Subframe Repair and Front Suspension Install
Anything worth doing is worth doing right, and right now. My recent purchase of a great 1967 Poncho Firebird convertible has turned into a pretty fast paced mini restoration. The car was a bit of a basket case in that the entire front clip was disassembled from the body when I bought it. The body work is a 7/10 already, which makes it a 100/10 compared to all of my other projects. So, my new Firebird has become the #1 project in the revolving door of cars that I'm currently wasting money on.
As good as most of the car looks from a few steps away, everything under hood was very unappealing. After wiring everything up for a test start to confirm the old Pontiac motor ran, I removed the engine/transmission and subframe to repair and repaint it all. In this article, I'll cover the repair and paint of the subframe and front suspension.
I removed the subframe with the engine and transmission still installed. Picked the engine and transmission off of the frame and placed it on the stand for a refresh as well. The subframe was tired looking through years of use and road miles. To get a good base for a new coat of paint, I first needed to remove all of the grease and oil. I used a Superclean degreaser and dipping a brush in it, I scrubbed all of the subframe I could get to. Then, I followed up with a high pressure power washer to remove as much of the oil and degreaser as I could.
Most of this seems pretty simple, but here comes the error part of trial and error that can save you some time. I chose to paint my subframe with Por 15 rust inhibiting paint, which is an oil based paint. Degreaser + oil based paint means bad news. Even though I immediately power washed the subframe very thoroughly, when I tried to spray on the paint it ran off like water on a waxed car.
This was a big disappointment in what was so far a mad thrash of progress over a week and a half since purchasing the car. To resolve this I let the paint dry, which in places had covered and stuck well and others left blotchy or almost bare. I scrubbed the entire subframe with scotch bright pads to scuff the first layer of Por 15. I then washed and scrubbed it all with soapy water to try to remove the degreaser. Another round with the power washer followed.
Finally, to be certain that I could get it to stick well, I also wiped it down with wax and grease remover. Although my paint still took a few passes to stick well I finally got a good solid coat of Por 15 paint on the sub-frame and control arms. What lesson did I learn other than degreaser doesn’t like to be painted over? I suppose the easiest method would have been to sand blast the frame, or take it to a local sand blaster, which I was avoiding. I think the end result would have been a better smoother paint job with great adhesion. Due to the time crunch, I relied on the degreaser and power washer to prep the subframe and ended up with more work than if I had sand blasted it to start.
There were some repairs required to bring the subframe back to spec before painting it as well. A common issue with any subframe car is the corrosion around the body mounts that attach the subframe to the body. While I was reinstalling the subframe to the car to trailer it away from the previous owner, I noticed these holes had rusted and were much larger than factory. I used some subframe repair patches to weld on top of the frame rail and restore the correct diameter to locate the body bushings. There is a little thought involved in welding these pieces on the subframe correctly. I'll walk you through the process that I used that seems to have been successful.
There is quite a bit of adjustment room in the subfamily cage nuts that are contained in the floor of the Firebird body. I started the install bolts in the nuts and slid them as narrow and wide as they could be, to record how much of a tolerance I had to work with. Then moving them both to the drivers side I was able to confirm what the center to center of the mount holes of the subframe needed to be. I determined that 40 1/2" at the mounts on the front of the firewall seemed to be the sweet spot. Marking the center of washer patches I put them centered front to back on the mount and at 40 1/2" apart.
These washers were all tack-welded to the top of the sub-frame and it was re-installed to verify the fitment. I took my time and this project lasted about and hour and a half due to the attention to detail. In the end, it worked out perfectly and installed easily. I laid some heavier welds on the patches and verified that the body mounts fit snugly in them. The bolts for the subframe started easily and I got them all 1/2 in stalled before I began to tighten any of them. Due to being able to install the subframe within a 1/4 front to back, and drivers side to passenger side, the alignment and body panel fitment on subframe type vehicles can be quite fickle.
Each time you disassemble a car this far, you have to start over on your alignment and body panel shims. Don't take anything for granted with the body panels as the change in a door gap may be just enough of a change that the front edge of a door may contact the back of the fender as it opens. So please use caution re-installing the body and verify the fit before opening doors and hinges.
After installing the freshly painted subframe and control arms, I upgraded the old drum brakes to something a bit more adequate. I chose to go with the 2" drop G-comp spindles and the drilled and slotted stock style disc brake kit. This was actually a very affordable brake kit and will work well with my 15" Pontiac rally wheels. I of course painted the spindles, steering arms, calipers and brackets all black before installing onto my new frame.
Since the G-comp spindle moves the center of the wheel up 2” on the upright to lower the car, and the caliper and bracket have to move up on the spindle as well. This would in turn move the steering arms upward and change the geometry of the steering. Therefore there is a second set of holes lower on the spindle that allow for the stock positioning of the steering arms. This makes for no change in bump steer from the factory steering design. It also makes for more hardware to attach it all.
I went to the local hardware store after measuring what was needed to correctly assemble the spindle and factory type disc brakes. The extra bolts could be included with the spindle, but often this spindle is used with several different brake kits. The disc kit is regularly installed on stock spindles as well. So, I took my hardware list and created a new bolt kit, G-comp spindle w/ stock disc hardware that is suggested to be sold along with either the spindle or the appropriate disc brake kits. For $6.99 this hardware will save you several trips to the local hardware store that seems to only have 3 grade 8 bolts in the length you want for some reason.
Overall, this project of overhauling my front suspension was quite rewarding. It took two full weekends of work. I'm left with a great looking sub-frame hanging off the front of the car. All of the components have a fresh coat of paint and new ball joints and brakes. The next step is to fix a few things on the engine and paint it with a fresh coat of Pontiac blue correct for the year of the car. Stay tuned, I'm making a mess in my garage to hopefully have the Firebird back in one piece before Spring.