Wire connector on replacement brake proportioning valve
10-29-2017, 03:07 PM
#21
Melting Slicks
I wish I knew how to post pictures of the inards of the Prop valve. Try Google for pix. The valve moves front to back and when it does or I should say if it does due to issues, there is a little nub that triggers or pushes up on the switch (light on)
And the little tool is from PAR? Performance something-something? sorry. Google that too. Proportioning valve tool.
And the little tool is from PAR? Performance something-something? sorry. Google that too. Proportioning valve tool.
Last edited by Buccaneer; 10-29-2017 at 03:07 PM.
10-29-2017, 04:40 PM
#22
Le Mans Master
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 6,891
Received 2,123 Likes
on
1,630 Posts
Yours, if defective may not return. But a quick jab of the pedal usually works.
What that drawing does not show is the spring in there. It is spring loaded. Few people have successfully rebuilt those things. Bunch of "O" rings, can't really lube the seals because you will contaminate the brake fluid. New ones sell for around $90.
What that drawing does not show is the spring in there. It is spring loaded. Few people have successfully rebuilt those things. Bunch of "O" rings, can't really lube the seals because you will contaminate the brake fluid. New ones sell for around $90.
Last edited by HeadsU.P.; 10-29-2017 at 04:42 PM.
10-30-2017, 12:57 AM
#23
Melting Slicks
Yours, if defective may not return. But a quick jab of the pedal usually works.
What that drawing does not show is the spring in there. It is spring loaded. Few people have successfully rebuilt those things. Bunch of "O" rings, can't really lube the seals because you will contaminate the brake fluid. New ones sell for around $90.
What that drawing does not show is the spring in there. It is spring loaded. Few people have successfully rebuilt those things. Bunch of "O" rings, can't really lube the seals because you will contaminate the brake fluid. New ones sell for around $90.
I'll give it a try or buy a new one if that fails.
11-02-2017, 11:01 PM
#24
Melting Slicks
Just a thanks for the info on resetting the brake light, which mine was stuck ON. Slammed the brakes a few times and light went out and is working fine now.
Last edited by Buccaneer; 11-02-2017 at 11:02 PM.
04-18-2019, 11:41 AM
#25
Resurrecting an older thread, mainly to clarify IF the 68/69 Switch on the Proportioning Valve is actually different functioning than the later ones.
The "pin" style later switches appear to have a plunger-like function with the pin actuating under a spring if the valve body moves laterally due to imbalance in brake pressure.
My '69 switch is like the one on the left of the picture, with a square profile tip, not the pin, and I don't think it is intended to move within the switch body.
I THINK the square tip only makes contact with the valve body (which is profiled with a wider middle gap than the later ones to match the pin), when the valve body shifts to imbalance mode, thereby grounding out the circuit and lighting the warning light. So, the circuit gets grounded when the shifted valve body makes contact with the switch tip, rather than the switch tip actually pressing in internally to complete the circuit. See second picture.
Would appreciate any expert inputs - thanks!
The "pin" style later switches appear to have a plunger-like function with the pin actuating under a spring if the valve body moves laterally due to imbalance in brake pressure.
My '69 switch is like the one on the left of the picture, with a square profile tip, not the pin, and I don't think it is intended to move within the switch body.
I THINK the square tip only makes contact with the valve body (which is profiled with a wider middle gap than the later ones to match the pin), when the valve body shifts to imbalance mode, thereby grounding out the circuit and lighting the warning light. So, the circuit gets grounded when the shifted valve body makes contact with the switch tip, rather than the switch tip actually pressing in internally to complete the circuit. See second picture.
Would appreciate any expert inputs - thanks!
04-18-2019, 07:49 PM
#26
Le Mans Master
Well, I was the design engineer for these things back in the 70's. You are correct in your assumption that the 69-73 style just shorts the switch wire to ground to turn on the light. The downside of this design is that, because of the spring return, the failure light goes out when pressure is released. So uncle Sam said the light MUST be latched "on" in the event of a partial system failure. So if you look at the picture in post 20, you can see that the switch plunger climbs a ramp on the piston and stays there. No spring return. The 2 plunger style designs are basically the same with the 78-82 being the cost reduced (plastic body) version. At the same time, the connector was changed to add a shroud around the terminal post to protect it during assembly in the vehicle. Hope this helps.
04-18-2019, 11:04 PM
#28
Thanks Duke.
So the valve body slides sideways as the pressure imbalance is sensed, but the switch doesnt move at all on the '69-'73 right? The plunger part is wider than the pin version on the later swicltches but it looks like it is not intended to move in and out as the valve body moves. I believe this version only makes contact when the valve body moves sideways and it touches the fixed end of the switch. This grounds the circuit and lights the warning light.
Am i correct?
So the valve body slides sideways as the pressure imbalance is sensed, but the switch doesnt move at all on the '69-'73 right? The plunger part is wider than the pin version on the later swicltches but it looks like it is not intended to move in and out as the valve body moves. I believe this version only makes contact when the valve body moves sideways and it touches the fixed end of the switch. This grounds the circuit and lights the warning light.
Am i correct?
Last edited by Bergerboy; 04-23-2019 at 12:05 PM.
04-19-2019, 09:23 AM
#29
Le Mans Master
Thanks Duke.
So the valve body slides sideways as the pressure imbalance is sensed, but the switch doesnt move at all on the '69-'73 right? The plunger part is wider than the pin version on the later swicltches but it looks like it is not intended to move in and out as the valve body moves. I believe this version only makes contact when the valve body moves sideways and it touches the fixed end of the switch. This grounds the circuit and migjts the warning light.
Am i correct?
So the valve body slides sideways as the pressure imbalance is sensed, but the switch doesnt move at all on the '69-'73 right? The plunger part is wider than the pin version on the later swicltches but it looks like it is not intended to move in and out as the valve body moves. I believe this version only makes contact when the valve body moves sideways and it touches the fixed end of the switch. This grounds the circuit and migjts the warning light.
Am i correct?
04-22-2020, 06:46 PM
#30
WHAT IS THE THREAD SIZE ON THE 67-68 COMBINATION SWITCH??? The 67-68 appears to use a different combo valve than the remainder of the C3 years????/
Resurrecting to ask what the threads are on a 1968 switch? To see what GM Combination/Proportioning Valve Bleed Tool to get????? Meanwhile I sent an email to Willcox asking for what tool would be used, or what the thread size, would be for a 67-68 which use this specific combo/proportioning vlv:
https://willcoxcorvette.com/corvette...ng-valve-67-67
If I get an answer I'll try to get back here and update. Not even sure that the tool would be needed for a 67-68????
Resurrecting to ask what the threads are on a 1968 switch? To see what GM Combination/Proportioning Valve Bleed Tool to get????? Meanwhile I sent an email to Willcox asking for what tool would be used, or what the thread size, would be for a 67-68 which use this specific combo/proportioning vlv:
https://willcoxcorvette.com/corvette...ng-valve-67-67
If I get an answer I'll try to get back here and update. Not even sure that the tool would be needed for a 67-68????
Last edited by carriljc; 04-22-2020 at 07:15 PM.
04-24-2020, 10:08 AM
#32
This Willcox image shows different thread size for the 69-73.
I am not disputing your experience --- however somebody could replace the older type with the newer type.
I am curious about what is different about the 1967-68 though???
Here is the link for the 67-68 definitely different "proportioning valve":
https://willcoxcorvette.com/corvette...ng-valve-67-67
And below are the thread sizes reported by Willcox website:
I am not disputing your experience --- however somebody could replace the older type with the newer type.
I am curious about what is different about the 1967-68 though???
Here is the link for the 67-68 definitely different "proportioning valve":
https://willcoxcorvette.com/corvette...ng-valve-67-67
And below are the thread sizes reported by Willcox website: