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Brake Fluids?

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Bret

Bret

Yoda
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Ok I admit it - I’m confused.

Brake fluid specifications:
Haynes says – Hydraulic fluid to SAE J1703, yada, yada, yada.
Bentley says – Lockheed Universal brake fluid (series 329S) or Castrol Girling Brake Fluid: Alternatively use brake fluid conforming to DOT-3. Blah, Blah, Blah…

While:
Moss & Victoria British catalogs lists three different types:
Lockheed(DOT-4), Castrol(DOT-4) and Silicone(DOT-5).

Sense, I have now way of knowing for sure what I actually have in my 78B’s master cylinder, I am just going to assume that I will have to flush the system. The question is what type of fluid should I go with?

I just want to be able to go a round the corner to pick-up brake fluid without getting a headache every time.

I’m thinking of going with an over the counter DOT-4? What do you guys think?

FYI – the brakes are fine & just doing a break job and decided to replace the standard brake lines with stainless.
cheers.gif


[ 01-23-2004: Message edited by: Bret ]</p>
 
castrol lma, it seems to work better with the English rubber and you can get it at Pep Boys and other local parts stores
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Bret:
I just want to be able to go a round the corner to pick-up brake fluid without getting a headache every time.

I’m thinking of going with an over the counter DOT-4? What do you guys think?
<hr></blockquote>

I've been using Castrol LMA because everyone swears by it...on the other hand I'm not so sure it isn't just Castrol's branded DOT-4 fluid, nor am I so sure the "LMA" actually absorbs appreciably more moisture than other DOT-4 fluids.

On the other hand, how often do you have to go around the corner to get brake fluid? If you switch to DOT-5 (yes, there's a fairly hefty debate on DOT-5, it's worth reading up on) the chances are you won't have to worry about flushing it as often due to moisture (it won't absorb moisture like 3/4 at all), nor will you have to worry about buying only a fresh bottle and not storing it (DOT3 and 4 do absorb moisture and you can't really store an unsealed bottle of it, supposedly you can buy a bottle of DOT5 and store it indefinately). If you happen to get a leak, or spill it, you won't have to worry about the fluid eating your paint. It's also very good (supposedly) at preserving the rubber rather than deteriorating it.

Some people make the claim that DOT5 doesn't work very well, it causes a spongy brake, it's very hard to bleed, etc. Other people say that's mostly nonsense and they haven't had any trouble. I've talked to a lot of people on both sides of the fence, so I guess you take your chances.

I want to rebuild my brake system this year and in the process want to switch to DOT5 purely because of the paint-friendly aspects of it.

[ 01-23-2004: Message edited by: aerog ]</p>
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by aerog:


<snip>

Some people make the claim that DOT5 doesn't work very well, it causes a spongy brake, it's very hard to bleed, etc. <hr></blockquote>

I once flushed the system on my EType and replaced with DOT-5 and my experience was t hat it was impossible to get the brake not to fill kind of spongy.

Basil
 
I am doing the same change of brake lines (and some suspension work, if my recent elbow surgery heals quickly) and have looked at so many negative comments about DOT5 that I a convinced to go with the DOT4 ...but I am following this tread closely and trying tokeep and open mind.

So what do the 2700 members of this Forum think???

Bruce
confused.gif


PS...I wonder how the brake fluid would do as a cleaner for the paint overspray that I have all over my engine compartment and suspension? Will it harm the wiring and non-metalic components?
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Kim de B:
Bret -- Did you see your X-ray B article in the latest MGB Driver? Photos look great!<hr></blockquote>

Hey Kim,

No I missed it – stupid bone head that I am, I let life get in the way and let my membership lapse. Currently in the process of renewing and looking to see if I can get some back copies of the November/December issue. But the guy’s email who handles back copies of the MGB Driver came back as not deliverable. I’ll keep trying.

Thanks,
Bret
 
Here's an experiment. I haven't actually tried it so it's probably safest to assume I'm an idiot and don't know what the heck I'm talking about but I think it ought to work.

Take a small sample of your fluid, put it in a clear glass container (a test tube or small vial would be ideal) and add some water. If the fluid mixes with the water it's glycol based (DOT 3 or 4). If not it's silicone (DOT 5).

If it's glycol based it's safe to just top off or bleed with any other glycol fluid. As Chuck points out Castrol LMA performs well, is reasonably priced, readily available and generally compatible with British seal materials.

Ford Heavy Duty Brake Fluid is an old racers' "secret". Ford created it way back when to solve problems with fluid boiling in certain big-@$$ Lincolns. Then they decided it was cheaper to put high performance fluid in everything than maintain inventory of two different fluids. It's cheap and available at any Ford dealer.


PC.
hammer.gif
 
3 and 4 will mix fine because they're both glycol based. You'll sort of get something in between the two depending on the mix ratio.

Old DOT-4 fluid that has absorbed water will be operating below DOT-3 specs and causing corrosion anyway so it's a good idea to bleed the system and replace glycol fluids once in a while.


PC.

[ 01-23-2004: Message edited by: PC ]</p>
 
Aloha All,

I'm sure George is correct, there will never be consensus on the silicone vs glycol based brake fluid debate. I have converted and used DOT 5 (silicone) brake fluid in three LBCs, MGTF (about '85) and 2 TR3As ('95 and '99). The conversions were always after a rebuild of all master cylinders, wheel cylinders or calipers and clutch slave cylinder. I have not experienced a spongy feeling brake pedal,dissolver or swollen "rubber" components. Gravity bleeding or using a mini-vac to draw the fluid through the lines worked for me, but it does take a few hours to purge air from the hydraulics.

DOT 4 fluid is not as moisture absorbent as DOT 3, however it does occur and moisture absorption does reduce the boiling point of the fluid. This is a another reason to periodically flush and replace DOT 3 or 4. There is a new brake fluid on the market with a DOT5.1 specification which is also a glycol based fluid. It is not compatible with silicone based fluid, but I'm sure it will add more to the debate.

Glycol based fluids are clear when new and tend to become amber with absorption of water. Silicone fluid is died purple but may lose the color over time. This may help you identify what type you have.

I am pleased with silicone and think it has many merits that out weight the other brake fluid specifications. It is generally not recommended for racing applications (lower boil point the DOT 3 0r 4) and cars with ABS systems.

Safety Fast,
Dave
 
I just converted my 3rd LBC to silicone DOT 5 brake fluid.
I did my Austin A40 in 1997 and have not had any hydraulic problems since.
Last year I converted my Sprite.
Last week I converted my other Sprite.
Meanwhile my wife's sprite with Castrol DOT 4 needs a wheel cylinder or master rebuild or some hydraulic work at least once a year.

I am sticking with Silicone. No more paint problems, no moisture absorbsion which causes pitting of the cylinders when not used much, and the pedal feels just fine.
I agree with the s l o w bleeding process and I have notice that silicone eats pressure operated brake light switches but overall, I feel it is better.
 
Any time I do a complete brake job, I go to 5 because of the paint/ water absorbency issues. I have successfully done the change on a fairly new M/c with only new rear cylinders. No problems.
Bleeding does take a couple of days, but then you're home free.
As for mixing with unknown 3 or 4, there is another option; 5.1.
It mixes with either 3 or 4, so any car that I don't know the history on gets that. It does take paint, does draw water.
3 will eat out natural rubber brake parts, which is why years ago only 4 was used in English cars.
 
Hmmm? That's good to know for the next time I think I might need to top off my brake reservoir. But because I don't know when the last time my brake system was flushed - I'm going to go ahead and do it this time after I replace the stainless steel brake lines and upgrade the pads & rotors.

cheers.gif
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Bruce74B:
...have looked at so many negative comments about DOT5 that I a convinced to go with the DOT4 ...but I am following this tread closely and trying tokeep and open mind.

So what do the 2700 members of this Forum think???
<hr></blockquote>

Using DOT5 in both cars -- mainly to safeguard the paint. Brakes are fine & firm. I think one problem area may be that air bubbles stay suspended in DOT5 a looooong time. Pouring very carefully (e.g. down the clean blade of a screwdriver) may minimize bubbles -- also waiting a few days between topping off the reservoir and bleeding may help.

Certainly not as cheap and not as easy as DOT3/4.

I doubt there'll ever be consensus on this, just one of those things each must decide for themself.
 
DOT 5 user and have buddy who has had DOT 5 in his Mini Minor for over 10 years with no problems...in Florida where there is a huge amount of moisture. Haven't noticed sponginess but would put up with a little bit of it just for the saved maintenance and longevity of brake and clutch system parts. I have replaced flexible hoses in my brake system which helps, I think. Love the fact that if I spill fluid it doesn't hurt anything.
 
I use Castrol that is easy to get at Pep Boys.

I don't think there is anything that special about the silicone fluid.
I used it for a couple of years, not worth the trouble. It still has to be changed out periodically, like the Castrol. On my B, I noticed globules of water suspended in the Master cyl. while using it.

How often do you spill fluid on the paint ?
(it doesn't remove paint instantaneously!)
rolleyes.gif
 
I just flushed my 78B’s entire brake system with DOT-3 last weekend sense I had no idea what it was. As stated in my other post (MGB Brakes) the old fluid appeared to be very contaminated because it had a dark caramel or golden brown color. As I purged the system using the normal bleeding procedure it is now almost completely clear as if it came out of the bottle.

As I’ve already stated - while I do plan on replacing the stock units with cross drilled rotors and some upgraded Semi-metallic performance pads, I am very impressed with the stock Brakes when they are set-up & adjusted properly.
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Bret:
... the old fluid appeared to be very contaminated because it had a dark caramel or golden brown color....<hr></blockquote>

That's not too bad. I've often seen fluid come out black.


PC.
hammer.gif
 
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