2 years chasing low pressure at the caliper...

[Dana67Dart]

i literally took the block out tonight and checked it, front and rear aren't connected and it's drilled properly.. and i should get rid of my prop valve to pay another 80 to 120 to add a prop valve? not arguing with you, just doesn't make sense

You have a system that was not working. You removed a part and replaced it with a different part and now it is working. That says to me the part you removed AND the only part in your system you hadn't changed several times was the issue.

Leave the "t" and the adjustable proportioning valve and drive it.

My reasoning for change the t etc is that down the road you can go into a parts store and get parts for a 73 Dodge dart with disk brakes and all the parts will bolt on. No remembering, no modifying.

 

[Icetech]

You have a system that was not working. You removed a part and replaced it with a different part and now it is working. That says to me the part you removed AND the only part in your system you hadn't changed several times was the issue.

Leave the "t" and the adjustable proportioning valve and drive it.

My reasoning for change the t etc is that down the road you can go into a parts store and get parts for a 73 Dodge dart with disk brakes and all the parts will bolt on. No remembering, no modifying.

I haven't replaced anything yet, i took the block out to make sure it wasn't made wrong or had issues... new parts are coming on friday.. drdiff also says to do it the way i have it setup... it's not a big deal, will get it figured, just annoying right now.

 

[Dana67Dart]

I haven't replaced anything yet, i took the block out to make sure it wasn't made wrong or had issues... new parts are coming on friday.. drdiff also says to do it the way i have it setup... it's not a big deal, will get it figured, just annoying right now

I thought your post said you did but looking back i see you were quoting someone else's post.

I would take that posts info and duplicate it.

Easy test.

 

[Dave999]

two types banjo bolt/banjo end pairings
those with the fluid passage in a deep groove in the banjo
those with shallow or no groove in banjo and an necked in section in the bolt
(there may even be some with a combo of the two depending on intended use, fuel supply etc)


if you use fat bolt with shallow banjo
brakes don't work very well.

could be a problem if you fit metric calipers on a car with a imperial brake pipe
you have to use metric banjo bolt and it may in some cases not pair well with the orginal banjo end on the pipe... or you get some funky new pipes and the manufacturer can get the banjo bore and OD right but seems to have thought you owned a nissan audi or toyota when it comes to their configuration in respect to fluid path.

i.e mix and match toyota and mopar and have problem

you of course do not have to use banjo/bolt connection, if you get slightly longer lines, and the correct copper washers, and pay attention to routing, and pipe movement at full lock, the pipe can screw directly into caliper. you may have to experiment to achieve this, if it was not the orginal design for the brakes

there were both types, banjo or direct into caliper available for mine with appropriate hardware, so i went with the pipes with fewer parts

https://www.ebay.co.uk/itm/177776669487

see how some neck down and some don't... need right kinda banjo for your banjo bolt

Dave

 

[CFD244]

Following.

 

[66fs]

I don't think I have ever used banjo bolts that come with rebuilt calipers. I always use the original hardware. The Chinese can't figure inch stuff out. I bought rear brake cylinders that were tapped 1/4-20 and supplied with metric bolts (which went in the trash). Same goes for flex lines. I'm thinking the Banjo bolts may be your problem. Pretty sure you have tried everything else I could think of.

 

[1MeanA]

Can we see a detailed pic of the banjo bolt fittings

 

[Icetech]

K.. i have tried 2 types of banjo bolts, they may be metric thread, may not.. i don't get hung up on metric or imperial. as long as it's the right thread it will work. Have tried 2 types of banjo hoses also.. one a more factory type and one that drdiff sells...

here's pics of it all.

BTW... tried a T tonight and as expected it did around 700 really standing on it (should be 1200-1500)

also, the factory style has the smooth inside that would need the shouldered down bolt.. the one that's on the car now has a groove inside the banjo to allot fluid through either type of bolt..

 

[Icetech]

Soo.. after testing again tonight i modded the brake pedal some more.. I now have a 8.9:1 pedal ratio... I should now be able to do 1400 at the MC maybe more.. so... will see.. now supposed to exceed 1200 but just seeing how it goes

 

[Icetech]

just did the math.. 100lb on the pedal should give me 1500 at the MC

 

[Icetech]

btw, love b-bodies.. can pull the pedal box in like 10 mins.. would be faster if i had someone to hold nuts on the firewall side

 

[YY1]

I don't see the passage in that banjo fitting.

 

[1MeanA]

I don't see the passage in that banjo fitting.

It does not look like there is one. He will need to measure the location of the groove in relation to the port in the fitting. It would be odd if they do not work together but you never know.

 

[Icetech]

I don't see the passage in that banjo fitting.

i'm not using the one posted, i had just tested with it, the hole is where the hose comes into the fitting, and the bolt has room for the fluid to flow...

I now get 900psi at the caliper if i stand on it.. still not great but at least drivable.. Took it for a quick ride and they "work" but i need to get a better bleed done, a bit spongy so a couple of pumps to get a good bite, promising though.. still stupid to go through all this and not be able to fix the actual problem...

I do need to dogleg the brake pedal a little more, it's bout 1" too high and i catch it with my foot..

 

[Icetech]

It does not look like there is one. He will need to measure the location of the groove in relation to the port in the fitting. It would be odd if they do not work together but you never know.

Last time i had it apart i checked that and they line up fine. it's working for now.. hope it gets a little better when the pads break in a bit

 

[MobileCustoms]

At least you're getting closer to driveable!

 

[jos51700]

Other thing to note is DOT5 has higher compressibility than DOT3/4. You have to work harder to get the same fluid pressure.

Um, no.
That's not how hydraulics work.
Not even close.

 

[MV8]

YES, Goldduster318 is correct, but it isn't enough to be a primary consideration in a brake system. How much goes up with pressure and fluid volume.

I think the breeze master with the ratio modded pedal travel is probably at the end of it's travel with full pedal pressure. Can check where that is with open bleeder.

Looks like the ABS Breeze master which doesn't have traditional compensation ports, but that shouldn't matter.

 

[8formulas]

So at the end of the day, what was the problem?

The brake pedal? The M/C?

 

[goldduster318]

Um, no.
That's not how hydraulics work.
Not even close.

You will have to move the master cylinder further with DOT5, even in an incremental state. And yes, it does have some compressibility, its also never 100% free of air or water in any of our cars. Since you don't believe me, please read the following excerpt from SAE:

Compressibility

This is not a specific DOT call-out, yet it is critically important to racers and enthusiasts. SAE J1705, Appendix A, A.2.2.8, states “Air Solubility – It has been reported that dimethyl polysiloxane fluid, which is a major part of silicone-based, low water-tolerant type brake fluids can typically contain dissolved air at a level of 16% ±3% by volume at standard temperature and pressure. This compares with a typical level of 5% ±2% by volume of dissolved air for glycol ether based type fluids. An increase in brake pedal travel may be experienced under severe operating conditions, especially at higher altitudes and high temperature conditions. "The term “dissolved air” (air absorbed from the atmosphere) should not be confused with the term “entrapped” or “free air” since their effects on brake system performance can be entirely different. Air that has been absorbed from the atmosphere does not result in an increase in fluid or system volume, whereas entrapped air or free air does occupy system volume and can be easily compressed when force is applied to the system.“ The SAE standard continues, “A.2.2.8 – Compressibility – Silicone based brake fluids are more compressible than conventional brake fluids and the difference is magnified at higher temperatures.” Silicon-based brake fluids are described by DOT 5 (not to be confused with DOT 5.1), which should never be used in a racing vehicle due primarily to its compressibility.

You want the least compressible fluid possible in the system. To make it clear, DOT5 is Silicone fluid and DOT 3 or DOT 4 is Glycol ether fluid. This is the reason why I would never recommend it in a "marginal" design system without a booster like in one of these cars.

Nobody should "need" an 8.9:1 pedal ratio. Eventually the pedal will hit the floor, especially if there is a leak. It's still an input/output force ratio.

Locking pressure on most modern cars is around 1500 psi, I'm expecting at least slightly less on one of these systems. If 900 psi will lock the wheels then fine.

 

[Icetech]

So at the end of the day, what was the problem?

The brake pedal? The M/C?

No, still have no idea what the issue was.. a normal manual brake pedal ratio is 6:1 i raised mine to pretty much 9:1 which is crazy.. so now i make 1400-1500psi at the MC and only 900 at the caliper...

at 1500psi the tires should be locking up easily, it still wont panic stop but it is drivable now at least. i just hate that it's not right, especially when everything in the system it correct..

 

[Icetech]

Nobody should "need" an 8.9:1 pedal ratio. Eventually the pedal will hit the floor, especially if there is a leak. It's still an input/output force ratio.

Locking pressure on most modern cars is around 1500 psi, I'm expecting at least slightly less on one of these systems. If 900 psi will lock the wheels then fine.

nope.. will not lock the wheels... but it will actually stop without making me need to change my shorts... and i agree.. the ratio is nuts but i am out of ideas for now. I have to get the motor out in the next week so i can prep the new one to go in..

 

[8formulas]

OK, thank you. I'm learning a lot here. Please keep us posted.

Thanks and good luck.

 

[philthyphil]

Waiting for a reply to see if anyone else has had experience with a Right Stuff Master cylinder. My brake pedal is spongy and low and fades,did same as Icetech as far as throwing parts at it

 

[Icetech]

my brake ordeal is on hold while i get the new motor done.. hope to have it moving again in 2 weeks or so