Vintage Mustang Forums banner

1 - 20 of 26 Posts

·
Registered
Joined
·
3,999 Posts
Discussion Starter #1
It's not that I don't like the way it works when it's working and not leaking. I like the way it prevents nose dive and all but I'm replacing it every year. Another commie 100% failure rate part. Always starts leaking from the safety switch. Read reviews from NPD to Amazon and its the same story because its the same commie valve. I thought a cooked my rear brakes a couple weeks back as brakes were acting funny. Upon inspection they didn't look too bad. At yesterday's autocross I had all kinds of brake weirdness but still a firm pedal. Today I found the leak.

I guess I should try the Wilwood manual proportioning valve to the rears? It's not really a street car but I really don't want to add adjusting brake bias to the days racing surface and temperature to the long list of things I'm already clueless on! Genius me hid the valve in the most impossible spot to get to with the engine in the car.

762597
 

·
Premium Member
Joined
·
11,796 Posts
I guess it is safe to assume you have a dual piston MC so I'd deep six the combination valve. Use a T to split the line going to the front brakes, L and R. Put your PV in the line to the rear brakes. I see you have an RPV in the rear line. I'd leave it out witth only the PV for trial purposes. If you find the rear brakes work fine with the PV only then don't bother installing the RPV.
 

·
Premium Member
Joined
·
3,046 Posts
Any way you can pull the switch and just plug the hole?
 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #4
I guess it is safe to assume you have a dual piston MC so I'd deep six the combination valve. Use a T to split the line going to the front brakes, L and R. Put your PV in the line to the rear brakes. I see you have an RPV in the rear line. I'd leave it out witth only the PV for trial purposes. If you find the rear brakes work fine with the PV only then don't bother installing the RPV.
I just ordered the valve from Amazon and it will be here tomorrow! Wilwood Disc Brakes I'm going to reuse the original distribution block with the rear port plugged for the fronts. I'm thinking of mounting it far left under the dashboard so I can adjust it from the drivers seat. Too old to climb out of the #[email protected]%^ racing seats as it is! I'm going to leave the RPV in place I think because it works or doesn't harm anything. I'm going to have to remove the MC, booster, and probably the clutch master cylinder to get the job done as it is.

Any way you can pull the switch and just plug the hole?
It is my understanding is that switch part of the combination valve is supposed to be dry unless the valve is leaking internally. And my brakes have gone funky.
 
  • Like
Reactions: Redneckgearhead

·
Registered
Joined
·
3,380 Posts
A combination can't prevent brake dive any more than a shock can prevent body roll. All it does is slow front brake application, brake dive will be dictated by suspension geometry, wheelbase, CG height (weight transfer), and deceleration rate ( G's ).
 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #6
A combination can't prevent brake dive any more than a shock can prevent body roll. All it does is slow front brake application, brake dive will be dictated by suspension geometry, wheelbase, CG height (weight transfer), and deceleration rate ( G's ).
Not sure that your statement is in line with other sources I have read recently, but since it is a "cough, cough" race car now we will see what the manual valve brings. I hope I can figure out a way to mount it inside so I can continually back it off until I don't spin out in every corner next weekend! It is the Hoosier Challenge after all, and that's a big deal to us country bumpkins!;)
 
  • Like
Reactions: Redneckgearhead

·
Premium Member
Joined
·
11,796 Posts
I hope I can figure out a way to mount it inside so I can continually back it off until I don't spin out in every corner next weekend!
Don't become so distracted by trying to adjust the PV that you run off the track and wreck the car!
 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #8
Don't become so distracted by trying to adjust the PV that you run off the track and wreck the car!
Noted! Given that Grissom AFRB is the only thing going now due to the virus, I'd hate to launch it off the "hill", former artillery bunker. I saw it happen last last year and it wasn't pretty. Something about a new Mustang and "ice mode"?
 

·
Registered
Joined
·
3,380 Posts
Not sure that your statement is in line with other sources I have read recently, but since it is a "cough, cough" race car now we will see what the manual valve brings. I hope I can figure out a way to mount it inside so I can continually back it off until I don't spin out in every corner next weekend! It is the Hoosier Challenge after all, and that's a big deal to us country bumpkins!;)
Oh I've read that too, that doesn't mean it's correct. If it does anything, it would just slightly delay brake dive. But as we know, most braking force is generated by the front brakes, so there's only so much the rear can do when it only contributes 30% or less to braking.
IMO the delay is more about getting rear drum brakes to apply in concert with the fronts, due to the greater travel/fluid they require.
 

·
Registered
Joined
·
861 Posts
Since hydraulic fluid does not compress, the length of the line to the rear brakes should not be a significant factor.
 

·
Registered
Joined
·
3,380 Posts
I didn't mean travel as in length of brake line, I mean't drum brakes have more "take up" travel than disc brakes.

Reading more, I think I see what they mean about brake dive is during "normal" street light brake application. With disc/drums you may effectively only have front brakes on initial or very light brake application, the combination valve would bring the rears in to play, providing braking with minimal dive ( or rear "lift" ). So I can see the logic on that point, I always think of things from a performance angle, as in moderate to hard braking :)
 

·
Spammer Hammer
Joined
·
9,661 Posts
This is why it is imperative that for those whom track their cars (I.e. don’t do a whole lot of backing up which adjust the rear shoe pressure) check and adjust the rear shoes before every event. I learned this a couple years ago from the vintage race guys. This will almost certainly eliminate severe pedal travel prior to rear shoe engagement.
 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #13
This is why it is imperative that for those whom track their cars (I.e. don’t do a whole lot of backing up which adjust the rear shoe pressure) check and adjust the rear shoes before every event. I learned this a couple years ago from the vintage race guys. This will almost certainly eliminate severe pedal travel prior to rear shoe engagement.
I have the car on the lift between weekends rotating the tires and such and always adjust the rear drums until they drag a little. The only backing up I do is off the trailer and onto the lift.

I got the old, err new, combination valve off and got the original block installed for the fronts to MC. I'm bleeding a lot from my arms as I type. What a pain! I'm going to mount the manual proportioning valve under the dash under the cig lighter. that lets me run the lines through the abandoned throttle rod hole. I have a 2 day event next weekend and this going to be a quick and dirty, but safe install. I love that NiCopp brake line!
 

·
Registered
Joined
·
5,955 Posts
This is why it is imperative that for those whom track their cars (I.e. don’t do a whole lot of backing up which adjust the rear shoe pressure) check and adjust the rear shoes before every event. I learned this a couple years ago from the vintage race guys. This will almost certainly eliminate severe pedal travel prior to rear shoe engagement.
Damn, I'm glad I know you... ;)

Great information!

Allen
 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #15
Is it a race car if you can adjust the brake bias from the drivers seat?
763019


All I did was swap the combination valve for the adjustable proportioning valve and now I've got the long travel brake pedal that I hear so much about? I pressure bleed a gallon of brake fluid through the system and the MC has check valves that work. I'll get the better half out in the garage tomorrow and bleed it the old fashion way.:eek:
 
  • Like
Reactions: Badbenz94

·
Spammer Hammer
Joined
·
9,661 Posts
Install some Earl’s solo bleeders. They are awesome.

 

·
Registered
Joined
·
3,999 Posts
Discussion Starter #17
Install some Earl’s solo bleeders. They are awesome.

763021


Scratching my head on how that could work!
 

·
Premium Member
Joined
·
3,046 Posts
View attachment 763021

Scratching my head on how that could work!
I believe that when you loosen the bleeder, you get a gap between the brass seat and the threaded part, push the brakes and the pressure overrides the spring pressure and allows the fluid and trapped air to escape, as soon as the pressure in the system drops below that of the spring the spring seats the brass back on the seat in the caliper/wheel cylinder not allowing the air to be sucked back in.... maybe I'm crazy....
 

·
Registered
Joined
·
4,508 Posts
I use a clear rubber hose (~3 feet, thinnest that will fit over a nipple) in a jalopeno jar (tall and skinny) with a hole punched in the lid so the hose is kinda held tight. The hose is stored in the jar which contains the mess. The hose is ends in an inch of fluid. It is a simple one person system. I've tried everything in my time under cars and have landed on this system for the last 10 years. It Always works. If you know a nurse or someone with an asthma nebuliser ask them to give them for the old hoses (replaced regularly). They have a plastic nipple that is perfect but otherwise just using clear rubber tubing from Lowes is great for watching the air. I start with the left front so I can actually watch the tube since its long enough to put the jar at the door. Its especially good for replacing the fluid (which I do every time I open the system) - you can see when the clear fluid is coming out. The rest of the wheels, I pump 5-10 times then go check to see if there are bubbles in the tube. If so I do another 10 pumps till the hose is completely full of bubble free clean fluid. The key is to just crack the valve about a 1/2 turn, if you open it too much it pulls air around the threads. I put a box end wrench with a half turn clearance on, then the tube so I can close the valve quickly without removing the tube. I can usually do a system with half to 2/3 of a quart of fluid. I always use a new sealed bottle for a fluid replacement and save open bottles for top ups since the fluid absorbs water from the air.
 
1 - 20 of 26 Posts
Top