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Discussion Starter #1 (Edited)
Recently, I read Buening’s thread about building his own RM style adjustable motor mounts and then offering his design to others, I thought I’d do the same. Share my work that is…

I present, “Build your own CA, Boss 302 style engine cross member for 1965-66 only”.

A short while back, I posted a picture looking for some dimensions on the actual piece CA sells. Not that they are really that critical. but I really wanted to know the distance dimension in my original post from the edge of the lower control arm slot to the vertical face where the tube attaches so I could calculate where to cut the original cross member. And, the material thickness they use. I had sent an email to CA (prior to posting the picture and request, but didn't expect a response). Surprisingly Scott responded a few days later with my picture marked up.

With those and dimensions off my own car, I created a solid model in Catia at work. Then over to the drafting side, I fully detailed the part. The result is THIS pdf file.

Next was a quick design of what will be used as a weld holding fixture. It’s actually just a 32” long 2 x 10, a 32” long 2 x 2 and another short piece of 2 x 2:



Now to test the theory, I started with the original cross member and (I have a lot of tools available to me, but a press brake isn’t one of them), an 8” section of 2 ½ x 2 ½ x 3/16 wall square tubing that will become the brackets:


From that piece of tube, I cut the bracket blanks using a cutoff wheel on my angle grinder:


Made a slice where the bend would go and cut off the corner:


Bent the flanges:


Laid out and drilled some holes:


Cut a piece of 1 ¼ round bar (because it’s what I had) to make the spacers from:


Faced that piece:


Bored it to 0.50 inch:


Turned it to an inch in diameter:


Cut off 0.565 or so with a parting tool, twice:


And have a couple of spacers:


Then assembled the fixture. I’m guessing most people reading this know how to cut a board and shoot a couple drywall screws, so I left out the pictures of that.

So, here the original cross clamped to the fixture:

I marked the holes where the cross is bolted to the car onto the fixture:


and transferred the hole location to the top side of the fixture:


then back down.



This was done so when lining up the new loose end brackets, I would see the vertical lines in the hole to locate the bracket:


Clamped the end brackets into place and marked the top of the fixture where the vertical flange is located:


Removed the new end brackets, put the cross back in place and transferred the locations for the vertical cuts from the fixture to the cross:


Clamped the new end brackets into place again. Used some scraps from the angle cuts as shims to set the cross at the same height to the fixture as the end brackets:


After a quick trip to the wire wheel, I aligned the newly cut cross member tube between the brackets against the lower fixture stop and making sure I had equal distance at the top to the fixture top rail:


Tacked the tube to the end brackets:


Removed from the fixture and fully welded. Fits the fixture with no twist!


Trimmed off the bracket material that was above the tube and touched up the sharp edges with my angle grinder:


It fits! No modifications necessary! I’ll take it to work after the first of the year for sand blasting and paint. The Boss 302 suspension manual states to weld the spacer once final location is determined.

Couple of notes:
I’m guessing a stack of flat washers could be used in place of the spacers if you can get them to add up to the right dimension to fit your car.

Flat stock could be used instead of the tubing. I would have if I had access to press brake. The tubing I used is welded. I was able to locate the seam on the top, rear side of the bracket. I had to grind the weld on the inside side of the tube down to get the bolt to seat properly to the car. A longer piece of tubing could have been used to get both pieces out of the area without the weld. Yeah, I’m cheap.

I have adjustable TCP control arms and the horizontal slot really wasn’t necessary on my car. I don’t have eccentric eliminators on my lower control arm mounts. I could have just drilled a single hole and not slotted it.

If someone with a CA cross member for a ’67 on up car wants to take my pdf and mark up the dimensions:
From the bolt hole that holds the bracket vertically to the horizontal lca bolt.
From the horizontal top of the bracket, vertical to the lca bolt.
From the center of the bolt hole that holds the bracket vertically to the rear face of the lca mount bracket.
I should be able to extrapolate the dimensions into everything else needed for those cars and will make a separate pdf detail drawing.

Questions, comments?
 

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Very nice! I had problems with my oil pan just touching the stock crossmember several years ago. I purchased a Control Freak crossmember from NPD. I was surprised that it bolted to the frame and it came with longer bolts for the lower control arms. It really helped stiffen up the front end. Did you gain any oil pan clearance with this mod?
 

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Discussion Starter #3
Very nice! I had problems with my oil pan just touching the stock crossmember several years ago. I purchased a Control Freak crossmember from NPD. I was surprised that it bolted to the frame and it came with longer bolts for the lower control arms. It really helped stiffen up the front end. Did you gain any oil pan clearance with this mod?
Thanks. Yes. I dropped the tube relative to the brackets about 1/4" before I tacked it together. I have a Canton 15-630. It was close before (maybe 1/8"), so a little more room now.
 

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Discussion Starter #5
Where do the spacers go?
If you look at the PDF, you will see them on there. They go between the front side face of the vertical flat new piece I made and the rear face of the lower control arm mount.
 

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HSR,

This is great! I've been trying to figure out a way to do this for a while. Problem is.. I've welded in eccentric lower control arm adjustments for my LCA's so I've been worried that a pre-made unit would work and still allow me to use the eccentric adjustments.

Do you think it would be a big deal NOT to have the spacers welded in?

Thanks again for your efforts!

-Shannon
 

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Discussion Starter #10
I can't imagine it would make that big of a difference with the clamping force of the lower control arm bolt. And only one side is welded. Meaning the spacer to the cross.

I noted welding the space on the detail drawing because the Boss 302 manual states to do so.
 

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In my egg nog induced stupor, another thought occurred to me. I could try to find a grade 8 nut that gets sandwiched between the arm mount and the new cross member that functions as a spacer... Grade 8 shims (washers) could then be used to make up any difference.

Any thoughts?

-Shannon
 

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I would really be interested in making one of these for my 70... I hope someone ponies up the dimensions for a 67 and up X-member
 

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I've almost got all of the 67-70 measurements from another member on here. I'll work with he and HSR to get the 67-70 drawings finalized as well. With my motor relocated, I too can't use the CA crossmember in stock form.

Those that are making these, keep in mind that when you weld the spacer to the back of these brackets you are essentially locking in your camber adjustment from the LCA. From what I understand, you'd only be able to obtain camber adjustment from the UCA....which requires shims or aftermarket tubular UCAs. A spacer that isn't welded may be better suited for a daily driver. The Boss 302 manual was written for racers, which maybe others could chime in but must prefer to lock in their alignment like this. A nut and washer shims would definitely work for those that don't have a lathe. One might also find a spacer/bushing from Mcmaster Carr too.

Good work on this HSR. I like the ingenuity of the board jig for the common guy making this. To even further strengthen the design would be to use larger diameter or thicker wall round/square tubing either bent or mitered/welded instead of the stock tube between the brackets. Add a jack pad to the bottom center and you'd be golden

I'll eventually be making one for my 70 and incorporating the eccentric eliminators to it. I won't know how the eccentric eliminators will work until I get the crossmember fabricated.
 

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In my egg nog induced stupor, another thought occurred to me. I could try to find a grade 8 nut that gets sandwiched between the arm mount and the new cross member that functions as a spacer... Grade 8 shims (washers) could then be used to make up any difference.

Any thoughts?

-Shannon
Shannon, I got pics of the hardware and install instructions for the CA 67-70 crossmember and they use a nut as a spacer for these (see that thread), so yeah you should be able to use a nut on the 65/66. I'm not too familiar with the 65/66 cars but after thinking about it awhile I don't think the 65/66 cars had slotted holes in the lower shock tower/LCA mount for camber adjustment like the 67-70 did, so welding the spacer or using a nut shouldn't affect the natural state of the alignment capability like I originally thought. You'd have to slot the lower shock tower/LCA mount hole and use eccentric bolts or eccentric eliminators to avoid using shims on the UCA for alignment changes. Hopefully I didn't confuse people with my above post, I'm so used to the later cars :eek:
 

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HSR,

This is great! I've been trying to figure out a way to do this for a while. Problem is.. I've welded in eccentric lower control arm adjustments for my LCA's so I've been worried that a pre-made unit would work and still allow me to use the eccentric adjustments.

Do you think it would be a big deal NOT to have the spacers welded in?

Thanks again for your efforts!

-Shannon

I've been running one on a '66 for almost 20 years without the spacer welded in. You will be fine... When I lowered my motor last winter, I had to rebuild mine to take out some of the "V" the aftermarket designer put in to make room for the corners of my Mildon RR oil pan.

For those building one, make sure the flat stock under the pan clears the edges of the pan before heading upwards to the mount plate. Just in case you decide to do something else later. I also ran into another issue when lowering 1" and moving rearward a 1/2 inch to place a Tremec shifter correctly in the stock hole. My oil drain was up against the crossmember and could not be removed. So I had to tuck the crossmember just under the pan but above the drain, probably just a Mildon thing but something to consider...

M
 

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Excellent point. I plan on taking a 2x8 or 2x10 much like the OPs jig, cut out the area at the top of the board for where I think the oil pan is, and then fit it up over the frame rail holes and check the board for clearance to the oil pan. Keep cutting and trimming the opening/notch on the board until you get the clearance, then you have a template for the upper face of the tubing to trace onto the 2x10 wood jig.
 

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Sorry for the thread dredge, but is there any chance the pictures could be reloaded as well as the PDF? This looks like a great mod and the pictures would be helpful
 
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