ScottEwine

Good morning all,

I am planning on replacing the welded crossmember on my 1973 4-speed frame with an aftermarket crossmember. My question is, if I weld in the removable cross member brackets, how do I get the weld nuts on the bottom of the frame installed? I know that the frames have a lot of weld nuts installed that are not necessarily used, such as for the rear sway bar, but I don't think these are installed, am I correct?

Thanks,
Scott

ScottEwine

Here is the plan I have come up with:

1. Grind out the welds on the current crossmember and remove it.
2. Clamp the Paragon crossmember brackets and Gforce crossmember in place and tack weld the brackets.
3. Mark the position where the holes need to be in the bottom of the frame.
4. Install (2) 3/8-16 Rivnuts ( http://www.rivetnutusa.com/rivnut-ca...omponents.html ) on each frame rail.
5. Complete the welds on the crossmember brackets and put some chassis paint on it.
6. Install the new crossmember.
7. Have a beer or two.

Any other suggestions or guidance would be appreciated!

Scott

bazza77

Yes you are correct , the manual frame didn't get those captured nuts .

Have you priced the tool that is used for the installation ? They are quite expensive . Especially for just 4 rivets of the size you would want .3/8 or 1/2 inch ?

I have a set of those (different brand ) ,they are handy ,they came with different size pieces but not up to the size you want .I use them for dash board mounting pieces and small stuff ,so there's no real load on them .

Have you rang the company and asked just what the load rating is ? they say class 5 hardware , so I assume its not for heavy duty applications.


If your handy with a welder and ok with flipping the frame over you can make something a lot cheaper and with proper grade nuts and install it your self.(that would be my first choice )

derekderek

PM David Howard. He is kind of a frame guru. Has a few designs that may be easier to do with the body on.y

ScottEwine

Thanks, I will PM him. Just to clarify, the body is off, I have the suspension and tires on but no engine yet.

ScottEwine

Thanks,

A welder friend of mine suggested the rivnuts, he has the installation tool and the rivnuts so the cost for me is $0. But he is also a great welder and I would like to do the best fabrication within reason and I can pick up the frame with my forklift to where it will be easy to work on.

What would you do if the frame was flipped over and you had a welder?

Scott

DUB

Knowing that this cross member has a bolt that runs though the cross member and the new bracket you plan on welding in. NOT all of the support for this cross member is on the area where you plan on using the riv-nuts. So it is not like the four bolts on the bottom of the frame are holding the cross member UP.. The long bolt...if positioned correctly...will not allow the cross member to drop down and it is taking almost all of the load.

Becasue if you stop and look at the cross member...those tabs where the lower four bolts go where you plan on using the riv nuts is NOT reinforced or gusseted due it is not made to do that. You can bend that tab by tapping on it with a hammer....so it alone by itself is not designed to be seriously structural. And that is where the long bolt comes into play and changed how strong this area is when all six bolts are installed.

DUB

Richard454

Don't know if you are going to be running sidepipes- but you body is off-

My body was NOT off- so I didn't want to weld- and I'm running sidepipes-

No plates- or welding needed-drilled some holes and ran bolts through it.




Cut out the crossmemeber w/ a sawzall-






Wood mock-up-




Bought some 3" x 1-1/2" x 3/16" 36" in length steel rectangular for about $20.





Slides in the drivers side-



Test fit


Drilled a few holes-modded the OEM bracket- painted it up- bolted it in- TKO 500

bazza77

If you can get them for 0 and there strong enough , just get them and put them in ,but for me …..

First I would clamp on the crossmember in the correct position ,then flip it over.
mark where the holes/nuts were needed and extend those alignment marks further out so they don't get lost when I start cutting.
Getsome plate steel (same or slightly thicker ) and weld the 2 nuts on(each plate) leave some excess plate around the nut holes/threads.
whatever size plate you end up with , copy that size onto some cardboard with the nut holes marked , get the nut holes in alignment on the frame and mark where the edge of the new plate sits

cut a hole in the frame and place the new piece in , hold it in situ by either bolting in a piece of scrap steel across each new hole (so it cant fall in ) or just tack some scrap across the top (easier)
you will more than likely cut across the frame join so there will be a double thickness there, if you fully weld your new plate(with bevelled edges)it will be plenty strong
that's what I would do if I was keen to not have those flanges in the cross piece.

DUB

Nice idea Richard.

DUB

ScottEwine

I contemplated something like this, but will be using rear exhaust so I need either the holes or the open area in the aftermarket crossmember.

OMF

If you are planning on running headers.........
I'd make sure the cutouts for the exhaust on that cross member are inline with the header collectors.......if the exhaust can run straight back without bends in it, efficiency will improve.

ScottEwine

I have received the information from David Howard on the brackets that are welded onto the cut ends of the existing crossmember, they are a cheaper option which I think will be just as strong as the original. So I guess my question is, how big is the advantage to having the larger open area that you get with the custom crossmember? Does that make it easier to mate up the exhaust in an LS conversion?

DUB

If you are asking is there an advantage to not having holes in the cross member like the factory one has. Yes there is an advantage due to you are not restricted to one specific area you have to run the exhaust THROUGH.

So with the cross member you showed a photo of. More area means more options in how you run the exhaust if needed. And for the new cross member not having holes init...if needed... you can literally drop down the entire exhaust system as a whole if service work needs to be done fit the system is welded up and not clamped or flanged together.

YES..as you know an exhaust shop can bend a pipe to fit whatever a car needs. And how teh pipes are joined can be done several ways successfully. Some are more 'user friendly' than others so it all depends on how you want the system built for any future work you may need to do on it.

I always look into the future and consider what it will take for me or the next guy who may need to take something apart and take the time to build it so it is not a pain in the backside to do something.

DUB

crf311

pauldana

like to see some pictures when you are done.. thx pd

ScottEwine

TimAT

That is exactly how I did mine. I used a 2x3 piece of tube, Cut the original with a sawzall. Slid the tube in. clamped it down and drilled 6 holes, then welded nuts on the inside. I used some 3/8 socket head capscrews. I even located and welded the original parking brake guide wheel in place.

carriljc

Couldn't we use the "stubs" from the manual crossmember to bolt on this aftermarket crossmember? Seems like it would be easy enough to drill a horizontal hole for the upper bolt, and then deal with the vertical as already suggested.