Topic: 69 Mach I Panel seams\joints

[jamesp]

New to the forum.  I did searches but wasn't able to find my answers so I apologize in advance if I'm asking something that has been asked before.

I'm restoring a pair of 69 Mach 1 Mustangs.  A 428CJ R code and a 351w 4v, both 4 speeds.

Anyway, my cars were both in pretty bad shape so I don't have a ton of reference.  As I'm taking stuff apart and putting stuff back together I'm running into some questions.

Cowl seam sealer/welding: one of the cars had the cowl completely rusted through.  I cut out the old one and am almost ready to weld the new cowl to the firewal, A pillars, etc.  I know there was something between the welds on the firewall and around the parts of the cowl that connect with the interior.  I'm assuming this is seam sealer.  Is this correct?  If I put seam sealer down where it was before, then mate the cowl to the firewall, etc. i need to spot weld the two together.  What does that do to the seam sealer?  Doesn't it burn off, or at least effect the weld?  Do I put the sealer on and let it dry, then weld?  Or put it on and quickly weld it together?

What goes between where panels butt join:  I've noticed that in at least two areas there are panels that meet and don't appear to just be welded together.  One area is the small filler panel between the rear window and the trunk, where they meet the quarter panels on each side.  The second area is where the bottom of the quarter panel meets the rocker panel just below the doors and under the rear windows.  Are these panels simply welded together?  Or is there some kind of seam sealer placed between them?  If something is placed between, what is the process for replacement (similar to the question above)?  Put sealer on, let dry, spot weld?

Leaded seams: I'm aware that were the roof joins the A pillars and at the rear of the roof that the joints are filled with lead from the factory.  On one car I have to replace the roof as it was vandalized severely.  Once i get the new panel in place, I'd like to not use lead if possible.  What seems to be the best alternative that won't absorb moisture, crack, etc.?  I have no problem using lead if that seems to be the consensus but I'm just curious what people use.  I've heard that some people use a fiberglass impregnated type of body filler.  Is that good/bad? 

I don't want to do these things wrong as it is much more difficult to take it all apart again and redo it than to do it right the first time.

Thank you very much

[jmlay]

I have not touched the cowl but I did cut out my firewall last weekend. I have seen allot of comments on the net in regards to the firewall to cowl having a panel bonding agent utilized. On my January San Jose Mach1 the seam between the cowl & firewall was a non-hardening seam sealer. Thus I would expect the same between the upper & lower cowl.

While I have not used either I understand "Metal to Metal" made by Evercoat is a quality filler for a large fill like where the roof meets the quarter.

[J_Speegle]

Welcome to the site - must have missed something reading through the posts

For any of us to provide good specific guidance you'll need to provide when and where the car (s) were built. IF they are from different time periods or plants ask in two different posts. Too easy to confuse details and we don't want that Sealers and seam sealers can differ in location, type of application and even if it was used in a particular location

I'm moving the thread over to the 69-70 section since its a specific question rather than a general one


Welcome ot the site - hope you find the information here helpful in your concours efforts

[jamesp]

Sorry for the lack of specifics.  The particular car I'm inquiring about the cowl sealer is a 69 Mach 1, May 1st, 1969 built in the Metuchen plant.

The 428 car was built in Dearborn on May 7th, 1969.

Funny story.  Got the May 1st car as a parts car for my May 7th 428 car.  When it showed up it wasn't much of a parts car, so now I'm restoring both.  Dug quite a nice hole for myself.   

[J_Speegle]

Many of the joints in the unibody originally has a weldable seam sealer applied to the joint before they were welded together. I have no idea of where you would get a similar product today. Products like zinc oxide welding primer, weldable expanding sealers, flowable heat during sealers and others were all used according to Ford documents depending on the specific joint and location. .  Original stiff is often dried up and gone and many just try to get by with pushing some new sealer into the gap if there is any. On the positive side these cars do not see the elements and will not in the future, like what was originally designed into them

There are allot of drawings and descriptions in the Body assembly manuals available through Jim Osborn Reproductions (carried by most of the Mustang supply houses)  Though it spends a few pages describing and listing all the different types of sealers, Jim didn't include in the manuals a complete break down of the individual panel assembly or specific location of the application of each. Though not 100% correct as to how the cars were really built they can be a helpful manual in your restoration library


But bottom line is IMHO that each of the panel joints you asked about did originally get sealed. Currently I don't know of a sealer that can be applied to the surfaces of a joint before they are welded together and will assure that the weld will be a solid one on completion. Believe each of these areas, by restorers often now have the sealant squeezed into the gap and seam after welding - leaving little or no visible clue that its there. Except, for example spots like the exterior seams of the panel below the rear window.

As for a good current  lead substitute I think I'll move the subject back again to the general body section since we didn't get into specifics constrained to a specific year or plant in the responses   That way more are likely to respond with their 2 cents

[Rsanter]

More and more body shops are going to spot welding the cars back together after a collision.
Go to a body shop supply place and then will have the weld through seam sealer.

If you are using the spot welder correctly then the pressure applied between the tips will squeeze out all or most all the sealer from where the fusion weld will happen. The remaining sealer will stay in the joint and fill any small gaps

Lead is great but you have to know what you are doing or you can have bigger problems.
Use an epoxy based bondo type filler or the fiber filled filler.
It's not original but you can also just weld in a strip of metal and metal finish/blend the panels and then you will need very little filler.
Once painted nobody will know either way

Bob