I am swapping in a T56, and the trans mount is further rear than the auto or T5. Most aftermarket crossmembers reach forward to use both pair of factory holes. I got a custom cross member (Thanks, Nuf!) that uses the rear pair, and requires an addition pair of hole to be drilled.

My question is; what is the "best" way to mount nuts to the back side of the holes, inside the frame rail? Obviously welded so an additional wrench to hold the nut is not required.
My though is:
- drill a small, bolt-sized hole in a piece of sheetmetal (x2)
- weld the nut(s) to the sheet
- drill a large-than-the-nut, over-sized hole in the frame
- weld the nut/plate to the frame.
- grind/sand smooth and paint.
The extra thickness from the extra layer of metal is insignificant.

Is that it? Am I over thinking it?

 

what i did was i drilled the hole needed for the crossmember then had a half cut closed wrench that i put electrical tape over the top to hold the nut on the side . then slide that piece inside rail and tighten down when i was done i had enough room to pop the wrench off and remove it

 

I take a plate of metal 1" wide x 1/4" thick x 6" long, drill and tap two holes 10x1.5, start another hole right in the middle of the plate, mark the frame and drill the 3 holes where the cross member is to mount, slide the plate up into the frame locating it with the two holes that are tapped, Now weld the center hole and grind, Now you can screw the bolts in like the original.

 

Thanks, Don. That is the kind of plan I was aiming for.

Since I am reusing one of the factory threaded nuts, I will likely do something similar to you suggestion for the single addition hole (on each side)... Weld the nut, instead of tapping, on a thin sheet metal, locate the nut to the new hole in the frame, then plug weld the plate through 1-3 previously drilled small holes.

Do you have suggestion on how or where to "slide it into the frame"?
...Perhaps I should be under the car when I consider this question.
...Perhaps the large access hole (seen between the xmember and header in BottledZ28's picture) in front the the crossmember mount will work... Just a little fishing with a magnet or wire...



Thanks to BottledZ28 for the image.

 

I ended up putting extra bolts in the back of my crossmember. I used a 3/8 bolt and fed it upside the rail. I cut a flat spot in the end of the threads so I could used a flat head screw driver to hold it while I tightened the nut



I also made my own crossmember and run the angle iron up and run two bolts through the frame

 

That looks stout! I like the factory, captured nut arrangement, so once the PITA is done once, any subsequent assembly/disassembly is a simple, single tool process.

BTW, Did you put (anti-)crush sleeves in with the cross bolts?

 

the front subframe in my 95 Neon was held into the car with some pretty beefy bolts (14mm, i think) that threaded into a captive nut on a clip that slid over the tab on the body that they bolt to.. drill a hole where you want it, put a slot in the side of the subframe rail, and slide the nuts in...

 

here is mine....

 

Nice! Looks like you took the factory auto cross member, chopped the ends and welded L brackets on each side. Very nice indeed.

 

Here's another option using knurled inserts sometimes known as nutserts that will work to add another bolt hole, or repair stripped ones. See post here:

https://www.thirdgen.org/forums/susp...ml#post6108373

 

Did Holley steal your idea for their Black Heart T56 swap cross member?

 

I like the tapped plate idea.. how do you remove the factory welded in 'threaded things' in the frame so the new plate sits flush??

 

The stock bolt location(s) on a thirdgen sit to far forward for a T56 so there isn't a real need to fiddle with it but I surmise that you could just just pull the plate out.

Here's a shot while I was making my crossmember. It shows the stock bolt locations of the rear most 2 and where the T56 mount is. I think this shot really puts it into perspective of how bad of an idea it is to use only the stock thirdgen transmission crossmember bolts when swapping in a T56. I have more pictures and info on my build thread starting here: https://www.thirdgen.org/forums/memb...ml#post6085499

 

anyone have frame rails for where the crossmember bolts to the transmission?
mine on the drivers side needs to be replaced because of rust,,anyone scrapping a thirdgen with a good one on the car? or is there a company out there who sells these?
thank!

 

No company sells them. No yard will let you use tools that create sparks or have a flame. Doubtful anybody parting a car would want to take the time and go through the difficulty of removing a transmission subframe rail and still have it be usable. Your best bet will be to cut out the offending area and weld in a new section or make your own rails out of 2x2x1/8. Stock subframe material is 16 gauge I believe, not bigger than 14 for sure.