Finished my Cobra Automotive-like 70 Engine Crossmember

[buening 63]

I made a thread awhile back about two options for my design, the original Cobra Automotive style end brackets and what I felt was an improved version. I decided to run with my version, but in the end I doubt it will matter much. I would like to thank VMF member hsr for getting the ball rolling on this and obtaining and drafting the dimensions up for the 65/66 crossmember, and would also like to thank VMF member jmn444 for measuring his CA crossmember and marking up the dimensions that are different on the 67-70 crossmember.

A little background on this. I installed a T56 trans in which I lowered the motor 1" and moved it to the rear 1.25". This meant the stock crossmember no longer fit. Rather than just making one similar to stock, I decided to tie in the LCA mounts to add more rigidity much like the Cobra Automotive crossmember does. I also wanted it to serve as a jacking point for now.

So since my situation was custom due to the oil pan location, I simply drew up the end brackets on a 2x8 piece of board, and cut out the center to follow the factory crossmember shape. I then put the board up in place like it was the crossmember, marked where cutting needed to occur, put the board back on the bench and cut as needed. I repeated this over and over until I had enough clearance. It resulted in the top of the crossmember center section being 1.25" lower than the stock piece.

The below drawings and dimensions are not intended for stock location engines. It will work for stock location engines, but it will just hang down lower. No guarantees of fitment for aftermarket oil pans. I'm working on drawings for this crossmember with a motor in its stock location, in case someone else wants to use this.

For the end brackets I used 2"x2.5"x3/16" angle. I believe the CA piece used 1.5"x2 5/16" bent plate. For the center sections, I used 1.5"x1.5"x3/16" square tubing. Since the CA piece had 1.5" for the top leg of the end bracket with 3/16" thick, that meant if I used 1.5" square tubing with those CA dimensions the tube would stick out past the bent plate/angle 3/16", thus the reason to bump up to a 2" top leg. Now for some drawings and pics. I put some up close pics of the drawings as well as an overall view, as I'm not sure the dimensions will show too well in the overall view due to its length and picture size limitations.



End Bracket:









And here is the finished product (still in painting process though):

 

 

 

 

 

 

Comparison to the stock piece:
 

And pics of it sat in place (but not fully installed). Pictures didn't turn out too well since I was on my back and the chrome oil pan created some nasty reflections/backlighting

 

 

As you can see, this car is no trailer queen by its dirt and grime. Its a driver It doesn't help the oil pan and PS pump is leaking, adding to the grime.

I have the Pro-Motorsports Eccentric Eliminators sitting on the workbench. My plan is to use a longer bolt with a nut in between this crossmember and the LCA, and another nut and washer on the face of this crossmember. For the pictures I just have the crossmember bolted in but not hooked to the LCA, as I have other suspension mods planned in the future and I don't want to mess with the alignment just yet (since its getting warmer out and I'll have the urge to drive the car).

I was a bit torn on how to handle the eccentrics. I had thought about removing the eccentric holder that is spot welded to the LCA mount and welding it to the face of this crossmember, which would make alignments MUCH easier. However, I was a bit concerned about the increase in bolt length and the distance between each eccentric plate. In the end I decided to leave it as is.

I also did not capture the top two dimensions of the overall view and the picture is tiny. The top dimension from frame bolt hole to frame bolt hole is 2'- 5 3/8". The dimension below it is from the centerline of LCA slotted hole to centerline of LCA slotted hole, and is 1'-7 1/8"

[prayers1 153]

Great enginuity! I'm sure it took a lot of thought & time, I can appreciate that.

I never knew they had one. I think yours is a little stouter.

I have a 289 w/ a stock pan and had to use 5 washers on each side of the cross member just to clear the pan. I'll be putting in a 351C and your cross member will come in handy. Are you thinking of production?

GREAT JOB!

[buening 63]

Attached are PDFs of the stock mount as well as my modified crossmember with the motor 1" drop and 1.25" relocation to the rear. Again, due to the width to height ratio the dimensions appear small when printed on 8.5x11 paper. I recommend zooming in to see the dimensions. I can plot PDFs out in sections like my pictures above if there are requests for this.

Thanks prayers1! Not into production, just a DIY guy hoping to provide drawings and details to help others make theirs.

I can help with modifying these drawings if someone has a custom application. I would basically need the dimension from the bottom of the frame rail to where you want the top of the crossmember center tube, as well as the top width of the center tube. If you notice the attached PDF drawings of the stock vs my modified one, as you move the center tube up with a set top width of tube, your angles and lengths of the side tubes all change. I can get that altered in CAD pretty quickly, so don't be shy to ask!

 

 

Crossmember - Modified.pdf

Crossmember - Stock.pdf

[Ry-speeed 14]

Great re-engineering!

 

At first glance I thought the inner slots were to serve as a location to bolt in a R&P. That would be in the design criteria if I were redesigning a cross member.

 

I don't fully follow how you planned to tie-in the UCA mounts as your cross member appears to bolt a few inches behind the OEM UCA position.

 

Looks great, props for posting up your drawings for reference.

[buening 63]

Thanks! Ya know, if I knew of an R&P that could be pulled from an OEM vehicle that DIDN'T lose turning radius you damn right I'd have made provisions and mounted the rack to this crossmember. In fact this would be a perfect candidate for a rack mount should anyone want to use the J-car rack. It would likely take a bit of re-work depending on the bolt spacing of the rack mount as well as getting the mounting height/location correct.

 

The slotted holes are actually for the LCAs, not the UCAs. The slots accomodate the camber adjustment made with the LCA eccentrics. Hopefully I didn't mistype in my book of a post

[buening 63]

Pics of the eccentrics that come with the Cobra Automotive crossmember. The thought process for tieing the crossmember to the LCA is the same, except instead of the oval/eccentric washers I will be using square plates with holes drilled (see below for Eccentric Eliminator pics)

 

 

 

 

 

 

[Mach1 Driver 560]

Looks like our comrades are at it again up above in post #7. More hacking. I thought Obama told those dang Russians to "cut it out" 

[rwcstang 201]

Looks like our comrades are at it again up above in post #7. More hacking. I thought Obama told those dang Russians to "cut it out" 

this made me laugh out loud!! 

[Vicfreg 773]

I have one similar to this, and it has a round jackpad welded in the middle of the lower cross member.  This makes it easy to use the cross member to jack the front of the car up.

 

Nice job with this one, looks great!