1970 Mustang Retromod - Boss 351

[Cantedvalve 128]

Today was a twofold affair. First we fit the trunk corners and the taillight panel. All is well there, things fit reasonably well.  The trunk corners will need a bit of massaging, but that’s to be expected.  We had to take the bumper reinforcement brackets off because a) we couldn’t figure out how to assemble the corners and taillight panel with them there, and 2) they appeared to be in the wrong place… too far from the taillight panel.

 

[Cantedvalve 128]

Sexond, we started fitting the roof.  First run at it wasn’t very successful, as it didn’t want to fit,  we figured out that the passenger body side needed to move backwards, so we made a 1/2” adjustment there, and then we were able to muscle it into position.  Second issue is the rear crossmember stub on the driver side. We took some measurements between the front and the back crossmember stubs, and found the distance in between to be equal.  Then we measured the width of the stubs themselves.  Passenger side is 4”.  Driver side is 4.5”. Passenger side the crossmember fits well.  Driver side it doesn’t want to it well.  Pretty sure it’s a manufacturing error.  Nothing a bit more cutting and welding can’t fix.  Also found the same issue at the driver front that @Viperpete has with the flange on the body side not quite meeting up with the roof line.

 

[Cantedvalve 128]

After a fantastic call with @Viperpete last night on the phone where we compared notes, it LOOKS like I am on the right track.  We both have some of the same issues (the corner on the front roof crossmember that sticks out on the passenger side, the flange on the driver body side that doesnt quite meet up with the roof, etc.).  We did (I think) figure out that the rear roof frame stub on the driver flange is too wide, and it will need modified.  But that will come at a later time.  Right now we are working on the firewall.

Last night I began welding in the driver toe pan to the firewall.  I am using the "universal" 64-70 toe pans, so I know they wont be completely correct, but I didnt expect to have to metal work them as much as I did.  The contours of the firewall didnt match up to the toe pan very well.  I ended up hammering some stuff flat, some stuff needed hammered in, and what took the most time was completely reshaping the area under and around the steering column.  It wasnt even close, the bends were all in the wrong place.  So about 4 hours later between all the fitting, trimming, fitting, trimming, hammering - both myself and the toe pan - I got it to the point where it fit well enough that I didnt have to draw it together with clamps and I could just use clecos to hold it together while I trimmed it.  I got most of the firewall horizontal welding done, still have to do the trans tunnel and under the accelerator pedal.  Anyway, here is the results.

[Cantedvalve 128]

As you can tell from the pictures above, I removed the reinforcement plate that fits around the brake booster/master cylinder and the steering column.  This was initially to get rid of the rust between the panels.  However, upon removal I found the plate to be severly rusted on the inside as well, so I am making a new one.  I also didnt like the deflection around the mounting holes for both the steering and brakes, so I am making it from a thicker material.  I do have a question.  The tang circled in the following picture... does it have a purpose?  If not, I wont bother reproducing it.

 

[RogerC 136]

I think that's the spring anchor point for the top arm of the clutch bellcrank.

[Viperpete 36]

Nice work Jim! Glad I could help 

[Cantedvalve 128]

1 hour ago, RogerC said:

I think that's the spring anchor point for the top arm of the clutch bellcrank.

Oooo... I'll need to add that back in then.

[Cantedvalve 128]

Tonight I worked on my beefed up reinforcement plate for the firewall.  I made a slit in the back to allow me to bend it (it’s HSLA 050XLF steel at 0.145”), then welded the cut back up after the proper bend had been achieved.  I also started working on putting the holes in it for the brake system and steering column.  I test fit it before calling it a night.  Is it overkill?  Sure, but that section of firewall WITH the old reinforcement plate had flexed and the holes were out of shape.  Since rust caused me to make a new one anyway, I figured a bit more steel would help fix those problems.

I’m quickly running out of stuff to do given it is winter here and I can’t sand blast or put down epoxy primer.  Have to have access to both of those things before I can start welding parts together.  I can still strip the doors and get them ready for new skins.  Rear seat support has some repair work left on it.  Many small parts to sand blast in the cabinet, but I’m not able to prime them… unless… I can prime them at work!  Oh perfect!  But hey, don’t tell anyone!

 

[Cantedvalve 128]

Finished repairing the rear seat support today. It’s not going to look new, but it will do the job and largely won’t be seen. II’d love to find a 2” lightening die to put some rigidity back in the structure to prevent vibration/harmonics/whatever. Also did another assessment of the door we flayed. just needs the bottom repaired and the inside sand blasted… something we can’t do until better weather.

 

[Cantedvalve 128]

Date code on the door is 9M03, which I think translates to December 3, 1969.  The boy was all worried he was getting a 69 door because it had 69 glass in it.  Not the case.

[kblagron 20]

On 1/28/2023 at 7:47 PM, Cantedvalve said:

Date code on the door is 9M03, which I think translates to December 3, 1969.  The boy was all worried he was getting a 69 door because it had 69 glass in it.  Not the case.

My 1970 was built in August 69 and has glued in glass.  Still trying to figure out if I want to upgrade or not.   The glass is good, but one has already separated, I figure the other probably isn't far behind.

[Cantedvalve 128]

Probably not uncommon to see interchangeable parts interchange early in the model year.

[Cantedvalve 128]

Been working on the firewall. Spending a lot of time on it because a) it needed help, and b) I am making some subtle modifications that should help with strength.

The metal was thin where the export brace bolts up and the holes were wallerd out, so I cut that out and welded in new metal. When I did, I dropped it down around 5/32” because I am planning to integrate an export brace reinforcement into that area. I am not fond of just welding it to the outside of the cowl, so I am integrating it into the firewall. It will get plug welded on, and when it’s done, won’t be easy to see. I finished on the flat piece that goes on top of the firewall where the export brace bolts on. Turned out very nice, and flush to the top flange where it will be welded. I will have a vertical piece on the inside of the firewall that will plug weld also and weld to the top piece. It increase the strength of that area nicely. 

I also took off this little bracket from the driver side of the firewall next to the export brace flange. I have no idea it’s function. I know someone smarter than me can tell me. If it is of no use (as it isn’t on my 1970) I may leave it off.

[jmlay 80]

Wire harness retainer attaches to this tab.

[Cantedvalve 128]

Okay, back it goes.  What part of the harness?  I’m guessing the wiper motor?

[aslanefe 333]

1 hour ago, Cantedvalve said:

Okay, back it goes.  What part of the harness?  I’m guessing the wiper motor?

Yes, wiper motor harness.

[jmlay 80]

Also the hood scoop turn signals, if equipped.

[Cantedvalve 128]

So we worked on getting the roof to fit today. We have the body sides squared and wheel wells in place. All good, but the roof just doesn’t want to fit.. It feels out of square. I can line up the front corners and the passenger rear. The driver rear feels “short.” The roof doesn’t overlap the quarter panel by much towards the rear… certainly not enough to plug weld it. Everything else seems good. We will keep working on it.

[Cantedvalve 128]

Last night I worked on correcting the driver side rear roof crossmember stub. The piece that the crossmember welds to. It was too wide by 0.5" and it was too far back by about 1/8". Fixing that solved the problem seen here...

 

I also worked on trimming up the front passenger side from the corner that still sticks out...

[aslanefe 333]

8 hours ago, Cantedvalve said:

Last night I worked on correcting the driver side rear roof crossmember stub. The piece that the crossmember welds to. It was too wide by 0.5" and it was too far back by about 1/8". Fixing that solved the problem seen here..

I also worked on trimming up the front passenger side from the corner that still sticks out...

 

Those rosette (plug) welds looks nice, almost no grinding necessary. A lot of times mine builds up and I need to do a lot of grinding, need to figure out what I am doing wrong to make them like yours all the time.

[Ridge Runner 1,112]

I had an old snap on welder for mufflers it had timed spot welds and stitch weld ,i used 025 wire ,it also had a spot weld cone ,kind of looked like a cotter pin nut on the end ,that thing could make a spot weld that only needed a wipe to finish it off .it finally burned up and they want a fortune for a new or even used one ,i would love to find another one ,it loved thin metal !

[Ridge Runner 1,112]

If you ever get a deal on one of these grab it ,if you dont want it let me know because i do ! The top tips down for welding under the car 

[Cantedvalve 128]

1 hour ago, aslanefe said:

Those rosette (plug) welds looks nice, almost no grinding necessary. A lot of times mine builds up and I need to do a lot of grinding, need to figure out what I am doing wrong to make them like yours all the time.

Those are the best ones I’ve ever done.  The rest probable look similar to yours. I got one of those backing clamps that helps prevent burn through, and I turned the welder up.  Worked well. Doesn’t always though as you can’t get that clamp behind everything.

[Cantedvalve 128]

Here are some pictures of what I am doing in the export brace area. First one shows you the replacement flange from the top. I grabbed some steel corners (came in on some flat stock, used to prevent damage in shipping) from work that were going to the scrap bin, and what do you know, perfect width.  The rest was trace and cut.  Second picture shows the 5/32” inset from the top of the flange where the reinforcement plate will go.  It will have a companion plate running downward inside the firewall to give it additional rigidity.

[aslanefe 333]

59 minutes ago, Ridge Runner said:

If you ever get a deal on one of these grab it ,if you dont want it let me know because i do ! The top tips down for welding under the car 

There is a Tecna 3664P resistance spot welder for $3500 OBO about 200 miles from me, but it is 3 phase which I do not have in my shop :(