Rear frame rail replacement. Sanity Check...

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1966Mustang
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Rear frame rail replacement. Sanity Check...

Post #1 by 1966Mustang » Sun Dec 14, 2014 12:56 am

Ok, car is on jack stands and level at each end side to side, not front to back. I need to replace the rear frame rail upper sections, trunk floors and rear trunk support because they're rusted out. And the rear taillight panel because... at some point the car was hit on the DS rear and the repair was pretty crappy. The rear bumper was shimmed out with lug nuts... anyway... bad bad bad. Passenger side frame rail looks like swiss cheese.
My plan for restablishing all this with a plumb bob is...
Drop a plumb bob from the front lower control arm mount points, draw a line between the points.
Drop a point from the front leaf spring holes and draw a line between those points... frame side.
Drop a point from the existing rear shackle mount points, draw a line between those.
Establish a centerline from the lower radiator support all the way to the back of the car.
Get the centers of the spring perches off the axle, make sure all the centers are in agreement.

Then make some sort of jig...
Get some square tubing (maybe unistrut) and attach through the front leaf spring mounts on each side past the rear on each side. Attach a cross brace someplace connecting each side and square the unistrut brace up. Add a brace from the unistrut up to the axle snubber plate so it doesn't move. This should stay relative to the framerails. I should be able to establish the heights and mount points from the old to put the new pieces back where they belong.
Kinda like this...

http://4.bp.blogspot.com/_23Tu1EcVfgc/T ... 0_2505.JPG
Found here..
http://dougs65mustangrestoration.blogsp ... chive.html

Anyone see any issues with what I have planned?

Thanks!

Perry


'65 Mustang Coupe, C4, DUI, CompCams 260, Addco 1", StreetOrTrack Front Bilstein Coilover System, Bilstein Rear Shocks, 4-1/2 leaf springs.

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Re: Rear frame rail replacement. Sanity Check...

Post #2 by bubba22349 » Sun Dec 14, 2014 11:15 am

Sounds like you have a very good plan, here are few suggestions that maybe of help. The car should also be level front to back as well as side to side you can use the door sill or rocker, and or the bottom of front and rear frame (torque boxes) sections with the car level in two directions then the plumb bob points will be more accurate (vertically plumb too). Next check (and it's very important) that the frame is still square. I do some diagonal measurements of the front frame section (you can use some matching factory mounts or holes), next do the rear section of frame, and last a measurement of the whole frame from a front to rear point. If the car is still square your good to go if not you will need to use a porta power or jack to square it up (within a 1/4 inch is ok less is better yet). If your doors line up nice you could weld in some temp bracing 1 inch square tube works well in an X to help keep the body shell from moving around. Depending on if the rear frame rails have any strength left sometimes it's easier to do one side at a time. You might consider putting in a set of temp or permanent sub frame connectors to help it all stay in position. Good luck on the rebuild. :nod:


A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Rear frame rail replacement. Sanity Check...

Post #3 by 1966Mustang » Mon Dec 15, 2014 12:14 am

Thanks Bubba. I'll do all that you suggest. For right now it looks like the rear quarters and wheelhousings are staying on, so I'll run bracing the cut stuff. Doors are still on and doesn't look like the gap moved at all when I was putting it on stands.
Good suggestion on the subframe connectors. Thats something I want to do anyway, might as well do that now.

-Perry


'65 Mustang Coupe, C4, DUI, CompCams 260, Addco 1", StreetOrTrack Front Bilstein Coilover System, Bilstein Rear Shocks, 4-1/2 leaf springs.

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Re: Rear frame rail replacement. Sanity Check...

Post #4 by DannyG » Fri Jul 07, 2017 10:25 am

Dragging this back from the past, how did that frame rail job go for you ?
Any advice or lessons learned along the way ?
DannyG



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