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

Hi...After rebuilding the F & R suspension, to be able to get a four-way alignment, I had to chip off the original tar like substance that was on the top of the front strut tower assembly, as seen from the 'frunk'...It literally was as hard as a rock!

I would like to restore this area to its original looking appearance...I have looked at quite a few different 3M seam sealers but the original substance somehow seems to be made of a different type of material...Is it?

Does anyone happen to know what the substance is called, including where I could purchase it?..

Thanks in advance!

I think it went by the technical sounding name dum-dum.

edit: just googled dum dum putty and got a hit for it as a sealing compound - I did not check availability.

I can appreciate your originality efforts, but if the car is not in a weather or salty air local let that dog lie. knock down the rough edges of the existing areas that have cracked with a dremmel wire brush unit then just touch the paint up some. seems the texture of that is kinda smeary and likely not able to be matched easily. anything you gob on there may look like a turd in a punch bowl...

Thanks,

I was just searching for essentially the same material because I need something to seal up the rubber furl line grommets that are located at the tunnel. It has to be the same stuff. Really didn't want to use black silicone or RTV sealant. Just in case I ever needed to access it for whatever reason.


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I love that it is called 'dum dum'
I won't miss it. For the sake of accuracy in restoration, I can understand, but no, I wont miss it.. What was is it's intended purpose anyway?

I just found this on the Eastwood site. They say it is even paintable too.

https://uploads.tapatalk-cdn.com/201...895666d0ee.jpg

https://uploads.tapatalk-cdn.com/201...1758dbf5f6.jpg


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Dum dum is different. That's the stuff used in fitting window glass. It is soft and pliable.

Other thread you started mentions bituminous sealant (aka tar).
Basically it is roofing patch.
It is what we used to seal floor patches 30 years ago in a body shop I worked in while going to college. Likely the same stuff. Never really hardens, can be stinky when it gets hot in the sun for about a year!

Definitely not Dum-Dum since this has to remain pliable for many years; we have used it daily for over 30 years to seal wires. A similar product to what you are looking for is a rubberized undercoating; I have purchased that as a spray-on coating. Once it sets up fully, then it can be painted.

I used asphalt based gravel guard and it worked perfect. \there are many different tpes to choose from , just spray it on and it seals. go to your local flaps and ask for it. some of it is paintable.

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

I've still got a roll of flat/thick/kinda sticky/moldable material that came with my Griffith AC system that you wrap around the some of the fittings and expansion valve at the evaporator. That stuff seems very similar to whats "was" on my front shocks. I definitely did not replace it after the refresh. I'd supply to anyone for free if interested. Have to check that I actually still have it. Maybe cheap and easy to obtain from anyone who works on AC systems.

I'll be up for some if the offer still stands once you locate it. Will be using for the fuel lines and the AC


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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!

Is this available in smaller quantities elsewhere?

From what I have found, no. A local Automotive paint supply "Jerry's Paints" sells the 3M equivalent. Same deal, pliable, never hardens and is paintable immediately. However, also comes in a 2 lb package. It sells locally for $24.99 and on Eastwood for $16.99, but with shipping its the same price.

I know I am going to order or buy some locally.

Cheers

Would this actual item description or number be listed in the PET? I do not have a hard copy to reference for you, sorry

Thanks!..I'll have a look at PET and see if they show it...As I was saying, I would be most interested in knowing what the 911 Concours d'Elégance restorers are using.

I know what you mean, but if at all possible, I would like to bring it back to the factory look even though the 'frunk' carpet covers it... I did however chip it all out without damaging the paint underneath it...Amazing but true!

Due to the tires wearing so evenly, all the way around, it was the first alignment that the car has ever had (125K km)

I decided to have a four wheel alignment after I had replaced all of the front and rear bushings.

*Weissach Porsche also are the Lambo dealer in Vancouver, so they use their Lambo shop to do all of their alignments...I thought that if the 'Princess' kissed 'Herr Frog' that he would turn into a 'Prince' :D

http://forums.pelicanparts.com/uploa...1501566696.JPG

Didn't mean to mislead with the dumdum suggestion.
I agree it is more tar/petro based.
I've never seen anything in PET about it, but I've only look at '86+.

There have been some older threads on this very same question, and as luck would have it, the one I recall is the one I can't find for you. In it, someone (the esteemed late Early_S_Man /Warren Hall ?) listed several products he thought might be suitable equivalents - and this was over 10 years ago.

Suggestions as to the purpose of the application included sound-deadening, waterproofing, and alignment preservation (like loctite).

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.

Bitumen or similar
 

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.
http://forums.pelicanparts.com/uploa...1501622189.jpg

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.

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

http://forums.pelicanparts.com/uploa...1501625151.jpg

Interesting...Thanks.

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.

http://forums.pelicanparts.com/uploa...1501629138.JPG
http://forums.pelicanparts.com/uploa...1501629221.JPG

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

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!

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!

The bitumen will not harden and get that dried look.

Lorne 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.

Lorne,
I disagree.

Regards
Peter

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.

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.

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


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Pete,

How much are you looking to use for your 356?

Trev


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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.

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

I used it, looks 100% stock