I'm working on a 70 A-Body that I'm considering installing subframe connectors. I would like to obtain some input from my extended family. The motor will be a 340 stroker (727 and 3.91 gear) that may see a few runs at various Mopar events throughout the season (maybe 5-months, if were lucky in the mid-west). The subframe connectors that I'm considering are manufactured by US Car Tool. Thoughts?

Thanks
Vinny

I used the U S Car Tool frame connectors on my 1967 Belvedere and they worked great

They make a huge difference for the good. Mine are the old 1.5"x2 or 3" wide tubing from direct connection connectors on my 71 E body. They were quick and easy to install especially since I had my car turned sideways on a rotisserie.

The ones your wanting to install are by far the toughest to install and requires tons more welding.

Are they better than the ones I used? Probably, but are they worth the extra hassle installing them? I don't know since mine made a night and day difference. My 74 does not have them and you can tell. The 71 is pleasure to drive because it handles great, way better than my 74 without frame connectors. I welded mine in one night in about an hour and was done. That will never happen with the ones you are thinking about using.

Yes put some kind of connector in there.

great investment, even if it's a 6 cyl. totally worth doing. ties the whole car together and gives it a nice tight feel. improves the ride and makes it feel so much tighter of a vehicle, no matter what the HP rating is.

Weld in's are the only way to go IMO,

no before/after cuz it was the stock car but as said everyone has said from day 1 that it is highly beneficial/definitely recommended. Way back a chassis guy said that bolt in types that are then welded in is the best.

I agree with everyone. Either make some or buy them, worth their weight in gold IMHO.

I have learnt recently that SFC are sometimes unnecesary on street cars which maybe can see track couple of times a year, where the torque boxes are enough, even to hold the convertible setup. SFC are more to cars which consistently see the tracks.

But to each own

Same here, for a Duster I built, if the car is undercoated it's a pain cleaning the contact points for welding and I had to add a little extra clearance for the emergency brake cable, minor trimming and a floor jack to hold them in place while welding, came out great. Key point: don't weld them in with the interior installed or...

I made my own for two cars out of 2 x 3 steel rectangle tube, .100 wall. On a b-body if you slot open the front of the rear sub-frame the 2x3 slides right in and mate the other end of the tube to the torsion bar crossmember. The tube protrudes and inch or two into the rear passenger seat feet area. A little trimming of carpet insulation and a rubber floor mat on top and it's not even noticeable.

Adds a whole lot of chassis rigidity. Before, when we jacked up the front corner of the car, the door on that side didn't open/close well. After, on or off the jack, the door opens/closes like butter.

I paid a local guy who builds drag cars to install a set into my Fifth Avenue. Just used 1.5" x 3" box tube he picked up at a steel supply. Cost was $350 when all was said and done. One of the best cost to benefit upgrades I've ever done. The only reason I could see not to do it would be if you were worried about the originality of the car.

Since I'm more of a stock restoration guy, I was planning on installing the bolt-on style connectors. I really don't like the idea of permanently welding something in.(even though I know it's more effective) After looking under my Dart convertible, I don't think it's possible to install the bolt-on style with the factory torque boxes in the rear. Not sure what I'm going to do now.

The A-Body was originally an undercoat delete unit (CA car). When I purchased the vehicle, I had it media blasted. The underbody floor pan is now in gray e-coat (body in primer at this time). I'm more for restoring a Mopar back to stock, but I don't want to end up with large fender/door gaps due to body twist.

The bolt on style of subframe connectors that are reference, I'm assuming additional holes must be drilled in the underbody subframe?

yes, additional holes must be drilled. you can find installation instructions by search for Mopar frame connector instructions to see how easy they are.

i'm planning to go this route and once installed have them welded in. i want to make sure, by doing them myself, that i don't have issues with opening and closing doors.

i thought about the US ones but after the 'incident' with them and having to remove the carpet i decided to go this route.

Do the bolt ins work very well? I want to add some. But really want to keep the underside stock if possible

Made my own using 2x3 tubing. Total cost was just over $20. Cut open the rear subframe and they slid right in and made for a very strong weld. I welded the front to the torsion bar crossmember. They protrude through the rear floor area about an inch and a half but with carpet you'll hardly notice them. They add an unbelievable amount of rigidity to the body.

Before these were installed... if I jacked the body up behind the front wheels the doors would become misaligned and wouldn't open or close properly. In other words the body flexed quite a bit. Now I can jack it up anywhere and there is no movement of the body at all. As a note... I welded in the subframe connectors with the doors on and closed to insure things were as straight as possible.

Well worth the effort.



The final product from the underside... gives the car basically a full frame.

well now you've done it . we haven't had this battle for about a year so we are due

I also used the US Car Tool SFCs on my Challenger. As everyone said it really stiffens up the car.

Challenger1 brings up a good point about the amount of effort to weld in the bolt-in style vs. the US Car Tool type. It was much more time consuming fitting, grinding and welding them than I expected. Overhead welding is not for the faint of heart! They do however have a nice factory-like look once they're done and painted up to match the rest of the underside.

The square tubing that some others on here welded in where they protrude through the floor would allow you to weld much of it from inside the car making the welding much easier if it's not on a rotisserie. There are pros and cons to the different types to consider.

US Cartool for my Demon.
Definitely recommend!

Here is my 71, I blasted the bottom clean on a Sat afternoon and Sat night I welded in 4 factory style torque boxes and 2 DC bolt in frame connectors. Took 2 hours max for all of it. They do not protrude through the floor of the car. They are about an inch lower in the rear than the flush style like US offers though.