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Triumph TR6 - Silicone (DOT 5) Brake Fluid

How do I know if the PO put silicone brake fluid in my TR? I've read that DOT5 is supposed to be colored purple, but was this always true? Thanks. Rick.
Rick Orthen

I've been using silicone brake/clutch fluid in my TR3A since I did my total restoration 11 years ago. That equals 60,000 miles. I changed all the rubber hoses and seals before filling with silicone. Don't mix and hope !

I have only seen purple silicone brake fluid, even when I bought some at a Harley dealer in their Harley labelled plastic bottle. After about 5,000 miles, it has turned black and you can't tell any more.

If you syphon out a bit, or drain some out, let it sit a few days in a clear bottle. The black will settle to the bottom and the rest on top will turn purple again if it really is silicone fluid. If it stays black, it's not silicone fluid.

Let us know what you find out.

Don Elliott, 1958 TR3A
Don Elliott

My suggestion is just flush out the old real well and add your preferred fluid. Why take a chance?
Don K.
DON KELLY

Don
Unfortunately this is not an option for Rick O. DOT 4 or DOT 3 are to say the least not compatable with DOT 5. Yes one could flush the system, but then all the rubber components of the ENTIRE brake system will need to be replaced (if a mix of DOT 4to DOT 5 occurs). Rick, I do not envy your situation. Good luck.
Rick C
P.S.Mine is purple also.
Rick Crawford

Thanks for your input Rick and Don. I stirred up all the black crud in the master reservoir and it settled back out within a couple of minutes. Definately dealing with two phases here. Next, I'll take some out and check the color. My fingertip smell test tells me that it is NOT a glycol (DOT 3/4) fluid (not much odor at all). What if I take a sample from the master and mix it with some DOT 3/4--how fast does it congeal? Also, I thought that black crud only occurs with glycol fluid since it attacks the seals more so than silicone, true?

Thanks folks!

Rick
Rick Orthen

Oh yea, forgot to ask: when you refer to "flushing" the system, what do you use?
Rick Orthen

I don't know about what happens when you mix them. All I know is what I was told. I don't know if it will congeal. Just don't mix them in your system. Suck or syphon some out the master cylinder reservoir and let it sit a day or two in a clear bottle. That'll tell you.

Don Elliott
Don Elliott

The ? Rick wanted to know was whether it has silicon in it . I am hoping there are no TR guys running with 3 0r 4 in their system. If there is they deserve what falls upon their brake system. I was going on the assumption that silicon and dot 5 are compatible if a very small trace of silicon is present,as in a good flush job. Thoughts?
Don
DON KELLY

Don K
I agree with you 100%, does it have silicone in it? We appear to be are interpreted the question differently. To me, the not said question is "what the heck do I refill it with"? Keep in mind Don that it is a BIG NO NO!! to mix DOT4 and DOT5...even after a flush!! I agree with you that DOT 5 is best choice especially with us northern folk who park them for too many months of the year.Don, maybe I am missing something in your statement re DOT 5 and silicone being compatable...DOT 5 IS silicone (brake fluid). Sorry Don K, but I still gotta disagree with you. Rick can not just simply flush and add his preffered fluid (DOT4 or DOT5). Rick, you have to determine what is in there (in both systems). You are obviously going to do the Don E test. Maybe the congeal question should be asked of a fluid manufacturer. The product to do the flush with is then going to be what is currently in the system(s)...DOT4 or DOT5. What colour is the fluid???? Rick, the black crud does not sound good. Have you considered taking the master clutch off (the easier one)and examining the seals?
Rick C
Rick Crawford

It's unfortunate that this thread seems so confusing, but my only question was how to determine if my TR has silcone fluid (since I want to renew it). If I can go by color, than purple = silicone and amber = glycol. The black crud I presume is normal seal wear debris that accumulates in any hydraulic system, especially a glycol-based one.

I'll keep you posted.
Rick Orthen

OOPS, wher e was my brain that night? Too many Valentine glasses of wine. following is a small article i had on hand.

Re: DOT5 Silicon Brake fluid in ABS systems?[900/1996] posted by abe crombie on
Friday, 21 January 2000, at 2:28 p.m.

The makers of the rubber pieces that are used in brake systems recommend that if DOT5(silicone) fluid is used then all parts should be new and the system should be flushed with solvent to remove all traces of glycol based brake fluid. The reasoning is that the DOT5 stuff is non-absorbent of moisture and the DOT 4, 3 etc. is. The mixing of the glycol and silicone in the system will allow moisture absorption of glycol to get moisture mixed with the silicone and this is not good. This leads to a high viscous sludge according to someone I know that did this to a classic car. It is almost impossible to get all traces of brake fluid out of a Hydraulic Modulator (the abs unit thing). There are pressure damper chambers and storage chambers that are not in the hydraulic circuit when you bleed. These areas have circulation when the ABS is active (a first roll test makes system valves and pump active) and would contaminate your best efforts at getting all the traces of conventional fluid out. The system on GM products of older vintage is simpler and may not have the storage chambers or maybe your dad is just lucky.
If you actually get the details on this stuff it is not really intended for active vehicles but is rather for race cars which will see high temps for extended periods and for classics which aren't used much and are big targets for moisture corrosion. Classics and race cars will have most of their systems installed as new parts.
Save your dough and periodically flush/bleed your brakes

Jury still out on last paragraph.
Don
DON KELLY

Found this too, rather seems to be on the mark (marque) check it out
http://members.aol.com/tfrecord/page30.html
Don
DON KELLY

Don,
Ya had me worried for a second..after all you got 5 in your 6. Hope you did not have TO MUCH of the fruit of the gods that night. Another interesting artical (and a whole bunch more stuff Bill North) is at :
http://www.vtr.org/maintain/index.html
They mention DOT 5.1 (glycol base!!). I guess Someone figured that life needed to be more confusing.
Rick C
Rick Crawford

Perhaps this will be the end of this story. I took a sample of the fluid and put some DOT 4 glycol in it. Guess what? The two did not mix, like a Lava lamp. So I guess the PO put silicone in the system, so I'm stuck with it for now. I don't want to flush and change all the seals to revert to DOT 4 or 5.1. Interestingly, the fluid in my car is clear (no purple hue at all), so not all silicone is tinted apparently. After studying up on this subject with your help, I'll get rid of the silicone when its time for other hydraulic work. My TR is a daily driver (weather permitting), so silicone loses its advantages. Thanks again for you insight!

Rick O.
Rick Orthen

Rick O,
Silicone or Dot 5 doesn't lose its advantages because
you drive daily. That is when it is at its best!
As long as you are not racing the car,ie. repeated
high speed stops then the silicone will do every thing
that dot 3&4 wil do and more. It won't pull in moisture
the way Dot 3&4 will so you can drive all winter and not worry. Just flush the system. Grab an old turkey baster and draw out the fluid in the M/C. Fill with new Dot 5, bleed the farthest brake, passenger rear first thendriver rear, then passenger front then driver front. All the while filling fresh fluid to the M/C. Keep going around in this order until clean fluid
with no bubbles comes out of every bleeder hole and
you are done. Put the cap back on and you are finished.
However, you might want to take a laundry pen and mark on the M/C DOT5-SILICONE so there is no doubt in the future. Also check the clutch fluid at the same time
and perhaps flush that while your hands are dirty.

Christopher Trace

Thanks for all the advice. I suctioned out the MC reservoir and got all the old fluid/crud out before adding purple DOT5. Vacuum-bled all brakes and saw small amounts of glycol coming out. [Vacuum dragging the lines is infinitely easier than the pump method!!] Apparently, the PO didn't do a complete bleed before. The clutch cylinders have glycol, which I refreshed with Castrol LMA. Will switch that over to DOT5 when either of the cylinders needs some work.

Thanks again!

Rick O.
Rick Orthen

I am thinking of getting a 74 TR6, and the one I am looking at has a slight leak near the MC.

Is DOT 3 bad for these systems? I am pretty sure that the current owner does not have silicon, the fluid color is a light amber.
Ignatius Rigor

Hi Ignatius. Where is the leak occurring? Sometimes, the fluid will just seep past the cap threads and make it look like the MC is leaking at the connections. Can't really offer a diagnosis until you pinpoint the leak. If you are not going to do a major hydraulic overhaul, I would at flush your system with new Castrol LMA ("low moisture activity") fluid after the leak is fixed. Based on my experience, you can't judge silicon strictly on color (see previous posts).

Look forward to hearing back from you.

Rick O.
Rick Orthen

Hi Ignatius
And I thought this subject had been beaten to death. First off, yes stay away from DOT 3. If u stay with DOT 4 use CASTROL LMA (Low Moisture Absobtion). DOT 3 will absorb more moisture that DOT 4. The best way to determine what is in the system seems to be Rick Os method ( 5 entries above this). Ignatius, consider that if u buy the car u will want to do work on the brake system anyway..just for your personal safety and piece of mind. After all, the car is pushing 30 years. First thing u want to do is flush the system...sorry do not know what to use even after I asked the experts. CAUTION: DOT 4 will eat paint!!! You can see from above that the consensis is to go to .5....consider it down the road.
The slight leak can be many things. You have not mentioned exactly where at the MC...loose brake line connection...bad seals in the MC...?? is there signs of fluid inside the car at brake pedel area?--rebuild of MC. Go for reduction in selling price because u will be putting money into the hydraulic SYSTEMS. What shape is the rest of the car?
Rick C
Ignatius, be so kind as to start a new thread please. These long threads are well just that..to long...it is kinda a leaky MC story.
Rick C
Rick Crawford

This thread was discussed between 14/02/2002 and 15/03/2002

Triumph TR6 index

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