Those of you who have removed and subsequently replaced your front cross member, either with a permanently welded or bolt-in replacement: what type and size of tubing did you use? I'm looking to use some schedule 40 pipe but am undecided on what diameter to go with. Just looking for some comparison to what others have used.

My knee-jerk reaction was to use 2" NPS schedule 40, which has an OD of 2.375" and uses 6" diameter flanges as a standard. Now I'm wondering if that's large enough, or even if the 1.9" OD of 1.5" NPS would be too small.

 

pipe is for fluids, anything sold as pipe sizing is the incorrect option. tubing is for structural loads. I would recommend doing some moment of inertial calculations to determine a minimum stiffnes required. What is your reason to replace the cross member?

 

True, I had initially looked at NPS due to the availability of slip-on weldable flanges making material sourcing and assembly/install simpler. Perhaps I'll look more towards A500 rated tubing. Schedule 40 is pretty heavy stuff, I wouldn't be concerned about its structural integrity but NPS material and forming methods aren't as strong as a standard hot or cold rolled steel.

I want to replace the front cross member to maintain (or regain) some structural rigidity that was lost after removing the OEM cross member. I was planning on doing some moment calculations but I've long since tossed my old cross member and don't have anything to take measurements from to find out the moment of the original cross member.

 

I used DOM 3" 1/4 tube it's very heavy stuff I'm sure it's much stronger than the oem crossmember that's just spot welded into place. It may have been a bit over kill but it's work out great and really cleans up the engine bay. If I was to do it over again I would have made it a bolt in setup, for ease of removing the engine and transmission in one shot.

 

I ended up deciding to copy Matt's 2.5" square tube design pretty much to the T. I'll update when I've got everything machined and welded together.


Sounds BEEFY!!

 

2.5" square tube by 1/8" thick is what I went for

 

That's what I ordered also. I'm making 1/4" thick 4" square flanges welded to the tube, and 1/2" thick 4" square flanges welded to the frame rails with 4x M10x1.5 tapped holes in the corners.

 

Pretty much exactly what I did except I used 1/4" plate with nuts welded to the back of it welded solid to a 1/8" plate which is spot welded to the frame rail just incase I ever want to remove it without doing too much damage to the frame rails. The 1/8" plate also added some strength by being the same width as the frame rails. In the event an impact ever happened on the crossbrace the idea is that it wouldn't dent the middle of the frame rail. (but this was before I knew the frame rail have gussets in the middle) So keep that in mind where your bolts are going to enter. When I get home in a couple weeks I can take a measurement for you if need be.