Alternative method for skinning front cap - roof raise?

[PNW_Steve]

Hey Everyone,

Working with Asetechrail we came up with the plan to skin the front cap by inserting the new metal behind the top portion of the front cap and extend down and laying on the front of the lower portion of the front cap.

I was working yesterday and a curious gent stopped by and was asking questions about the conversion. Turns out that he has background in automotive sheet metal.

He offered a suggestion and was pretty outspoken that his way was better.

As I am fairly ignorant when it comes to metal work I thought I would see what you all think?

He suggested that I rivet or weld a 1-1/2" strip of sheet metal along the inside of the front cap extending down 3/4" then attach the new skin to the outside of the lower front cap and the outside of the new strip. butting the new skin to the lower edge of the top portion of the cap. Then seal the whole thing up with seam sealer.

What do you all think?

While I am at it, I was reading up on the 3M seam sealer and it says to apply urethane or epoxy primer to the surfaces being bonded. It said that applying to bare metal, high build primer and painted surfaces would not provide good adhesion.

Anyone have any thoughts on this? Is there a specific product suitable for bare metal or rustolium primer surfaces?

Thanks.

S.

[EastCoastCB]

what kind of 3m seam sealer? there are many.

[Mr4btTahoe]

His method is probably better... however why not just weld the whole piece in instead of using sealant?


That or do the overlap method with seal sealer.


The issue will be while driving in the rain. The pressure will push water up hill... without a GOOD seal on those seams, you'll get water coming in.

[family wagon]

I can see how his method will leave you nearer to having a flat surface on the outside rather than the step you'll have with a lap joint. But is that any better? It isn't as if this would be the only lap joint on the whole vehicle. As for whether wind-driven water will behave differently with one joint versus the other, I can't say. It does seem like his method will produce twice as much joint, and that might be viewed as a negative.

I used an ACDelco seam sealer 10-2013. Can't find any technical documents for it right now, but the description given on various online stores says "high performance seam and joint sealer with excellent adhesion to most surfaces. It is water resistant, stays permanently flexible, and withstands weathering, oxidation, salt water, gasoline, and most solvents. This product is safe to use on automotive paint."

[PNW_Steve]

Originally Posted by EastCoastCB

what kind of 3m seam sealer? there are many.

https://www.ebay.com/p/3M-08362/1737...937e22fff8bc0a

[EastCoastCB]

Originally Posted by PNW_Steve

https://www.ebay.com/p/3M-08362/1737...937e22fff8bc0a

I've had no issues, nothing but stellar results using 3m dynatron 550 from Auto Zone.

[PNW_Steve]

Originally Posted by EastCoastCB

I've had no issues, nothing but stellar results using 3m dynatron 550 from Auto Zone.

Good to hear.

I had googled "how to apply 3M auto seam seamer" and got a video from 3M that indicated specific metal prep that prompted my concern.

Do you prime before sealing or use it on bare metal?

[EastCoastCB]

Originally Posted by PNW_Steve

Good to hear.

I had googled "how to apply 3M auto seam seamer" and got a video from 3M that indicated specific metal prep that prompted my concern.

Do you prime before sealing or use it on bare metal?

I've used it on primed metal mostly but have used it on bare metal that had been ospho'd then cleaned up.
The dynatron is easy to use and I've had no problems at all from using it. As I said there are many types of 3m seam sealer. They sell at least 30 or so.

[PNW_Steve]

If the $15 a tube sealer from Auto Zone works well in my application then problem solved.

Thank you for the good info. Much appreciated.

S.

[EastCoastCB]

Originally Posted by PNW_Steve

If the $15 a tube sealer from Auto Zone works well in my application then problem solved.

Thank you for the good info. Much appreciated.

S.

I think you'll like it. If they don't have it in the store you may have order it online. My local store keeps one tube in stock at a time.

[PNW_Steve]

Originally Posted by EastCoastCB

I think you'll like it. If they don't have it in the store you may have order it online. My local store keeps one tube in stock at a time.

My local store is 35 miles away. UPS is my friend

I just noticed that the drawing I made didn't make it into my post...

[burley bus]

Originally Posted by EastCoastCB

I've had no issues, nothing but stellar results using 3m dynatron 550 from Auto Zone.

https://pack-n-tape.com/3M-550-Dynat...-per-case.html

[PNW_Steve]

Image that did not make it in the original post:

[DoubleO7]

Isn't the upper cap and lower cap material directly above each other?
So either method, of rejoining the cap pieces requires the top cap material to be forced out over the lower cap material, right?


Yes or no really does not matter a whole lot but doing it the way shown in the diagram will show any imperfections more than the lap joint.

[boojiewoojie]

What about using 3m VHB tape?

[Brewerbob]

Originally Posted by PNW_Steve

Image that did not make it in the original post:

I don't like that. Granted I have even less experience than you but why isn't it lapped like shingles? Top piece is the "highest" and every piece below that is under the lower lip of the one above it. That's how my bus is put together in the first place.


For my raise, I think I'll weld in a piece of angle iron at the new joint. Rivet thru the old, new, and angle. I'm adding 15" of metal. There's the original "dash board" where it was put together. I'll either add one or two piece across the front and add bracing where I cut the old.