BOK

How much better is a ladder frame for offroading as opposed to a unibody?

Most will say a ladder frame but then again I've also heard some claims that the latest stock version of the Jeep Cherokee(unibody) will outperform a stock runner (3rd gen w/factory locker).

Are these false claims or is there some truth behind it?

To tell you the truth I don't think I've ever really understood the pros and cons of ladder verse unibody for offroading.

gwhayduke

I think the general reply is that a frame provides a rigid structure to bolt your body and suspension to. Although I don't believe it's valid. Anyone who has watched a pickup do any wheeling can tell you the bed flexes in relationship to the body.

Other than the fact that you can't do a body lift, I don't think it makes a whole lot of difference which you have. As long as you have traction, clearance and gearing.

Bundubasher

Is the "ladder frame" the same as "monocoque"? And is this what we have on a 2nd gen Runner?

gwhayduke

The monocoque that I'm familiar with was used on the E-Type Jaguars. It was essentially a square tube frame that was similar to today's space frame but didn't enclose the driver.

This is way out of my expertise though. I'm sure some others here at the board have a better knowledge base.

Bundubasher

Just been on the web and found a good source of tech info:

http://autozine.kyul.net/technical_s...tech_index.htm

Most 4x4s are ladder, and 99% of modern mass produced cars are monocoque.

Firefyter-Emt

OK here is a proffesional answer for you.. A uni-body is safer in a collision (to a point) due to the fact that it is made to fail and crush absorbong the impact energy and transfering it along the "cage" that is designed around the passanger compartment. A full frame is stronger anyday of the week, but the energy of an impact is transfered more directly to the passanger compartment making it not as safe from a soft tissue injury standpoint. For off road, a full frame is going to be better every day of the week over a uni-body. It will also allow more flex in the way the frame is designed to twist (ever look at a FJ40 front end? The fenders are made to slide past each other and the grill has a center mount to pivot on..)

BOK

Thanks!

That sheds some more light on the matter.

Icepick

IMO unibodies are much more succeptible to metal fatigue after years of off roading. You need the vehicles chasis and frame to be able to give a little. Just like bridges and buildings are designed to flex.

Victor

I had a unibody car that creaked a lot - the body was quite fatigued. I'm sure the newer unibody SUV's are a lot stronger but I guess thats why most of them come with AWD and not 4WD - you can't wear out the body if it never gets abused offroad.