Brake Valve on the side sub frame for a 69 camaro

[enio45]

Im cleaning out and rebuilding the brakes on a friends 69 Z 28 and was wondering if anyone has taken the brake valve apart. I was considering doing this as part of the cleaning process etc.....

Does the nut just unscrew - anyting inside i need to worry about?

Thanks for the advise

[sah62]

Does it look like the valve described on my web site?

http://www.musclecarresearch.com/1970-gm-pd-valve-autopsy

If so, there are three o-ring seals in the valve that can degrade over time. They're made of a special EPDM rubber compound that's compatible with brake fluid. The o-rings you can pick up at your local parts store aren't a good replacement because they're usually made of nitrile/buna-n rubber that isn't compatible with brake fluid.

I'm currently looking at the possibility of producing a rebuild kit for valves like the one pictured on my site. I'd appreciate your feedback in this thread if you think it's a worthwhile project:

http://www.yenko.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=453720

[enio45]

Scott - i have that valve on my camaro as well - however in addition to that one there is another valve down on the subframe under the driver seat (called the hold off valve) that has one inlet and one outlet. There is a large nut on it that gives access to "something" inside.

Here is the ebay pic
http://cgi.ebay.com/ebaymotors/67-68-69-Factory-Disc-Brake-Hold-Off-Valve-SS-RS-Z28-/200615080462?pt=Vintage_Car_Truck_Parts_Accessorie s&fits=Year%3A1969%7CModel%3ACamaro&hash=item2eb59 7320e

let me know what you think for this valve to rebuild?

[mockingbird812]

Hold Off Valve (referenced above) (http://cgi.ebay.com/ebaymotors/67-68-69-Factory-Disc-Brake-Hold-Off-Valve-SS-RS-Z28-/200615080462?pt=Vintage_Car_Truck_Parts_Accessorie s&fits=Year%3A1969%7CModel%3ACamaro&hash=item2eb59 7320e)

[sah62]

The fact that it can be opened up means it might be rebuildable. It all depends on what's wrong and what's inside. Is yours not working? Would you be willing to take yours apart and share pictures or send it to me so I could take a look?

[m22mike]

Sam and Eddie
If I may correct your nomenclature just a bit.
The round valve under the master cylinder is the "hold of valve" It holds off the front disc brakes untill around 40 psi. and allows the rear brakes to come in first to prevent nose dive.
The other valve on the frame is the rear brake pressue regulating valve.
Keep in mind Sam that all the companies out there selling these two valve's have no idea what there called. Like the link you posted.
Both these valves have been discussed at length over at CGR, and explained by John Z in detail.
Now...carry on

[169indy]

Can I send someone a image of one apart for them to post.

Jim W

[mockingbird812]

Aye-aye Mikey....thanks for the correction. Good to know. (are you saying that you can't believe everything you read?!!!!!!!!!!!)

[enio45]

Did the nomenclature corretion really come from the OHIO guys??

[enio45]

Indy -send them to mockingburg for posting!!

[email protected]

[mockingbird812]

you bet! send me the pix.

Yea Eddie - those Ohio guys must have woken from their deep winter hibernation or something. <<GRAEMLIN_URL>>/hmmm.gif

[Dusk Blue Z]

I did a lot of checking into these in the spring trying to bleed my brakes before the first car show of the season. There is nothing inside that is rocket science, an O ring, spring, metal washer, snap ring, spool valve, and a cup washer. I have taken a couple of one’s apart and the seals usually swell up right after disassembly.
The repops on ebay are not built like the original ones either inside or outside (surprise). I did find this place that would rebuild the valve with the correct seals for brake fluid. http://www.resleeve.com/index.htm I have not sent mine in yet, but will do it over the winter.
Mike

[mockingbird812]

Good info Mike - thanks.

[mockingbird812]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 169indy</div><div class="ubbcode-body">Can I send someone a image of one apart for them to post.

Jim W </div></div>


Jim forwarded these photos and description to me via email:

<span style="font-weight: bold"><span style="font-style: italic">&quot;Hi there this is 169indy (Jim Weaver) of Bremerton.
I took apart my vavle on my 69 pace car.
Here a couple of pics. The valve was full of gunk (Tech for CRAP)
The disassy was not very hard and I just cleaned the parts up and relubed with DOT5 and reinstalled being careful with the softgoods.

2 pics

I included another pic I lifted from CRG
NOTE also included is a pic of the one near the booster (photo credit JOHNZ)


Thanks for posting them

Jim&quot;</span></span>
http://img.photobucket.com/albums/v697/mockingbird812/sYc%20site/MeterValve31.jpg http://img.photobucket.com/albums/v697/mockingbird812/sYc%20site/MiscPictures341.jpg http://img.photobucket.com/albums/v697/mockingbird812/sYc%20site/MiscPictures342.jpg

[sah62]

If I can get my hands on valves like that to take some measurements I'm sure I can provide the rubber seals and springs needed to rebuild them. Does anyone know of a cheap source to find them used?

[169indy]

Thanks for posting the images.
Kind of crude, I never thought about them being public and I would have been more carefull with the labeling.
Valve,,,(SP) my error.

P.S. &lt;Point of clarification&gt; Notice the Date code on it, afterward sending them,,, I recalled this example is from my 12E 1968 Camaro hence the late 1967 date code stamping on the brass body.

O-rings are easy to find (Viton) material is a good choice. The shaped seals are going to be he difficult items to source.

Used valves should or could be found via swap meets for cheap.

JIM W

[sah62]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 169indy</div><div class="ubbcode-body">O-rings are easy to find (Viton) material is a good choice. The shaped seals are going to be he difficult items to source.</div></div>

Viton is not compatible with automobile brake fluid [1]. EPDM is the way to go. The other seals are a little more difficult, but they're doable.

[1] One source: http://www.elderrubber.com/material.htm

[m22mike]

Scott
These two valves are often sold on ebay if your looking for some practice units, I wish I had some extra's. Maybe someone here will help out.
I have taken apart several round hold off valves and hust cleaned them up and re used all the internals.

Mike

[sah62]

Thanks, I'll keep my eyes open. What would be some good keywords to look for on eBay?

[m22mike]

Just search 69 Camaro and Nova in ebay motors, parts and accesories. I will keep a look out too. Also search proportioning valve.

here are a couple, even if you buy one and don't use it, you can always re sell it.

http://cgi.ebay.com/ebaymotors/69-Camaro...sQ5fAccessories (http://cgi.ebay.com/ebaymotors/69-Camaro-Disk-Brake-Proportioning-valve-_W0QQcmdZViewItemQQhashZitem20b8cbcb80QQitemZ14053 9317120QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries)

http://cgi.ebay.com/ebaymotors/67-68-69-...sQ5fAccessories (http://cgi.ebay.com/ebaymotors/67-68-69-Chevelle-Camaro-disc-Brake-Proportioning-Valve-_W0QQcmdZViewItemQQhashZitem53e7ed0560QQitemZ36037 3355872QQptZVintageQ5fCarQ5fTruckQ5fPartsQ5fAccess ories)

[Dusk Blue Z]

sah62 PM sent.

Mike

[sah62]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: m22mike</div><div class="ubbcode-body">Both these valves have been discussed at length over at CGR, and explained by John Z in detail.</div></div>

Wow, as I'm reading through eBay ads I see what you mean about the confusing nomenclature. Lots of people don't seem to know the difference between the pressure differential, proportioning, and metering/hold-off valves. I'll have to add that info to my web site.

[mockingbird812]

Scott,

I for one am ignorant (or have misinformation) and wouldn't mind a refresher on each of these components and how they interrelate.

thanks!

[169indy]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sah62</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 169indy</div><div class="ubbcode-body">O-rings are easy to find (Viton) material is a good choice. The shaped seals are going to be he difficult items to source.</div></div>

Viton is not compatible with automobile brake fluid [1]. EPDM is the way to go. The other seals are a little more difficult, but they're doable.

[1] One source: http://www.elderrubber.com/material.htm </div></div>

You are correct for the most part,
EPDM is Good for DOT 3,4, &amp; 5
VITON is in fact good for DOT 5

I use in Silicone based DOT 5 brake fluid.

REF:
2.2.4 Ethylene Propylene Rubber (EPR, EPDM)
EPR copolymer ethylene propylene and ethylene-propylenediene
rubber (EPDM) terpolymer are particularly useful when
sealing phosphate-ester hydraulic fl uids and in brake systems
that use fl uids having a glycol base.
• Glycol based brake fl uids (Dot 3 &amp; 4) and silicone-basaed
brake fl uids (Dot 5) up to 149°C (300°F).

2.2.7 Fluorocarbon (FKM)
Fluorocarbon (FKM) has excellent resistance to high temperatures,
ozone, oxygen, mineral oil, synthetic hydraulic fl uids,
fuels, aromatics and many organic solvents and chemicals.
Low temperature resistance is normally not favorable and
for static applications is limited to approximately -26°C
(-15°F) although certain compounds are suitable down to
-46°C (-50°F). Under dynamic conditions, the lowest service
temperature is between -15°C and -18°C (5°F and 0°F).
Gas permeability is very low and similar to that of butyl rubber.
Special FKM compounds exhibit an improved resistance
to acids and fuels.
Heat resistance
• Non-fl ammable hydraulic fl uids (HFD).
• Silicone oil and grease.
• Mineral and vegetable oil and grease.
Not compatible with:
• Glycol based brake fluids.


I have easy access to most material types. O-rings, It is as you state the shaped seals are a very big problem to source.

I like your site and efforts look very good and helpful

Jim

[169indy]

I like to study the Section 5 Brakes of any GM Chev Chassis Service Manual.

Definitions from them: 1968

A) &lt;&lt;SWITCH&gt;&gt; A New brake pipe distribution and switch assembly is mounted below the main cylinder. Front and rear hydraulic brake lines are routed from the main cylinder, through the brake pipe distribution and switch assembly, to the front and rear brakes. The switch is wired electrically to the brake alarm indicator light in the instrument panel. If a leak in either front or rear system occurs, the pressure differential (150-250 psi) during brake application will cause the piston to compress the springs and move (the piston) in the bore until it touches the electrical contact (grounding the circuit) which causes the parking alarm brake lamp on the instrument panel to light.

B)&lt;Lower Rears&gt;&lt;PRESSURE REGULATOR VALVE&gt;&gt; On certain models the rear brake hydraulic line is routed through a pressure regulator valve mounted on the left subframe rail. The valve controls the hydraulic pressure to the rear brakes resulting in the correct pressure balance between the front and rear hydraulic systems.

C)&lt;Upper Fronts-DISC BRAKE Car&gt;&lt; PRESSURE REGULATOR VALVE&gt;&gt;Models with disc brakes have a pressure regulator valve mounted below the main cylinder. The valve meters the hydraulic pressure to the front brakes resulting in simultaneous braking balance between the front and rear brake systems. This valve guards against premature lock-up of the front wheels when the brakes are applied.

I know my 69 Pace car stops very nice and maintaining a correct bleed and brake system maintenance should be considered one of any enthusiast first priorities. Going FAST is easy, Stopping is Critical.
Try stopping a 1925 Hudson super 6 at 35mph, external friction OD brakes on the REAR only, You have heard of ARMSTRONG steering, try one step above Fred Flinstone BRAKES

Jim W

[lzdick]

Jim, you have a PM.