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Author Topic:   Brake Lines
Racer98
Dirt Maniac

Total posts: 142
posted January 23, 2005 07:28 AM  
I must use a stock brake master cyl. I have disc front and drum rear, and I use a master off a 76 chev, manaul brakes. Just wondering which line go's to the front side and which goes to the back. I also was thinking on tying the front and back brakes together so that there was equal pressure to all 4 corners, anyone ever done this?

marshalr
Dirt Maniac

Total posts: 148
posted January 24, 2005 09:56 AM  
If you have a single master cylinder that feeds both front and rear brakes tying them in to one single hydraulic circuit will not work too well.
Stock disc brake caliper pistons offer much more surface area as a piston than the rear wheel cylinder pistons, thus with equal pressures applied you will get different forces.
You can identify which portion of the master cylinder is designed to feed the front disc brakes by the reservoir size. Bigger reservoir feeds the front discs.

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Some People Race For A Living; I Live To Race

Speedway65
Dirt Freak

Total posts: 344
posted January 24, 2005 10:57 AM  
We use a single ford style master to feed both front and rear,and we ran all year without a problem.Biggest thing with us is our driver uses very little brake at all,if any!The only time we really use it is when you have to make a complete stop and so far so good!

Clyde Torkel
Dirt Full Roller

Total posts: 33
posted January 28, 2005 11:40 AM  
For dirt where you want more braking on the rear and are not allowed dual master cylinders and proportioning valves use the m/c lines tied together. This will equalize the pressure. Disc brakes take much more pressure to actuate than drums. This s because drums have a 'self energizing' effect built in caused by the geometry of the shoe attachments. Disc brakes have only direct clamping pressure and thus require more pressure for the same braking effect. This is not to say drums are better only that for some purposes they have qualities that make them preferrable.

sc1 racing
Dirt Freak

Total posts: 419
posted January 29, 2005 02:20 AM  
if you are running a stock porpotioning valve you will be wasting your time tring.i swapped lines around and tried everything i could, but could tell no canges..you can buy the in line valves, and hide them where you can adjust pressure, but that is about the only thing that will get what your wanting..

if you want alot of rear bake get an old car emergency brake set up. put it in the car, and grind all the teeth off where pedal wont stay down. it will work just like a brake pedal only it will just operate the bake brakes. i was still using it on my street stock untill we could run aftermarket with adjustable brakes..

iowa_dirt_track_girl
Dirt Freak

Total posts: 461
posted January 29, 2005 10:21 AM  
Just wondering We used to put the lines on in reverse in other words the back lines would be the first to react then the front it takes some doing but its not that bad of job (if I can do it then anybody can LOL )

BIGDADDYBOZ
Dirt Freak

Total posts: 466
posted January 29, 2005 07:58 PM  
I would never use a single feed master. I ran one this year and it was terrible if you need to use your brakes. It was on a metric Hobby Stock.

Istock66
unregistered Total posts: 466
posted January 30, 2005 01:03 PM           send a private message to BIGDADDYBOZ   Edit/Delete Message   Reply w/QuoteBBBBBB
boz Im gonna say I told you so, also what you had was dangerous.


1. it doesnt matter which lines you plumb to where on a master cyl, the pressure is the same, there is only one piston in there and it doesnt have any idea where its sending fluid. the reason the fronts work better is the fact that disk have no slop to take up, maybe a 1/16 of piston travel and youve got brake. it has nothing to do with a prop valve.

2. drum brakes take more fluid movement to work, they have to push the pistons out, and take up the slop in the brakes, springs etc.

3. the stock prop valve does nothing at all unless you break a line, then it has a valve in it that moves and blocks off fluid going to that half of the system. period thats it.

4. you need to remove the stock prop valve, or youll have a pain in the but bleeding, they have a reset button on them that must be pushed, or line pressure relieved in order to bleed properly.

5. a master with the res in halfs is safer because a leak in the front or rear half still leaves you with brakes at the other end.

All of this info is readily available in any chilton or haynes manual.

trust me guys will get on here and argue that they switched their lines and won 20 races etc,it happens every time this subject comes up. Im telling you right now that did nothing maybe they finally got their brakes blead properly by dumb luck!!

hope this helps, I am not trying to argue with or put anyone down, just giving out the straight facts for at least the 10th time on here, brakes are a safety issue just like a fuel cell, helmet etc.

robhbk24
Dirt Freak

Total posts: 372
posted January 30, 2005 03:10 PM  
i agree with most of that and i have heard/read about the reset valve but on both of our cars (mid 80s metric chassis) i use all stock brake system all oem replacement style parts with a factory propotioning valve and i just bleed them reg. never have had any problems got all kindsa brakes. i would love to switch to rear disk someday but for now the rear drums work fine as along as i adjust them out regularly. i had heard bout the reset switch before and wondered what diff does it make?i agree that the prop valve is only there in case of a line break and thats why i leave it there. i would rather have some brakes than none even if it is only enough to slow me down before i squish it into the wall.jmo.i also use the factory power booster hooked up if gm is willin to give me power brakes i'll take em. has anybody ever tried the odd ball mastercylinders that came on the diesel metrics or the ones that came on the buick gn cars some of those operated diff i wodered if they were any better. i agree with the fact that brakes are a saftey item i have tried 3 wheel brakes in the past and hated them. i would rather take the time to fix my handling woes than try to hide them with no rf brake, i have the line pinched off 3/4 way to reduce press to that side, and it seems to pull a little to the left but i can keep it straight in a quick stop without to much effort. but as far as some guys eliminating the rf all together i did not like that at all, all it took was one time when i had to lock em up that i realized that no rf brake was not neccssarliy a good thing.

Istock66
unregistered Total posts: 372
posted January 30, 2005 03:21 PM           send a private message to robhbk24   Edit/Delete Message   Reply w/QuoteBBBBBB
rob, you should be faster or at least have more consistent brakes if you eliminate the booster.


its based on vacuumn which can vary greatly from corner to corner etc. giving you a diff amount of pedal at diff time

you really dont need the prop valve its a secondary safety since your master has two sides it wont empty completely ever.... I would remove it for bleeding sakes.

if it happens to be frozen or stuck like many are in the middle you wouldnt need to reset it, probably the case in your situation. they really dont work that well but trust me if it ever works correctly you will not get any fluid out of the shut off side without reseting it.

o5racer
Dirt Freak

Total posts: 402
posted January 31, 2005 09:14 AM  
The factory proportioning valve is usually set at 60/40 or 70/30 with the higher percentage going to the front brakes. If they came from the factory with 50/50 most of the cars out there would have rear brake lockup problems on the street in wet weather. The best thing to do is get rid of the OEM valve so there is no restriction in the lines. Unless you get into a stepped mastercylinder where one piston is larger than the other(some of the newer frontwheel driv cars use them) the preassure will be the same out of each port. The larger resivoir is for the calipers and the smaller one is for the wheel cylinders. The calipers will use more fluid as the pads wear, thats why the factory runs the larger res to the front brakes. On mine I run the larger res to the rear brakes(2 calipers) and the smaller res to the fronts(one caliper).
Nick

gahainsey
Dirt Maniac

Total posts: 113
posted January 31, 2005 12:39 PM  
The real story on the factory COMBINATION VALVE
It does three things.
1) redirects first 1-200 psi to the rear brakes to overcome drum brake shoe return spring force.
2) Pressure reduction in the line to the rear brakes. (same as the one in the aftermarket proportioning valves minus the knob. Drum brakes require less hydraulic pressure because of the self energizing effect.
3)Pressure differential sensor to switch warning light on if front or rear circuit of brakes develops a leak.

Some also incorporate a residual pressure valve in the rear brake circuit to help overcome the return spring force.

robhbk24
Dirt Freak

Total posts: 372
posted January 31, 2005 01:52 PM  
i get the idea behind not using the booster cause of vac issues, years ago i had a monte and with the cam in that you had 1 good push and that was about it but with the cam i have now i have never had a problem. i have tried not using the booster by just unhooking the vac and did not like it the pedal was way too hard to push for my liking.i run the extreme bottom alot so my brakes tend to get a work out unless they move the infield uke tires in far enough that you can hook the left front on the lower birm.they don't do this often.lol.too bad you can pretty much flat foot it on the bottom when they do that. i have more valves here so i might try gutting one out this year and see what happens. i had one that was froze up years ago on a parts car we bought and you were right you could get no fluid to the back at all.

Istock66
unregistered Total posts: 372
posted January 31, 2005 04:15 PM           send a private message to robhbk24   Edit/Delete Message   Reply w/QuoteBBBBBB
If you state your source on these two points I would appreciate it, because in my chilton, and haynes manuals for ford ranger, ford full size, chevy nova, chevy camaro, jeep cj series, nissan sentra,subaru chiltons, toyota tercel, gm master mech truck dealer repair manual.. It says differently.


1) redirects first 1-200 psi to the rear brakes to overcome drum brake shoe return spring force.
2) Pressure reduction in the line to the rear brakes. (same as the one in the aftermarket proportioning valves minus the knob. Drum brakes require less hydraulic pressure because of the self energizing effect.

ROB,
IF YOU REMOVE THE BOOSTER IT WILL BE EASIER TO PUSH THE BRAKES THEN WITH THE BOOSTER IN THERE BUT NOT CONNECTED TO VACCUMN.

gahainsey
Dirt Maniac

Total posts: 113
posted February 01, 2005 04:50 AM  
you can read about it at: http://auto.howstuffworks.com/master-brake2.htm

    

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