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I have to replace both rear frame rail sections and the trunk floors. I've measured everything and it is all straight...thank goodness.

After removing the trunk floors, can I drill out the 6 spot welds holding the frame rail to the Rear Trunk Brace, cut the rail, and then use the spot weld holes as an alignment reference for the new rails? I will of course measure between the ends of the frame rails and from the rails to the floor. BTW - I also have to replace the Trunk Brace and Reinforcement. TIA

Gregg
 

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Nope. Won't work.

The replacement frame rail I just installed started at the same point as my old frame rail, and ended at the same point...put it DID NOT follow the same path to get there. Besides that, those holes you're talking about wouldn't be anywhere near precise enough to locate from anyway.

I've only replaced one frame rail in my life, so maybe someone with more experience would have a better plan...but here's what I'd do.

I'd replace them one at a time. I'd use measurents from rail construction hole to construction hole sideways and diagonally to check my measurements. IIRC the print shows these are supposed to be held within .010" or some damn thing. If you're measuring with a tape measure, you can't even measure that accurately...so you'll just have to make sure it's dead nuts on the tape.

As far as the up and down part...what I did was jack mine all the way into the floor pan and hope for the best. I installed a new trunk floor and ended up using sheet metal screws to suck down the last 1/4" or so to the rail, and then welded it in. In fact I used sheet metal screws on the whole darn thing every few inches, once I had it located, to bring everything together before I started welding.

Anyway, that's what I'd do.

Good luck!

Phil

p.s. I had my car supported under the front frame rails, the engine crossmember, under the floorpan (via boards, concrete blocks, and shims) and under the very back of the trunk. You have to get it up and flat. On my convertible I used the doors as a reference. As long as the doors were opening and shutting well, I figured I had the car pretty much where it need to be.

Rereading your post I now understand that you are only replacing the back section of the frame rail...sorry about that. Your idea might work fine in that case. Just make sure the rear shackel mounts end up where they were.
 

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On mine there are two construction holes on each frame rail. That's what locates the frame in the press when it's bent. It's the two points on the frame that everything is measured against once it is made. Therefore they are assumed to be "right" and you measure everything else from them. If you look at the framerail print (I found one in one of my mustang magazines) the dimensions they show are between centerlines of those holes. They show a dimension side to side and diagonally. If you look under your car, they should be there...unless you have a ton of rust holes, or someone has bondoed your frame or something. I don't know if your replacement piece would have the back construction hole in it or not. My full frame rail (actually 3 repair sections welded together) had both construction/locating holes.

Here's a picture

http://home.earthlink.net/~pirateship/DSC24803.JPG

You can see the rear construction hole if you look real close. Look just to the right of the tip of the shackel bolt. You see that little white circle? That's one of the construction holes. You might take it to be a "drain hole" or something...but that's actually what the whole shootin match is setup off of if you look at a print.

Good Good luck to you. You laugh...you'll cry...you'll drop flaming hot magma in your eye!

Safety glasses will be required.

Phil
 
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