Monday, June 4, 2012

Floor Repair - The Underside part 1

An hour here and hour there...that's how it's been on the Mustang of late.  With high school graduations last weekend and this one, I've had a handful of open houses to attend.  I really don't mind since I've been mentoring these young adults as their pastor for the past 10+ years.  They are moving ahead in life in remarkable ways...nursing, pre-law, engineering, theater, the Marines.  I am proud to say that these half-dozen young adults give me hope for our future and I feel privileged to be part of that in some small way.   I've also been the primary care-giver for my 88 year old mother-in-law while my wife is with our daughter who gave birth to little Judah last week.   My M-I-L has been struggling with her recent decision to give up driving.  I've been her chauffeur taking her to hair appointments, the grocery, and other errands she did on her own.  I don't mind because I know she is safe and everyone else on the road for that matter.  Welcome to the "sandwich" generation.

After I got home from one of these open houses, I decided to hit the garage again.  The weather was near ideal in temperature.  So I opened up the garage door, fired up the classic rock radio station, and set out to start working on the underside of the floor.  The top looks pretty good from the passenger compartment.  The underside?  Well, that leaves a little to be desired...

This is the "wide angle" shot of the floor on the driver's side.

It looks pretty rough as this is where I added the rod to make up for the gap in the floor seam and the patch where the E-brake cable bracket was located.

This is the section ahead of the transmission crossmember and showing the bottom of the toe board I replaced.  It's obvious that I'll need to do some serious metal work here.
I need to get the metal work done on the driver's side first since I have to put the seat riser in and want to be sure all the welding is done before I put the skim coat of Everlast Metal-to-Metal to take the last of the imperfections out of the floor.   (Bodywork on the underside of a car.  Who'da thunk???)

The first step I took was to position the car on it's side which was easy with the rotisserie.   Because I hadn't begun work on the floor bottom, I took my 4" grinder with a braided wire brush and cleaned up the metal and crud.  I noticed on the areas were there wasn't any surface rust that the bottom of the floor was painted black.  If I worked an area long enough, I stripped the black off to find bare metal with no other color primer, once again confirming the factory black.

Just as I was getting started, I noticed a guy on a motorcycle pull into my driveway.  I didn't know the bike or the guy.  He said he was riding by, saw the rotisserie and stopped to take a look.   After brief introductions, I showed him around the Mustang and some of the interesting facts about the car...being a 1-of-1, where that info came from, the VIN locations, the paint info I got off the MCA forum, etc., etc.  Basically, I was giving him the archaeology of my '68 Mustang.   He has a restored 1924 Franklin and was sharing the archaeology of that manufacturer with some fascinating detail.  To make a long story short, 45 minutes later, he departed and I got back on the car.   This is going to keep happening and I've gotten used to it since a person can't drive past the house when I'm working on the car and not notice it, especially when the sound of grinders, sanders, compressed air, and weld flash draws attention to it.    Anyway....

I took my 2" air sander and 4" electric grinder, both with 36 grit sanding heads to work down the welds and rod remnants.   Then I started spot welding some of the noticeable places along the joint were I needed to add metal.   After that first pass, I looked at the floor through the passenger compartment and could see numerous places where there were pinholes.  I used a white paint pen to push the paint through the pinholes and then marked them on the bottom side...

This is the view from the passenger compartment of the driver's side floor to transmission tunnel joint.  You can see some of the bigger pinholes of light along the weld joints.

This is the underside of the back half of the driver's side floor pan where I started the spot welds and marked where the pinhole areas needed to be repaired.

This is the front half of the floor pan.  The long circled area is where the metal got thin from grinding out the flange of the old seat riser.
I fixed these areas and continued to add metal to the joint where the wider gap and metal rod was added.  Then I'd go back and look at the floor from the inside to see where the pinholes still remained.  I swear they were multiplying the longer I worked on it.   Part of it was that as I filled the larger, more noticeable pinholes, smaller ones became more visible.   So what I did was put my halogen light on the passenger side of the floor to provide enough bright back lighting so I could see any pinholes from the bottom...

The halogen work light gave enough light to see the pinholes from the other side.
After getting the light set up, I looked carefully along the joint to mark where I saw any light coming through.  Unfortunately, there were plenty of places, each one that I marked with the white paint pen...

All the white "tick marks" are where a pinhole was found.

Talk about tedious work.  The trick was to fill the spot without blowing through.  This is when I wish I had a TIG welder for this type of fine work.   As is usual, there were a few spots that did blow out and then I started the "stitch n grind" process to fill the area.  In one area around that square patch I put in, I was able to use my copper backup I made.  I held it in place on the back side by reaching through the shifter hole in the transmission tunnel.  That was nice.   I may enlist the help of someone to hold it in other places where I need to fill the pinholes.  It works as such a great heat sync and backer.

I was focusing on the area of the floor where that square patch is because I needed to put the E-brake bracket back in place.  I took the pivot arm off the bracket and then glass bead blasted it.  That media blast cabinet was worth the $70!   Now I have this nice clean part to weld back on the car...

I aligned the bracket with the two spot weld drill holes in the floor to find out how it will fit with the repair joints in the floor...

It fits pretty good, but I'll have to get those pesky pinholes closed up and do the finish grinding, that I'm sure will show even more pinholes.

I closed up shop as I had about an hours worth of light and needed to get the grass cut before the rain moved in tonight and tomorrow...or at least that's what's forecasted.   I'm hoping I get an evening this week for a couple of hours to finish up the transmission to floor joint and get this bracket reinstalled before I leave for west Iowa in the Omaha area to see my new grandson.   I'm taking this Sunday off so I can be there for his baptism...and to give him the Mustang swag I ordered that came in the mail, that looks awesome.   I've got to start this little guy off on the right foot in both his spiritual and automobile development, right?   Because that's what grandpa's do...or at least this one.


  1. Ugh... filling pinholes. I can't think of a more time-consuming task than that. Well, other than chasing blowouts around maybe. Keep up the good work! It WILL pay off.

  2. Yes definitely dog work but probably beats wrestling with sticky door strikers!! :)


    1. RJ, in the famous words of NCIS Jethro Gibbs, "Ya think?" LOL!

  3. Alex, it will pay off for sure. The tedious nature of welding on thin metal creates its own challenges. But that's the nature of the beast.