Question For Our C2 Brake Experts

[Patrick B.]

[Ronald L.]

Re: Question For Our C2 Brake Experts

I put the old VB product in a mid year for a couple years, thats the stuff I bought in 1980....then a decade later, with ss sleeved the originals, 2012-ish, the new fluid leaked after a year. By 2019 LS has warranty void for using dot5.


Could be quailty of the seals. Do not know.

I don't have the bottles from 1980 now, Good you did the study, what was the molecular composition of the Dow Corning Midland Mi product? And what does carquest 2020 label say?

Larry, Illinos is in the rustbelt Just like Missouri & Michigan, temperature impact to the car and even humidity are mitigated by being inside and in a bag.
I would love to see 100 in April ... really that extreme of temperature swing Oct-April?

What about your fuel? and your fuel system?

There is no sunload pressure or intense engine heat deteriorating the primitive plastics and rubber components.

What data do you have that suggests this is necessary?

[Larry E.]

Re: Question For Our C2 Brake Experts

ron: Thanks much for your interest/response. I'll answer your questions under them>

larry, illinos is in the rustbelt just like missouri & michigan, temperature impact to the car and even humidity are mitigated by being inside and in a bag.
Ron: Can't help where i live; so we can only live with the cards dealt. Bags are the only way i know of to store my cars. Have used them for many years with great results.(except for the brake fluid lately) which can be tolerated.

I would love to see 100 in april ... Really that extreme of temperature swing oct-april?
Start my storage towards the end of september/start of october. 100 degrees is not that unusual
and of course the winter will bring below 0 temp for sure at times. Humidity readings from mild to wild.
What about your fuel? And your fuel system?
Have cured that problem a long time ago; use nothing but "pure" 100ll av gas. Will not gum up for
a very very long time; cars run just like they where designed when made.

There is no sunload pressure or intense engine heat deteriorating the primitive plastics and rubber components.
There may be no deteriorating but there sure is shrinkage/expansion in the seals which cause
small leaks or vapor that can not be detected and then reabsorbed in the bags collection pots.
If you search(see thread#4) and bring up my original thread it explains how this it done.

What data do you have that suggests this is necessary?

my data is simple>this dissappeance of fluid only happens during storage; for the most part
everything returns to normal in the summer when car is used and pedal is pressed often.

Thanks ron

patrick: I wish someone would do a study on which type of seal has the less expansion/shrinkage
characteristic.jmho>larry

[Patrick B.]

[Larry E.]

Re: Question For Our C2 Brake Experts

Patrick: Have not found anything of any consequence. Since adding 70-80% of DOT#5 this Spring in
the Master Cylinder I have not had to add more and the brakes work fine. Also I might add when car is
taken out of the "Omni Bag" in the Spring(April) I find no evidence of a leak. eg.>No puddle/liquid on the
bag floor just the liquid in the three pots in the bag as we discussed. Should be interesting for the results
next Spring having the Brake system under light pressure for the entire 6 months. Thanks again>Larry

[Larry E.]

Re: Question For Our C2 Brake Experts

Hay Patrick: Just came up with a thought. If you care to do this? Get one of your EPDM o-rings.
Get a precise measurement of the diameter and then put it in your Kitchen Freezer for a couple of
days. Then take it out and measure it again. Let us know if any shrinkage occurred and if so how much?
Thinking this could be my problem. Larry

[Gary B.]

Re: Question For Our C2 Brake Experts



Based on my quick review via Google, other formulations of rubber (SBR, NBR, silicone, natural) have coefficients of thermal explanation that are comparable to or greater than that for EPDM. For car applications, I think the O-ring OD must be designed to accommodate a shrinkage of 0.5% from cold temperatures while still sealing. I doubt cars in North Dakota or Alaska leak brake fluid past the caliper O-rings during the winter.

Gary

[Larry E.]

Re: Question For Our C2 Brake Experts

Based on my quick review via Google, other formulations of rubber (SBR, NBR, silicone, natural) have coefficients of thermal explanation that are comparable to or greater than that for EPDM. For car applications, I think the O-ring OD must be designed to accommodate a shrinkage of 0.5% from cold temperatures while still sealing. I doubt cars in North Dakota or Alaska leak brake fluid past the caliper O-rings during the winter.

Gary

I doubt cars in North Dakota or Alaska leak brake fluid past the caliper O-rings during the winter.

Gary: I doubt if the cars you are talking about are stored for 6 months straight with a non pressurized brake system in a non-heated environment that
have temp range from 100+ to -10 degrees.Still like to see the "freezer experiment". JMHO>Larry

[Patrick B.]

Re: Question For Our C2 Brake Experts

Larry- I can certainly do that experiment. I would put the o-ring on a piston and measure the interference fit to the caliper bore diameter at room temp and after being in the freezer. I will go where my stuff is stored on Wednesday.

[Gary B.]

[Larry E.]

Re: Question For Our C2 Brake Experts

Thanks Patrick and Gary for the help. Maybe will get to the bottom of this yet. Larry

[Ronald L.]

Re: Question For Our C2 Brake Experts

Are we talking a car with GM design seals or these O-ring sleeved calipers?

Gary - thank you fpr bringing out the engineering, shrinkage needs to be calculated on a volumetric basis.

Guess what... back in the late 70s I was in the GM labs doing those exact tests on rubber and plastics ... unfortunately my personal focus was finding the original heater hose supplier and purchasing a special run of the original hose.

Larry, just FYI, my personal 66 sat in Missouri for 6 years in all the 100+ heat, humidity, and -20 deep freezes, and it does not leak.

Something else is up here.

[Larry E.]

Re: Question For Our C2 Brake Experts

Are we talking a car with GM design seals or these O-ring sleeved calipers?

Gary - thank you fpr bringing out the engineering, shrinkage needs to be calculated on a volumetric basis.

Guess what... back in the late 70s I was in the GM labs doing those exact tests on rubber and plastics ... unfortunately my personal focus was finding the original heater hose supplier and purchasing a special run of the original hose.

Larry, just FYI, my personal 66 sat in Missouri for 6 years in all the 100+ heat, humidity, and -20 deep freezes, and it does not leak.

Something else is up here.

Ronald; Also thanks for the help! Just curious>On your above car in Missouri was brake fluid DOT#3 or DOT#5? From
what I can gather the DOT#5 will cause more problems with what we are talking about then DOT#3.
CASE IN POINT>MY OTHER 66 CORVETTE (BASE ENGINE WITH MANUAL BRAKES) WITH DOT#3 WHICH IS
STORED IN THE SAME BUILDING/TYPE OF BAG) SAME TEMP RANGE > HAS SHOWN NO LOSS OF BRAKE FLUID
WHAT-SO-EVER. fyi>LARRY

[Ronald L.]

Re: Question For Our C2 Brake Experts

new DOT 5.

DOT 3 absorbs water, moisture from the environment. And over years degrades. Depending on where you are at in the world, that can be a lot faster than what we see in the USA.

[Mark F.]

Re: Question For Our C2 Brake Experts

I was a huge fan of “Click and Clack” and was surprised when Ray said one day that most rubber products exhibit opposite properties of most materials…it shrinks when hot and expands when cold. At the time they were talking about fan belt squeal…the hotter a belt gets the tighter (not looser) it fits…

Dunno if that applies to EPDM and other synthetics…

At least one website also states the same thing…
Interesting, eh ?

https://www.coirubber.com/can-rubber...20relationship.

Rubber experiences changes in properties from the temperature changes. This allows the rubber to become more elastic. Entropy and temperature are the two factors that play a critical role in whether the rubber will be stiff or flexible. If the rubber is presented in a high-temperature environment, then the long chains of polymer shorten cause the rubber to contract. While in a low-temperature environment, rubber can expand. Temperature and entropy are in a correlated relationship...