[1971BB427]

Originally Posted by NEW INTERIORS

Very true... I think if your building a gasser,, They need to be out,, But if your on the ground,, I like them as close to the inside lip of the fender that you can get away without any rubbing.... I see so many pro street cars that the back tires are 3'' inside the lip... That points to me someone didn't know what they was doing..

I'm glad to hear that! We think alike; I hate the pro street look with tires too far in. Just poor taste, or poor planning to me!

[Onebad79malibu]

Thanks folks,I know exactly what you mean,I don't like the looks of the tires being too far inside the wheel wells.Ive just finished reading several articles on back halving g body's.With all the available wheel and tire options,wouldn't the rear end width be a determining factor in the overall width in between frame rails???Im thinking if I locate my frame rails close enough together my wheel and tire combo is almost limitless??????But I'm old so I could very well be not thinking about it right lol.Thanks for everyone's input its been very useful!!

[1971BB427]

Yes, tire/wheel size will determine axle width. Plus frame clearance also. Unless you plan to start reworking the frame rails you really need to be sure the axle width is enough to handle whatever backsapcing the wheels you like will handle, plus clearances.
I'd do the sheetmetal tubbing first. Then once it's done you can get measurements from the existing axle to see what space you have from inner wheelwell edge to outter edge. After that you can measure the hub face to see what you have for outside and backspace on the car.
Once you know the figures you can determine what wheel/tire will work. Most tire companies will give you tread width, but they also have sidewall width or cross section. That will be the true test of what clears, as it's the widest portion of the tire. I like to leave an inch inside, and about 1/2"-1" outside depnding on what side deflection your rear suspension might have. My panhard bar keeps my axle pretty solid, but normal deflection is less than 1/2", so I like 3/4" clearance to the tire for a little room.

[Onebad79malibu]

I will also be cutting down the rear end myself and sending the axles off to be splined.We have a very large swap meet coming up in February and there is usually a massive amount of tires and wheels to choose from.Im hoping this year will be no different and am able to find what I'm looking for.In the mean time I'm going to start removing existing tubs and floor and trunk panels,I'm not sure my trunk hinges will be in the way but if I have to I can move them and pin the deck lid.Just getting anxious to start in it.Thanks everyone!!

[Onebad79malibu]

I guess I forgot to mention I am a carpenter,business owner by trade, so I got a head start on using a tape measure and a couple son in laws that know absolutely everything from scientific engineering to having their wives figured out so I should be in good hands so I'm hoping ill just be sitting in the corner drooling on myself while they figure out how to open the trunk!!lol!!!

[Onebad79malibu]

Picked up some 31/14.50/15's over the weekend.I got the interior removed and got the divider out behind the back seat.Im thinking of removing the trunk hinges and doing a pin on trunk????My next question is where to cut the floor out??Im assuming right at the area where the trans tunnel ends in front of backseat????I want to get frame rails cut off but I need to know how much floor to remove.Thanks guys!!!

[1971BB427]

I never cut any more than abosolutely neccessary! You can always cut more, but it's tougher to put some back! Do some measuring for tire/wheel clearance and then figure out if the frame rails need to move, and if so how much. Once you see how much they need to move you can measure from the inner existing edge and see what needs trimming. If the frame needs to be relocated in, make the cut in the trunk into the inside edge of the frame. That way the wheelwell wont be an issue for any reason.
If you want to leave your hinges just cut the down support loose from the inner wheelwell, and leave it hang while you tub. Once you've tubbed the wheelwell you can then make up metal to reattach the support for the hinges back to the new tub.
Sometimes it's easier to cut off the rear frame rails first. Then narrow them outside the car and build up your backhalf. Then you can move it under the car and jack it up to see what obstructions you have and address the wheelwells then. After cutting away the sheetmetal you can raise the frame into position, weld it in and do any gussetting. Then you can start rebuilding the new tubs where they need to be with the modified frame.

[Onebad79malibu]

Good advice.Ill cut out the frame tomorrow.I built a heavy duty table and plan on building my rails on it.Ive built hundreds of motors,and build custom homes for a living and project managed a 5 million dollar hospital addition,but this is by far the most intimidating job I've done yet lol.Im assuming I will cut the frame toward the front of the car beyond the mounting points for rear end bracing where it connects to frame right where frame turns?If that makes sense

[1971BB427]

I would usually cut the frame before it rises for the rear axle clearance. Where to cut depends on where various body mounts are. I would also tack in a metal brace between the frame rails on the portion that will stay with the body so the frame wont move. Doesn't have to be anything huge, and some 1.2"-2" angle tacked in will keep things located so they don't spring when you cut behind to remove the back half.
Then once the back frame is removed I would build a crossmember to span the frame rails, and weld it in permanently. After that the brace can be removed. This crossmember will be what you attach your narrowed frame back half to when it's done.
This is a picture of my buddy's old '37 Plymouth coupe's frame where he back halfed it for monster tires and wheels. You can see how they built a crossmember, then narrowed the rails and reattched them. The body is still off, so I can get some other pictures if you need any further looks:


If you're going to keep the car lower, then you'll need a offset in the crossmember to give driveline clearance. His car is a gasser style, so no offset needed in the center for driveline clearance.

[aosborn]

Originally Posted by NEW INTERIORS

I always buy the tires I want to stuff under what ever I want to build... Set the tires in place and build everything around the tires...

I totally agree. EVERY chassis or suspension project should be built around the tire/wheel combination you want to run. That is assuming you will be building a custom width axle to fit the car.

If you are using an existing axle, then you need to start from its dimensions and figure out the wheel width, offset and diameter first, then buy tires that fit those wheels.

Once you have the actual tires and wheels you will be using, put them under the car and then mock up the body to get your ride height and rake figured out. Yes, you need to cut sheet metal to do this step.

Only after all that is established can you start to install your suspension.

Regards,

Andy

[NEW INTERIORS]

The thing is... Depending on if your useing a 4 link or what ever,, You need to know what your going to have in front of the rear end because this will say where your crossmember will be, then work back from the crossmember,, You can tie the crossmember into the front part of the frame,, Then set you 4 link or what ever your useing off it, Make the frame kick up's, tie back into your body in the back by the body mounts,

Really hard to give a step by step on the web,, But the car will need to be set up at ride height so you can figure everything out...

Once you have the tires under the car in place,, You can take your measurement from inside rim to inside rim.. This will be your over all measurement for the rearend,,(minus the thickness of your two hubs..)

Where people get into trouble is not setting the wheels being use under the car (IN PLACE) before starting anything.. By doing it this way the tires will end up where they need to be.. Doing a bunch of figuring without doing it this way will have your tires sitting somewheres under the car,, Might end up not being where they should be.. It's really easy to do,, When it's done the right way..Do what it takes to have the wheels right.. Are you will be sorry later when it's to late..

[Onebad79malibu]

Thanks for the great info and pics.I picked up a set of 31/14.50/15's that I will be using.I guess my main question is wher to cut the floor at in front of where the back seat was located.Everyrhing Ive seen it was cut right where the. Trans tunnel ends ate the bav seat.Is this correct??That should give me plenty of space to instal crossmember.I am going with a 4 link set up btw.Thanks guys.Sorry if the questions seem like no brainers but I don't want to fabricate more sheet metal than neccassary.

[NEW INTERIORS]

Originally Posted by Onebad79malibu

Thanks for the great info and pics.I picked up a set of 31/14.50/15's that I will be using.I guess my main question is wher to cut the floor at in front of where the back seat was located.Everyrhing Ive seen it was cut right where the. Trans tunnel ends ate the bav seat.Is this correct??That should give me plenty of space to instal crossmember.I am going with a 4 link set up btw.Thanks guys.Sorry if the questions seem like no brainers but I don't want to fabricate more sheet metal than neccassary.

You really don't need to go to much ahead of the crossmember.. About three inch's should be enough to get in there and weld... Your 4 link will determine how far forward your crossmember will be..

[Onebad79malibu]

Hey all!I began to start cutting the sheet metal out for my tub job.I guess I didn't realize the support bars for the rear end were bolted to the sheet metal in the floor board in front of the back seat.So the sheet metal has to be cut back to where the frame is parallel with each other before it curves underneath and rises for the shock and spring mounts?????ive got a sheet metal brake so I can fabricate a new driveshaft tunnel if I have to.Am I correct in this way of thinking???Thanks guys!!

[NEW INTERIORS]

Originally Posted by Onebad79malibu

Hey all!I began to start cutting the sheet metal out for my tub job.I guess I didn't realize the support bars for the rear end were bolted to the sheet metal in the floor board in front of the back seat.So the sheet metal has to be cut back to where the frame is parallel with each other before it curves underneath and rises for the shock and spring mounts?????ive got a sheet metal brake so I can fabricate a new driveshaft tunnel if I have to.Am I correct in this way of thinking???Thanks guys!!

We need pictures to say what to do on THAT car..Without seeing it, it's hard to say for sure.. Post pictures and it will be easier to say..

Here's a Mustang I did..Might give you some ideas..The four bar came right off that crossmember..