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Rear frame crossmember discrepancy - 1/4" short
#1
I'm not sure how many of you have worked with the current rear crossmember reproduction - but for those who have, I'd appreciate your advice with the following problem:

[Image: 71_mustang_crossmember_2.jpg]

The rear edge of the rear frame crossmember - according to what I've seen - is supposed to lie on the same plane as the taillight panel, allowing the taillight panel to butt up to it from the back. Simultaneously, the panel sits on the same plane as the lower halves of each quarter panel, which fit on the front edge.

However, the reproduction crossmember rear lip sits a quarter inch too far forward (test fits of the trunk result in the trunk hanging over the crossmember by the same amount), despite the crossmember having been welded directly to the original left framerail end. The framerail is unchanged from stock and is undamaged.

Though I do not have the scrap that I removed from the car, I did bring up a photo from the job - wherein the original crossmember appears to be 1/4" longer than the reproduction:

[Image: 71_mustang_crossmember_1.jpg]

Now, if I push the quarter extension and dropoff together, I can close the gap, though the trunk still sticks out about 1/8", which is enough to keep the taillight panel from fitting.

Has anyone experienced this before with one of the repops? If so, what did you do to correct it?

-Kurt

[Image: satellite-valiant-mustang-license-tags-signature.png]
How to buy a '71-73 Mustang:
Rule #1: Assume all classic car sellers are guilty until proven innocent.
Rule #2: No classic car dealer is ever innocent; thus, they are all guilty.
Rule #3: Buy from trustworthy people: Fellow forum members. Visit 7173Mustang's For Sale forum.
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#2
K,
Even though you may think the rail is unchanged with out the trunk in.. the rail can move since the car is resting on the wheels..You need to check measure from center of the front leaf spring bolt to the center of the rear UPPER leaf spring bolt...Check all your dimensions as per this chart
http://www.429mustangcougarinfo.50megs.c...sions1.jpg
Let us know what you find..I had checked the repo rear cross I bought against the old one I had & it was a pretty much perfect match..
Also the trunk floor is over size..you have to trim the rear flush to the crossmember ONCE the crossmember is installed correctly

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#3
Qcode351mach;108641 Wrote:K,
Even though you may think the rail is unchanged with out the trunk in.. the rail can move since the car is resting on the wheels..You need to check measure from center of the front leaf spring bolt to the center of the rear UPPER leaf spring bolt...Check all your dimensions as per this chart
http://www.429mustangcougarinfo.50megs.c...sions1.jpg
Let us know what you find..I had checked the repo rear cross I bought against the old one I had & it was a pretty much perfect match..
Also the trunk floor is over size..you have to trim the rear flush to the crossmember ONCE the crossmember is installed correctly

I'll take those measurements and post them later today.

Mind you, I can see where the rail has the potential to move upwards or down, but I cannot see where it would compress in length. I also watched the back end closely as everything came out and have yet to see any evidence of movement (not that this is conclusive).

That said, with exception to the rear portion of the panel in question, the areas where the panel butt welds to the dropoff matched up in height and location to the ghost marks of the original panel, prior to primering.

One other oddity I did notice is that the lip on the inner edge of the reproduction panel (the one that meets the inner edge of the framerails) points forward on the reproduction, though the original was reversed, and would be accessible only with the removal of the trunk:

[Image: 71_mustang_crossmember_3.jpg]

Was that the case on your car as well? I'm curious if these oddities might have something to do with the NJ production.

-Kurt

[Image: satellite-valiant-mustang-license-tags-signature.png]
How to buy a '71-73 Mustang:
Rule #1: Assume all classic car sellers are guilty until proven innocent.
Rule #2: No classic car dealer is ever innocent; thus, they are all guilty.
Rule #3: Buy from trustworthy people: Fellow forum members. Visit 7173Mustang's For Sale forum.
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#4
K,
If all measurements are good..simple fix..2 options..1 install 1/4" plates (bar stock home depot) spacers between back rail & cross..or slice top part..move rear section out..fabricate strip of sheet metal join the 2 pieces together..

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#5
1/4 on both sides as I can understand where the pass side could be tweaked by a 1/4 from the hit
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#6
OMS;108650 Wrote:1/4 on both sides as I can understand where the pass side could be tweaked by a 1/4 from the hit
Or secondary damage to the torque box rear floor..Measure measure measure

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#7
OMS;108650 Wrote:1/4 on both sides as I can understand where the pass side could be tweaked by a 1/4 from the hit

I could understand it on the passenger's side, but not on the driver's.

Qcode351mach;108646 Wrote:K,
If all measurements are good..simple fix..2 options..1 install 1/4" plates (bar stock home depot) spacers between back rail & cross..or slice top part..move rear section out..fabricate strip of sheet metal join the 2 pieces together..

The latter is what I'm going to do if all measurements check out.

EDIT: 51.34", on the dot.

-Kurt

[Image: satellite-valiant-mustang-license-tags-signature.png]
How to buy a '71-73 Mustang:
Rule #1: Assume all classic car sellers are guilty until proven innocent.
Rule #2: No classic car dealer is ever innocent; thus, they are all guilty.
Rule #3: Buy from trustworthy people: Fellow forum members. Visit 7173Mustang's For Sale forum.
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#8
I'll bet you'll find that when you set the trunk pan in, the drop-offs will line up with it a lot better. Not to mention, depending on which drop-offs you bought, there might be some 'left-over' material at the botton (where the quarter panel meets up with it). IIRC, the ones Don sells are pretty much spot-on (correct size, shape, right 'dimples' and holes), but the ones CJPP sells are less 'accurate' (i.e. incorrect dimples, no holes bored in the proper locations, etc.) but have more sheet metal to work with on the bottom (i.e., trim to fit around the bottom of the quarter panel).

At least, that's what I ran into. Actually, I didn't have the benefit of having any of the original sheet metal or welds in there when I did mine, so maybe I'm missing the point of your questions. But, the trunk pan is key, and Scott reminds everybody doing this to dry-fit everything before sparking the first weld for the best results. Based on his results, ya can't argue with that logic! Wink

You're doing GREAT!!

Eric

[Image: mach1sig2.gif]
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#9
Mister 4x4;108658 Wrote:I'll bet you'll find that when you set the trunk pan in, the drop-offs will line up a lot better. Not to mention, depending on which drop-offs you bought, there might be some 'left-over' material at the botton (where the quarter panel meets up with it). IIRC, the ones Don sells are pretty much spot-on (correct size, shape, right 'dimples' and holes), but the ones CJPP sells are less 'accurate' (i.e. incorrect dimples, no holes bored in the proper locations, etc.) but have more sheet metal to work with on the bottom (i.e., trim to fit around the bottom of the quarter panel).

At least, that's what I ran into. The trunk pan is key, and Scott reminds everybody doing this to dry-fit everything before sparking the first weld for the best results. Based on his results, ya can't argue with that logic! Wink

You're doing GREAT!!

Eric, the left dropoff is the original to the car; hence why I'm not considering it trimmable. Only the right dropoff is getting swapped.

The dropoff I bought from NPD have the holes already punched in it - probably the same ones Don sells. I won't be installing it until the quarter is installed.

-Kurt

[Image: satellite-valiant-mustang-license-tags-signature.png]
How to buy a '71-73 Mustang:
Rule #1: Assume all classic car sellers are guilty until proven innocent.
Rule #2: No classic car dealer is ever innocent; thus, they are all guilty.
Rule #3: Buy from trustworthy people: Fellow forum members. Visit 7173Mustang's For Sale forum.
  Reply
#10
cudak888;108659 Wrote:Eric, the left dropoff is the original to the car; hence why I'm not considering it trimmable. Only the right dropoff is getting swapped.

The dropoff I bought from NPD have the holes already punched in it - probably the same ones Don sells. I won't be installing it until the quarter is installed.

-Kurt

Yeah, I saw that after I posted - I get it... I wouldn't replace it either since it's still good. And yeah, I think you're right about NPD's and Don's drop-offs being from the same manufacturer.

You're still doing GREAT! Wink

Eric

[Image: mach1sig2.gif]
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