Ladder frame vs. monocoque chassis longevity

[omaroo]

Opinions...

Ladder frame chassis have been around for decades and have proven extremely tough in off-road applications.

The Cherokee and Grand Cherokee's have a monocoque chassis design that makes for a lighter and stiffer body which handles the on-road sector arguably better than a ladder frame-equipped fourby.

My questions is: How have owners of both types of design found their particular choice over the years?

Given that the XJ has been around for a decade or so, have owners had any body/chassis actually break on them? I've seen plenty of ladder frame chassis break and need re-inforcing after the event (or replacement), but would like to know if similar experiences have been had wit the monocoque chassis owners.

This should spark up a few responses.

[billsta]

i twisted the WJ body that bad that the door donr open or close.
i think some of the XJ guys will tell you that they have problem wiht the tail gate when its twisted up..

i think stress fracture is bad on a monocroque. hard to get to and cant SWAP for a new one.

[omaroo]

Did the body recover at all... or is it permanently twisted now? Doesn't sound good.....

[MattW]

I think ladder frame chassis would be better for modifying. Cant do body lifts on monocoque.
The ladder frame will break the mounting points between the body and the chassis which can be fixed but the monocoque will twist everything.

[xjdavid]

I have had my xj for 6 years and have done a lot of hard 4wding with no problems. The monoque chassi gives a lower centre of gravity and results in a lighter vehicle. This gives the xj just about the best power to weight ratio of any 4wd. But the best test is that the yanks have been wheeling these thing for 20 years and I havent heard any complaints. I have heard that if 35" tyres are used and you do a lot of rock crawling then you may experience some problems. All up seems to be a weapon to me. Dont know why some 4wd mags knock them. Dont know much about the jap stuff but. The twisting as spoken about above is only temporary.

[OzJeeper]

There are pros and cons to both types. If we talk about "breaking" the thing then the seperate chassis will win out on repairs. I ended up with a bent chassis on the '82 Cherokee and it was replaced under insurance. Cost about 4k all up and I still have this Jeep on the road.
However, if you bend any part of a monocoque chassis it's replace the vehicle. They can do a stretchy/pushy/bendy job on the thing to get it straight again, but it will bend again in the same place in similar circumstances. There are a number of monocoque chassis vehicles (no brands mentioned!) sitting in wreckers yards with bent monocoque chassis from a difficult recovery with a winch! Winch mounting points bent the front of the car!!!
This could also happen to a ladder chassis - but it can be replaced... Found a bit of rust in my CJ10 chassis - no probs - palte and weld and it's still as strong as.

But I do like the light kerb weight of the newer XJ/ZJ.

I think that's almost 3c worth

[Wooders]

Well In our XJ I havn't had any problems with the tailgate closing - but I do get an annoying squeak from the front drivers door seal which I al told is partly attributed to the flexing of the monocoque frame.
Also in Jan04 Jp they have a writeup on installing a stage II Chassis Stiffner to their Project XJ - I don't know if anyone is interested but check out their website: www.tandjperformance.com (they do a lot of Jeep speed stuff too )