Rear shock access hole cracks

[Perry Weaver 0]

is there a known problem with the 69 fastback floor plan cracking around the rear shock holes? Any suggestions as to why this happens. 

[shelbyshelby 52]

Mostly what I have read is the air shocks folks used in the day caused cracking in this area. From my experience though it’s usually the top layer of metal where the shocks rubber plugs mount. So I’m thinking it’s more to do with unibody flex rather than air shocks. I’ve seen more than a few drag cars both coupe and  Sports roofs with cracks around the rear window area. I think the back half of these unibody cars are taking a beating when used any other way except a 230 hp daily driver. This is just another opinion of course. 

[barnett468 418]

post a photo.

 

The cracks can occur when stiff shocks or air shocks are used. If it is the hole the shock shaft goes thru, it can easily be fixed and reinforced by welding a washer to the bottom of the hole. A hardened one is best.

[Ridge Runner 1,112]

Stif shocks ,air shocks or just stiff adjustable shocks cause the shock bracket to flex ,pushing upward ,this causes stress cracks through the upper access holes . I have seen air shocks punch through the shock bracket it self 

[Mike65 475]

My 69 Coupe already had a washer welded to one of the shock holes to fix that problem, also the upper floor where the shock top mount access hole plug goes in was cracked on my Coupe & I welded them up.

[fvike 173]

My Fastback had that. Welded it. 

[barnett468 418]

wow, someone beat the crap out of that car to get cracks like that.

[Mike65 475]

23 hours ago, barnett468 said:

wow, someone beat the crap out of that car to get cracks like that.

Not necessarily my 69 Coupe had the same cracks in the rear shock access holes as fvike.

[fvike 173]

23 hours ago, barnett468 said:

wow, someone beat the crap out of that car to get cracks like that.

I know the car had an accident crashing in a highway off-ramp divider in the early '90s, so who knows. But it doesn't look like it had a hard life. The car is mint underneath. The cracks was in the sheet metal, not the actual shock mounts. I think this is just the softness of the SportsRoof chassis. The air shock theory is interesting to me. These cracks were in the car when I got it (2004), and they looked like scissor cuts more than anything. Looked to me like something that has been made over time. I think a sudden impact would have left a more drastic clues, or at least other damages to the area around it. In this picture, I had scraped the under coating, and pressure washed it. It was clean as can be. Can even see the assembly line dolly mounting marks at the rear. I added the subframe connectors in 2005, so the cracks was there before I did that.

 

[barnett468 418]

2 hours ago, Mike65 said:

Not necessarily my 69 Coupe had the same cracks in the rear shock access holes as fvike.

Well unless you were the original owner or knew the original owners, you wouldn't know how it was driven or what shocks it may have had if they were not the originals.

 

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[unilec 57]

fvike, interesting rotisserie you have there, how do you get it in and out of your workshop?

[aslanefe 333]

5 hours ago, unilec said:

fvike, interesting rotisserie you have there, how do you get it in and out of your workshop?

Looks like pallets and pallet jacks.

[fvike 173]

9 hours ago, aslanefe said:

Looks like pallets and pallet jacks.

Bingo!

 

19 hours ago, barnett468 said:

Well unless you were the original owner or knew the original owners, you wouldn't know how it was driven or what shocks it may have had if they were not the originals.

 

.

I do have a fairly complete history of the car, as I came in contact with a PO and got a lot of info. There are a few holes, but the car had an interesting life, like most of these cars had. They was meant to be driven, and they were driven!