Does anyone know what type of tar??..to use? -> Top of front strut towers

[RSTarga]

Just a tar based undercoating. You can use the spray rubberized undercoating from paint shops, but the original was applied with a brush. You could probably find some roofing sealant at Home Depot or Lowes that would work. Like what they use for roof flashing.

[Jesse16]

This is what left of a little roll of left-over stuff that came with my Griffith AC system. Thought I had a bigger roll somewhere but not seeing it. Still very pliable after many years on the shelf.

[drcoastline]

If you are just looking to recreate the look of the material on the strut tops, get some Upol Gravatex black. Apply with a 1" chip brush or an acid brush to get the look, texture and brush marks. The Gravtex has some body and will dry hard like the tar stuff. It will also provide the locking properties that the original product did. I believe the tar was used in a similar fashion as a thread locker to help lock the camber plate bolts and washers in place.

[drcoastline]

Here's a pic for reference. Not my car.

[A horse with no name]

Interesting...Thanks.

[NICE 69 S]

OK, this is great stuff for sealing holes, and is available at Home Depot in the Electrical section, pretty sure for under $3 for a pound.




Also available at HD in the roofing section is something that looks just like the roll of stuff that Jesse16 has above, but you have to buy a roll 6" wide by 50', and is $26.

Bob B

[Peter M]

Originally Posted by A horse with no name

Thanks everyone for your input. I have used all of the above mentioned materials, including the 'roll on roofing'

If possible, I would like to use whatever the 'stuff' was that Porsche used.

Quote: "It's bitumen. Often sold with names such as brushable bitumen or bituminous hydroseal."
"Should be able to buy it at your local hardware shop"

Re 'quote'...This, I think, is more like what the substance was as it was, as previously mentioned, 'as hard as a rock'.

Maybe someone who is in the professional restoration of 911's may be able to verify to the forum what the actual substance is?

Thanks in advance!

LOL, I thought I was helping, not contributing to two pages of confusion!

We call this material bitumen but I understand in North America you guys call it asphalt. It's the same stuff.

Just looking at a Home Depot website for example, I suspect looking at the SDS this is the type of material you are after to replicate what Porsche used at the factory:
Henry 101 4.75 Gal. Unfibered Foundation Coat-HE101571 - The Home Depot

I'm sure if you look further you'll find it in smaller containers as you don't need much to top the suspension towers, like less than half a cup.

If the bitumen is a little too thin, just leave the lid off the tin for a while and it will thicken up or otherwise brush on an 2nd coat.

I've perfectly replicated this sealant on two old 911's now using this bitumen material because that's all it is: bitumen mixed with a hydrocarbon solvent to make it brushable/workable.

I hope the bitumen/asphalt explanation helps.

Did learn something about dum dum which was new to me!

[A horse with no name]

Thanks...Yes, I believe that's what it is; tar-aka- bitumen, asphalt.
I'm going to look a what Home Depot has, including possibly picking up a small chunk of tar from a roofer that does 'tar & gravel' roofing.

BTW, how did the bitumen that you used on your resto's set?...Hard?-Soft?

Thanks in advance!

[LM3929]

The bitumen will not harden and get that dried look.

Lorne M.

[Peter M]

Originally Posted by A horse with no name

BTW, how did the bitumen that you used on your resto's set?...Hard?-Soft?

Thanks in advance!

The paintable bitumen I use is touch dry overnight and is very firm to touch within days because the solvent evaporates off quickly

I've used this material for sealing water tanks and roofing previously and it goes rock hard after about a decade just like it does on our suspension towers. I've also used hot applied bitumen for road building for the last 25 years so when I first saw it on my first 911 a few years ago I knew exactly what it was.

Hope all this helps.

[Peter M]

Originally Posted by LM3929

The bitumen will not harden and get that dried look.

Lorne M.

Lorne,
I disagree.

Regards
Peter

[A horse with no name]

Originally Posted by Peter M

The paintable bitumen I use is touch dry overnight and is very firm to touch within days because the solvent evaporates off quickly

I've used this material for sealing water tanks and roofing previously and it goes rock hard after about a decade just like it does on our suspension towers. I've also used hot applied bitumen for road building for the last 25 years so when I first saw it on my first 911 a few years ago I knew exactly what it was.

Hope all this helps.

Thanks again Peter...With your first hand experience on your own restorations, including my experience of 'chipping' it off, confirms to me what I thought it was -> tar / bitumen.

PS - I've also seen bitumen up close when being pumped off of bulk tank trucks -hot- at an asphalt plant...The small puddle of bitumen, that was left on the ground due to uncoupling the hose from their rig, I noted, firmed up pretty quickly as it cooled.

[Peter M]

Yes, hot bitumen solidifies very quickly on cooling. Unfortunately bitumen at 180 degrees C isn't the most convenient material for 911 restorers (and the factory!) to use so that's why we use bitumen cutback with a solvent to make the material temporarily workable.

With road building, besides using heat to temporarily reduce the viscosity, we also add cutter (kerosene) and/or flux (diesel) to modify the viscosity for reasonably short periods or about a year or so respectively.

[bugstrider]

Originally Posted by adias

Is this available in smaller quantities elsewhere?

How much did you need? I just picked up a 2lb package of the stuff.


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[bugstrider]

Originally Posted by Peter Zimmermann

Brilliant! Exactly what I need for the 356 that I'm replacing the harness in...

Pete,

How much are you looking to use for your 356?

Trev


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[Edoyle]

I know through BMW I can buy butyl tape that is 1 inch wide. I imagine with a few strips of that laid down you can hit it with a heat gun and it will blend together.

[bpu699]

Just use 3M black seam sealer... works fine, semi-pliable, and paintable. 20$

I used it, looks 100% stock