A Historical Quiz

[Easy Drifter]

Before Silicone sealants came into wide spread use to seal gearboxes (mostly Hewland) there was a gasket often used when you changed gears. (Two actually.) Most teams did not bother as the surfaces were so good. However wether you used the gaskets or not a sealant had to be used.
How could you spot a team's gearbox man in those days before silicone?
What was the sealant called?

As an aside if you got so much as a drop of oil on that sealant you usually had a leak. Silicone was a vast improvement in sealing qualities and not as leak prone and easier to clean off. Whichever product was used all the old stuff had to be cleaned off. By the way the back of the car was normally jacked up to keep the oil from leaking over the machined surfaces before you could bolt them together. You still didn't have much time.
One guess as to one of my jobs!

Starter will probably get this one.

[Rollo]

It really depends when.

In the 1920s and '30s it wouldn't have been uncommon to find either hemp twine or leather being used because of the absorbent properties. In the 1940s Union Carbide came up with Nitrile, which is otherwise known as NBR. In 1953 DuPont came out with Polytetrafluoroethylene (PTFE).

The point to be made here is that I've seen all of these on various cars at various stages. When I had the gearbox out of a 1924 Packard, there was so much fibrous residue from twine that had been packed into the shaft seals, the only thing we could really do was to use a flame canister and burn it all out.

You can now buy cements which bind PTFE directly to rubber, which is brilliant for gearboxes. As for actual brands, well I've probably seen different companies' stuff, so I shan't make a comment there.

[Easy Drifter]

I was referring to racing gearboxes which had constant ratio changes and basically Hewland boxes. We would sometimes change ratios at a new track 3 or 4 times a weekend.
Pretty well everybody used a certain material on Hewlands and similar boxes on rear engined cars until silicone became available.

[Rollo]

Do you mean Hylomar?

[Camelopard]

Gasket goo?

I had several Escort Twin Cams in my younger days and even gasket goo couldn't stop them leaking oil. :)

[Easy Drifter]

You have it Rollo. Rolls Royce's Hylomar. The mechanic who put the casings on always had a blue finger from applying the Hylomar. He often was not the one who actually changed the gears. There were two reasons for this and one was speed of getting the change done. While the cluster was being changed the other one was cleaning the old Hylomar (later silicone) off the machined magnesium surfaces before applying the new. Second reason was to keep the Hylomar/silicone out of the actual gearbox. I was the blue finger man!
By the end of a season it would take weeks before your finger was back to a normal colour and you did get some strange looks from non racers!
With silicone no problem. Acetone was used to do the final cleaning of the machined surfaces after they were very carefully scraped with a gasket scraper. Also got the silicone off your hands. Hard on the hands but better than the blue digit!
Smoking anywhere near acetone was a real no no. Extremely volatile.
Later when running methanol we added acetone for cold weather starting and often sprayed it into the injectors on cold (below 50F) days to get the engine to fire. Worked better than gas.

[Camelopard]

In the early to middle eighties when I was building silos, we used Sikaflex which although green stained your hands brown. It was horrible stuff but meant that the grass silos would not leak water and the sealed grain silos were air tight. I think it must have been one of the first Polyurethanes.

The stuff we used previously was a bitumen based mastic which was easier to get off using solvents.

[markabilly]

when I was much younger I used to get the blue finger, but it was not from Hylomar.....