Installed new rear rails, trunk transition issue?

[kenyu73 10]

I finished welding on a pair of complete rear frame rails. Besides making sure the height at the key frame spec locations is correct (which it is), there isn't alot of side to side measurements to set until to weld on the rear trunk support. The spec says 43" from the rear/back holes which is close with plenty of side wiggle room. The holes spec is correct by the torque boxes (37 3/4").

 

I have the floor transition dry fitted in just for a preliminary fit. The problem is that the shock support isn't even close! I cant adjust the torque boxes as they're welded to the rockers and I cant squeeze in the rear frame or it'll be WAY off spec.

 

I bought all the parts from CJ Pony Parts and they appear to be the correct year. The frame rails were bought pre-welded as a complete frame.

 

I hope CJ Pony didn't screw up the welding of the 3 pieces of the frame.

 

Advice? I'm hoping I dont have to 2x4 sections of the frame and pull and twist other sections to get the fit correct.

 

Thanks!

 

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[fastwayfirebird400 14]

I take it you didn't take and photo a BUNCH of measurements of all metal that was to be cut out beforehand? Specficallly the framerails front middle and rear. My framerail outside measures 39 3/8. The transition pan width is 37 3/4 wide. Mine is factory. I do have a gap on both ends of about 1/4 inch. If you need a pic let me know.

[kenyu73 10]

I take it you didn't take and photo a BUNCH of measurements of all metal that was to be cut out beforehand? Specficallly the framerails front middle and rear. My framerail outside measures 39 3/8. The transition pan width is 37 3/4 wide. Mine is factory. I do have a gap on both ends of about 1/4 inch. If you need a pic let me know.

 

I took lots of pictures, but not many measurements. Are these measurements across the transition pan (those lower tabs)? I have the frame spec for the front frame points and the rear frame points, just not the middle area around where those transition tabs are.

[kenyu73 10]

These are my measurements. They seem match up to be a bit incorrect here and there compared to your numbers... my frame is out a bit to far... my Tab is a bit shorter as well.

 

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[428scj 10]

Ive had issues with the drivers side rail being off about an inch and just needs a pull before welding.Are the holes in the transition pan and the bolt bosses welded on the rail lining up?Ive never seen a shock support off that much.

[Fordrevhead 29]

Eric,

 

I went back and reviewed your project thread as this one photo struck me as odd (on a 69 coupe!) when I saw it the first time and would explain why your rear rails are off!

 

:wacko:

 

[fastwayfirebird400 14]

Where your is 37 3/8 mine is 37 3/4 Not that big of a deal. Where yours is 41 mine is 39 3/8 It looks like that is where most of your extra comes from.

[kenyu73 10]

Ive had issues with the drivers side rail being off about an inch and just needs a pull before welding.Are the holes in the transition pan and the bolt bosses welded on the rail lining up?Ive never seen a shock support off that much.

 

The frame rail doesn't have the bolt bosses installed. I need to transfer them off my old frame.

[kenyu73 10]

Eric,

 

I went back and reviewed your project thread as this one photo struck me as odd (on a 69 coupe!) when I saw it the first time and would explain why your rear rails are off!

 

:wacko:

 

 

Yeah, it had me concerned too, but the sticker says 65 to 70 or something of that nature. I ordered the LH and RH a different times and both came with 65-68 with a 65-70 sticker. The measurement holes near the torque box match up ok, so I think that area is OK. If anything, I'm wondering if the welder messed up putting the 3-piece rail set together. They probably have a jig, but I dunno.

 

CJ Pony says earlier models must be modified to the 69/70 style. Sounds like my should have been a straight fit.

 

EDIT: put the wrong link in last time....

http://www.cjponyparts.com/RH-FULL-REAR-FRAME-RAIL-COUPE-FB-1964-1970/p/M162R/

Edited April 17, 2011 by kenyu73

[kenyu73 10]

Oh no... I think I read the comment text for this part wrong....

 

RH FULL REAR FRAME RAIL COUPE-FB 1964-1970 Part Number: M162R Mr. Mustang Part Number: RH MM102 A 103H

 

EARLY STYLE MUST BE MODIFIED TO FIT 69-70

 

 

I think there should be a comma in there...

 

"EARLY STYLE, MUST BE MODIFIED TO FIT 69-70"

[Fordrevhead 29]

There are a lot of parts out there like that. Some I have returned and bought the Dynacorn parts because by the time I would have modified them I'd have more money in labor then just buying a better or more specific part.

 

In your defense you didnt have much left of the old parts to compare to. This leaves you at the mercy of the new parts.

 

Anyway, it's good that the measurement there is ok. I can measure whatever u want on my 70, let me know.

[428scj 10]

A modification to a rail would be a trim.They would not sell parts that are off that much .Do the holes in your trunk floor drop offs line up with the holes in the bottom of the rear rails

[kenyu73 10]

A modification to a rail would be a trim.They would not sell parts that are off that much .Do the holes in your trunk floor drop offs line up with the holes in the bottom of the rear rails

 

I ended up blocking the front and rear eye bolt with a 4x4, notching the horz tab on the frame a bit behind the transition pan frame tabs and pulling things tight with a ratchet strap. It came together rather nice.

 

I'm going to dry fit the trunk drops today and see how things line up before putting a few spot welds to the transition pan metal.

 

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Edited April 19, 2011 by kenyu73

[Legion 10]

I used the same method when I replaced my rear frame rails. I only replaced the back 1/2 of each frame rail but replaced the transition pan/brace. I had some slight sag when I removed the transition pan...in hinds sit I would have welded a temporary brace between the old frame rails, replaced the transition pan and then replaced the back 1/2 frame rails.

 

I was a little concerned about ratcheting the frame rails together, but I test fitted the tail light panel, trunk drop offs and rear trunk brace and everything lined up rather well.

[Fordrevhead 29]

I ended up blocking the front and rear eye bolt with a 4x4, notching the horz tab on the frame a bit behind the transition pan frame tabs and pulling things tight with a ratchet strap. It came together rather nice.

 

I'm going to dry fit the trunk drops today and see how things line up before putting a few spot welds to the transition pan metal.

 

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Hmmm, that looks familiar. :thumbup1: