MG Midget Forum

Hi guys. I'm looking for some input on the pros and cons of using DOT 5 brake fluid in my '61 Midget. I had read prior to replacing the old slave and master cylinders in said car, that the DOT 3 and 4 were susceptible to absorbing water and corroding the hydraulic lines over a short time frame. Like one to two years. Also, that the DOT 5 didn't absorb water and provided a longer life to the lines and fluid. So, armed with this new information, I purged my old system of the slave and master cylinders and flushed the lines till all the fluid ran purple, (DOT 5). I'd like to know your opinions on this issue. Did I screw up or not?

Opinions are all over the place with this one. DOT 5's big advantage is het tolerance, we generally don't have to worry about heat. As long as you purged the system of al remains of 3, 4 however I don't have an issue with using it.

DOT 5 can seep a bit but doesn't bother finishes.
One works about as well as another in most cases.

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Iceman

Atlanta GA

71 MG Midget

62 AH MKII
67 Midget
71 Midget

AGAIN: What is that, eight times this week ??????

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IN ALL SUBJECTS.: For those who believe, no proof is needed. For those who don’t believe, no proof is possible.

"Strive for perfection in everything. Take the best that exists and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough"
Sir Henry Royce
co-founder of Rolls-Royce .

"I take no credit for my own, of another man's fame".
Joe Baba 2021

Had dot 5 in my MGB for over 10 years with no issues, my late father in law did the change. So dont worry about the doom mongers DOT5 is ok.

Personally I dont think dot 5 is worth it. You'll most likely never see any difference. Has an automotive technican I never suggested changing fluids. Mainly because there was debate if dot 5 would destroy seals in abs systems that use dot3. That and not getting the system completely clean before hand could make a nasty mess later. But my dad uses it in his VW and has never had a problem so.

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If you never try to do it You will never be able to do it

I used it in my 72 MGB when it first came out in the seventies. Car was only a few years old and needed a brake rebuild. A friend now owns that car and I don't believe he has ever even bled the system. Has rebuilt the master a couple of years ago though. Car is pushing 200K.

I have used it in other LBC's since with mixed results. Seeping from calipers till they are thoroughly worn in I have experienced and also think that since it has a higher viscosity it seems like the brakes might be a little slower. Perhaps my imagination. Doesn't ruin paint though and I am planning on putting it in my current rebuild Mk3 Sprite.

Kurt.

I used it in my Midget after my second restoration (had this car for many, many years), based on driving a friend's Bug eye with it, and realizing the brake feel was really no different than with dinosaur oil.

For me, the two big reasons for using it were: cars that sit a lot (and even classic cars used as daily drivers often end up suddenly sitting for a few months at a time, due to winter road salt and family things), the rear wheel cylinders can easily develop a leak during those down times. Mine ruined all of the paint on that wheel by the time I'd noticed it. The second reason was a full body repaint during this restoration. During reassembly I had two brake fluid leaks (one was a dumb mistake by me leaving one fitting loose by accident, the other was a PDWA leak that occurred a year later), both would have been catastrophic (!) with regular brake fluid, paint wise, and "newly restored bodywork and all new paint" wise. Instead, they were only minor clean up incidents, thanks to silicone.

One thing to note with Si fluid: moisture can still get in the system (it has to breathe to deal with expansion from heat during use, so it can draw in humid air during cool down each time). As it turns out, water is denser so it will settle at the lowest point. So, it is still a good idea to bleed a bit at each corner every two years, just to expel any moisture that got in.


The only other caveat is that air bubbles don't settle out quickly so take care when pouring in new, to not get any bubbles in it, and to leave it sit for 24hrs to let any bubbles settle as much as they can before bleeding.

N

I wouldn't do it just because of what is said about DOT 3 or 4. It isn't worth all the hassle of removing and replacing and bleeding, etc. But since you have already done it I think you are all good. You did NOT screw up.

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Jere McSparran
JMAC Engine Shop
Website: http://www.jmacengineshop.com
email: jmacengineshop@gmail.com
Phone: 217-232-7303

Here is a good article on this subject. Personally I won't allow silicone of any type in my garage because of what it does when painting. Don't like fisheyes.

http://www.mossmotors.com/SiteGraphics/Pages/Brake_Fluid/page4.html

That's interesting, Rick. I had heard about dot 5 being "compressible" and really couldn't buy into the fact that a fluid could be compressible. Personal experience might make me agree on that now. I do remember when taking advice from Moss that they are interested mainly in selling you something though!

Kurt.

I have a completely new hydraulic system on my restored Bugeye and bought dot5 since it doesn't eat paint, but I didn't consider the problems it causes with painting. I'm building a new shop and the last thing I want is paint contamination on my future projects. I've only done small paint jobs in the past, but I have a few cars that I want to learn how to paint and I'm not going to take a chance. Thanks for the heads up!
Rut

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1960 Bugeye,1275, 5 speed
1970 MGB, Pale Primrose
1967 Triumph TR4a
1966 Triumph TR4a
When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon

Can Silicone brake fluid be used in the clutch??
I "THINK" I read that silicone fluid should not be used in the clutch hydraulics -- I think I read this!
ANyone encounter this advisory?

It might be because of the retained air in the Silicone? Or its greater compressibility??

Chuck: Look at my JOURNAL POSTS> Just put it up this afternoon. I would not use anything else. Make your own Decision

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IN ALL SUBJECTS.: For those who believe, no proof is needed. For those who don’t believe, no proof is possible.

"Strive for perfection in everything. Take the best that exists and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough"
Sir Henry Royce
co-founder of Rolls-Royce .

"I take no credit for my own, of another man's fame".
Joe Baba 2021

yeah, I use Dot 5 in my clutch too, even after I read some thoughts that there would be some trouble because of the length of the stroke, but it works fine, just like in everything else