Friday, January 22, 2016

Prepping the new Front frame rail/shock tower assembly - old stuff cleaned up, new stuff prepped for installation

Getting the old damaged shock tower assembly out of the car felt like a pretty big step in the project - a sort of inflection point in the trajectory of the project, delineating the "tearing it all apart" phase from the "putting it back together" phase.

Then I realized how much work still remained just to get the new part installed...from cleaning up the metal interfaces on the car where the new part will be welded in. plus all the test fitting and measuring of the new part to ensure proper placement, plus identifying and prepping all the new plug weld locations on both the car and the new assembly. It's a surprising amount of work still to do.

Here's where I left off last time - the shock tower assembly is out, but I'm nowhere near ready to install or test fit the new one until I clean up a little bit.


First off, the radiator support is in the way. The new part will slide in from the front, but this piece is in the way (I should have seen this coming, actually). I am going to replace this whole assembly a little later on as well, so I can whack it up as needed to make my life easier for this part of the process. Two easy cuts remove most of the interfering parts on the passenger side and the top brace.



This is the remaining piece of the frame rail still welded onto the strut rod (the diagnoal piece here). I need to remove the remnant so I can test fit the new assembly, and I might as well just clean and prep the metal for welding while I'm at it.


I already had the spot welds drilled, they were just stubborn and wouldn't separate. Now that I could see the top, it was easy to clean up the drilled holes and remove the piece. Then I ground down the remaining bead welds, smoothed it out, and put some weld-thru primer on it. Notice I left the area around the holes bare metal - I don't want anything contaminating the welds, to the primer is just used to protect bare metal. I also took the time to strip the paint off this piece on the sides and top as the whole engine bay will get primed with epoxy later as well.



After a little weld cleanup on the firewall where the old rear apron was attached, we're left with a "car" that's ready for test fitting. The old cowl brace is attached here to help hold the new assembly during fit-up.


The sexy new assembly. I love shiny new parts. 


Fitting the new piece with clamps and the cowl brace. There's also a bar under the frame rails to help level and support the piece. Shown here, it's nice and stable, even though there aren't any screws or welds holding it in place yet.


The view from the engine bay. This is after a lot of measuring and tweaking for fit and dimensional harmony. I scribed all the plug weld locations on the new assembly so I can strip just The e-coating. It is fine protection for metal that is hidden from view post-welding, so I only want to take off what's needed for welding. It looks like a great fit....except...


...except for that gap between the firewall and the rear apron! The new piece is properly located, so I can't just slide it rearward to close the gap - it's 0.33 inches, more than 5x the dimensional tolerance for this part. Upon inspection, there are two things going on.

First, it's common to have a little gap here apparently, but most folks just 'force' the gap shut with sheet metal screws and weld it down. I'm not interested in that because this gap is just too wide.

Second, I think some of this gap is due to the force of the front end collision. The firewall is shoved aft ~ 0.2 inches. I'm not going to be able to pull that back, and I'm not going to replace the firewall, and since everything else lines up an this wont affect anything else, I'm going to come up with a solution...later.

I pulled the new assembly out and starting the cleaning process. The firewall is pretty gross. There's paint, dirt and sealant all over it. It also looks like someone waved a can of black spray paint in here at some point in the past. Ick.



Nothing provides quite the rush that stipping does. Look at that clean, bare metal. 



The other side was just as bad. This is where the steering column, brake booster and wiring looms come through the engine bay. 


Stipped bare. This is a messy chore, but I love the results. 



Time to prep the new assembly - stripping off all the e-coat from my earlier scribe marks. Again, the factory weld/sealant manual describes where and how many welds for each junction.


These are for the strut rod support to weld to the bottom of the frame rail.


 Here's where the frame rail joins the toeboard/firewall.


The two holes for the sway bar bracket to strut rod support.


This is the flange on the rear apron that is supposed to be welded to the firewall. I have a cunning plan - so I won't need this particular flange.


So I zinged off the flange at the bend a left a nice straight apron. Stay tuned for the cunning plan.


During test fit, I noticed the holes in the toe board didn't fully overlap the frame rail flange. I needed more metal. So I cut as strip of metal and butted it up for welding.


Now the flange will completely cover the holes in the toeboard.


This section of toeboard where the frame rail fits will be hidden forever, so it gets a coat of primer - again, leaving the hole perimeters bare for good weld purity.


After all that, NOW we're ready to start fitting for installation.

Next up - dry installing the new assembly, test welds, and body panel fit check.


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