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TR2/3/3A Brake/Clutch fluid question

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Crankshaft

Crankshaft

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I'm in the process of rebuilding the clutch m/c and from the looks of the fluid I have drained so far, I need to purge the entire system. Are there any pit falls facing me or is it just a matter of bleeding until clear fresh fluid appears? Also I have seen "synthetic" fluid on the shelf, is that what I should use? Also wondering about changing to easy bleed fittings at this time, and also rebuilding the brake m,c at the same time. I'm a firm believer in "if it ain't broke, don't fix it" so should I wait to do the brake later? As always, all advice is welcome.
 
Bleed until fresh with no bubbles. Some bleed the MC before installing but I've never had to do that. If your fluid is dirty it's likely deteriorated rubber, could be slave also. It's a good idea to bleed the system out every couple years anyway so I'd at least do that to the brakes. If doubt do the brake MC but then there are rear wheel cylinders and calipers so where to stop. The parking brake offers weak back up. A search will show quite a bit on silicone vs Dot 4. I switched when fitting fresh MC's a couple years ago with success. Easy Bleeders are great IMO, make it an easy one man job with little mess.
 
I love the Easy Bleeders. I put them on the rear, the front, and the clutch slave on my 1961 TR3A. Please note that the rear and the front take different easy bleeder fittings. I had good luck with the ones I ordered from a guy on eBay. He also has a list of which part number to order for which car and for front, back and slave, which made ordering easy and accurate.
Regards,
Bob
 
Just a side point, "synthetic" brake fluid is NOT the same as DOT 5 silicone brake fluid. "Synthetic" has become a marketing term, legally meaningless. All brake fluid is synthetic, whether the word is on the label or not.

Personally, I'm a big fan of DOT 5 Silicone, been using it in all my Triumphs for 25+ years, but there are valid pros & cons both ways.

Since they share reservoirs (on a TR3A) and the discoloration indicates either contamination or really old fluid; I think at a minimum you should bleed all the brakes until you get clean fluid at each port. Unless you use DOT 5 silicone, you really should do that every couple of years. Conventional brake fluid absorbs moisture from the air and deteriorates with time until it becomes quite corrosive as well as boiling easily.

 
If I were to convert to silicone, is it still just a matter of bleeding both systems until new fresh fluid appears?
 
Crankshaft said:
If I were to convert to silicone, is it still just a matter of bleeding both systems until new fresh fluid appears?
Click to expand...

That is a subject that is, at best, debatable.

I did it that way on both my TRs more than a decade ago and just recently on my Jaguar. I had no problems with any of those.

I sucked as much old fluid out of the reservoir as I could -- filled it with DOT5 -- -- let it sit overnight (DOT5 seems to hold bubbles in suspension longer) -- then just bled until I saw purple coming out.

But since it is something real important that we're discussing (brakes!) I'll emphasize -- that is what I did and what I experienced. YMMV, use at your own risk, do what you think is best, always let your conscious be your guide, don't follow leaders, watch the parking meters, etc.
 
Like Geo, I've done it and it seemed to work well enough for me. However, I had the brakes apart for other reasons later on, and discovered some black tarry goo in places that I believe was the remains of the old DOT 4 fluid. It does not mix with DOT 5 at all, and is more dense, so I believe any remaining droplets of DOT 4 sink to the bottom and lay there sucking up the dye from the DOT 5 as well as any dirt, wear particles from the seals, etc.

Another anecdote (that doesn't prove anything) - On Stag #1, both seals in the brake master cylinder failed nearly at the same time, just a few months after converting to DOT 5. When I got it apart, the cups were much softer than usual (about like al dente pasta) and had torn apart between the base & seal surface.

And yet another concern : The hydraulic brake light switch used on TR3s sometimes doesn't seem to like the DOT 5. After converting my TR3A, the apparently original switch stopped working within a year; as did the reproduction from Moss; as did the similar switch from FLAPS (originally fitted to some old Ford pickups IIRC). Other folks have reported not having such problems, so maybe it's just the luck of the draw or whatever. And I can't really prove it was the DOT 5 (I also had higher power brake lights on the TR3A), it just seems suspicious. But I finally converted to a mechanical switch. Even the first mechanical switch on my TR3 gave me headaches, which in retrospect I blame on DOT 5 leaking from the reservoir, down the pedal and wicking it's way inside the switch. Fixed the leak, replaced the switch, it's been fine for about 4 years now.
 
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