt water) doing so will be rusty from being dipped in a salt bath constantly. even vehicles which are only a few years old will deteriorate rapidly if they have been used like this. moisture- when moisture gets trapped, say inside the boxed in frame rails of our comanches, it will cause rust. rust from the inside-the worst kind. by the time you see it, it's too late, the whole area is fubared.

as for the comanches being more prone to frame cracking...well, the "frame" on our trucks is (correct me if i'm wrong here) double stamped sheetmetal. which while relatively strong (mostly because it is boxed) is also very thin. this means the rust has less metal to eat through before it causes catastrophic damages.

mine cracked above the front hanger on the passenger side leaf spring. i was on a trail when i compressed that side flexing, and when i got home, i found my frame had cracked and compressed on itself about 3/4". not fun to try and spread back out without breaking it more before welding.

if your truck is dirty, the cracks will be harder to see, if it is covered with some sort of undercoating, they will be harder to see. basically if you don't see bare metal (or at least paint), they'll be harder to see. hell, if you have a bunch of scaley rust, it might be hard to see the cracks. clean under your truck, get a good light, lie underneath and have a look. you shouldn't need to put in on a lift- you'll still see the same thing, the only difference will be whether your lying on your back looking straight ahead, or standing up, looking up.

 

if you find any cracks, please fix before driving, safety first. 8)

[Bacon]

oh yeah, and any exposed (bare) metal will begin to oxidize -read: rust- within 24 hours simply due to the moisture in the air. at least here in eastern canada that's the way it is. i'm guessing in texas it might be a different story.

[87manche]

I've seen two with broken backs.

 

One was a terminal case of brown cancer, 20 years in ohio will do that.

The other just looked like someone had severly overloaded the truck.

 

Both broke after the cab, in the section of frame before the wheel arch.

[Eagle]

I have seen only one MJ that broke, and it broke where all pickups do -- just behind the cab. I was told by the guy who bought the truck (for parts) from the original owner that it was habitually overloaded, so you can't really fault the truck for breaking.

 

I think this is LESS of a problem with MJs than other brands. My brother's 92 Nissan broke, and he never hauled anything heavier than a couple of 50 pound bags of bird seed in it. Look at Chevy PUs on the road and you'll see that the frames on a LOT of them aren't quite ship-shape and Bristol fashion.

 

And any frame that breaks can be repaired, don't let anyone tell you otherwise. It ain't necessarily cheap, but it can be done. Little bro's Nissan is whole again. There's a shop near us that specializes in that. (And since there aren't a lot of MJs in this area, you can extrapolate from that that MJs are not the only trucks that crack frames.)

[Pete M]

Fully boxed frames are awesome. :D Even if they are made from sheetmetal.

[HOrnbrod]

I think this is LESS of a problem with MJs than other brands. My brother's 92 Nissan broke, and he never hauled anything heavier than a couple of 50 pound bags of bird seed in it.

 

Yeah, birdseed will do that. I haul it all the time, but so far, so good.

[Gearhead88]

I've never seen a cracked frame on an MJ , I ve seen a few XJ's crack around the steering box area , brought on by large tires and extensive offroading in rough / rutted conditions.

[Bacon]

Fully boxed frames are awesome. :D Even if they are made from sheetmetal.

 

amen brother :bowdown:

[JeeperjohnfromPA]

I've some BAD rust through in the area just before the spring perch on the passenger side frame rails.

 

I made some measurements, and stopped at a metal fabircation shop today, he's making me two pieces to weld in, and is only charging me $20.

 

that should 'shore up' the rotted area, I'll POR the heck out of the inside of the frame rail and cross my finger.

It was so rusted out there because a PO had Four wheeled it, and never realy tried to clean out all the MUD that got up in there, (the mouse nest wasn't helping the situation either).

 

I'm gonna take a Good look at m y wifes 2001 XJ and make sure to spray something up in in there to protect it too, BEFORE her's starts to have problems.

[Pete M]

Just take care that you don't plug up any possible drain holes.

[pingpong]

I know there are tons of pics of cracked XJ and MJ frames out there.. BUT I HAVE not experienced this.. and I have beat the snot out of just about every XJ and MJ I have owned. Granted most of the rigs I have owned have been relatively rust free.. and all of them the rockers were intact, and never wrecked.