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?
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?