Oh the HORROR, the HORROR
Printable View
Quick and easy way of testing the rod length adjustment (from Jegs site);
Use the following procedure to check the push rod adjustment.
CAUTION: Wear protective goggles when performing the following procedure! Brake fluid may erupt from the master cylinder with sufficient force to cause personal injury.
1. Remove the master cylinder reservoir cap or cover.
2. While an assistant slightly depresses the brake pedal, watch for fluid to erupt in the reservoir when the pedal is depressed 3/8” to 1/2”. This indicates correct push rod length. On dual system master cylinder, fluid may spurt only from the front reservoir.
3. If the pedal travels more than 1/2” before master cylinder fluid erupts, the push rod is too short. If nothing happens no matter how far the pedal is depressed, the push rod is probably too long.
Navy
I hope you get this figured out, because I have the same setup on my 34 ,an have the same problem. Except I ran mine for about 30,000 mile probably on the front brakes. But parked it an haven't drove it in about 7 years been meaning to get back on it .Jonathan
Navy-since you have power steering and need to redo the pedal/mounting bracket----think about using a hydroboost master cylinder from a late mustang AND the ford rear disc package from ford performance parts--------
Navy-know what you mean--------however I have seen numerous (over many years since disc brakes )times that a package didn't work but that the person had no idea that his rear brakes weren't even working(post #86) ---when I get involved in something with 4 wheel brakes I take a very close look at an exact replication of something OEM-------Corvettes work fine, Lincolns, and Mustangs plus since so many use Ford 9iners rears , (or even 8.8) the explorer package does too. If not a race car I will look at the combo valves/masters from an oem and not mix anything up-------You got to remember that Speedway thinks brakes are to toss the vehicle sideways entering a turn on a dirt surface-usually ovals
Jerry: I think I'm going to do just that, use stuff off a Ford. I've had this stuff from speedway since March 2015, painted parts etc. so they won't take it back. Why does education have to cost me so much time and money ! I'm just hoping that a match will work to match my GM front end-spindles, calipers etc. Most likely not but I'll try. Gotta have brakes on all 4'S.
Brake calipers are made by a few companies ------the fronts aren't the problem
its the rears and balancing them so they don't lock up since the weight transfer/etc is toward the front so they must reduce the rears--and this causes a problem then with trying to get enough brake force for a park/emergency brake on the rears--so the best out was to go to mech shoes for park/emergency brake and a smaller caliper than the front on a disc for the normal brake--butttttttt, disc brakes take more pressure to work so all of them are boosted-now on bigger cammed or supercharger/etc engines lack of vacume!!!!!! so , diesels have some engine driven vacume pumps and some other vehicles use hydraulic pressure from power steering-goes back to Mk3 Lincolns 69-70s--------
There is a few pics of the Mustang hydroboost in some pics on my gallery for a 32 Ford I build for customer
http://www.clubhotrod.com/photopost/...VC-626F_1_.JPG
http://www.clubhotrod.com/photopost/...VC-626F_1_.JPG
hope this is visable
Awful small, Jerry
Click it in post #92---------
Update Starting with basics, increasing the ratio means rebuilding the brake mount.
I very well may end up with booster of some sorts as Jerry has suggested but this is my 1st step.
I'll have a longer pedal with a shorter arm connected to the push rod. Going from 5:1 to 8:1 ratio.
This will help but I know it isn't going to fix the entire problem.
http://i990.photobucket.com/albums/a...psu0lukhnj.jpg
one of the reasons I was reluctant to do this was because of the lines that I'll have to replace now. $#it happens.
http://i990.photobucket.com/albums/a...psnv0yb2i0.jpg
Went to junk yard and got complete brake setup off a Ford Explorer and will test this system before any painting ect. pic's of the new/old set and the Explorer stuff. http://i990.photobucket.com/albums/a...pser2n0t79.jpg
http://i990.photobucket.com/albums/a...psft4ygwn1.jpg
$85. for both sides vise $450 I spent on the new stuff that doesn't work for my app.
No-good, bad and ugly !! That's the results of changing out the bakes system to to the Ford Explorer disc brakes.
No difference in the way the brakes act. Only stops the rotors from spinning ( barely) when I hit 900 + psi and that's lots of pressure on the pedal. I even went and by-passed all the valves etc.
Jacked the front up and just a light touch of the brakes and they lock up hard ( can't turn by hand ) with under 100 psi showing. The Explorer calipers have a smaller piston than the GM calipers I thought that would make a difference but no.
2 sets same results means its got to be ?
Master cyl. 2 new ones ( disc/ disc ) have been tried 1 " and a 1.125" bore not much difference
Power booster works as tested and with out vacuum connected its very hard to hit 500 psi.
No air in system bled the system twice no air bubbles using power bleeder lots of fluid flow.
Changed the ratio on the pedal still no go.
Slight toe pressure on my 2500 dodge brakes begins to slow it down and that weights 7000 lbs. and this
won't even stop just the spinning rotors.
An the winner is ? I don't know but my ears are open.
I always wonder if I needed bigger line going to the rear, usually one line for 2 calipers. Jonathan
1" bore Corvette MC with double diaphragm 8" booster. It MAY be a 1 1/8. Sorry, I can't remember for sure. Vacuum is high. 18+ inches.
2 pound residual valves front and rear.
Adjustable proportioning valve set to max pressure (not needed)
Stock Ford brake pedal (7 or 8 to 1 ratio)
80's Thunderbird front calipers on Chassis Engineering brackets. Granada rotors.
Explorer rear brakes. Just like the ones you have.
OK. I remembered a few things while on my way to work.
The MC is a 1" bore. I wanted to change it to a 1 1/8" last year before we did the Power Tour, but couldn't find one with the correct port setup.
I started out with an 8" DD booster, but it failed and I replaced it with a 7" DD unit that I had in the shop. So the current unit is 7".
The lines are 3/16" and I'm using -3 braided stainless hoses at all 4 corners.
The pedal travel is pretty long with the stock pedal. That is the reason I wanted to go with the larger MC, but the brakes work fine and the pedal effort is very light.
Navy, I feel your pain, I was hoping to hear all was good this time around.
JMO, but the only thing left that you have not changed out is the the line to the rear itself. Is it possible the bends or something else is restricting the rear line?
This has probably been mentioned before. Assuming the same pressure on the pedal and the same pedal ratio, a smaller bore master cylinder gives more pressure, but takes a longer stroke to move the same volume of fluid. A 7/8" bore will give 1.7 times the pressure of a 1- 1/8" bore, and 1.3 times that of a 1" bore.
Navy, My front calipers have a 2.358 bore and the rears have a 1.886 bore. That alone may contribute to my success. They just aren't that different in size.
I wanted to go to a larger MC to reduce the pedal travel. With my high pedal ratio and a booster, I could afford the increase in pedal effort.
I still would call Master Power Brakes and go over your system with them, it will only cost a phone call. I still am a firm believer in swapping known good for known bad, pull off one rear caliper and one front and swap them, put a socket in if you want to simulate the rotor if they won't bolt to the brackets, neither of these will cost a dime, and will tell you if its a valving or line issue (backwards RPV?). Just my two cents worth that I have mentioned long ago, I am sorry for your trouble but throwing money at it is something I have done before as well and it is not always the solution, could be your old calipers where fine.
what is that object marked cpp? in the photos
Classic Performance Products Adjustable Proportioning Valve w/ Brake Light Switch:
Adjustable Proportioning Blocks With Brake Light Switch
Look at the second picture down on Speedway's ad to see the logo side.
I agree.Quote:
Originally Posted by Matthyj
Roger Thanks----I knew it was a cpp valve, issue with it is that it doesn't apply pressure to the rears first before the fronts-------OEM combo valves have a feature where initial pressure is applied to rears before the fronts. Without this I don't believe that the oem rear calipers will work properly which will inhibit them from auto adjusting the parking parts------
That valve is strictly a junction block to include the stop lite switch and the rear prop valve-does not satisfy the requirements for a street system.
Navy-I noticed in your pics that you ran a rod from your shifter to a pivot toward the rear of trans and then another forward to the shift arm-----good thinking to keep the geometry correct for trans/shifter notches-I did that on a car I built for a customer and the paint shop outfit left if off when putting body/frame back together---and then--------Also they sent out the polished stainless exhaust headers/side pipes(Cobra type) and had the powder coated a lite grey------------
Also I noticed on the pic of your brake pedal that you not only had an arm at a wierd angle and length but that you had shortened the foot arm by 4 or 5 inches?????? Both of those effect your leverage tremendously but also both arms are on the same side of pivot and would have extreme geometric moment of force ---------
I had originally shortened the foot pedal for fitting in the cab, I have returned it to its original length and lowered the pivot point to allow its use as such . The arm angles are due to the firewall/toeboard angle.
I'm going to the junk yard and get a combo valve and see what effect it has. I'm going to call the brake co. and see what they say or don't say.
Thanks to all that are giving me input.
at the junk yard see if they have Mustang hydro boost(power steering) brake system. don't know what all years but 2000-04 for sure-------since you have power steering------
That valve is available in a stand alone version called a hold off valve. It plumbs into the front brake circuit and prevents any pressure from getting to the front calipers until a preset pressure is reached. I've seen 100 psi listed.
Here are some links
ECI Hot Rod Brakes and Brackets Brake Facts
Brake Metering-Hold-Off Valve
I have one on my T-bucket, but not on my 46.
too many mods and stand alone parts being used-------use a OEM type combo valve with a master that has residual valves build into ports and problems will go away-assuming that leverage ratio / geometry is correct on pedal.
Jerry, I would agree, but most disc master cylinders intended to be mounted on the firewall don't have residual valves in the ports. They aren't needed when the MC is mounted above the axles.
If the MC has removable seats in the ports you may be able to add them, though. The hard part would be locating the individual residual valves. I can remember when they were sold in parts houses.
A factory style combo valve would be great if it didn't have a proportioning valve in it. Finding a factory valve with a fixed prop valve that would work in a custom installation would be a crap shoot at best.
I think you have a couple ideas backwards------disc brakes need 2 lb valve to keep pads near disc-and masters have them----combo valves don't have proportion valves -they have the front delay valve-OEM systems are designed as needed to be without proportion valves-hotrodders and racers create that need with either race braking needs or in the case of street rodders the big/little tire deal crated imbalance the system wasn't designed for
Somehow whole thing didn't post---------With a OEM type combo valve ( for street/road driving/braking) you shouldn't need a separate additional proportioning valve unless your caliper size/ disc diameters are why out of balanced size--again the big/little tire sizes really compound area for improper components.
Sorry Jerry, some may not have one, but the classic definition of a combo valve is that it has a prop. valve.
https://www.mpbrakes.com/techtalk/co...-brake-systems
The Combination Valve - How Master Cylinders and Combination Valves Work | HowStuffWorks
Brake Combination Valve Function
All I know is that when this is done and over we'll all be a bit smarter about putting 4 wheel disc brakes on a street rod. Here's a pic of my pedal after changes.
http://i990.photobucket.com/albums/a...pshilslouu.jpg
thanks again for the post !
Just curious, and I may be wrong, but could you have changed the point of attachment at the travis rod and added the leverage needed without modifying the pedal arm?
Today I called Power Master Brakes, here's what the tech had to say
Don't need any kind of proportioning valve
Power brakes should have a pedal ratio of 4 to 1
Manual brakes should be 6 to 1
My calipers will always be a problem, and who ever sold them to me was incompetent.
IMHO the only one who is incompetent is the tech at PMB.
and a larger diameter disc
In my case the discs are very close to the same size, so no advantage. The point I was trying to make is that in many cases, street rods are built using what parts are available or will fit. That doesn't mean they are going to work together.
In the case of GM metric calipers, typically they have a 2.496 bore in the front. The rears can range from about 1.88 to over 2". Choose the wrong bore and you can wind up with a situation that has the front brakes stopping the car, while the rears never do much of anything. If the fronts are too much larger than the rears, the line pressure required to allow the fronts to stop the car will be too low to allow the rears to offer much clamping force. In most cases, you're never going to want more braking on the rear that the front, but you do want a relationship that allows complimentary action. Bore size, for me, is just a convenient way to compare.
My Ford calipers are actually closer in bore size than some combinations of GM parts. I agree that area is a probably a better description, but bore size will work as long as you understand that bore size will determine area.