TR2/3/3A Brake Fluid

[Redoakboo]

When I bought the car, the owner was using DOT 3 synthetic. Is that still a good product to continue using? I plan on bleeding the clutch slave cylinder as what I have gotten out so far is pretty black.

 

[TR3driver]

This is an often debated topic, with no clear winners. Personally, I much prefer DOT 5 silicone. It doesn't turn black, doesn't corrode brake components, and won't eat paint when it does leak (due to worn-out seals, etc). But it does have disadvantages too. You can read more about pros & cons at
https://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

That article references several technical papers, which you can find at
https://drive.google.com/open?id=0B2H2NJt34OffdnhWS19scjlNUU0

I particularly enjoyed the Browning paper, as it shows that conventional (DOT 3/4/5.1) fluid absorbs not only water, but salt; and can do so right through the hoses! It's no wonder the stuff becomes so corrosive over time!

I've seen this multiple times (although never quite this bad). This was the clutch slave on TS13571L when I started reviving it from a 34 year hibernation.

 

[Redoakboo]

Does DOT 5 mix with DOT 3?

 

[bobhustead]

They don't "mix". If the question is whether the system needs to be flushed of all 3 before starting the 5, there is some disagreement on this forum. The instructions on my fluid container said something like 'add the 5 and bleed til purple is coming out the bleeders'. I did and it has been fine for 5 years.
Bob

 

[TomMull]

They don't "mix". If the question is whether the system needs to be flushed of all 3 before starting the 5, there is some disagreement on this forum. The instructions on my fluid container said something like 'add the 5 and bleed til purple is coming out the bleeders'. I did and it has been fine for 5 years.
Bob

I did the same although I just finished my second year.
I would also mention that the DOT 5 appears to be a poorer lubricant and my newly rebuilt and honed master cylinders are a bit slow to return. Not really a problem with the brakes but I can't "sped shift" with the clutch. I don't remember having the problem with rebuilt cylinders using DOT3 so I can only assume the DOT 5 contributes. I do plan to polish the bores before next season and continue using DOT5.
Tom

 

[Geo Hahn]

Not only do they not mix -- but the distinctive purple colr does some strange things as shown here:

https://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

I have also just added the DOT5 to the system and bled until I saw it come through. The results have been fine on 3 cars - 18 years in one case.

 

[poolboy]

Empty the reservoir first, would be my recommendation.
I absconded with a turkey baster for such duties.