Topic: Coating on top of fender apron

[Gbailey1018]

I am in the middle of my long-awaited paint and am getting very close to reassembly.  When the fenders were removed, I could see underneath (where the fender was bolted to the apron) there was some type of thick coating that appears (to my untrained eyes) to be glue, deadener, gap filler, etc.

Is there supposed to be any type of material laid between the top of the fender apron and the backside of the fender?  Or should the top of the fender apron be 100% smooth with nothing on it rather than black paint?

Sorry I don't have a photo that is more of a closeup, but hopefully you can see what I am referring to, especially on the passenger side.

[carlite65]

strip caulk is usually found there. it is not the butyl type stuff sold today.

[Gbailey1018]

Thanks so much for your prompt reply. 

So I assume this was done at the factory?  What purpose did it serve?  Was it a gap filler?  Rattle reducer?  Moisture prevention?  Did all cars have them?  Is it functionally necessary?

FWIW my FB was built at SJ in April 68.   

[J_Speegle]

Thanks so much for your prompt reply. 

So I assume this was done at the factory?  What purpose did it serve?  Was it a gap filler?  Rattle reducer?  Moisture prevention?  Did all cars have them?  Is it functionally necessary?

FWIW my FB was built at SJ in April 68.

Yes all cars. " Is it functionally necessary?" You would have to ask one of the original engineers. Not really our focus though here

Sealed the wheel well area from the engine compartment. to keep the rain, dust and water out of that compartment as best they could. Applied to the fenders is sometimes would squeeze out though not often but can often be seen where the drivers fender notch is for the VIN (at some plants) stamp

Might be able to see some on one of the unrestored examples posted in that section of the site

Use a dark grey or black product not the light gray some suppliers sale or that can be from as NOS/service parts.

[jwc66k]

From the old grey cells (sometimes used as a memory bank), the "black sealer" was intended to keep the fender in place after it was adjusted to the hood and doors, and then all the fender bolts tightened.
Jim

[Gbailey1018]

So just to confirm, a concours restoration would require this sealer be spread between the fender and the apron?  Does it get spread the entire length of the apron, or just a portion of it? 

Is this the stuff?  https://www.npdlink.com/product/stripping-caulk-cord-black/106653?backurl=search%2Fproducts%3Fsearch_terms%3Dfender%252Bcaulk%26top_parent%3D200001%26year%3D

[J_Speegle]

So just to confirm, a concours restoration would require this sealer be spread between the fender and the apron?  Does it get spread the entire length of the apron, or just a portion of it? 

Unless the product was not pressed on fully and it fell off that was the intend - along the full length or pretty close to it along the whole fender to inner fender and shock tower length

There have been a number of threads on the subject one of the more resent discuss different "current" products. The longest thread I could find using the search feature and the words "butyl fender sealer" was the one below

https://www.concoursmustang.com/forum/index.php?topic=15605.msg97791#msg97791


Here is a thread on the 67 San Jose application with examples. Would apply pretty well to 68 model year also

https://www.concoursmustang.com/forum/index.php?topic=12906.0

What you don't want is allot showing/exposed and or get a product that will remain tacky for long periods of time since it will "grab" and hold lint, threads and anything else that touches the exposed surface.