Locking the rears is a very BAD thing.

 

There is no need to get uptight - I was not trying to pick at what you said, but using the wrong terminology confuses issues when people are trying to understand things.

The only point at which leverage is gained or lost in the system is through the brake peddle pivot point. smaller piston = hydraudic advantage = more PSI (pressure).

I was referring to an aftermarket proportioning valve that allows finer tuning of the system to get a better balance - with the springs that is in there you don't have a lot of ability to fine tune with it - all you can do is change it to something else that may or may not be adequate.

We put one of these on my fathers chevelle and it helped out quite a bit, but he had drums in the back and disks up front. If the MC doesn't help mine - I might throw one of them inline and see what results it yields.

 

That's fine, but I thought you were trying to argue semantics. Leverage has a broad meaning. If a accuser has leverage against you in a court trial, it doesn't mean they have a teeter totter up your ***.



The aftermarket ones offer adjustability, but, all the ones I've seen simply proportion and nothing more. So they reduce rear line pressure at all braking levels, which results in premature front pad wear. Basically, in street driving and light braking, a 50/50 pressure balance works fine, and the oem combination valve gives you exactly this until you exceed a certain pressure, called the "knee point" or "crack point".

If you want to control the rear line pressure with a prop valve, then make sure to remove the combination valve entirely and cap off the warning sensor hole with a metal plug. It also isn't the solution for everyone.

On my setup for example, I'd actually need to put more pressure to the rear lines than the fronts, even during maximum braking. This is because the larger front rotors and pistons can do way more with the same amount of line pressure.

In a straight line, at -1 G, the rear brakes can still do 35% of the braking. Obviously this wouldn't be safe in a turn or on uneven road surfaces. GM however, uses only about 20% of the rear brake in the early cars at max braking. They're leaving a lot on the table.

 

Ok, I understand all of this theory but that still will not explain why the brake will suddenly sink all the way down and having a new MC and no leaks.

 

You have a different problem.

 

Thanks mate, glad you enjoyed it here Did you pay your speeding fine before you left??

The J55 is a 13" front brake package, as apposed to the standard 12" JL9s. Both calipers take the exact same pads. I seriously doubt youll fit them under a 15" wheel, but ive never looked into it.

 

The brakes on my 87 are great...tried them this weekend. Regarding the proportion valve....someone once told me there is an alignment tool for it, is this correct? Thought I checked on it for my Explorer when I had it, and I think there is. Could your problem be it's out of alignment?

 

......ttt

 

ttt.....just keeping it moving...

 

No such thing. I think under some conditions, such as during brake bleeding, the combination pistion can shift in the m/c and possibly restrict pressure to either circuit.

 

......ttt

 

.......ttt

 

......ttt

 

5,000 views on a hi-jacked thread's not enough?

 

..i don't understand your poorly "veiled" statement...care to elaborate?....a lot of people have brake problems and this link is worth a read.......

 

Hi my car had brakes that were so hard you would not drive to close to someone.Rebuilt all brakes test booster all working I read the forums and see abs fuse works maybe I take mine out brake are better that I have felt them. Fronts are working good enough that you can hear frt tires gripping but rears are not so good will install bias spring and see

 

...what good will that do as it (spring) is only a band-aide for an existing problem....gm doesn't put that spring in there from the factory!...

...abs has little to do with braking force as it only comes into play when different speeds (skid) are detected at the wheels and the abs modulates the brakes to attempt to keep the car straight....

 

Same problem here. My ABS light is on and had the wheels off to pull the bearing hubs...Just for fun, I put it in gear and watched while I pressed on my brakes, hard, and it took a few seconds to stop just from idle speed. When there is a problem with the ABS, is it supposed to just shut your brakes down??? Seems like that would defeat the whole purpose of stopping, don't you think?

 

.....first, if you need to get a HELMS SERVICE MANUAL if you plan on keeping the car!......next, abs does not "shut down the brakes"!!.....i explained what the abs does in the previous post!...read it!...

 

All i was saying that when i disabled abs i got good brakes.Abs does limit brake pressure to brakes when you skid maybe internals are sticking and blocking flow my pedal was hard to push and felt like no assist when i remove fuse pedal feel changed to when you push it the pedal it has some play and not rock hard.Also just because gm didnt make the part it dose not makes it a bandaid the spring increases rear brake pressure.