Need help very bad brake problem

[OpelWagenGT]

So I recently replaced the brake master cylinder because the one that I bought just back in August failed due to one of the seals. That MC was not covered under warranty so I bought a different one. I have had it on there maybe a month or two now and have started to have a serious problem with it. Here is the problem: I start out driving in the morning and the brakes are great everything is normal. Once I drive a mile or two and the car warms up the brakes start to stiffen, as the pedal doesn't move as far and it feels stiffer. If I drive even longer the pedal eventually won't really move at all and the brakes are dragging but only in the front. What this leads to is when I stop and the pedal feels like this smoke pours out from under BOTH of my front fenders. This leads me to believe that it has nothing to do with my calipers as I replaced them back in August also. The only thing I can think of to do is whenever I stop I crack the bleeders on the calipers and a little bit of fluid comes out. This releases the pressure until I drive for a while again. I replaced the entire brake system when I fixed up the car and decided to use DOT 5 silicone brake fluid. When I looked it up some people said that silicone could possibly expand from heat but said that it really wouldn't make a difference. At this point I am at a loss and can't pay to take my car to a mechanic. I really need help specially because this car is my daily and I can't drive it like this. So, if anyone has any ideas what could be wrong please let me know.

thanks,

Aron Chaudiere

[banzai510(hainz)]

put dot 3 in there.

 

Im not a brake expert but try the dot 3 stuff first.

 

Since you put both new calipers on there I wouldnt think it was this.

 

Is there a proportioning valve or something?

 

 

I had this happen to my Jeep Cherokee. brakes were fine

changed the pads then the brakes locked up and got hot. I had to change both calipers. I dont know why just by putting new pads back in there and sqeezing the caliper back ,made them get stuck when I hit the brake. Figure that one out.

My 510 I never have changed the calipers and just replace the pads and had car over 22years. No proplems.

 

Guess you could try to see when its stuck try to pull the caliper off and see if the piston is stickey

 

maybe the MC ??? Howw fast are you at swapping parts???????

[Logical1]

I agree with Hainz, Bleed those babies dry and flush with dot 3, then bleed and re-fill. I know you can use dot 5 in datsuns but dot 3 has never treated me wrong :) If they are starting to drag once the car warms up then its a obvious fluid expansion issue. Do you have a brake booster? could this possibly be a crazy over-vacuum on the booster malfunction? I have never had a booster and like it that way ;) The less vacuum hoses, the better!

[datzenmike]

Your pedal free play is not adjusted properly. The pedal should have about 1/8" of travel before the push rod contacts the piston inside the master cylinder. Without this play, the piston does not fully return and release all the fluid under pressure back into the reservoir. Each brake application will add to the pressure until the fronts are locked on.

 

If the free play is good then there is something preventing the pressure from venting.

 

 

I see you have a brake booster. Same thing applies. Not enough play and it's like you are resting your foot on the pedal. The booster just transfers the motion to the master.

[banzai510(hainz)]

The pedal should have about 1/8" of travel before the push rod contacts

 

 

kinda assumed he did this already. As for the Dot5 I would really only be guessing.

[MikeRL411]

Did you do a complete, repeat complete, system flush before you used the Silicone DOT5? [DOT5 being silicone based is a compressible brake fluid [improbable as that sounds] and tends to feel mushy in use.] If not, you have contaminated fluid. As to the suggestion to "reload" with DOT3, you will need a complete system flush before the brakes can be refilled. Why not go Castrol DOT4? Designed for disc brakes and fully compatible with DOT3 plus higher boiling point, so no brake seizure when the fluid gets hot. I have been using DOT4 in my RL411 for 42 years and have never had a problem with it.

[OpelWagenGT]

Hi thanks for you help here is the situation

 

it is a 1200 coupe so no it does not have a brake booster

 

I used silicone because it does not retain moisture and therefore rust things

 

also as I said the entire brake system give or take two small short lines was replace and I did flush for a long time with new DOT 5 fluid

 

I will check on the pedal adjustment maybe it needed to be adjusted differently for the new MC that I have

[thisismatt]

This problem comes up all the time, and more often than not it's because the push rod is adjusted too tight into the MC. There needs to be a little bit of play. DOT 5 fluid is a bad choice for a non-race car for a few reasons. Regular fluid gets dark and darker the more it absorbs water, giving you a good indication of when the fluid needs changing. You're right, silicon fluid does not absorb water, and thus doesn't change color, but it also isn't as dense as water. This leads to the water going to the lowest points in the braking system, which are your calipers. Here the water collects causing corrosion and lowering the boiling point of the fluid at your calipers (so why put in DOT 5 fluid in the first place...oh yeah, protect your engine bay paint). Plus, it can damage seals that weren't designed for it. If DOT 5 was better there would probably be some regulation requiring automobile manufacturers to use it.

[datzenmike]

Thanks Matt. I just bought some DOT 4 synthetic for my 710 flush. I will re-think and research this now.

[datzenmike]

[DOT5 being silicone based is a compressible brake fluid [improbable as that sounds] and tends to feel mushy in use.]

 

My research indicates that synthetic has a different viscosity so the mushy pedal may be just sluggish fluid?

[fisch]

Not that I have much to add. But I've been reading about fluid this week for the '59. The brake parts are so old, I read that DOT 3 is not a good idea. It will eat the rubber, especially if it still has the old rubber. (I have DOT 3 in the 521 and it seems fine, but it isn't that old.) Concourse type dudes seem to go with Dot 5. But most folks I read about seem to go with DOT 4 for cars like the '59.

 

And I also read that DOT 5 is spongy.

 

I chose DOT 4 from NAPA.

[datzenmike]

Looks like the DOT 4 I have is compatible so will use it. It is a synthetic blend. DOT 5 is total synthetic and best in a clean new system. DOT 5.1 is compatible with everything but DOT 5.

[OpelWagenGT]

This problem comes up all the time, and more often than not it's because the push rod is adjusted too tight into the MC. There needs to be a little bit of play. DOT 5 fluid is a bad choice for a non-race car for a few reasons. Regular fluid gets dark and darker the more it absorbs water, giving you a good indication of when the fluid needs changing. You're right, silicon fluid does not absorb water, and thus doesn't change color, but it also isn't as dense as water. This leads to the water going to the lowest points in the braking system, which are your calipers. Here the water collects causing corrosion and lowering the boiling point of the fluid at your calipers (so why put in DOT 5 fluid in the first place...oh yeah, protect your engine bay paint). Plus, it can damage seals that weren't designed for it. If DOT 5 was better there would probably be some regulation requiring automobile manufacturers to use it.

 

I'm going to try adjusting the pedal becuase that seems to be the most likley problem I just didn't think about that.

 

on the other hand when I researched it I found very different explainations that what you are telling me. Almost everything that I read said that DOT 5 silicone brake fluid is almost always compatible with regular brake parts except in some very rare cases. I did read about water settling in the system but this is assuming that there is a way for water to get in (remember this is an all new brake system). Also the readings I did were talking about the only reason that DOT 3 exists is because it is the minimum requirement allowed in terms of its boiling point. Most of the sources said, "just because you can buy the cheapest minimum requirement fluid, doesn't mean you should". As far as automobile manufacturers go if you read about it you would see that Silicone fluid is not to ever be used with an ABS system becuase of its high boiling point it does not work. And lastly why would you expect the car manufacteres to want to use anything that is more expensive because it is better, they are the reason that the "minimum requirement" is there.

 

With enough said, I am pretty posative at this point that my fluid is not the problem given that the whole brake system workd fine for a good 6 months and then when I had to replace the defective MC problems started to arise.

 

Thank you guys for all your help none the less, and I honestly don't notice a difference with a mushy pedal or anything like that, but that is just me.

[datsunaholic]

DOT 5 isn't synthetic, it's silicon based.

 

What it's good for is very high temperature applications (like racecars) and boat trailers (with surge brakes) because they get submerged. Military also uses it- I have 2 ex-Military trucks so that's what they have in them. EXPENSIVE.

 

My Grandfather switched to it in his old '79 LTD, which made it a bit of a hassle when I had it, but didn't have it long.

[Eastcoast521]

Maybe a dumb question but are you sure the MC is the correct one for your car? Sounds like there is some sort of check valve or residual pressure valve that shouldn't be there.

[OpelWagenGT]

When I ordered the MC, it said it was for my car and it was the only place tht had one in stock.