This is not so much of a race car question, but hoping you guys can post your thoughts.

A friend of mine wants to tub his 71 Charger. This is basically a cruiser, has never seen the strip, but might maybe once or twice just to see what'll run. So a little thought session came up with the idea of useing another set of stock rear rails (his are not in the best of shape to try and remove from the car in one piece), and basically move the rails in farther, and put the springs back under the rails as they are now.

The whole point in doing this is a couple of things, we can run a 29x18.5 tire and rework the stock trunk floor (and still have a very usuable trunk)and rework the stock tubs and not have to mess with the outside of the car using after market tubs or cutting the quarters as it has been painted (car is currently mini-tubbed, springs moved in with 29x13.5 tires). This will also allow use to slightly rework and keep the backseat also, and basically keep it all unibody and keep the intergrity of the car without a rollbar or cage.

So what are the thoughts on this? I have seen leaf spring tub jobs in the past, that still seem to perform decent, so it doesnt seem out of reach to me.

Can't see why that won't work??

The process(I think) your wanting to do is called mini tubbing That is the way the old SS cars had to do back before full tubs where allowed by the sanctioning bodys back when You basically remove the stock wheel tub and split it in the middle and slide the inner side over to the frame rial and add a piece in the middle wide enough to mate the two parts together and weld them up Maybe someone on here that has a car done like that will post a picture for you to see, a picture is worth a thousand words

I dont think of this as minitubbing since he actually is replacing the frame rails with a narrow version of the frame rails. I wonder if the car will tip side to side a lot easier with springs in so close to each other. Would be great to hear from someone who has done it.

Cab, we already mini-tubbed the car, now we want to full tub it. But we want to cut and move the full frame rail in about another 4" or so. And then still take the stock tubs and stretch them even more than the mini tub job. I hope that explains it better, i know sometimes my posts can be confusing.

I don't see any reason why this wouldn't work, i just want to see what you guys think about it. I had a friend that had a similar setup and his only complaint was the springs "wore out" faster being that they were closer together and had much mor moevment than being farther apart---but he raced his and it had aftermarket rails and a rollbar---something were trying to not due with this project.

My Challenger is race only,tubbed with leaf springs.I had superstock springs for years,and went to monoleafs with caltracs.
With the springs and shocks so close to the center of the car,I still have trouble getting the car to 60' as good as it should.
he best I have gotten is a 1.42,and it should be in the 1.35-1.38 best I can figure.
It does roll ove on the right rear some.
All this being said,I think on a street car with good shocks you would be okay?

I bought a 69 Dart last year that was set up with tubbs and leaf suspension. Here's a pic or two of it, maybe it will help....

second pic...

third pic...

Not sure what the trunk floor looks like on that B body, but the things that come to mind that might get in the way of moving the rails are the spare tire well (if there is one) and the gas tank.

The biggest concern however is the attachment point to the rest of the chassis. The place where the front spring hanger bolts to is all part of a boxed in assembly that ties the frame rail to the outer rocker, floor pan, front spring hanger location, etc. Moving the rail means you need to somehow extend that structure to tie the moved frame rail back into it. Backhalf or chassis cars accomplish this with an entirely new rear main cross member.

The factory frame rail also gets a lot of its strength by being welded to the bottom of the trunk floor pan. The contour of the existing floor pan needs to match up to the rail when the rail gets moved. And you have to look at whether the rear cross member, where the bumper bolts on, has room to attach the frame rail to once its moved.

65Hemi how does the Dart act when going around a corner. Is there excessive roll to the car?

This is excactly how my car is done. Got new frame rails welded them to the floor all the way around tied them in with frame connectors and boxed it to the rocker support with square tubing. 1.37 best '60 on superstock springs.

On the inner side of the rails, i will have to redo the flange to meet up to the floor, so the rails are welded to the floor pan on both sides. On the trunk floor, there is no tire well, and he already has a fuel cell in it---basically the trunk floor is pretty much flat--typical B-body. That helps a bunch in this process. The springs will be put under the rails, just as they are now on the first mini tub job. The rear bumper crossmember will allow me to attatch the rear of the rail--just like factory. On the front sides of the rail, i was thinking of getting the typical ladder bar front crossmember so i can run it rocker to rocker with the front of the rails attached to it. This seems like the most solid way to do things to keep the rigidity in the car--in my mind anyways. I appreciate all the thoughts on this, thanks guys

This Valiant has the factory rails moved in, just like you are talking about. The car looks like it was made that way at the factory.
So yes you can do it.