Subframe Crisis

[69Z28freak]

Any idea what this was?



This...



And this...



And this...



And this...



And this...



I am not sure how bad it is yet, but I will find out soon enough. It looks like the subframe washers have disintegrated. When I loosened them up with the impact driver, the old parts just crumbled into dust. I am hoping that the subframe is ok. And that it does not need to be removed and repaired.

The original plan was not to remove the subframe, but that plan may change, depending on the severity of the rust damage.

If anyone has experienced this situation before I would love to hear about it and hear about some solutions to this potentially nasty situation.

[Sauron327]

Pulling a subframe and leaving the nose installed is an easy task. Read the assembly process, although that document is not required for subframe removal. Bushings are supposed to be replaced, and the frame sandblasted and/or repaired before bodywork and paint as per standard practice. Many don't even install the subframe until after paint and the nose is bolted on first.

[69Z28-RS]

Any idea what this was?
.... photos removed for brevity....
I am not sure how bad it is yet, but I will find out soon enough. It looks like the subframe washers have disintegrated. When I loosened them up with the impact driver, the old parts just crumbled into dust. I am hoping that the subframe is ok. And that it does not need to be removed and repaired.
The original plan was not to remove the subframe, but that plan may change, depending on the severity of the rust damage.
If anyone has experienced this situation before I would love to hear about it and hear about some solutions to this potentially nasty situation.

that looks like a mixture of rusted down metal and dirt to me...  You're up north where they salt roads?
You definitely should pull the subframe and derust it, treat it, prime/paint it ..  after all ..  our PRIMARY task with these old cars is to PRESERVE..

[tmodel66]

By all means pull the subframe and inspect, clean, repair if necessary, prime with epoxy and paint. I think you will regret it down the road if you don't.

[Mike S]

 Not meaning add to your fears (well maybe...) if the body mounts are that bad then I suspect the metal contact under them may be rusted q lot and if too much then the rubber mount can eventually push through the chassis and you'll have sag. There are repair kits sold to weld in round plates where the mounts sit on the chassis rails. You also want to inspect where the rubber meets the floor boards to make sure it not rusting in that direction. Like others have said, if you don't address this now you will likely so soon afterwards.

Mike

[69Z28freak]

Thanks guys that is all good info. Looks like I will drop the subframe and and inspect and repair now while I am at this stage.

[68camaroz28]

Good deal Mike deciding on removing the sub-frame as you will have work to do. But make it fun and fill in the pits so it looks new after you have addressed any fatique areas. When a hood is open the sub-frame is very visible so take advantage of it. Long term you will be glad you did.

[69Z28freak]

Good deal Mike deciding on removing the sub-frame as you will have work to do. But make it fun and fill in the pits so it looks new after you have addressed any fatique areas. When a hood is open the sub-frame is very visible so take advantage of it. Long term you will be glad you did.

Thanks Chick. I will take all the great advice and apply it. I guess the next question is, once it is all cleaned up and repaired, it will be paint vs powder coating. What did you use on your subframe.

[68camaroz28]

Good deal Mike deciding on removing the sub-frame as you will have work to do. But make it fun and fill in the pits so it looks new after you have addressed any fatique areas. When a hood is open the sub-frame is very visible so take advantage of it. Long term you will be glad you did.

We used Dupont hot rod black but you can go many ways with it.

Thanks Chick. I will take all the great advice and apply it. I guess the next question is, once it is all cleaned up and repaired, it will be paint vs powder coating. What did you use on your subframe.

[Kelley W King]

Even though powder coating is not original I did it and am very pleased with it. I piled the subframe, A arms, inner fender wells and anything else black on a pallet and took the whole load to coater. He told me the price would be based on how long it took to sand blast it. When I picked it up for $600.00 and saw how the powder coat went places that I could not paint I loaded the rear sub frame, rear end housing and anything else I could and went back with another load. If you really want original you can still paint over it but the guy mixed the color so good I did not. People at shows often say what paint is that because it looks so good then I tell them it is not paint.

[68camaroz28]

I think powder coating is great! But if you have pits in the sub-frame, rear, whatever, your going to see them after powdercoating, hence the reason for using traditional painting techniques if some fill in and there are needed. Sub-frames around the battery area normally have pitting and when I see an outstanding looking car with a pitted sub-frame it just takes so much away.

[69Z28freak]

I am thinking I may paint it when the underside gets painted. They should be the same color correct? I am going to blast it myself.

[z28z11]

Not to add to your task, but you need to consider the inside of the sub as well. If you don't have a stripper (read as alkaline immersion company) near you, I suggest using a converter, or a system like Eastwood's internal spray coating, to treat the inside of the frame while you're treating the outside to a restoration. Imagine how much is inside, out of sight, that could rear up and show from the inside/out one day -

Just my opinion -

Regards,
Steve 

[69Z28-RS]

I am thinking I may paint it when the underside gets painted. They should be the same color correct? I am going to blast it myself.

As several people have noted, you have some *repair* issues on your subframe, and possibly your floor, before yuo get to the paint stage.   The subframe should be removed to allow the repair process to be completed properly.   Re color:   The subrame was 'coated' or possibly dipped in a black semi gloss paint.   I used 'GM reconditioning black' which I believe best emulates the factory coating, although better paints exist for maximum protection.   The floor on my car has areas of 'gray', areas of black, and areas of body color (orange in my case).   It's clear that achieving a 'nice even color' on the bottom of the floor was not a consideration.   The first paint applied was likely for corrosion protection, and after that it seems it was 'over spray' from other paint processes.   if you want your floor 'pretty', then you could certainly pick a color (gray, black, or body color) and make it all the same, but I don't consider that to be 'original'.

[69Z28freak]

Hey Gary. Since my car has already been painted and I am doing everything backwards, I am leaning towards just painting the bottom black. Was think a 60% gloss. Considering the same for the subframe, firewall & inner fenders.

Current plan is to remove the subframe and sand blast it. Remove the A-Arms and rebuild them. Then most likely paint them or powder coat them. Also paint the subframe after what ever damage needs to be repaired. I don't think there is any damage to my floor, but will confirm that soon. So far the bottom of the car is like new, as it was covered in dealer installed undercoating. I suspect that the reason the subframe bushings and possibly the top of the subframe where the bushing are mounted, rusted due to moisture getting trapped between the rubber bushing and the metal bushing. Over time in our climate, they all fuse together due to trapped excessive moisture.

The same thing happened on my '68 Camaro driven in the same climate it's entire life. However the top of the subframe where the rear bushings meet the subframe, completely fussed to the subframe. Requiring major repair. Hopefully that will not be the case this time.