[S10xGN]

Hi All,

I finally got to make my "maiden voyage" in my '72 Maverick project, encountering a few minor problems. My main concern is the brakes (manual disc/drum setup). The pedal is firm, but goes to the floor. I bench-bled the M/C initally when I started the system using silicone fluid. After fixing the leaks, I switched over to DOT #4 fluid. I drained as much silicone as possible, I then flushed the system with methanol, then added the DOT #4 and bled everything until I got the DOT #4 at all wheel cylinders.

Would pressure bleeding help? Is that something I can do at the house? What's the max pressure I should put on the M/C?

TIA!

Russ

[T-bucket23]

Explain firm but goes to the floor, that is contradictory.

[carsavvycook]

I am thinking you have done some damage to the rubber seals, and brake hoses. These were designed to use DOT3 brake fluid only.

The only other thought I have, is, there is still some air in the system to be bled out.

The only way to tell if the rubber has been effected, is to take the master cylinder apart, and look at the rubber seals for swelling. I would start here, then check the rest of the system.

[S10xGN]

I should have posed this as a question: Will a pressure bleeder adequately bleed the M/C as well as the rest of the system?

Russ

Originally Posted by T-bucket23

Explain firm but goes to the floor, that is contradictory.

Sorry, it's a manual brake system, thus the pedal is firm. It stops, but goes to the floor. If it was "boosted", it prolly wouldn't be firm?

Originally Posted by T-carsavvycook

I am thinking you have done some damage to the rubber seals, and brake hoses. These were designed to use DOT3 brake fluid only.

The only other thought I have, is, there is still some air in the system to be bled out.

The only way to tell if the rubber has been effected, is to take the master cylinder apart, and look at the rubber seals for swelling. I would start here, then check the rest of the system.

The silicone fluid was in there just long enough to check for leaks, maybe a week total. Would this (really?) be an issue?

[carsavvycook]

"The silicone fluid was in there just long enough to check for leaks, maybe a week total. Would this (really?) be an issue?"

I have seen it several times, that I remember, over the years. I always ask what brake fluid was added, when a vehicle get's towed in for brakes, with no pedal, and the master cylinder reservoir is full.

I have found swelled, and 'soft' seals, or shrunk, and 'split' seals.

I have never done a comparison test, and all I have is DOT4 fluid here right now, with no wheel cylinder cups.

Dot4 fluid should be fine, when used with DOT3 parts. It is the Silicone fluid, I have seen used, that will attack the rubber that is not made for silicone fluid usage. How long it takes, I do not know.

The use of Methanol to flush a brake system, I have never heard of. How it would effect the rubber would be very interesting to find out.

I will try to acquire some seal-able glass jars, and some Silicone Brake fluid, and some Methanol, and some wheel cylinder cups early next week. I will then post the results of my findings.

[ericnova72]

I think the Methanol was the problem, just like it is in fuel hoses that aren't compatible with alchohol fuels. This has especially come to light with the recent push of E-85 fuel. All the fuel hoses, seals, needle and seat tips etc have to be compatible with alchohol or they will swell.

[carsavvycook]

Originally Posted by ericnova72

I think the Methanol was the problem, just like it is in fuel hoses that aren't compatible with alchohol fuels. This has especially come to light with the recent push of E-85 fuel. All the fuel hoses, seals, needle and seat tips etc have to be compatible with alchohol or they will swell.

I agree! My tests should prove it.

[S10xGN]

Originally Posted by ericnova72

I think the Methanol was the problem, just like it is in fuel hoses that aren't compatible with alchohol fuels. This has especially come to light with the recent push of E-85 fuel. All the fuel hoses, seals, needle and seat tips etc have to be compatible with alchohol or they will swell.

Might be the case *if* the meth was in there longer than the length of time it took to flow clear, maybe 10 minutes. I just can't see it guys, sorry... Eric, I appreciate your time in testing, hope it's not the issue (at least in my timeframe).

Russ

[S10xGN]

Fixed!

I'm pretty sure most of the pedal problem was due to the rear brakes not being fully adjusted. Originally I had run the car (on jackstands) at idle in reverse and tapped the brakes a few times. This time, I ran it up to 2500 in reverse and slammed the brakes about 20 times. I also built a pressure bleeding adaptor for my M/C, put 30# air pressure on it, and rebled the brakes but that didn't really change anything...

Russ

[scrot]

Methanol .
Where did you get that from?
Do you mean methanol racing fuel in the brake system?

I will try to acquire some seal-able glass jars, and some Silicone Brake fluid, and some Methanol, and some wheel cylinder cups early next week. I will then post the results of my findings

carsavvycook, I'll be looking forward to that test.
I love that kind of **** (tests).

[carsavvycook]

Originally Posted by scrot

Methanol .
Where did you get that from?
Do you mean methanol racing fuel in the brake system?



carsavvycook, I'll be looking forward to that test.
I love that kind of **** (tests).

I have not been able to find any sources to get any yet.

I really wish I could. I want to know the effect it has on the rubber parts in brake systems.

The only source I have now, is nitro methane.

[Torque454]

Originally Posted by carsavvycook

I have not been able to find any sources to get any yet.

I really wish I could. I want to know the effect it has on the rubber parts in brake systems.

The only source I have now, is nitro methane.

Methanol is used for BioDiesel production. I am in the process of getting the stuff around to make biodiesel. I have been told on many ocassions that the YELLOW bottles of "HEET" gas line antifreeze are methanol and can thus be used for small "test batches" of biodiesel. So maybe a yellow bottle of heet will work for your test?

[GrumpyOldMan0_0]

Silicone-based brake fluids are regarded as DOT 5 brake fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

[powerrodsmike]

Silicone fluid by itself it not noticeably compressable, but it does aerate and all the little bubbles are compressable.

Using silicone fluid in a brake system then running dot 4 afterwards usually will swell the seals, but I have heard that flushing with denatured alcohol usually will keep the seals from swelling...Methanol is alcohol. I never chanced it myself, being as I have had too many cars in my shop that needed every rubber part replaced after a switch from dot 5 to dot 3 or 4. I never did a study on how long it took for the silicone to permeate the seals enough that a switch down to dot4 would swell them up.

A quick test is to take a new cup seal and push it against a suspect seal...the seals should compress equally..if one seal is noticably softer than the other..it's trash.

Later, mikey