Hesian isolation of steel and ally
 

I would welcome some feedback on materials that members have used to replace this isolation,dampingmaterial on the Superleggera body tubes (403) where they contact and corrode the aluminium.

Galvanic action minimisation
 

If the aluminium has not yet been joined/wrapped yet then a coat of epoxy primer/paint is always a good start for the steel surfaces .
However, there will be movement between surfaces due to different expansion rates of metals which could affect a painted surface.
Galvanic corrosion protection tape such as 3M Scotchrap is probably the best and easiest solution.
If the joint is already in place and then the use of a penetrating metal sealer such as Rustmaster metal sealer can be used.
One other thing to watch is where dissimilar metals are joined by rivet, screw, bolt. Where these types of joints are required you can go through a lot of trouble with plastic washers and pastes but the easiest is to use anodized rivets, bolts etc. These will other a good first line of defense.

scotchwrap
 

Thanks, that was one i had missed. Looks interesting.

I'm in the middle of rebuilding a 403 and have also started to think about this. As well as the hessian around the tubes in the roof, there is also a lot of felt used where aluminium panels are screwed, bolted or riveted onto steel. Where there is a chance of relative movement, I think it's important to use something to stop vibration and drumming, as well as to stop corrosion. I'm think of using one of the Dynamat products between the superleggera tubes and the roof. However, the hessian was also used to sew the headlining to the tubes, so I'm in two minds. Where felt was originally used, such as under the removeabel floor sections, I am thinking of using felt again, but synthetic felt rather than the old natural materials felt.

Mikebro,
Seeking a supplier of industrial felt in Melbourne as I have head lining off for rear window repair and also felt is required between fuel tank and the straps holding it in place . Yes, that's out too!
Suppliers website infers they can apply adhesive backing - which might have some benefit, if you can slide it in between the frame & the body.
Must say the original material around the fuel tank , if it was the original, seems to have survived well, and managed hold copious amounts of dust.
Would dust be a problem in Scotland?

Yours in passing ,
Camkram.

Hessian isolation of steel and ally
 

Crankam

No, mud and therefore rust is the problem in Scotland not dust particularly. For instance when I first dropped the petrol tank there was mud lodged in every crevice in and around the tank carrier assemblies.

Mikebro

Mikebro,
Does size matter?
Picked up 'water resistant felt '- 3.2 x 50mm roll last week for slipping between the steel tubing / alum body last week .
Primary purpose of purchase was to place around the fuel tank between tank & straps - stop wear from friction than corrosion.
And to start collecting more of the dust & mud I managed to displace when removing the tank.

Material originally used appeared to be 4 mm - supplier has 3.2 & 4.5 thickness, so I selected the thinner, thinking it can be more readily inserted into tight spaces and secured than trying to force the material into where it don't fit. Bit like life eh?

Yours in passing,
Camkram