• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

stiffening rear frame rails ...make this sense ??

acii

Well-Known Member
Local time
9:27 AM
Joined
Mar 14, 2020
Messages
51
Reaction score
15
Location
Germany
Hy all

i have to replace both rear frame rails on my 70er charger.

I am thinking about stiffening the rails.. as i saw some threads about stiffening the torsion bar crossmember...
Would be a kind of boxing the rails ....
the rails originally are not making the strongest appearance ...pretty flimsy

Does it make sense ??

THanks for advice !!
Cu
Achim
 
Hy all

i have to replace both rear frame rails on my 70er charger.

I am thinking about stiffening the rails.. as i saw some threads about stiffening the torsion bar crossmember...
Would be a kind of boxing the rails ....
the rails originally are not making the strongest appearance ...pretty flimsy

Does it make sense ??

THanks for advice !!
Cu
Achim
No reason you can't. You could stitch weld a horizontal strip of steel maybe 1-2" below the flanges, even use a "T" shape piece to gain more strength. Do you need extra strength? How much horse power are you planning?
Mike
 
Pointless for a stock or near stock power level. The rails are essentially boxed anyway since they are 3 sided with a floor pan closing the 4th side.
 
I would say leave em alone ,
What is your game plan that you need to
Stiffen them unless they are soft from rot issues? Now putting in sub frame connectors and torque boxes definitely if your going to push it hard...
 
thx for ur advice..

horsepower-wise i dont wanna go for a big number .. something around 350 - 400...(more or less stock).

I was just thinking ... also like the famous example to add some stiffening plate to the lower control arm (front suspension)..

But it looks like to be pointless ... so i will most likely drop that idea :) or maybe add one ore two plates for my good conscience

CU
Achim
 
I'd be leery of doing a bunch of unnecessary welding on the rails with the 4th side opened up. It may move around on ya and cause more harm than good...
 
It would take more than 400 horse power to twist a frame that was built to handle more than that from the factory. Everything is made to give a little, changing that would make the car feel stiffer. I've never done it to a mopar, but I have other cars and could feel it.
 
I would say leave em alone ,
What is your game plan that you need to
Stiffen them unless they are soft from rot issues? Now putting in sub frame connectors and torque boxes definitely if your going to push it hard...
I have reading on here about the Torque Boxes. Your profile pic caught my attention since I am an Aircraft mechanic and we operate a small fleet of Hueys. I am saving a 1968 Super Bee (383 4 speed) which, does not have them installed. I am on the fence with installing them. I know, from our Hueys, we make airframe repairs and stiffen up one area, and soon enough we are fixing another area. Would this be the case if I were to go that route on this car? I don’t plan on racing the car, but do plan to smoke the tires......occasionally...... To torque box or not torque box......that is the question?
 
With a manual transmission I think it is a good idea. Not to hard to fabricate/install either.
Mike
 
I would say that it isn't necessary even with a manual car or even a moderately powerful engine. The rear frame rails are boxed in (as stated) and connected to the trunk pan which is connected to the tail panel and quarter panels, Dutchman panel, roof, etc. so the transfer of energy under load is pretty well transferred throughout the car. That said (and if you are concerned about it) it would not hurt to put some spot welds into them or even put some 4-6" runs of welds along the sides where they meet the floor pan.

These cars are as I am sure you know spot welded and back in the day it was the sum of all of the spot welds that provided the rigidity of the car (which was/is not all that great). If you want the car to be stiff (read handle) welding up the seems and putting some really good welds on all of the cross members and rear frame rails really helps. You would be surprised at how well this works and how much stiffer the car will get. You couple this effort along with torque boxes and subframe connectors and that car will be solid.
 
Since I was having the front K-member and suspension replaced with QA1 stuff, rear leafs replaced with Calvert split mono leaf springs and sliders, I figured it was a good time for front spring bolt reinforcement plates in front and behind the factory sheet metal mounts, 4 torque boxes, and subframe connectors, since I was upgrading to the MAX all of my drivetrain components. This will help resolve a long standing launch traction problem, along with the Assassin traction bars. It will help now, and it's all ready for the 541 stroker I'm working on having built.
Oh, and it's a manual transmission car too...
 
Auto Transport Service
Back
Top