Repair leaking proportioning valve

[ecogabriel]

I have been curious to take apart a proportioning brake valve to check what is in there and -most importantly - why they do start leaking even when they are working OK. I got the prop. brake valve in both my 3G and my 5G civic leaking slowly from the mid-section where they are joined together. I got jy replacement units but after a while they too start leaking.

Too bad because new ones are expensive and there is nothing wrong with the old ones except for the slow leaking.

Finally, I got a set of security bits and decided to take one apart. I found the one for my 5G Civic first so that is the one I took apart. I had thought it should have been an an o-ring sealing both halves. Just take a look at what I found (sorry for the quality it is a phone photo)



I got some measures after removing the o-ring. BTW, it is completely flattened
The outer diameter of the groove is about 26.6mm; inner diameter is about 21.5mm. Depth is 1.4mm.
I bet the most likely ring size is 22mm ID x 2mm thickness.

Even though it is from my Civic, the bodies of both valves are identical (only the bracket where they attach to the car's body is different) so I bet the orings should be the same... in any event, I will find and take apart the spare one I have for the 3G (once I find it).

I will try sourcing a suitable o-ring - I may even go for a 2.5mm thickness ring to see how it fits, but I have a question regarding what is the BEST or adequate material for the o-ring. According to this website, EPDM should be the one to choose

O-Ring Material Guide

(EDIT) There may be more choice of materials, according to this website

eFunda: O-Ring Materials Compatibile with Chemical Brake Fluid

EDIT #2: found the 3G brake valve. O-ring dimensions are exactly the same.

I would appreciate comments so I can go ahead with the procedure and report later. Thanks

[ecogabriel]

Got a pack of EPDM o-rings.
I could not find metric sizes for those, but the 020 size is in the ballpark in both inner and outer diameter. Thickness is slightly less (1/16in or 1.8mm v. 2.0mm), but given the age and condition of current seals it should work fine.
For $6 shipped (bag of 50) I would not complain especially if it works.


EDIT: I went with EPDM after checking in different websites what materials would work better.
O-Rings in all sizes, compounds and durometers from Sealing Specialties, Inc.

My only concern is the size regarding thickness, but I could not find metric sizes in that material. If it works, we will be able to recover functioning valves with no other problem than leaking o-rings.

[Dr_Snooz]

My first stop would be at my nitrile o-ring kit. Nitrile is pretty stable for most auto repair applications. Looking at the valve, I suspect that anything I have in that diameter would be too fat.

My next stop would be at Napa to match up the oring with their kit. Hit or miss there too though.

My last stop would be to smear the old oring full of RTV and bolt it back together. (Don't get any in the passages, of course).

That may seem too hillbilly, but that's probably what I'd do. Sounds like you're more willing to put the time into finding the right orings though.

Let us know how it all turns out.

[ecogabriel]

the inch size is: ID 7/8", OD 1", thickness 1/16".

Nitrile (Buna-N) appeared as not recommended for brake fluid applications, that is why I discarded going and getting one of those...

[Vanilla Sky]

I know brake fluid softens nitrile gloves, so I would avoid it completely in the brake system.

[Dr_Snooz]

the inch size is: ID 7/8", OD 1", thickness 1/16".

Nitrile (Buna-N) appeared as not recommended for brake fluid applications, that is why I discarded going and getting one of those...

Interesting. As far as I've always known, gasoline was about the only place where nitrile was not recommended. Here's a good reference for anyone who cares.

O-Ring Material Guide

Most everything else says stuff like "recommended for most auto applications." Not very helpful.

RTV (ie: silicone) is also not recommended.

Anyone have a gasket maker recommendation for this situation?

[ecogabriel]

Interesting. As far as I've always known, gasoline was about the only place where nitrile was not recommended. Here's a good reference for anyone who cares.

O-Ring Material Guide

Most everything else says stuff like "recommended for most auto applications." Not very helpful.

RTV (ie: silicone) is also not recommended.

Anyone have a gasket maker recommendation for this situation?

NO idea what gasket maker may be made for use with brake fluid; it seems that if there is not an o-ring or gasket from the proper material, you are out of luck. I know one may buy there is possible to buy EPDM in sheets (I had seen that while looking for the o-rings)

Some of the places were I looked for info are below (some are in other postings)
EPDM Rubber, EPDM Rubber Molding, EPDM, Ethylene-propylene
Rubber Compounds of O-Rings - Viton, Neoprene, EPDM, Nitrile

Marco rubber is also listed (Dr's suggestion)

After reading in a few places about what to use for material would be best for withstanding brake fluid (marco rubber among those) I ordered them (bag of 50) here,

EPDM 70 o-rings - Orings and More

I'll report once I get them installed and working; my only concern is thickness but I've been thinking on ways of taking some slack out of the groove if necessary...

The real deal would be finding a supplier of metric sizes; maybe someone working with hydraulic systems or aircraft may know better.

I have made my bet; it looks like close to working so we'll see how it goes.

[cygnus x-1]

The 020 size will probably work ok. It's a bit skinny but I'm pretty sure that middle area in the valve is mostly an air space and is not under any pressure. Before you put it back together, I would recommend tapping out the threads with the appropriate tap (M6 I think). The valve that I took apart had the screw threads staked on the back end, so unless you ground off the staking first it would mess up the threads as the screws came out. I would also use new screws to put it back together.

C|

[lostforawhile]

what are the rubber pieces in the calipers made out of? whatever they are made from should be the right material

[AZmike]

I replaced that o-ring a few years ago and haven't had any problems since.

[Dr_Snooz]

That's all well and good, but WHAT did you replace it with?

[ecogabriel]

what are the rubber pieces in the calipers made out of? whatever they are made from should be the right material

Got my o-rings in the mail today.



From what I had read in several sites, EPDM is the right material to use. Actually, like the rubber in the brake system, it is attacked by mineral oils.

I wonder if you may have access to metric stuff because of being around aircraft; I would not mind paying a few dollars for the right sized o-ring.

I replaced that o-ring a few years ago and haven't had any problems since.

Did you get the right (metric) size? I do not know the effect of brake fluid on nitrile, but if the effect is swelling then they may work even better than the rings I chose (as long as they do not disintegrate or harden as rock)

The 020 size will probably work ok. It's a bit skinny but I'm pretty sure that middle area in the valve is mostly an air space and is not under any pressure. Before you put it back together, I would recommend tapping out the threads with the appropriate tap (M6 I think). The valve that I took apart had the screw threads staked on the back end, so unless you ground off the staking first it would mess up the threads as the screws came out. I would also use new screws to put it back together.

C|

I have checked them today; they do fit in the groove no problem. Also, they protrude above the surface of the valve body so I expect them to seal well.

EDIT: I forgot I had a photo (hope it shows the protrusion a little bit; it can be felt with a finger)



When I took the valves apart, they all have fluid in the middle section. Since I also removed the valves in each half, it seems there is no fluid flow between the halves except for some minimum amounts.

I have realized I need to take the valve completely apart and remove the valves from inside each half - some parts that were supposed to move were stuck. Apparently, contaminated brake fluid left rusty residue inside the proportioning valve locking it. Fortunately, I had long removed the old fluid and tons of rust from the front brake cylinders.

I'll do a how-to and post it in a new thread.

Thanks

[lostforawhile]

Got my o-rings in the mail today.



From what I had read in several sites, EPDM is the right material to use. Actually, like the rubber in the brake system, it is attacked by mineral oils.

I wonder if you may have access to metric stuff because of being around aircraft; I would not mind paying a few dollars for the right sized o-ring.



Did you get the right (metric) size? I do not know the effect of brake fluid on nitrile, but if the effect is swelling then they may work even better than the rings I chose (as long as they do not disintegrate or harden as rock)



I have checked them today; they do fit in the groove no problem. Also, they protrude above the surface of the valve body so I expect them to seal well.

EDIT: I forgot I had a photo (hope it shows the protrusion a little bit; it can be felt with a finger)



When I took the valves apart, they all have fluid in the middle section. Since I also removed the valves in each half, it seems there is no fluid flow between the halves except for some minimum amounts.

I have realized I need to take the valve completely apart and remove the valves from inside each half - some parts that were supposed to move were stuck. Apparently, contaminated brake fluid left rusty residue inside the proportioning valve locking it. Fortunately, I had long removed the old fluid and tons of rust from the front brake cylinders.

I'll do a how-to and post it in a new thread.

Thanks

we dont have anything like that, have you tried MSC?

[ecogabriel]

we dont have anything like that, have you tried MSC?

No, I did not.

I just looked it up and there is only one metric ring that would have fit, but it is way too thick (3mm cross v. 2mm that is what we need) Besides, it is viton that apparently is not recommended for braking systems.

Materials: Viton, Nitrile, Silicone, Polyurethane, EPDM, Fluorosilicone, Teflon, PTFE filled, PEEK, Nylon, Acetal

[cygnus x-1]

I searched around and couldn't find anywhere that directly lists a 2x22mm oring in EPDM. The closest I could find was these guys:

Rocket Seals

The one you have there looks like it would work though.


C|

[Dr_Snooz]

That RTV is starting to look a lot better ain't it?

[AZmike]

I have one of those cheap Harbor Freight o-ring kits. I used one that had a good diameter match and was thick enough to sit proud of the machined surface. Unfortunately, I don't know the size. I figured it wouldn't work and I would have to put an old 35/40 valve back in so I didn't take any notes.

[ecogabriel]

I have not posted yet, but I have repair and replaced both valves (3G and Civic). Though it is very early to say, I have not seen leaks. A how to on checking the valve's internals is in order... I would be throwing away one of the spares because some of the internals are way too stuck. I also noticed how contaminated fluid (w/water) has to do with valves getting sticky.

[lostforawhile]

That RTV is starting to look a lot better ain't it?

brake fluid will eventually eat through RTV

[ecogabriel]

brake fluid will eventually eat through RTV

EPDM expands when exposed to mineral spirits ( like brake cleaner) in the same way that rubber in the brake system. So EPDM works fine

EDIT (4-25): I checked the prop valves in the 3G and the Civic. No leaks.

I would like to post a how-to, but too many things are going on at the same time. For one, I have to still fix my A/C...

[epic1400cs]

I just found out this informative thread!
I am swapping ALB to non-ALB and prop valve for SEi I have seemed to have been leaking.
Just found 2mm Section 22mm Bore EPDM Rubber O-Rings in UK.
Hope it helps!

Simply Bearings Ltd

[Legend_master]

I just found out this informative thread!
I am swapping ALB to non-ALB and prop valve for SEi I have seemed to have been leaking.
Just found 2mm Section 22mm Bore EPDM Rubber O-Rings in UK.
Hope it helps!

Simply Bearings Ltd

Just ordered mine from there. Gonna be putting them in a 30/30 SEi valve. Thinking about maybe even swapping the top to have a 35/30 valve. I ordered 2mm section 22mm bore, let's hope it fits!


2mm Section 22mm Bore EPDM Rubber O-Rings Simply Bearings Ltd

[Legend_master]

Looks like this valve is a little more intricate then expected. You can actually interchange the valves. This means we could build whatever proportion we want front and rear. Also means there is a little more cleaning involved then expected. This Sei valve was actually locked up due to rust.

[Legend_master]

Removed the snap ring, and got the valve apart.

[dieselgus]

http://www.summitracing.com/parts/ttn-45203

Picked up one of these kits for shits and giggles one day at the parts place. They also make other kits with different rubber types. For the price, you can't go wrong. Distributor o ring size is in there, idle air valve size, plus several others. Worth a shot.