DOT 3 or DOT4 Brake Fliud

[YankeeTR]

When the early TR's were built (pre-67 or so) there were not ANY DOT spec for brake fluids...no DOT3 or DOT 4. So to argue that natural rubber parts need DOT 4 is incorrect as the early cars would have used a non-DOT fluid with great success (since the 1930's anyway).

The US DOT did not have any standards on this stuff until the late 60's....how did we ever manage to actually carry on with life before the government started telling us what is good for us?

 

[TR3driver]

The US DOT did not have any standards on this stuff until the late 60's....how did we ever manage to actually carry on with life before the government started telling us what is good for us?

True ... the DOT itself did not exist before 1966 so no DOT standards either.

The DOT brake fluid standards do not specify the composition of the fluid (except for DOT 5, which must be a minimum of 70% by weight of "a diorganic polysiloxane" but additives can be anything). Instead, they are performance standards. And they only test with SBR (styrene butadiene rubber) cups, not natural rubber.

So you are also quite right, it's not the "DOT-4-ness" of the fluid that indicates whether or not it is compatible with old British brake seals.

I guess before we had the DOT to tell us what's safe, we just had to believe the car maker ...

 

[TR3driver]

BUT not if you have previously used DOT 3 or 4, then you will run into problems.

I have done exactly this on several cars now, converted to DOT 5 by just filling the MC and bleeding until clean, purple fluid comes out. No problems at all with the old seals & hoses.

Did that to an 80 Chevy in about 1988 ... in 2003 the hydraulics were still working fine with the original seals at 3 corners & all original hoses, MC, etc. 23 years and an estimated 250,000 miles is pretty darn good !

Of course the old seals & hoses are still old seals & hoses; if there is any doubt about their condition then you should probably replace them anyway just to reduce future problems. But there is no reason to throw them away just because they've previously been used with DOT 3/4.

 

[dklawson]

I hadn't thought about the "birthdate" of DOT and the "standard" fluids we used on our car's brakes. What I do remember is all the Bentley manuals telling me to ONLY use Castrol LMA brake fluid in my LBC.

The point about the performance specs (not the composition)defining the fluids is correct. However, what appears to have happened is that to meet these standards, most fluid producers appear to have settled on comparable chemical systems for their brake fluids. This would be a happy-coincidence or... competitive analysis. Anyway, I'm glad that we have the DOT standards. In this case government isn't bad.

SIDEBAR:
Government standards and industry/society standards aren't automatically "bad" because they come from "the man". As an ME I'm aware that historically several standards were established by my professional society in an effort to improve public safety. An early example of this would be boiler codes implemented in the early days of steam power. A more modern example would be fire hoses. There was a time when each town might have had their own size and thread style hose couplings. Today, there are national standards and this allows a fire department from Anywhere, USA to help any other town in need during an emergency. If I remember correctly, a number of the U.S. codes were developed jointly with Canada to establish a nearly universal set of North American codes.

 

[TR3driver]

However, what appears to have happened is that to meet these standards, most fluid producers appear to have settled on comparable chemical systems for their brake fluids.

I don't doubt some of them are the same. Given all the incest in the automotive aftermarket, likely some different brands of brake fluid are actually made by the same people.

But I am absolutely convinced that, at least 30 years ago when I did my tests, there was a definite difference between Castrol and Wagner brake fluid. The Wagner would ruin the seals in my TR3A in a matter of weeks, but the Castrol didn't. Unfortunately I didn't record the exact variation of either one; but my previous experience had led me to believe that all 'American' fluids would attack British brake seals.

In this case government isn't bad.

I have to disagree, in this case. The presence of the DOT standards has obviously led people to believe that all DOT 4 brake fluids are the same, while they clearly are not all the same. This is not a Good Thing, especially for the older cars with single-circuit brakes.
(Although, even dual-circuit brakes don't solve everything. I had a total MC failure on my first Stag just a few weeks after buying it. Then the rear brakes overheated from using the handbrake ... good thing no one was coming !)

Government standards and industry/society standards aren't automatically "bad" because they come from "the man".

That much, I agree with. But I've worked with the government enough to know that there is a lot of truth to the old adage about an elephant being a mouse built to government specifications.

Today, there are national standards and this allows a fire department from Anywhere, USA to help any other town in need during an emergency.

I am definitely not against having standards. But I don't think they should be applied blindly, without understanding what they do, and don't, mean.

Having a standard doesn't mean it can be applied without thinking.

 

[svtmikey]

Sorry, I was out of town for while...
Yup..Point Roberts..the only place in the USA that you have to go into Canada to go into the USA. You're in Seattle?
I'm there quite often.

 

[AweMan]

A recent corrrespondence with apple hydrolics, at the end I ask about silicone brake fluid,

Lazar
Apple Hydraulics
https://applehydraulics.com
1610 Middle Road, Calverton NY 11933
800-882-7753, 631-369-9515 (voice)
631-369-9516 (fax)



> Sir
> I have a 1956 Triumph Tr-3. The master cylinder needs
> to be rebuilt {resleved}.

1956 is split year, critical commission number is TS13045:

- early master is clutch+brake combo master ($195 for
complete rebuild with brass sleeving, for stainless add $25),

- late master is separate aluminum brake master ($95
w/brass, $110 w/stainless, but note that Moss etc. sell new
for something like $99

> I want a complete unit ready to instal out of the box.
> I have a complete, not frozen, core and will send it
> to you. {It is missing the fill cap, is this a
> problem?

OK, I guess yours is early type (later type has remote
reservoir, so cap is not part of the cylinder).

New, plastic cap $6, good used original (metal) cap $10.

> My question is when I send the core to you, can I
> include my credit card info in the same container?
> can You make the apropriate charges to the card # and
> repair and return. OR is there another "Prefered" way
> you would rather use?
> P.S. I plan to ship the core U.P.S.

Ship with whatever shipper is convenient to you, they all
deliver here. If paying with Visa, Mastercard or Discover
either include card info with the parts or ask that we
contact you for it - card is run on the day of return shipping.

> Please respond with your prefrence on conducting this
> transaction.
> This car will be an occasional driver, {Not everyday
> by no means} and will deffinately be sitting idol
> during the winter months, 6 months out of the year
> here! and maybe driven once or at the most twice a
> month the other 6 months. Short distances at that!
> So your recomendations on brass or stainless sleeves
> Is fine by me. Not worried about the extra cost. Or
> frequency of needed rubber replacement.

brass requires same care as original cyls (brake fluid
change), stainless does not, but steel is more abrasive
(harder on rubbers), so seals go out faster (and that's why
steel is not used to make brake/clutch cylinders!). If you
will actually use the car, go with brass, if it is for
parades and not much more, go stainless

> One other thing, wondering about silicone brake fluid
> Yes or No. All brake lines and wheel cylinders clutch
> lines and slave are new {they have never had any type
> of fluid in them.}

Note that new parts and rebuild kits are tested and
compatible with fluids originally approved for the car and
that does NOT include silicone fluid (DOT 5). We do not
guarantee that our rebuilt parts will work with DOT 5.

 

[TR3driver]

We do not guarantee that our rebuilt parts will work with DOT 5.

That's true, they don't. And if they find you are running DOT 5, they will blame their problems on it.
But if everyone switched to DOT 5, Apple Hydraulics would be out of business. Could it be they have an ulterior motive ?

brass requires same care as original cyls (brake fluid change), stainless does not,

I strongly disagree with that. Regardless of what material your MC is sleeved with, DOT 3/4/5.1 brake fluid absorbs water, rots, and has to be replaced periodically.

Most people seem happy with Apple's work; generally it's high quality and works fine. But I have never heard of anyone who had a problem that Apple didn't try to blame on something else.

{It is missing the fill cap, is this a problem?

You probably know this, but JIC : The fill cap is small, maybe 3/4" diameter and screws onto the early cylinders. If you are missing the larger cap that is held to the MC by 4 or 5 bolts then you have a much larger problem.

Good luck with your brakes. I owned a 56 TR3 for awhile and hated those front drum brakes. Always pulled, and never the same way twice. The front discs were a huge improvement.

 

[alansimon]

Hi,

I own a Triumph TR6 that got slight use and changed over to purple DOT 5 silicone brake fluid. Twice, I experienced sticking of the brake master cylinder whereby application of the brakes left them applied after the brake pedal was released. The only way to continue driving was to quickly release the hydraulic pressure in the system by loosening the front master brake tube. I also spoke to Lazar at Apple Hydraulics who mentioned that the main seal in the master cylinder most probably expanded and jammed the piston in the cylinder bore and the piston was not able to return to the "rest" position. This hypothesis is hard to dispute based on my observations with two separate brake masters, one a fluid change over and the other using silicone from the start.

Has anyone else experienced this problem? If not, which brand of silicone brake fluid did you use or where did you buy it?

Thank you.

 

[TR3driver]

Has anyone else experienced this problem? If not, which brand of silicone brake fluid did you use or where did you buy it?

I've not had the problem, with DOT 5 from JCW, TSi, and TRF. Don't recall the JCW brand name, but it was GE fluid I got from Ted (a close-out I think, he sold it cheap on eBay); and the stuff from TRF says "North American Oil co".

Hmm, I take that back, I did have a clutch master once that wouldn't return all the way. But I was more inclined to blame the internal spring, since it came out in 4 pieces !
/bcforum/images/%%GRAEMLIN_URL%%/jester.gif

And of course, I've never bought from Apple Hydraulics either. I've heard that story before, which makes me wonder if it's not something about their rebuilt MCs ?

 

[angelfj1]

So is it possible to buy rebuild kits for the master, wheel cylinders , hoses, etc. that are proven to be absolutely compatible with Dot 5?

 

[TR3driver]

So is it possible to buy rebuild kits for the master, wheel cylinders , hoses, etc. that are proven to be absolutely compatible with Dot 5?

I guess that depends on what you consider "proof". The DOT 5 standard requires it to be compatible with "styrene and butadiene rubber (SBR), ethylene and propylene rubber (EPR), polychloroprene (CR) brake hose inner tube stock or natural rubber (NR)". And the penalties for labeling something "DOT 5" when it doesn't meet the standard are severe. All modern seals are made with SBR; while as Glenn points out, some original seals for our LBCs were natural rubber.

There are certainly lots of nay-sayers around, with Apple Hydraulics being a notable one. Girling has also said that they do not approve (although I bet they sing a different song to military customers that insist on DOT 5). Long lists of the horrible effects of using DOT 5; it apparently causes everything from acne to fallen arches. Oddly enough, it's been accused both of making seals swell too much, and not enough (a neat trick). It's too thin, it's too thick, it's too soft ...

But it works great for me, in all my Triumphs and over several hundred thousand miles of hard driving; including doing battle in LA traffic every working day, and driving mountain roads as fast as I can on weekends. I drove my TR3A 1000 miles to VTR 2000, won first in class in the autocross, and drove 1000 miles home. Did the same thing in the Stag in 2005; except it was over 2000 miles each way. Both had DOT 5 (and still do).

I have all the proof I need.

 

[vettedog72]

Well you know, those drum brakes can get pretty hot on the rear maybe even boiling, especially when you leave the hand brake on.

 

[Andrew Mace]

Well you know, those drum brakes can get pretty hot on the rear maybe even boiling, especially when you leave the hand brake on.

...and the fronts can get pretty hot during, say, a long downhill descent where you can't rely just on downshifting.... /bcforum/images/%%GRAEMLIN_URL%%/driving.gif

 

[TR3driver]

As far as Dot 4 having a higher boiling point than dot 3. That is not true.

Actually, it is true; at least as far as the DOT standards are concerned. The specifications for DOT 4 are identical to those for DOT 3; except for the higher boiling point required (both wet and dry), and the minor difference that DOT 4 is allowed to get thicker at -40C.

IOW, DOT 3 that meets the DOT 4 temperature requirements IS DOT 4.

However, as I said Dot 3 abosrbs water at a much higher rate than DOT 4.

Just curious, how do you know that ? Again, the DOT test is identical in this area. Castrol advertises that their DOT 4 has "low moisture activity", but doesn't tell us low compared to what. I'm quite certain it's NOT low compared to DOT 5. In fact, according to this article, https://www.bobbyarchermotorsports.com/pdf_2848_2.pdf, DOT 4 fluid absorbs water as fast or faster than DOT 3.

Let's face it, how many of us actually drive hard enough to boil brake fluid anyway.

That's one of those things that tends to be a "once in a lifetime" experience. So far, I've managed to avoid it; but I have on several occasions gotten the pads/shoes hot enough to fade into uselessness. And I have no intentions of finding out if glycol would boil before my new Kevlar pads fade or not.
Even if DOT 5 didn't have a higher boiling point, I'd still use it because it does not corrode brake system parts, nor eat paint, nor degrade with time. Not to mention that little detail about glycol sucking not only water, but road salt, right through soft brake lines.

 

[Geo Hahn]

Wow, we could rename this thread 'Groundhog Day'... I have the distinct feeling I've been here before.

There are Middle Eastern religions where the differences are less passionately felt.

Meanwhile, I'll continue to use DOT5 for the reasons often cited and ignore the anecdotal 'evidence' against it.

 

[69tr]

I don't know what fluid was used in my car before I bought it. I have replaced the rear wheel cylinders, clutch slave cylinder and rebuilt the brake master cylinder. I figure that the other components have been changed in the past.

All this said, I figure that DOT 4 fluid will do very well for my driving style. My problem is that I am getting the car painted and am worried about brake fluid leaking and ruining the paint in the engine bay. This happened before and the results were not pretty.

Any suggestions other than replacing the complete system and using DOT 5?

Thanks, Pete

 

[TR3driver]

Don't replace the entire system, just fill the MC with DOT 5 and bleed at each bleed valve until you get clean, purple fluid.

DOT 5 is absolutely harmless to paint; in fact the same silicone is used in many paint care products. Do be warned however that it takes a special solvent to fully remove all traces of DOT 5 before painting. If you don't use the solvent, odds are very good that you will get "fish eyes" in the new paint. I use "Arcyli-Clean" (from PPG I think), but there are others that work just as well. It's recommended to use one of them even if you don't use DOT 5, since the silicone in other car care products can cause the same problem.

"Try it, you'll like it."

BTW, TRF is about the cheapest source of DOT 5 that I've found.

 

[Aldwyn]

You can also use a synthetic DOT 3/4... I have Valvoline SynPower Brake Fluid in my TR6. And it will mox just fine with conventional DOT 3/4 fluids so you dont have to do a full flush.

My brake master is currently leaking, and no paint issues! (but you can see where the conventional brake fluid has splattered!)

 

[TR3driver]

My brake master is currently leaking, and no paint issues! (but you can see where the conventional brake fluid has splattered!)

Interesting. I'd always understood that 'synthetic' DOT 3/4 was still glycol ... in effect all glycol is synthetic so it's just a marketing ploy. Eg,
https://adlersantiqueautos.com/articles/brake2.html

Also seems that, if it really won't harm paint, Valvoline would mention that in their advertising. But they don't.