When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Has anyone cut a manual cross member to add the American powertrain plates ( or similar ) with the body in place ? Any tips or guidance is appreciated!
Jim
I suggest you're better making your own, or modifying yours, AND making it such that the exhaust passes "under" instead of "through". Hell, if you're going to make it removable, then you might as well make it more useful.
My 68 has a removable crossmember. It's of the basic flange plate design. It was installed by JD Corvettes in Bellflower, CA. When I get my 70 into their shop, it too will be converted to a removable crossmember .
Just brought one to modify for my 76 auto for $75.00. It looks easy enough with the right tools and 3-5 hours work with crossmember out of car.. Once I get the surface rust stripped it will be go time!
The first I did mine, I added plates that I made to the original one. Worked fine...but the sharp bends from big block headers to get pipes through there was tough. But I did get 3" pipe through the holes.
Eventually, I did as mentioned...just made one from some tubing and made a new set of plates to attach to the ones I had already put on frame. This one tucks up tight to floor and allows 3.5" pipes to go straight back with no issues.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I put mine up on a quick jack so I was right there when I welded it. up close and personal. You have to take extra precautions so you dont burn your face and clothes, where a hat and a shirt buttoned all the way up as well as a full mask. If you can get a face sock thats a good idea too
Get the plates you want to weld in
mock them up under the car so you can see how much room you will have for tools bolting and unbolting them
Mark the cross member and use a straight edge to get a good lline
mark it with a white paint pen so it is easy to see
check the position again against your plates
use a reciprocating saw to cut up towards the body being aware and taking breaks to make sure you do not hit the floor. I flipped the blade over when i got close so I could get all the way through from the bottom
take the cross memeber out and tack the flange to the crossmember making sure its straight
put the mirror flanges on the stubs under the car and see if they fit.
grind and lee the cross member stubs so you get a clean weld
clean all the oil and anything flammable off the body and off the floor
drape a welding blanket over the stubs across the body so that any spatter and slag doesnt get stuck up there and cause any isuses
get a fire extinguisher and put it where you can get it while you are laying down under there
get a squirt bottle with water in it because a welding blanket will burn if its on a hot spot for an extended period of time. the squirt bottle and put out any small fire or any smoldering hot spots. you will need it. Its easier and less messy than the fire extinguisher. THe Fire extinguisher is a last resort and you can use the water to cool the body
just tack the flange in place on the edge
bolt in the removable piece and make sure the spacing is correct if you are or are not using spacers
remove the crossmemeber and finish all the welds, you cant do the top welds so do not bother unless you do some small ones on the inside. Do not weld near the bolts because they could prevent the bolts from seating flat
FRChutch
I concur. Make it "pass under".... if you're going to all that trouble you might as well make it better. I made mine removable, them I modified that to make it pass under, then I totally fabricated my own out of 1/8" boxed steel. It was all for entertainment but I think it would have been cheaper (and easier) get one of those bowtie overdrives crossmembers and just modify the ends to bolt onto the old manual tranny stubs after cutting the original.
You can see my adventure doing that in the link below. But really.... it's a lot better having the exhaust just drop right down and it's even straighter..... and I modified a fairly new 2.5" exhaust from Corvette Central...
The first I did mine, I added plates that I made to the original one. Worked fine...but the sharp bends from big block headers to get pipes through there was tough. But I did get 3" pipe through the holes.
Eventually, I did as mentioned...just made one from some tubing and made a new set of plates to attach to the ones I had already put on frame. This one tucks up tight to floor and allows 3.5" pipes to go straight back with no issues.
I had to wait for the electrician to add the outlet for the welder and that happened yesterday. Today I was able to cut the crossmember and do a rough mock up to set the plates for a tack or two. I hope to weld tomorrow and then get the new trans in.
Thanks for the help and tips!
Just brought one to modify for my 76 auto for $75.00. It looks easy enough with the right tools and 3-5 hours work with crossmember out of car.. Once I get the surface rust stripped it will be go time!
I thought that only the stick shifts had a welded in cross member and the auto’s were bolted on.
True enough, but the post from the guy with the automatic transmission was way out in left field.
He even said that it was easier with the crossmember removed and on his bench! Absolutely no concept of the welded in crossmember of a manual car.
It was just a bogus post.
And really, an automatic in a sports car.
Removable crossmember
