73 Roadrunner frame stiffening help and options

[BlooDSMeaR]

I have been looking for a set of sub frame connectors and also a set of torque boxes for my 73 roadrunner. In the short time of driving it, I have noticed considerable frame twist due to a powerful engine. On the drivers side door, the gap between the body and door is getting bigger. On the passenger side, the door gap is getting smaller. I also have noticed that the rear end is sagging lower on the passenger side. I am running MOPAR performance springs. I am not sure which ones.
Now to end any confusion, this car is rust free, running a 500-600HP small block. It is NOT a rust bucket. The frame is twisting.
All the hot rod shops have are 72 and older frame kits. I need one for the 73 body. Can any one point me to the right direction??

 

[multimopes]

It sounds like you might be prone to being a tad too heavy on the gas petal, LOL! I don't have much to offer as my 73 has a 6 point cage with only home built frame connectors and I am somewhere in the 375 to 400 HP range. I am sure that someone here will chime in. With that much HP you might inquire in the Racers section.
By the way, judging by your user name, you must have been a Dexter fan!

 

[Dennis H]

USCartool subframe connectors. Welded in.

 

[BlooDSMeaR]

USCartool subframe connectors. Welded in.

Us car tool has connectors up to the year 1972. Mine is a 1973. Are they that close to be able to use the set for the 72?

 

[Dennis H]

Us car tool has connectors up to the year 1972. Mine is a 1973. Are they that close to be able to use the set for the 72?

Don’t know. Someone here will. The windshield cracked on first romp with the new warmed up 440 in mine. Before connectors were installed. Stay out of it till stiffening is done. You will be pleased with the results. Solid, quieter, less flex, better panel fit.

 

[QuickBpBp]

My Road Runner ran Mid 10's through the mufflers with slicks. 3900lbs with me in it. Big block that 60 footed low 1.50's NEVER saw anybody movement and that was with-out a roll bar. It now has one as the whole car has been redone...

 

[Dennis H]

Who says there aren’t 1 of 1’s.

My Road Runner ran Mid 10's through the mufflers with slicks. 3900lbs with me in it. Big block that 60 footed low 1.50's NEVER saw anybody movement and that was with-out a roll bar. It now has one as the whole car has been redone...

 

[QuickBpBp]

Who says there aren’t 1 of 1’s.

Not a one of one. Many of my friends have Mid to low 10 second street cars and NEVER had issues A B and E-bodies.... As far as the OP's car the damage whatever caused it is done. It needs to go to a chassis shop instead cause welding in frame connectors NOW on a twisted body is a very stupid idea....

 

[Dennis H]

Yeah, I’m lying. Mine were put in after the pillar to pillar crack in the windshield. Musta been nuts. Its rigid now with no further problems. Drives straight.

Guess I should have bought a Plymouth instead of a Dodge.

 

[Badvert65]

The 73 and 74 B bodies had rubber isolated front subframes. What you need to do is replace the rubber mounts with solid ones from someplace like Firm Feel. I actually found a set of factory cast iron ones from a police car and installed them on my 74 Road Runner. Made a world of difference. I also got rid of the rear Iso-clamp rubber leaf spring to axle mounts. Not good for performance and handling.

 

[QuickBpBp]

Yeah, I’m lying. Mine were put in after the pillar to pillar crack in the windshield. Musta been nuts. Its rigid now with no further problems. Drives straight.

Guess I should have bought a Plymouth instead of a Dodge.

I am not talking about your car notice I said OP(original poster) in my comment. He is saying the car is leaning gaps are tight on one side and bigger now on the other. You can crack a windshield hitting a pot hole.....

 

[BlooDSMeaR]

Not a one of one. Many of my friends have Mid to low 10 second street cars and NEVER had issues A B and E-bodies.... As far as the OP's car the damage whatever caused it is done. It needs to go to a chassis shop instead cause welding in frame connectors NOW on a twisted body is a very stupid idea....

That was actually the whole idea. I have a buddy that runs a body shop and he has a frame bed. I do not want him to take the time to make a set of home made frame connectors, as he wants to get paid his discounted shop rate of $75 an hour. He is a buddy but not a good friend. He still needs to make a living and does not work for free. If I could buy a pre fabed set, and save 8 hours of fab time, that would be great for me!!!

 

[QuickBpBp]

That was actually the whole idea. I have a buddy that runs a body shop and he has a frame bed. I do not want him to take the time to make a set of home made frame connectors, as he wants to get paid his discounted shop rate of $75 an hour. He is a buddy but not a good friend. He still needs to make a living and does not work for free. If I could buy a pre fabed set, and save 8 hours of fab time, that would be great for me!!!

That's a great first move not mentioned in your original post. Get it to a chassis shop. More than likely they will have to be custom made. The 73-4 has a bolt in bushing style transmission cross member towards the backside of the front frame rails. While the floor pans are the same, the 71-2 kits I doubt would work with-out heavy modification...

 

[Montclaire]

You'll spend more on the Cartool ones paying him to lay down four long weld seams. Plus it's counter intuitive - the home fab ones are actually stronger as they go through the pan and have more sidewall area.

 

[Chad Witham]

The 73 and 74 B bodies had rubber isolated front subframes. What you need to do is replace the rubber mounts with solid ones from someplace like Firm Feel. I actually found a set of factory cast iron ones from a police car and installed them on my 74 Road Runner. Made a world of difference. I also got rid of the rear Iso-clamp rubber leaf spring to axle mounts. Not good for performance and handling.

I have looked on Firm Feel for these rubber mount solid replacements and have yet to find them

 

[Chad Witham]

You'll spend more on the Cartool ones paying him to lay down four long weld seams. Plus it's counter intuitive - the home fab ones are actually stronger as they go through the pan and have more sidewall area.

My Demon has 2x3 in it and they are welded to the floor where they pass through. It made a world of difference.

 

[Montclaire]

I have looked on Firm Feel for these rubber mount solid replacements and have yet to find them

http://www.firmfeel.com/b_body_late_mopar_sub_frame_isolators.html

 

[BlooDSMeaR]

I bought a set of polly pucks from Rock auto, they were only about $100 for all 6 needed pucks. 4 for the k frame and the 2 needed for the trans cross mount. I will be installing them later today to see if that helps any. First day of the race season is this Saturday. I have found another fabricator that is willing to look at the car to make a set of tq boxes and or frame connectors.

 

[BlooDSMeaR]

It sounds like you might be prone to being a tad too heavy on the gas petal, LOL! I don't have much to offer as my 73 has a 6 point cage with only home built frame connectors and I am somewhere in the 375 to 400 HP range. I am sure that someone here will chime in. With that much HP you might inquire in the Racers section.
By the way, judging by your user name, you must have been a Dexter fan!

Any chance you would be willing to take some good detail pics and post them up?

 

[Paul_G]

View attachment 741268
http://www.firmfeel.com/b_body_late_mopar_sub_frame_isolators.html

I was on the phone with FF this week and they said they have had fitment issues with the solid frame mount bushings. Thats why they are not on the website, but they still have some.