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Brake fluid quesiton

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TRclassic3

TRclassic3

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I know there has been discussion on this, and I could swear I remember one on just this subject but I couldn't locate. Here's the deal. While on a drive at the TRA meet (it was fantastic btw) I lost my clutch. We determined that the spring in the master had broken (geeez never heard of that before...yeah right). Almost unbelievalby fellow forum member Dr. John from the Soggy Bottom Triumph Research Lab had a brand new master with him. Apparantly the boffins insisted he take while packing for the trip. Anyway, we swapped out the master in the Ramada parking lot, but were then a bit stymied as we did not not what fluid the previous owner had used. We attempted to determine by look, feel, color or smell. None was conclusive. As a result we used a couple ounces of DOT4 in the bleeding process. So, the question is, now that I'm back home, what do I do? I could take the chance that it was 4 in it, but what if it was 5? What would be the potential result of adding a couple ounces of DOT 4 to DOT 5? Is a complete drain and refill the only option?

Thanks
 
I think the point is moot. There should not have been any repercussions in this short a period of time in having mixed fluids. For the relatively low price of a bottle of whatever fluid you prefer, a drain and refill is definitely worth it! For that matter, you might as well do the brakes, too, especially if you don't remember (or don't know) the last time that was done. More important with "traditional" fluid, which will take on water over time, but probably worth doing anyway.
 
The DOT 5 I have used was very purple. If it was DOT 5 it should be easy to tell.
 
AH HA....now that is kinda what I was expecting based on other synthetic or silicone fluids I've used in the past. The color of the fluid in it was rather clear...same as the dot 4 that was added.
 
Castrol GT LMA (Low Moisture Absorption) is your best bet in the 3. That's what I use in mine.

davidk is right, DOT5 is usually purple.
 
davidk said:
The DOT 5 I have used was very purple. If it was DOT 5 it should be easy to tell.
Click to expand...
Except that, over time, the purple dye tends to fade. Especially if there are any traces of DOT 3/4 left in the system.

I'm on Andy's side; I would do the drain & refill with the fluif of your choice, both clutch and brakes (since they share a common reservoir on a TR3).
 
The only thing I have to add, is that I switched over to Dot5. My master cylinder leaked at some point and it stripped all of the paint it touched.

So, I figured the Dot 5 would be cheap insurance against future leak/paint issues.

But like someone said above, the DOT 5 is very purple and it is not the same as "synthetic"
 
Ed,

When you rebuild/replace your brake and clutch cylinders, then that is the time to switch to Silicone(DOT5) fluid, if you want. But unless your system is failing, wait until it needs maintenance, or the winter, and drive the car now. We all know how hard you worked to get it going.

I run Castrol LMA because it's good stuff and because of the McLeod hydraulic throw-out bearing requires DOT3/4, so that's all I can run with the shared reservoir. Also I tend to change out the fluid at regular intervals, so the benefits of silicone are moot.
 
After it's been in there awhile it's not purple anymore and no longer has a grape flavor either.

But this got me thinking & experimenting.

If you make a couple of wicks out of a paper towel or such and wet the tips with brake fluid (one DOT4 & one DOT5) I think you'll find they burn differently.

Neither is particularly volatile but the DOT4 wick burns like an alcohol lamp, i.e. a flame but the paper isn't burning. With DOT5 there is a flame but the paper is burning right away.

Flame color is a bit different too but harder to describe.

PS - A thank you & farewell to Don Herbert -- TVs Mr Wizard -- for all he did to stimulate the scientific curiousity of my generation.
 
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