Improved braking?

[cruiseroutfit]

I think any modern braking system is going to have this combination valve in place, LC or Jeep or GM or Audi, or?....

Yup, newer Cruisers do... all the ones I work on have dual reservoirs from the factory, so no need to separate anything. The really old Cruisers are a single output and a single reservoir, so all the valve in the world isn't going to save you

 

[waynehartwig]

Yup, newer Cruisers do... all the ones I work on have dual reservoirs from the factory, so no need to separate anything. The really old Cruisers are a single output and a single reservoir, so all the valve in the world isn't going to save you

lol

 

[Green Leader]

It sounds like then what he needs to do is get proportioning valve that with handle disc/disc and then see how it runs is this correct from what i have read.

 

[bobdog]

It sounds like then what he needs to do is get proportioning valve that with handle disc/disc and then see how it runs is this correct from what i have read.

No it sounds to me like he really needs to upgrade to get better braking force, as that is what he wrote he is lacking. Better calipers with larger pistons and a bigger master cylinder to match, bigger rotors, or a more powerfull booster, hydrolic or vacume are really the only way. Proportioning is important and needs to be adressed if it is wrong but it sounds like the OP has other issues.

 

[gijohn40]

I could be wrong again but what I remember from shop is that the fronts have 60% of the stopping power and the remainder 40% goes to the rear...and this is the job of the proprotional valve to split... if you change that to 50-50 your losing your stopping power but if you change it to 70-30 then your adding more to the front and they will lock up while the rear just keeps rolling... this is why you need the valve in place...

as far as the safety portion... if fluid goes past the valve faster then its suppose to it sets off the safety lite and you can not get it to clear until you reset the valve by letting alot of fluid out the side that didn't fail... this is why sometimes when bleeding the brakes the lite comes on...

 

[BEHERSKE]

Do you have any suggestions for the upgrade? i know of some but we are talking a lot of money that i don't have. So i am trying to find a way that i don't have to spend a ton of money right now.

 

[jsudar]

I converted a car from disc/drum to disc/disc and I put a Wilwood proportioning valve on it in place of the factory thing and never had a problem. It was nice to be able to adjust the bias front to rear.

All the the manual prop valves do is reduce the pressure that is sent through them. If you put a manual prop valve in you simply limit the pressure to the rear brakes so that they will lock up earlier or later. You want the rears to lock before the fronts, but not much.

If you remove the factory valve you will lose some safety features such as the brake warning lamp that activates if you were to break a line or something. This may be ok for you, but doesn't really up the resale value.

I don't know too much about jeeps, but I know it takes more pressure to actuate drum brakes than discs. The drum brakes have to over come the return spring pressure before they start to work, while the front calipers require very little pressure before they start moving. Many manufacturers put some sort of valve in there so the front and rear brakes would actuate at the same time and not wear front brakes prematurely. This may be part of the master cylinder or part of the valve you want to remove--not sure on the jeeps. Just some things to think about.

 

[jsudar]

Just out of curiosity, did any jeeps every come with four wheel disc brakes?
maybe the grand cherokees or something?

 

[waynehartwig]

I don't know too much about jeeps, but I know it takes more pressure to actuate drum brakes than discs. The drum brakes have to over come the return spring pressure before they start to work, while the front calipers require very little pressure before they start moving. Many manufacturers put some sort of valve in there so the front and rear brakes would actuate at the same time and not wear front brakes prematurely. This may be part of the master cylinder or part of the valve you want to remove--not sure on the jeeps. Just some things to think about.

Not true... Drums take less hydraulic pressure and fluid to actuate than discs do. That's why drum brakes are more efficient. Drums use the rotating of the drum to aid in lock up as well. Discs rely soly on fluid and pressure. Without them, discs are junk.


As for 4 wheel disc on a Jeep - yes, Unlimited's, Rubicon's and some Grand Cherokee's have disc. Prop valve and master cylinder are the same on all Jeeps, regardless of drum or disc. ie an 04 Rubicon uses the same MC and PV as a 98 TJ.

 

[jsudar]

You are right, drums are more efficient brakes. To bad they can't shed heat like a disc setup.
Drum brakes do have the advantage of self-energizing once that have contacted the drums, however they do require more pressure to start moving because they must overcome the return spring tension. There is no return spring on a caliper, so it requires very little pressure from the master cylinder to get them to start squeezing.
Wilwood makes an inline residual pressure valve that will keep about 10 psi on the rear drums so that they actuate about the same time the discs do. Most vehicle manufacturers incorporate that into the master cylinder.
If a car did not have this feature the drums would never actuate under light braking and the fronts would wear prematurely. Under heavy braking it makes no difference.