interesting.....frame stiffeners

[freakjeep93]

CW reminded me. i read a article in petersons 4wheel and offroad ayear or so ago about xj frame stiffiners and they said that it chabged the dynamics of the xj alot. it nade it cirner better and all that stuff . but in reality you could make them for 20 bucks if you were creativeenough

[pingpong]

I say go buy some 31/2x 3/16 flat plate and weld in place. Adding dimple die holes if you have access if not cut 2 inch holes every 6" to inrease weld area. stitch weld the top off set from the 2" holes.

[FXWorks]

However, back to my original question...isn't the idea of the unibody so that it can flex?

 

Nope, never.

 

Flexing steel allows metal fatigue to occur more rapidly. This leads to cracking/tearing of the unibody.

 

Take a look at some of the SW big dogs and what their unibodies ended up looking like before they started adding plates to the unibody to reduce flexing. Cracks and such all along the firewall and tunnel in particular.

 

Make the suspension do its job.

[FXWorks]

In fact, very little about them is 'right'. Granted, I didn't bother to read any of this thread other than your post, but these products break about half of the basic rules of frame modification/repair.

 

Please elaborate. Are you referring to the vertical bits not being at 45 degrees to the stress/strain curve? This is additional metal, not replacement metal. This is not a "repair" peice.

[Eagle]

However, back to my original question...isn't the idea of the unibody so that it can flex?

In a word - no.

 

The idea of a unibody is to use the welded-together sheet metal panels to take up some of the stress so the "frame" doesn't do all the work. By distributing the stress through the entire body, the need for a rigid, separate subframe is eliminated. In theory, a properly designed unibody is stiffer than a vehicle with a body mounted to a separate frame, not more flexible.

[hugh]

I have to jump in here with a comment. On my 98 XJ I installed a similar plate for 2 reasons. The first was to stiffen up the bottom rails of the unibody, i did not care if a little flex was lost, the XJ right out of the box flexes way better than my previous 84 CJ 7. Having installed a 6 1/2 Iron Rock long arm kit it flexed even more. The 2nd and more important reason to me was having thicker steel running under the body. We do a few rock trails and usually at a real slow speed, If the body slides on or hits a rock the force is distributed along the length of the plate and the thin unibody "frame" doesn,t get crushed or deformed. When I pick up my long bed MJ this spring I have already spoken for a set of stiffeners for it too, think of it as armor.

[dakal]

my 2c

 

angle is always better than flat.

 

stiff is always better than flex- as someone said, let the suspension do the work.

 

it true in every form of racing ie extreme conditions!

[xj92]

I made my own stiffeners for my last Cherokee out of 4x6 box steel (1/4" wall) that I cut in half. I made the same relief cuts all the ones being sold have now and welded them up later. I also did all the holes and rosette welds. I now have an MJ instead of the XJ. If somebody offered an elegant enough product for the right price, I'd buy it. It's a pain drilling all those holes especially. Now if I get my plasma cutter before I do it next time that's another story, but with a hand drill and 4.5" angle grinder doing it yourself sucks. I also burned up my cheap hand drill with those hole saws, but didn't have any more trouble after buying a nice Milwaukee corded drill. It really did stiffen everything up. Rode much nicer after that and rocks didn't hurt it.