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Old 08-15-2022, 04:47 PM
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Default Roof cracking?

have the 70-73 models been prone to roof cracking? i know the later t-tops and possibly the wrap around rear glass on 75 and up.
I see tiny cracks in the paint on both rigth at the top corner above the passenger and driver chrome vindow trim.

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Old 08-15-2022, 05:47 PM
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Rear corner of door opening? Body flex due to lack of full chassis.

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Old 08-15-2022, 05:52 PM
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yes, the top rear corner of each door, a tiny vertical line towards the rear window and horizontal line up to the roof on both sides, about 1/2 inch in size (for now) i guess i should get some subframe connectors in place. observed this shortly after upgrading the motor with a topend kit.

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Old 08-15-2022, 07:01 PM
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cracks here and accounted for/

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Old 08-15-2022, 07:10 PM
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Originally Posted by djustice View Post
yes, the top rear corner of each door, a tiny vertical line towards the rear window and horizontal line up to the roof on both sides, about 1/2 inch in size (for now) i guess i should get some subframe connectors in place. observed this shortly after upgrading the motor with a topend kit.
Let's see the pics, this doesn't sound " common"

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Old 08-15-2022, 07:46 PM
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Quote:
Originally Posted by djustice View Post
yes, the top rear corner of each door, a tiny vertical line towards the rear window and horizontal line up to the roof on both sides, about 1/2 inch in size (for now) i guess i should get some subframe connectors in place. observed this shortly after upgrading the motor with a topend kit.
He's got is verticals and horizontals confused...

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Old 08-15-2022, 09:15 PM
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these cracks are where the lead filler was put from the factory;
I think that more often than not the cracking described is because someone used body filler in this area.

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1970 Formula 400
Carousel Red paint on Black standard interior
A no-engine, no-transmission, no-wheel option car.
Quite likely one of few '70 Muncie three speed Formula 400's left.


1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing)
2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs)
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Old 08-16-2022, 12:40 AM
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Not at the corners.

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Old 08-16-2022, 11:36 AM
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Quote:
Originally Posted by Formulabruce View Post
Let's see the pics, this doesn't sound " common"


A quick picture of drivers side.

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Old 08-16-2022, 11:37 AM
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Quote:
Originally Posted by FrankieT/A View Post
He's got is verticals and horizontals confused...
Yes, a little embarrassed

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Old 08-16-2022, 11:53 AM
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Quote:
Originally Posted by unruhjonny View Post
these cracks are where the lead filler was put from the factory;
I think that more often than not the cracking described is because someone used body filler in this area.
Mine has no body filler other than the factory lead and mine has about 1/2" crack on driver side only.
I have seen these cracks bigger and smaller over the 45 years of having these cars.

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Old 08-16-2022, 11:55 AM
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Yes, a little embarrassed
No need to be embarrassed.

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Old 08-16-2022, 05:35 PM
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Retention of moisture in that area can make this area worse for wear ( vinyl roof)
That said, you can put " Short strand" fiberglass filler in this area over lead that is still stuck to that seam where the roof overlaps the quarter. If lead has separated, there might be a gap under it and then led has to come off.
I have re leaded these seams and I think there may be a substitute now. If its all stripped in that area, one could weld the panels together to make it less apt to happen. These were panel spotted when new IIRC.
Starting in '73 at this area and bottom of A pillars, and rear tail pan/ bumpah mounting, the amperage of the welds was increased at Fisher Body to help meet the new 5 mph standards.
This is one reason why '72 bodies were crushed and written off after the strike.

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Old 08-16-2022, 06:52 PM
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Quote:
Originally Posted by Formulabruce View Post
..
Starting in '73 at this area and bottom of A pillars, and rear tail pan/ bumpah mounting, the amperage of the welds was increased at Fisher Body to help meet the new 5 mph standards.
This is one reason why '72 bodies were crushed and written off after the strike.
Just when you think you won't learn anything new;
BAM!!
It happens again!!

Thanks for sharing this!

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1970 Formula 400
Carousel Red paint on Black standard interior
A no-engine, no-transmission, no-wheel option car.
Quite likely one of few '70 Muncie three speed Formula 400's left.


1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing)
2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs)
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Old 08-16-2022, 09:09 PM
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My ‘78 non T-Top Formula developed these cracks 4 years after car was built..

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