Brake fluid

fordcragar

fordcragar

Senior Member
Not wanting to hijack another thread; which the OP was having issues on brakes not releasing. I've had some problems with my brakes on the coupe; which is using Dot 3 brake fluid. Jim Brierley mentioned that he uses Silicone fluid in his.

I replaced both front brake wheel cylinders last year, because they were corroded. I suppose that they will be fine for a few years.

Should I switch over to Silcone fluid? And if I were to switch, what would I have to do to the system? Completely go through the system and start over or do you just remove all of the old fluid and fill with silicone fluid?

BTW, this is a 31 Coupe with 40 Ford brakes on all four wheels.
 
I only use DOT 5 silicone brake fluid on any older cars that don't get driven much. I'd hone each wheel cylinder and master cylinder, blow out all the lines, then fill the system with silicone brake fluid.
 
Use a syringe or turkey baster and flush the lines with denatured alcohol and blow dry, it will remove moisture and contaminants.
 
Alot of hydraulic companies say not to use silicone in their systems. It tends to leak in a nonperfect situation. the other alternative could be to get stainless sleeves in the cylinders.
 
While not in any model A's but I have installed dot 5 in about a 1/2 dozen cars at least 2 of them have been done at least 6 years ago one I still have one I sold to a friend. Have not had any problems with the dot 5 however all vehicles I have done have been complete replacement of all brakes parts including lines hoses and cylinders. I have noticed that the dot 5 silicone is harder to bleed initially and have to make a few more passes on the bleeders to get a hard pedal. Another advantage is it does not eat paint.
 
I used DOT 5 when I totally replaced my system 15 years ago, and have had no problems. Prior to that, the old system using DOT 3 was totally frozen up and dried out after storage for 22 years.

I agree with others who urge you to be very diligent about scrupulously cleaning the old parts before switching to silicone.
 
older vettes with the 4 piston calipers were always a problem till we used stainless pistons and dot 5. a pressure bleeder works good on flushing the system out.
we use it on all old iron that sits
 
So what I'm hearing is to completely go through the brake system, replacing all the internal stuff in the wheel cylinder and master cylinder. While it is apart, flush all of the lines and reassemble.

My car was put together with a fruit jar master cylinder, so it would be a good to change that to duel cylinder as well.

My pickup has the same setup on it, so I'll have to do both. It gets a little annoying dealing with corroded brakes.
 
Silicone fluid can cause the rubber cups etc to swell. Rubber isn't compatable with silicone fluid thats why most companies that sell brake kits say not to use Dot 5 and using Dot 5 doesn't rule out getting water in the system, it just collects in the low spots.
 
Mitch//pa said:
older vettes with the 4 piston calipers were always a problem till we used stainless pistons and dot 5. a pressure bleeder works good on flushing the system out.
we use it on all old iron that sits
Click to expand...

I changed my 66 vette to dot 5 over 20 years ago. no more caliper problems.
 
While it is best to get all of the old fluid out of the system it is not critical. DOT 3 & 5 do not mix but they are compatible. I was working for LAPD in '82 and we converted all the new cars to DOT 5 before they went into service, we did not take any of the system apart, just power "bled" the system. Silicone fluid completely eliminated the need to change cylinders as they did at every 48,000 miles prior to that.
 
Jim Brierley said:
While it is best to get all of the old fluid out of the system it is not critical. DOT 3 & 5 do not mix but they are compatible. I was working for LAPD in '82 and we converted all the new cars to DOT 5 before they went into service, we did not take any of the system apart, just power "bled" the system. Silicone fluid completely eliminated the need to change cylinders as they did at every 48,000 miles prior to that.
Click to expand...

I concur! I have a jar of DOT5 I use just for flushing out DOT3. I reuse it whenever changing over another car. Then fill the system with fresh DOT5.
 
Interesting side bar on fluids. When you mix DOT 3 and 5 in a jar, the purple dye settles out of the Dot 5 and you end up with purple sediment in the bottom, a layer of clear silicone fluid on top and DOT 3 on in the middle!
 
Yea Jim, I noticed that after using the DOT5 for flushing out the DOT3, you end up with almost a colorless DOT5. Just pour the DOT5 off and back into the jar for the next time.
 
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