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68 Subframe Dilemma

5K views 20 replies 10 participants last post by  Daddio65 
#1 ·
I'm in the early stages of restoring my newly acquired 68 coupe and I've just noticed the passenger side firewall frame mounting bracket is bent. The plan is/was to remove the subframe to have it blasted and painted as it's got a fair amount of surface rust. I don't want to redo the front suspension and disc brake conversion and bolt it all to a cruddy looking subframe.

It looks like the frame was pushed back an inch or so on the passenger side as the bracket is clearly out of square.

So....once I have the subframe out, is there a way to see if the balance of the frame is still square? Is this worth trying to fix, or should I look at a replacement? How are the replacements in quality and fit?

Any advice or past experience you can share is greatly appreciated.
 
#2 ·
Just look for a used one. One from a68 and up Nova will work. Not very expensive. That said... Almost all of them have some kind of repair needed on the rusty mounts. The rusty mounts are easier to fix than a twisted frame.
 
#4 ·
My plan is to remove the subframe and try to see if it's compromised anywhere else. I'm just not certain how easy or accurate that can be. Any ideas on how to assess the frame once it's out?
I would take a bunch of pictures with high resolution and post them up or put them into an album that others can look at once the subframe is out.

Without having one right next to yours that is undamaged, maybe do some searches for pictures on the internet and maybe hit some shows to see what turns up.

Maybe too contact a local club and see if anyone else close to you might have a frame out of a car like yours or even in a car that you can look at and if you are lucky enough to find a person locally with his frame out, see if you can take yours over there and lay them side by side for comparison and what you might not see another set of eyes may pick up on something.

There are probably some specs in a shop manual and it may require some homemade measuring device out of some steel or wood to check center to center of holes on things.

I would also look closely at the firewall base mounts to see how they look too.

Jim
 
#5 ·
I've been in the collision and restoration business for decades. It is not worth the labor to yank a bent subframe when many straight ones are available. An easy hit like a mildly bent horn is no big deal. Hard hits are not worth the time. Full frame cars are entirely different.
 
#6 ·
Thanks for the suggestions. Once the subframe is out, I'll see if I can upload some pictures for feedback. I called around to several junk yards and no one has anything of this vintage, Camaro or Nova. Any suggestions where to locate a used subframe?
 
#9 ·
Update. I've removed the subframe and stripped everything off sans the motor mount brackets. As previously stated, the passenger side firewall mount is bent down and forward, which seems to indicate the frame shifting towards the rear of the car. When laying the frame on a level concrete floor, it does not lay flat so that tells me it's tweaked to some degree. Depending on how I measure it, the horns have about a 1.5" difference to the floor.

I have a quote for blasting and powder coating for $400, but that is before any repair work on the bracket. Now that I know it's tweaked, I'm leaning towards a getting a reproduction frame. A couple of shops in the area say they have had good luck with OER frames.

Thoughts from those that have been down this road before? I'll post up some pictures if I can figure out how.

Thanks in advance.
 
#10 ·
#12 ·
Lots of guys pulling out stock subframes to upgrade. Maybe try Pro tour or Lat G forums, you might find one with all the goodies on already.

I wish I was ready to change my stock one out, I'd sell you a real nice one. I found mine on craigslist for $300 3~4yrs ago.
My original one was beat up, sold it as a complete roller with stock style discs for $300.
 
#13 ·
I believe the factory chassis manual (or the assembly manual - can't remember which) has some very specific measurements and reference points you can refer to as well if you can get the frame up and level so you can measure different aspects. Just one more way to confirm what might be tweaked. The fact it doesn't set flat is not good.
 
#15 ·
X2 - If you are pulling out your sub-frame, definitely look into an aftermarket and price it out. You are wanting to do a brake upgrade and suspension anyway. Depending on the how far you want to go with the upgrades, an aftermarket with all the goodies may not be too far off when all is said and done.
 
#17 ·
Thanks, everyone for your input. My week got busy and wasn't able to check in. Some interesting stuff from the other forums that were referenced, maybe a possibility to pick up a used one from someone upgrading. I'm just trying to guard against mission creep and getting carried away. My goal is to make this a nice cruiser, no racing of any type, so I'm leaning towards staying with stock style subframe and going from there.

My main goal is to ensure I've got a solid and straight subframe as I don't want to deal with suspension, alignment, and panel fitment issues later on.

Thanks again, you guys are a great resource.
 
#18 ·
My main goal is to ensure I've got a solid and straight subframe as I don't want to deal with suspension, alignment, and panel fitment issues later on.
The nose does not rely on the subframe for panel alignment. After the panels are aligned and all hardware tightened, they will remain in place even after the subframe is removed. The subframe is merely an aid today for alignment because the factory used jigs that enthusiasts do not have.
 
#20 ·
Scott's not saying you can assemble the front end sheet metal using a bent/bad
sub frame as a platform to build from. The factory pre-assembled the front end
using jigs/bucks and then attached that assembly to the car. As hobbyist's we
don't have that luxury and hence have to use the sub frame in this case.
You'll find this article informative.
CRG Research Report - Camaro Assembly Process
 
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