Subframe Upgrades

[19Mopar69]

What sort of upgrades have you guys done to support the subframe when increasing power? Have a 1969 charger that started life as a 318/727 base model that currently has a 383 with a bit of engine work, probably around 400-430 horsepower. Working on a plan for a gen 3 - 392/5 speed conversion. Eyeing a stroker kit that would put it at about 600 hp. Wondering what has been done to make sure everything is properly supported for the extra power. I've heard torque boxes were added to somewhere in the front on the factory big blocks, but since this was a 318 it doesn't appear that it has them. I'll be upgrading the brakes, still figuring out sizing since a lot of the better ones i'm finding aren't compatible with my size cragars. I just got done redoing the entire steering and suspension, which included the borgeson steering box, so thinking I should be good there. This isn't a drag car, just a cruiser/backroad play toy so just wanting to be sure everything will hold up. Thanks in advance.

 

[493 Mike]

Welcome to USCT Motorsports - Get If Stiff
Mike

 

[ckessel]

There are several avenues to choose from. On my 67 wagon, I made a pair of connectors using 2" square, .120 wall tube. Welded to the trans crossmember up front and the rear rail. Didn't require removing carpets or seats. USCT or what I did on my 65 Coronet, 2x4" rectangle .120 wall, means taking the interior out. On the 2x4, that also required cutting the floor for them. What's your confidence level of skills required? Also when you do any of these improvements, the car needs to be on its wheels/tires, or on a 4 post lift, unless it's an empty carcass. If you do the work on jack stands or a two post lift, the car will sag since it's not supported like normal. If you ever have it supported like this when doing other work on it, have you noticed that the doors are harder to open and close? Thats because of the sag in the unibody. If you weld and structural items in when it's like this, your doors will stay that way.

 

[DeltaV]

Also when you do any of these improvements, the car needs to be on its wheels/tires, or on a 4 post lift, unless it's an empty carcass.

How about a mostly empty carcass on a rotisserie?

 

[ckessel]

Should be fine too like that.

 

[RR Fan Dan]

Sub frame connectors.

 

[Green72]

USCT is the way to go. But it does require lots of welding and the old sheet metal can be a bitch to weld!

 

[19Mopar69]

There are several avenues to choose from. On my 67 wagon, I made a pair of connectors using 2" square, .120 wall tube. Welded to the trans crossmember up front and the rear rail. Didn't require removing carpets or seats. USCT or what I did on my 65 Coronet, 2x4" rectangle .120 wall, means taking the interior out. On the 2x4, that also required cutting the floor for them. What's your confidence level of skills required? Also when you do any of these improvements, the car needs to be on its wheels/tires, or on a 4 post lift, unless it's an empty carcass. If you do the work on jack stands or a two post lift, the car will sag since it's not supported like normal. If you ever have it supported like this when doing other work on it, have you noticed that the doors are harder to open and close? Thats because of the sag in the unibody. If you weld and structural items in when it's like this, your doors will stay that way.

I’m pretty confident with most things. My welding skills aren’t where they’d need to be for me to do a quality job on something like frame connectors, so I’d likely have a welder or a shop do it.

 

[ButterscotchA12]

How about a mostly empty carcass on a rotisserie?

I just did that exact thing on my Torino with no issues. I completely stripped the car to a bare shell,then disassembled everything out of the doors and reinstalled them. I then did measurements before and after I put it on the rotisserie and nothing changed so I then welded my frame connectors on.

 

[Dennis H]

USCartool.