V1 Proportioning Valve??

[MJP61]

2 questions?

1. What are pros and cons of using a proportioning valve in the brake system?
2. Can I use the factory proportioning valve on my goblin, or should I leave it out?

 

[Ross]

The Cobalt proportioning valve is what most everyone is using, and it works, but it doesn't use the rear tires to their potential.
Now the goblin does stop faster than most any car on the street, so do you need to stop faster? Of course we do. Autocross rocks.

Pros:
- You can use more rear brakes
- Your power brakes won't be quite so powerful (this is an advantage, as the Cobalt power brakes are too powerful) giving you more brake pedal that is useable

Cons:
- the Cobalt uses double flares on the brake lines, and the 260-12627 Wilwood proportioning valve uses bubble flares, so you probably will be loaning out multiple tools from your local auto supply store, and learning new skills.

 

[Desert Sasqwatch]

2 questions?

1. What are pros and cons of using a proportioning valve in the brake system?
2. Can I use the factory proportioning valve on my goblin, or should I leave it out?

Hydraulic or vacuum proportioning valve? Both have their merits and can be used to set up the 'stock' brake system to fit your individual liking.
The vacuum valve is used to reduce the effectiveness of the too-big-for-a-Goblin brake booster. The brake pedal 'feel' can be adjusted for more effort to activate the brakes - what some refer to as 'using more of the pedal'.
The hydraulic valve, when installed into the front brake line, can help balance the brakes front to rear. With the 'stock' Coblat system, the front brakes over power the rear brakes and have tendency to lock up, the rear brakes don't do much up to that point. Reducing some of the line pressure to the front brakes makes the rear work harder and be more effective for 4 wheel braking, not just front wheel braking.

 

[ctuinstra]

Or you can do what we have at the moment, a little air in the lines in the front. Gives a nice softer pedal and not too much front brake. The redneck way.

 

[Dsteinhorst]

Has anyone made knuckles with caliper mounting bolt holes machined in a smaller bolt circle (closer to center)? This would help with brake feel, f/r distribution, and would also help clear smaller wheels (RPF1s)

Rotors could be turned down if necessary.
Does anyone have a drawing of the knuckles?

 

[George]

I made a pair for mine for wilwood calipers until getting a pair cnc made I run 16" wheels
Brad

 

[JBINTX]

Three of us in Houston are running this with much success.

Add-on brake proportioning valve

Doing some autocross, I found that you jamb on the brakes and the fronts lock instantly. Unless you are in a panic stop on the street, you’ll never experience this. At autocross, you find out quickly that you cannot jamb down on the brakes. After doing some research, I decided to decrease the...

dfkitcar.com

 

[MJP61]

I’m going to be mostly regular driving. Should I use the proportioning valve from my donor ? Get an aftermarket one? Or not use one at all? Suggestions and thoughts are appreciated.

 

[Ross]

Use the Cobalt one and drive it for a while. Then you decide. Some people want to cruise the streets and wave at people, others want the roller coaster ride, so press the brakes, and put them into the seat belts. Just my 2 cents

 

[MJP61]

Anyone have any video or pic of where the valve is mounted on the goblin? I just must have missed it if it was on one of the DF videos.

 

[Ross]

Here is a picture of mine.

 

[Dsteinhorst]

The factory brake proportioning is done within the system design. There isn't a separate proportioning valve like some other cars have.

 

[MJP61]

do I need the proportioning valve out of my donor? It’s located by the front left frame rail.

 

[Ross]

You have a donor with a proportioning valve? Take a few pictures, as that sounds like after market.

 

[Rauq]

That's probably the ABS module?

 

[k.rollin]

The kit is not configured to use the factory proportioning valve.

For those asking about the stock valve, see here: https://www.ebay.com/itm/Brake-Prop...2010-CHEVROLET-COBALT-PRX2-10RM-/402477136614

 

[MJP61]

That's probably the ABS module?

The car has no ABS. I will take a picture later when I get home.

 

[Dsteinhorst]

Is your car 4 wheel disc?

I'm currently trying to understand all the different brake packages available on the Cobalt/G5, and I seem to discover a new one each day.

 

[MJP61]

Is your car 4 wheel disc?

I'm currently trying to understand all the different brake packages available on the Cobalt/G5, and I seem to discover a new one each day.

Car from factory is front disc, rear drum, NON ABS. The proportioning valve is called “Rear Proportioning Valve” according to the dealer parts diagram.

 

[Dsteinhorst]

I could swear my donor with the same specs didn't have a proportioning valve, but I just looked through pictures, and sure enough it did.