body twist and damage from installing big block ?

[adk-roadrunner]

Hi I am starting the swap from 318 to 440 in my 73 roadrunner and am getting a bunch of crap from a buddy of mine and a neighbor who are both more ford and chevy guys. they keep saying that because its a unibody the car is going to twist from the power and i'll have to be carefull how heavy my foot is because i could start seeing cracks in the roof and chasis damage. I told them mopar b bodys came with big blocks and I doubt it but they just said the big block models prolly had more welds and different bracing than the sb models. is this just crazy or what.

 

[moparmarks]

Tell the chevy and ford boys to go pound sand. Your car is not going to break with a BB.

 

[vanrj1]

I'm not a pro body guy but just in reading, some of the beefyer mopars had torque boxes as did the convertibles. I would think if your under 500hp there wouldn't be a problem and with street tires they would break traction anyway. I would tie the frame with frame rail connectors jsut for extra support. JMO.....

 

[RustyRatRod]

I'd be more stern than pound sand. Those cars came with big blocks.

 

[CTMopar]

Maybe you should inform them that unibody cars are more rigid and less likely to twist than an on frame car (assuming the Chevy has enough torque to twist it). Thats why all newer cars are unibody, Chrysler was ahead of the pack in design.

 

[moparmarks]

First gen Camaros are uni-bodies. They just use a sub-frame like our C-bodies instead of a K-frame. Just remind your buddies that our Mopars cars came with Hemis, well not your 73/4B but you get to point.

 

[WP29440SE]

they are idiots

you can also inform them that mopar sent uni-body A Body Barracudas and Darts to Hurst to have race prepped 426 Hemis installed in them.

 

[Nick2317]

my 70 coronet has tourque boxes and frame connectors

 

[67 coronet]

unless you have enough power and traction to lift the front wheels you have no worries.

 

[Photon440]

Don't worry about it. Your buddy and neighbor are trying to discourage you from making your car faster than theirs.

 

[super-bee_ski]

Don't worry about it. Your buddy and neighbor are trying to discourage you from making your car faster than theirs.

Excellent quote from Photon440!
Yeah, "everyone" is an expert..(your buds and the neighbor experts..) LOL
So, as Rusty, Super77se, moparmarks, CTMopars and Photon440 and the "gang" here say, No worries!
CTMopars has a very good point in the fact that unibody cars are stiffer.
I just put a 426 Hemi in my 70 superbee. I did not install the torque boxes, but I have them.
Point is: you and I will not be out launching our cars at 5K on the tach.

 

[Dennis H]

Uh oh, when I had the 440 warmed up, the windshield cracked a little in the right corner on the first romp. USCartool connectors were added after the fact. 415 RWHP Chassis Dyno.

 

[Hemi Rebel]

http://www.forbbodiesonly.com/moparforum/showthread.php?33839-Stress-crack-drivers-side-door

 

[Propwash]

Well those ford/chevy guys were right on one thing, they do tend to twist, but I imagine not to the extent thy're portraying. Some areas evident of that are; cracks on the top of the quarter next to the jam opening (lot of us seen) and cracks on the cowl (usually buried by the fenders in the corners and inside the jam up front). They also sometimes like to crack from the lower rear corner of the door opening. All of that is from twisting. The Hemi cars and Convertibles had the 4 torque boxes (Hemi for power, convertible because of no roof support). If you're planning on getting over 400 RWHP, it's time to start stiffening it up. After market torque boxes are available from folks like Auto Rust Technicians. Sub Frame connectors are available from a wide variety of sources. Even if you're not at 400HP in the rear, tying the frame can make a noticeable difference in the cars handling. So, point of the story, if you're worried about twisting....install torque boxes and sub frame connectors and it you should be able to have a warm fuzzy feeling inside. If you're going for massive power or even a protouring theme, there are some threads in the member restorations that cover even more chassis reinforcements, including bracing in the inner fenders, towers, rear wheel houses, full seam welding..ect...ect...ect..

Good luck

 

[snakeoil24]

The cars do twist and crack around the quarter panels. Twist is for real, so install welded frame connectors and torque boxes you are not looking at much money. My 67 Coronet Hemi has cracks in the quarter panels by the back windows, no big deal just drill em and weld em.

- - - Updated - - -

they are idiots

you can also inform them that mopar sent uni-body A Body Barracudas and Darts to Hurst to have race prepped 426 Hemis installed in them.

Don't use Hemi Cudas as a example those cars had plenty of trouble with doors and quarters cracking.

 

[sublimegtx]

Well those ford/chevy guys were right on one thing, they do tend to twist, but I imagine not to the extent thy're portraying. Some areas evident of that are; cracks on the top of the quarter next to the jam opening (lot of us seen) and cracks on the cowl (usually buried by the fenders in the corners and inside the jam up front). They also sometimes like to crack from the lower rear corner of the door opening. All of that is from twisting. The Hemi cars and Convertibles had the 4 torque boxes (Hemi for power, convertible because of no roof support). If you're planning on getting over 400 RWHP, it's time to start stiffening it up. After market torque boxes are available from folks like Auto Rust Technicians. Sub Frame connectors are available from a wide variety of sources. Even if you're not at 400HP in the rear, tying the frame can make a noticeable difference in the cars handling. So, point of the story, if you're worried about twisting....install torque boxes and sub frame connectors and it you should be able to have a warm fuzzy feeling inside.

Good luck

The cars do twist and crack around the quarter panels. Twist is for real, so install welded frame connectors and torque boxes you are not looking at much money. My 67 Coronet Hemi has cracks in the quarter panels by the back windows, no big deal just drill em and weld em.

- - - Updated - - -



And all this time I thought it was just shoddy bodywork on my car, not the built 440. Estimated 450hp, someday I'll get it to the dyno

 

[Mr B Body]

My Brother's 70 Roadrunner has 495 RWHP, runs low 11's on street radials has been over 100 passes down the quater and has a completely stock chrysler unibody (note that it is a coupe car). It nearly pulls the front tires on launch. No cracks no bends. Now we do not recommend this, but this car holds together. BTW the frame connectors and torque boxes are in boxes next to the car.

 

[Diecastdeluxe]

I used to race my Road Runner at Thompson in Ohio, and I used the Landy setup of super stock springs, wedges in the perches and adjustable pinion snubber. I had over 200 passes on that car with no body stress, and that was before sub-frame connectors. However...I did see a sh*tload of GMs twist like a pretzel while lifting that driver's side front wheel.

 

[moparmarks]

The seam between the quarter and the roof is prone to cracking on the 67-9 Camaros. They need sub-frame connecters too.

 

[Ron 73]

Tell the chevy and ford boys to go pound sand. Your car is not going to break with a BB.[/QUOTE

X-2

I don't know where those guys come up with there facts, sounds to me they want you to come over to the Bow-Tie brigade.