426 Hemi torque boxes or frame extensions

[rick]

If I just put frame rail extinctions on and not torque boxes would that be strong enough for 600 hp thanks

[garner7555]

The big question is how much traction will you get?

[cdr]

both in my opinion

[Mike DC]

   
Think about this - the factory added torque boxes BEFORE subframe connectors. 

[Lennard]

With 600HP torque boxes are needed.

[fy469rtse]

I think there needed regardless of HP , helps stiffen up tired uni body frames,
Helps stiffen up chassis to meet the legandary status of these cars ,
Certainly wasn't impressed with my first ride in one without them ,
I think that's why there so popular with restorers of these cars

[myk]

Both...

[1974dodgecharger]

do 500HP cars need em too?  Though it only translates to 400 to wheel with only 415ft lbs.  Should I add em?

[six-tee-nine]

Both!

And subframe connectors are more work to install, so if you went trough the hassle of installing them then you might as well do the torque boxen in the same time.

And US cartool carries them both, so if you order the parts the same time, the additional shipping aint gonna kill you its just the extra cost for the parts.

If you look at the points you reinforce I can really imagine that it is a huge improvement. Did it on my 69....

[fy469rtse]

Also if they had been out when idid current car, radiator suport ,
Us car tool,
Car befits dramatically from fully welding K frame and gussets to steering box mounts,
Rear twist , box cross member solid mount high up replacing rear shocker mount ,
Under front fender , firewall to inner skirt braces, ,
Where do you stop, ? Depends on how badly you won't it to handle well
I will be doing this and more to next car

[Ghoste]

Another for both.

[myk]

Is there such a thing as having a chassis that's TOO stiff?

[Homerr]

No, not really.  Chassis stiffness is really about providing a stable and correct platform for the suspension geometry to do its work.

[tan top]

done both ,

[Ghoste]

The chassis should not move around, that is what the suspension is for.

[Mike DC]

Is there such a thing as having a chassis that's TOO stiff?

The NASCAR & F1 guys have been able to hit a wall on it.  More stiffness never really HURTS but eventually it just begins to chew up tires faster with no other gains to make up for it.  


That tipping point is way beyond anything our production-based cars will ever reach.  We can use as much stiffness as we can give it, in practical terms.   But you have to weigh stiffness gains against weight increases & general PITAs that extra bracing can bring. 

[myk]

Is there such a thing as having a chassis that's TOO stiff?

The NASCAR & F1 guys have been able to hit a wall on it.  More stiffness never really HURTS but eventually it just begins to chew up tires faster with no other gains to make up for it.  


That tipping point is way beyond anything our production-based cars will ever reach.  We can use as much stiffness as we can give it, in practical terms.   But you have to weigh stiffness gains against weight increases & general PITAs that extra bracing can bring. 

Interesting.  I just figured that if a suspension could be made too tight or stiff, then maybe a chassis could be similarly "over tuned."

[Ghoste]

An interesting point Mike.  I wonder if the F1 guys have made the chassis too stiff or they haven't been able to have the suspension and tire technology keep pace? 

[Mike DC]

 
They don't want the whole suspension very stiff, just the frame itself.  
       
Suspension designers are only trying to make the suspension (springs/shocks/sways) as stiff as they have to.  They want it as soft as they can get away with after the too-soft problems are resisted.  


They want the frame as stiff as possible to basically just take it out of the equation.  A flexing frame is a great big (and un-shock-absorbed) steel spring.  They don't want the springs/shocks/sways all mounted onto an even bigger spring.  It would limit how stiff & responsive they could make the parts that they do intend to fine-tune.  

[1974dodgecharger]

Good discussion going.....makes me want to go get the hotchkis braces to compliment the rest of my pieces and then add in some of the so called hemi torque boxes and noticed there r braces in the front wheel well area too and many other places, lol......might be the year of 2015 of chassis stiffening 

[Mike DC]

  
XV Motorsports (now defunct/renamed) did expensive computer testing on the Mopar unibodies.  They came up with a stiffening package consisting of:  subframe connectors, torque boxing, lower radiator support brace, and shock tower (to firewall) braces.  Some people do more areas but IMO this stuff is enough to call it good.  These were the lowest-hanging fruit on the B & E-bodies and the improvements were measurable.  


XV also commented that the original STOCK unibody stiffness was way above what they expected for a 1960s Detroit car.  It would have been tolerable even for a 2000s car.  (But they were testing decent surviving unibodies, not cars that were rusted to hell and then restored by amateur backyard welders.)    

[1974dodgecharger]

I was gonna buy a harbor freight ac/dc welder it costs 100 bucks do think thats sufficient to do the welds on these torque boxes?

[ottawamerc]

I was gonna buy a harbor freight ac/dc welder it costs 100 bucks do think thats sufficient to do the welds on these torque boxes?

A welder is one of those "things" that I would recommend getting a good 220V mig. I know cause years ago I bought the cheaper 120V mig, it does work but no where as nicely as a 220V one's that I have tried since! and it's actually easier to weld with a 220V as a newbie

Scott

[1974dodgecharger]

Thx Scott for that info...it will be my first time welding.  Watching youtube videos i want to tackle the chassis braces seems easy enough with hotchkis vs the cartool version.

I was gonna buy a harbor freight ac/dc welder it costs 100 bucks do think thats sufficient to do the welds on these torque boxes?

A welder is one of those "things" that I would recommend getting a good 220V mig. I know cause years ago I bought the cheaper 120V mig, it does work but no where as nicely as a 220V one's that I have tried since! and it's actually easier to weld with a 220V as a newbie

Scott

[Mike DC]

A 220v welder is a better item to learn with just because you can get the infinite-sliding voltage knob rather than a 4-click one.  It also helps to run the wire size on the small end of the recommended range and make up for it with a little more voltage, but that only works if your machine has the voltage capability to spare. 


If I was in the market for a 110v machine I would pick up a used one.  Lots of decent ones out there. 


Flux-core welding and auto bodywork do not mix.  Period.  Do yourself a favor and use shielding gas.  It only takes a few lbs of gas pressure to do the job so you shouldn't be going through very much of it.