800psi enough for manual disc brakes ?

Posted By: Uhcoog1

Re: 800psi enough for manual disc brakes ? - 08/27/12 04:14 AM

What pads do you have on the car?

Normal "street" pads have a coefficient of friction of .3-.4. Race pads might have as high as a .5-.6, almost doubling the friction, which almost doubles the stopping with the same pedal pressure/ line pressure. Keep in mind some may not have a good coefficient until warmed up.

It is definitely worth finding out what the coefficient of friction of your pads are, though I agree that 800 is low.

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 08/27/12 12:05 PM

Quote:

What pads do you have on the car?

Normal "street" pads have a coefficient of friction of .3-.4. Race pads might have as high as a .5-.6, almost doubling the friction, which almost doubles the stopping with the same pedal pressure/ line pressure. Keep in mind some may not have a good coefficient until warmed up.

It is definitely worth finding out what the coefficient of friction of your pads are, though I agree that 800 is low.

Thanks for the response Wade. To answer your question ; the brake set-up currently has whatever SSBC provides with their conversion package and there's not much information on their website. I suspect that the pads are nothing special....

I've purchased a set of Hawk HPS pads and will have the rotors resurfaced a few thou for cleanup before reassembly but want to address the low line pressure as well.

Ron

Attached picture 7352384-BPMM-446-1.jpg

Posted By: Uhcoog1

Re: 800psi enough for manual disc brakes ? - 08/27/12 07:57 PM

As stated above, you could also go with a smaller diameter MC. The amount of foot pressure required is a result of both the pedal ratio and the MC piston size; there is no real advantage to one over the other. The calipers won't care which one you change to get more leverage. That's assuming your pedal wasn't close to bottoming out as-is?

Posted By: BrianShaughnessy

Re: 800psi enough for manual disc brakes ? - 08/28/12 01:12 AM

Ron,

If you can pull a pad out and check for any codes on the back you can probably figure out what they sent by googling.

Aerospace sent dirt track racing pads with their rear disk kit... they made horrendous noise and absolutely sucked on the street. I changed them out for Hawk HPS also. Much better.

Posted By: hooziewhatsit

Re: 800psi enough for manual disc brakes ? - 08/29/12 04:55 PM

check out this thread to figure out the best way to improve your line pressure. Lots of good stuff there.
https://board.moparts.org/ubbthreads/show...e=4#Post7210853

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/03/12 09:53 AM

Thanks for the feedback so far

I've looked at the pedal ratio and taken some measurements ; the pedal ratio is 6:1 which seems OK from what i've been reading

I was mistaken in my previous post about lowering the pin on the brake pedal when the conversion from power to disc was completed several years ago. I did have to enlarge the brake rod hole slightly for the adjustable pushrod hardware but the hole is still in the original location and the pedal ratio is intact.

Next step is going to to be installing the guage directly to the output port on the master and measure line pressure there. This will at least confirm that there are no issues downstream of the master. At this point there is a linelock between the master and calipers so it's possible that the issue lies there but it doesn't seem likely.

Ron

Posted By: Uhcoog1

Re: 800psi enough for manual disc brakes ? - 09/03/12 01:14 PM

Do your lines still go through the factory distribution block?

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/03/12 01:39 PM

Quote:

Do your lines still go through the factory distribution block?

No sir....the rear (large) chamber from the master is plumbed into the Hurst linelock and from there the left and right calipers are plumbed in. Using the Hurst unit as a "T" because it has multiple discharge ports. The factory distribution block was deleted.

Rear brakes go directly to an adjustable proportioning valve that has a residual pressure valve installed.

All brake lines, hardware, wheel cylinders are new.

Thanks, Ron

Posted By: Supercuda

Re: 800psi enough for manual disc brakes ? - 09/03/12 03:15 PM

Quote:

Quote:

Do your lines still go through the factory distribution block?

No sir....the rear (large) chamber from the master is plumbed into the Hurst linelock and from there the left and right calipers are plumbed in. Using the Hurst unit as a "T" because it has multiple discharge ports. The factory distribution block was deleted.

Rear brakes go directly to an adjustable proportioning valve that has a residual pressure valve installed.

All brake lines, hardware, wheel cylinders are new.

Thanks, Ron

Can I ask why you plumbed it like that?

Posted By: Supercuda

Re: 800psi enough for manual disc brakes ? - 09/03/12 06:13 PM

Quote:

Sure ;

The stock distribution block was designed for 4 wheel drum setup and i was told it would not work with a disc/drum conversion

That would be correct

Quote:

with no residual pressure valve.

There is no, and never has been, any residual pressure valve in any stock MoPar distribution or combination valve. Whomever told you this doesn't know MoPar braking systems. In a stock system, all drum or disc/drum, the residual pressure valve is located under the brass seat in the master cylinder exit port(s).

Quote:

I did install a residual pressure valve after the adjustable proportioning valve as recommended by Wilwood with their tandem 1in bore master cylinder.

I do not know how Wilwood builds their stuff, but if they gave you the advice on how to plumb this setup they are pointing you in the wrong direction. It would be ok if is were all disc, or all drum, but for a disc drum combo you need more than just an adjustable prop valve in the back.

Quote:

The linelock is needed for racing so it was installed at the time the front brakes were converted over using the SSBC Force 10 Kit.

Thanks, Ron

The problem with aftermarket brake kits is that the engineering is only as good as what they want. You mix and match manufacturers and both will point to the other as the fault. Sounds like you need a smaller bore M/C and a real combination valve in place of your current plumbing.

Posted By: BergmanAutoCraft

Re: 800psi enough for manual disc brakes ? - 09/03/12 07:28 PM

You can play with this as much as you like. The bottom line is manual brakes + multi piston calipers = no brakes. Wilwood and SSBC are my two least favorite manufacturers for brakes. I love the PBR mustang stuff because it's OE quality and was designed for a car of similar weight/bias as our cars. I understand smaller wheel and tire combos complicate things. If you are dead set on man brakes, go back to a factory combo with an aggressive pad.

Posted By: AndyF

Re: 800psi enough for manual disc brakes ? - 09/03/12 07:49 PM

Quote:

Thanks for the feedback so far

I've looked at the pedal ratio and taken some measurements ; the pedal ratio is 6:1 which seems OK from what i've been reading

I was mistaken in my previous post about lowering the pin on the brake pedal when the conversion from power to disc was completed several years ago. I did have to enlarge the brake rod hole slightly for the adjustable pushrod hardware but the hole is still in the original location and the pedal ratio is intact.

Next step is going to to be installing the guage directly to the output port on the master and measure line pressure there. This will at least confirm that there are no issues downstream of the master. At this point there is a linelock between the master and calipers so it's possible that the issue lies there but it doesn't seem likely.

Ron

Checking with the pressure gauge is a good idea so you're on the right path. A 15/16 bore master cylinder might do the trick for you. If you have 15 inch wheels then you really should put a larger rotor on there.

An 11 inch rotor for a 4000 lb car is just asking for trouble. No one would design a system like that anymore. Go visit a car lot and look at 4000 lb cars with 300+ hp engines. They'll all have 13 inch or 14 inch rotors.

Posted By: feets

Re: 800psi enough for manual disc brakes ? - 09/04/12 06:25 PM

Quote:

You can play with this as much as you like. The bottom line is manual brakes + multi piston calipers = no brakes.

I don't know what you've been smoking but it's time to put it down.

The hot rod has manual brakes with 8 piston calipers up front and 4 piston calipers out back. The master cylinder is a manual unit off a 1981 D150.
Judging by your statement with 24 total pistons in the system you'd think I'd accelerate when I hit the brakes.

Rest assured that my brakes are the best they've ever been and are on par with any good non-electrically assisted/manipulated brakes on Moparts.

A manual master cylinder works great with fixed or sliding calipers. The type of caliper makes no difference. It's simple physics. You're making hydraulic pressure. As long as the master is properly sized and has the proper pressure applied you are going to get the correct line pressure.

Posted By: HPMike

Re: 800psi enough for manual disc brakes ? - 09/04/12 09:27 PM

Quote:

Quote:

You can play with this as much as you like. The bottom line is manual brakes + multi piston calipers = no brakes.

I don't know what you've been smoking but it's time to put it down.

The hot rod has manual brakes with 8 piston calipers up front and 4 piston calipers out back. The master cylinder is a manual unit off a 1981 D150.
Judging by your statement with 24 total pistons in the system you'd think I'd accelerate when I hit the brakes.

Rest assured that my brakes are the best they've ever been and are on par with any good non-electrically assisted/manipulated brakes on Moparts.

A manual master cylinder works great with fixed or sliding calipers. The type of caliper makes no difference. It's simple physics. You're making hydraulic pressure. As long as the master is properly sized and has the proper pressure applied you are going to get the correct line pressure.

Really shouldnt have any bearing on whether or not the car can effectively be stopped. Ive built many cars with manual discs and have no problem..

MB

Posted By: AndyF

Re: 800psi enough for manual disc brakes ? - 09/04/12 09:36 PM

I agree. I run manual brakes with 13 inch rotors and Viper calipers on my B-body car and I can launch a passenger thru the windshield if I stomp on the brakes. It is a simple late model aluminum master cylinder. My setup is plumbed just like the OP description. Line lock up front and a prop valve to the rear drums. Nothing else in the system.

Posted By: feets

Re: 800psi enough for manual disc brakes ? - 09/04/12 11:51 PM

The master I use is the modern style aluminum piece straight off the truck in the junkyard years ago.

I do have a twiddly knob style valve in the rear lines but it didn't need any twiddling when I upgraded to the larger brakes.
I can roll on the brakes and increase pressure until they lock. The rears lock just after the fronts. It takes a little pressure to get to that point but you don't have to stomp on them.
It's a really nice setup.

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/07/12 12:07 AM

Well, some progress was made

Spoke with several people bouncing ideas, theories and such to see if we could figure out what is happening.

Dwayne Porter my engine guy suggested that something was limiting piston travel in the master cylinder. He theorized that if the rear brakes were hydrolocked somehow that it would not allow the front brakes to develop enough pressure. That got me thinking

HP Mike spent some time on the phone with me and outlined what has worked well for him. One thing Mike stated about proportioning valve adjustment provided another clue. Thanks Mike

The tech at Wilwood's only comment was that 800psi was plenty ; "what's the problem"

The freakin car won't stop with me putting 300lbs of pressure on the pedal...that's the problem ! So i asked about adjusting the proportioning valve and whether or not that would have any effect on front brake pressure. His reply ; Absolutely not...they are independant systems.

So, on a hunch....i backed the prop valve off completely and Bingo....1200 psi to the front caliper !

So for anybody who thinks that the prop valve has no bearing on front brake line pressure....i'm here to tell you otherwise.

I have to thank Dwayne and Mike for steering me in the right direction.

New pads are installed and i have to rebleed the sytem and will use the gauge to adjust the prop valve for 600psi rear brake pressure and see what happens. While pulling the back wheels i found a broken Strange 3in wheel stud and need to get that fixed as well.

A further update will be forthcoming once i can test it out but it's looking much better...i'm cautiously optimistic

Ron

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 09/07/12 01:58 AM

Quote:

An 11 inch rotor for a 4000 lb car is just asking for trouble. No one would design a system like that anymore. Go visit a car lot and look at 4000 lb cars with 300+ hp engines. They'll all have 13 inch or 14 inch rotors.

Funny you should mention it... Up through '02, the 4,000+ lb Dakota's and Durangos had 11" rotors and tiny, single piston calipers. And it's no secret the brakes sucked on them!

Barely enough for one 55 mph panic stop.

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 09/07/12 02:10 AM

My Dakota brakes!

Stock baseline and follow up tests

After one stop on stock size tires my brakes were cooked and useless.

And my truck is one of the lightest out there, being a factory nonAC, no cruise, manual everything, 2wd, stick shift

A fully loaded 4wd Durango will easily weigh 800-1000 lbs more than mine. And I'm tipping the scales at 3900 with a full tank of gas and a 220lb driver... Yet the much heavier truck will have the same brakes

http://www.youtube.com/watch?v=rw0O7Hknzhg&feature=youtube_gdata_player

Posted By: jcc

Re: 800psi enough for manual disc brakes ? - 09/07/12 03:53 AM

Quote:

Well, some progress was made

Spoke with several people bouncing ideas, theories and such to see if we could figure out what is happening.

Dwayne Porter my engine guy suggested that something was limiting piston travel in the master cylinder. He theorized that if the rear brakes were hydrolocked somehow that it would not allow the front brakes to develop enough pressure. That got me thinking

HP Mike spent some time on the phone with me and outlined what has worked well for him. One thing Mike stated about proportioning valve adjustment provided another clue. Thanks Mike

The tech at Wilwood's only comment was that 800psi was plenty ; "what's the problem" The freakin car won't stop with me putting 300lbs of pressure on the pedal...that's the problem ! So i asked about adjusting the proportioning valve and whether or not that would have any effect on front brake pressure. His reply ; Absolutely not...they are independant systems.

So, on a hunch....i backed the prop valve off completely and Bingo....1200 psi to the front caliper ! So for anybody who thinks that the prop valve has no bearing on front brake line pressure....i'm here to tell you otherwise.

I have to thank Dwayne and Mike for steering me in the right direction.

New pads are installed and i have to rebleed the sytem and will use the gauge to adjust the prop valve for 600psi rear brake pressure and see what happens. While pulling the back wheels i found a broken Strange 3in wheel stud and need to get that fixed as well.

A further update will be forthcoming once i can test it out but it's looking much better...i'm cautiously optimistic

Ron

Posted By: autoxcuda

Re: 800psi enough for manual disc brakes ? - 09/07/12 06:50 AM

Quote:

My Dakota brakes!

Stock baseline and follow up tests

After one stop on stock size tires my brakes were cooked and useless.

And my truck is one of the lightest out there, being a factory nonAC, no cruise, manual everything, 2wd, stick shift

A fully loaded 4wd Durango will easily weigh 800-1000 lbs more than mine. And I'm tipping the scales at 3900 with a full tank of gas and a 220lb driver... Yet the much heavier truck will have the same brakes

http://www.youtube.com/watch?v=rw0O7Hknzhg&feature=youtube_gdata_player

Very cool test!

I see different rims in each test group. Did the tires change between test too? If so, what was the specific before and after tire model/size.

Did anything else change between the tests like shocks, springs, etc?

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 09/07/12 05:05 PM

Yes, the 2nd test was done with viper sized sticky tires.

315/35/17 fronts and 335/35/17 rears.

(baseline test was stock sized Dakota R/T tires, which were 255/55/17 all around)

One could argue that changing more than one thing at a time voids the test as a true brake test, but considering that I could not lock up the front brakes with stock brakes and stock tires, (only one rear locked up after they were heat soaked and not working properly) I could have done the same baseline test with the sticky tires and probably had the same results for the stock brakes.

now, if I was locking up and skidding through the stock tires, then I could see how a duplicate test with stock wheels/tires would be beneficial. but, like I said, even on the very first test with cold brakes, I didn't lock up the fronts.

Posted By: jcc

Re: 800psi enough for manual disc brakes ? - 09/07/12 06:04 PM

Quote:

One could argue that changing more than one thing at a time voids the test as a true brake test.

Well yes one could, and I would. If one wants to be certain, one has to follow the rules, if one is going to guess at the reason for the favored results, why not bypass the test and just guess?

And the risk to the cameraman at the roads edge for 9? full bore stops is right up there with the kid and the red fuel can strapped in the car seat.

Different pad compound on the stock set-up might have given the same results as the second "test". interesting, sorry but that's all.

You can tell making friends is not my priority here.

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 09/07/12 06:39 PM

Quote:

Quote:

One could argue that changing more than one thing at a time voids the test as a true brake test.

Well yes one could, and I would. If one wants to be certain, one has to follow the rules, if one is going to guess at the reason for the favored results, why not bypass the test and just guess?

And the risk to the cameraman at the roads edge for 9? full bore stops is right up there with the kid and the red fuel can strapped in the car seat.

Different pad compound on the stock set-up might have given the same results as the second "test". interesting, sorry but that's all.

You can tell making friends is not my priority here.

You're absolutely correct, I COULD have bought drilled/slotted/dimpled rotors and aggressive race oriented pads, and MAYBE achieved similar results, but I didn't. Why? because that's not what I wanted to do. If YOU want to buy the parts for me I'll be glad to test them for you on a different truck, repeating baseline and follow up tests, using the stock wheels/tires.

Posted By: jcc

Re: 800psi enough for manual disc brakes ? - 09/07/12 09:16 PM

Posted By: feets

Re: 800psi enough for manual disc brakes ? - 09/07/12 11:23 PM

You have questioned my input concerning brakes as well.

I agree with Tom. I'd like to know what your experience with brake packages really is.

Posted By: Blown 68 R/T

Re: 800psi enough for manual disc brakes ? - 09/08/12 04:03 PM

Quote:

I agree. I run manual brakes with 13 inch rotors and Viper calipers on my B-body car and I can launch a passenger thru the windshield if I stomp on the brakes. It is a simple late model aluminum master cylinder. My setup is plumbed just like the OP description. Line lock up front and a prop valve to the rear drums. Nothing else in the system.

Andy, Aren't you running a residual valve after the prop valve as well?I'm in the process of finishing my set up which is same as Ron's but was wondering if i should install residual valve or not, My master is not below the calipers so do i have to plumb one in.Does it act kinda like the same theory as a relay valve does on an air brake system at the rear axle?

Posted By: jcc

Re: 800psi enough for manual disc brakes ? - 09/09/12 01:11 AM

Posted By: feets

Re: 800psi enough for manual disc brakes ? DELETED - 09/09/12 01:47 AM

Post deleted by 70Cuda383

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/11/12 04:00 PM

Just an update :

Bedded in the new Hawk HPS pads and happy to report the car stops great...night & day difference !

I feel confident taking it to the track now and being able to slow down from 125+ MPH. Before it felt like a drum brake setup that was overheating and into severe brake fade.

To summarize ; I left the prop valve wide open. No premature lockup on the rear brakes.

Ron

Posted By: Labratt

Re: 800psi enough for manual disc brakes ? - 09/11/12 04:23 PM

(Brador!)

Posted By: Uhcoog1

Re: 800psi enough for manual disc brakes ? - 09/12/12 12:55 PM

Congrats on getting it fixed!!!

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 09/13/12 11:51 AM

OK, I cleaned this back up a little to keep it on topic. everyone's had their fun, time to get back on topic.

Posted By: feets

Re: 800psi enough for manual disc brakes ? - 09/13/12 04:48 PM

Quote:

OK, I cleaned this back up a little to keep it on topic. everyone's had their fun, time to get back on topic.

Great! Now the mods are acting like jcc and exerting their authority.

Posted By: Den300

Re: 800psi enough for manual disc brakes ? - 09/16/12 12:30 PM

@firefighter3931/Ron: I have the same set up and have the same problems.
So I would like to change to the hawk pads too.
Could you tell me the exact part number? thanks!

Dennis

Posted By: Winchester 73

Re: 800psi enough for manual disc brakes ? - 09/18/12 04:15 AM

Quote:

Quote:

An 11 inch rotor for a 4000 lb car is just asking for trouble. No one would design a system like that anymore. Go visit a car lot and look at 4000 lb cars with 300+ hp engines. They'll all have 13 inch or 14 inch rotors.

Funny you should mention it... Up through '02, the 4,000+ lb Dakota's and Durangos had 11" rotors and tiny, single piston calipers. And it's no secret the brakes sucked on them!

dont feel bad my brother in laws tahoe has smaller rotors than the cordoba brakes on my dart!looks even more stupid with 26' rims

Barely enough for one 55 mph panic stop.

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/18/12 03:22 PM

Quote:

@firefighter3931/Ron: I have the same set up and have the same problems.
So I would like to change to the hawk pads too.
Could you tell me the exact part number? thanks!

Dennis

Hi Dennis, the Hawk HPS pad for the SS Brake 4 piston caliper is : HB471F-510

http://www.summitracing.com/parts/HWK-HB471F-510/Application/?prefilter=0

The plate number is D11 which fits several Dodge/Plymouth & Ford factory calipers.

Happy to report the brakes worked great at the track stopping from 120+ MPH. The raceweight is 4200lbs so it's no lightweight, lol !

Make sure you adjust the prop valve wide open and adjust from there. Clockwise opens the valve, fyi

Ron

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 09/18/12 03:28 PM

Quote:

Congrats on getting it fixed!!!

Thanks ! Feels much better now and stops great !

Next problem ; traction

Need to play with the cal-tracs

The 572 is blowing the M/T Drag radials off even with a descent burn out and well prepped track

Ron

Posted By: Den300

Re: 800psi enough for manual disc brakes ? - 09/18/12 06:56 PM

Quote:

Hi Dennis, the Hawk HPS pad for the SS Brake 4 piston caliper is : HB471F-510

http://www.summitracing.com/parts/HWK-HB471F-510/Application/?prefilter=0

The plate number is D11 which fits several Dodge/Plymouth & Ford factory calipers.

Happy to report the brakes worked great at the track stopping from 120+ MPH. The raceweight is 4200lbs so it's no lightweight, lol !

Make sure you adjust the prop valve wide open and adjust from there. Clockwise opens the valve, fyi

Ron

Thanks Ron!

I also will play a little bit with the prop valve.
I also always thought it is just to reduce rear brake pressure. but
its worth a try to "close" the rear to see if I also can increaswe front pressure.

And its even heavier

4400lbs in race trim

Posted By: @#$%&*!

Re: 800psi enough for manual disc brakes ? - 09/19/12 01:34 AM

Quote:

Quote:

We should all be dead by now!

The biggest problem is keeping the sheet metal straight when driving in traffic these days.

In the past it wasn't an issue. Everybody's brakes sucked by comparison.
Now you have SUVs that can stop shorter than many old muscle cars. That means the old car has become the hazard.

That's what I was trying to say, thanks for the clarification.

Posted By: Lefty

Re: 800psi enough for manual disc brakes ? - 09/23/12 08:51 PM

A 1" MC piston is too large for manual brakes unless the front caliper pistons are large. You did not mention pedal ratio. You need at least 6-1 with manual brakes.

Posted By: Den300

Re: 800psi enough for manual disc brakes ? - 10/20/12 05:15 PM

Short update:
I bought me the EBC yellow stuff brake pads for my SSBC force 10 kit
as the Hawk pads cost roughly 50% more here in Germany.
Even though I drove only 15mls today and the brake-in procedure is not finished
I can say right now that it is a huge improvement over the SSBC pads!

Next step is to play with the prop valve. Maybe I see the same results as Ron.

Dennis

Posted By: firefighter3931

Re: 800psi enough for manual disc brakes ? - 11/16/12 11:32 PM

Thanks for the update Dennis

Good to hear the EBC pads helped....i'm sure they're better than the SSBC pads that come with the kit.

Ron

Posted By: Den300

Re: 800psi enough for manual disc brakes ? - 10/31/13 08:24 PM

Short update on the brakes.

Today I�ve been at the technical inspection.
Last time they measured 300 deca newton for the front brakes.
I changed the stock SSBC pads with EBY Yellowstuff and now they
measured 350 deca newton. that is roughly 17% more stopping power.
Not too bad for a pad change. Real improvment and the first time
I reached more clamping power at the front than at the rear (330daN).

Posted By: brads70

Re: 800psi enough for manual disc brakes ? - 10/31/13 11:01 PM

I've been using EBC Yellow pads in my Viper calipers( manual M/C) for a couple of years now. They work good, not the greatest cold but REALLY work better when hot! No more brake fade!

Posted By: BigBlockMopar

Re: 800psi enough for manual disc brakes ? - 11/01/13 10:20 AM

On my own Dart I've recently replaced a set of old stock metallic pads for a set of Hawk HPS pads and the difference is verry noticable at moderate to high speeds. Not so much at low speeds with less pedalpressure.
I also think these pads get better when warmed up a bit. The first few brake stops in the morning aren't that impressive.

The previous pads (found on a old car), while braking was OK, mainly did a good job of polishing the rotors to a mirror shine, while the HPS pads now leave a mat finish on the rotors, also telling me they're doing a better job of grabbing the rotor.

Posted By: Den300

Re: 800psi enough for manual disc brakes ? - 11/01/13 10:38 AM

I noticed the same. The yellow stuff pads srubbed more off the rotors within 600miles
than the ssbc ones within 4 years!

They also get better when they are warm.

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 11/01/13 01:15 PM

Once you guys get some miles on these set-ups, I'd like to know what your rotor life is like with these more aggressive pads.

Posted By: BigBlockMopar

Re: 800psi enough for manual disc brakes ? - 11/01/13 06:15 PM

I drive my car daily.
Although I don't travel a lot of miles every week due to the short local distances in my country, my car does do a lot of stop&go driving.

Posted By: brads70

Re: 800psi enough for manual disc brakes ? - 11/02/13 01:57 AM

Quote:

Once you guys get some miles on these set-ups, I'd like to know what your rotor life is like with these more aggressive pads.

Had mine on for 3 seasons now, so far so good. I drive it to Carlisle every year and lots of local shows. Take it out almost daily if weather is good. I'm going to get a set for the rear brakes too as I found while doing the Hotchkis autocross thing at Carlisle the fronts lock up way before the rears when they get hot.

Posted By: PolyDart

Re: 800psi enough for manual disc brakes ? - 07/03/14 08:45 PM

I'm bringing this thread up from the dead because I am having the same issue, but for a seemingly different reason.

I am also running a proportioning valve in my rear brake line and I thought that the original poster's fix would be a "voila" moment for me, but no amount of proportioning valve adjustment will give me more than 800psi to the front brakes. The rear brakes are also at 800 psi when allowed to get full flow from the valve.

I have played with the pedal ratio. The stock M/C pickup point is 1.5" below the pivot. The hole I drilled is 2.125" below.

The lower hole has a lower ratio, yet that's where I get the best pedal and pressure.

The problem with using the upper hole is that the brake pedal has a super long throw, and it barely makes 500lbs before hitting the floor.

When I do the calculations I get 7.6:1 for the top hole and 5.4:1 for the bottom.

Any suggestions? I'm ready to pull out what little hair I have left

BTW, this setup is in a '60 Dart. I am running '99 Ram front calipers and '04 Cobra calipers in the rear with a Wilwood 7/8" M/C.

Posted By: autoxcuda

Re: 800psi enough for manual disc brakes ? - 07/04/14 01:35 AM

Quote:

I'm bringing this thread up from the dead because I am having the same issue, but for a seemingly different reason.

I am also running a proportioning valve in my rear brake line and I thought that the original poster's fix would be a "voila" moment for me, but no amount of proportioning valve adjustment will give me more than 800psi to the front brakes. The rear brakes are also at 800 psi when allowed to get full flow from the valve.

I have played with the pedal ratio. The stock M/C pickup point is 1.5" below the pivot. The hole I drilled is 2.125" below.

The lower hole has a lower ratio, yet that's where I get the best pedal and pressure.

The problem with using the upper hole is that the brake pedal has a super long throw, and it barely makes 500lbs before hitting the floor.

When I do the calculations I get 7.6:1 for the top hole and 5.4:1 for the bottom.

Any suggestions? I'm ready to pull out what little hair I have left

BTW, this setup is in a '60 Dart. I am running '99 Ram front calipers and '04 Cobra calipers in the rear with a Wilwood 7/8" M/C.

What is the diameter of the piston(s) in the front and rear calipers?

How many piston in each caliper?

Posted By: 70Cuda383

Re: 800psi enough for manual disc brakes ? - 07/04/14 03:15 AM

More leverage and more pedal travel equals less line pressure? You sure ALL the air is out?

Posted By: PolyDart

Re: 800psi enough for manual disc brakes ? - 07/04/14 05:29 AM

Quote:

What is the diameter of the piston(s) in the front and rear calipers?

How many piston in each caliper?

I called Wilwood shortly after posting this afternoon. He asked about the calipers as well.

He's telling me that a 1" bore M/C would be more appropriate for the size pistons I'm running in the Dodge Ram calipers. He said I'm running out of volume and that's why the pedal is catching so low no matter which hole I put the M/C pushrod.

Posted By: BigBlockMopar

Re: 800psi enough for manual disc brakes ? - 07/04/14 09:34 PM

Quote:

When I do the calculations I get 7.6:1 for the top hole and 5.4:1 for the bottom.

That's 40% more pedalwork you're able to push now.
I'm pretty sure you need to go up in size on the MC again a bit to get the proper fluid-displacement and prevent the pedal from bottoming out.

Posted By: feets

Re: 800psi enough for manual disc brakes ? - 07/05/14 04:40 PM

Quote:

Quote:

What is the diameter of the piston(s) in the front and rear calipers?

How many piston in each caliper?

I called Wilwood shortly after posting this afternoon. He asked about the calipers as well.

He's telling me that a 1" bore M/C would be more appropriate for the size pistons I'm running in the Dodge Ram calipers. He said I'm running out of volume and that's why the pedal is catching so low no matter which hole I put the M/C pushrod.

Yep!

You've run out of master cylinder.

Dig up the brake math spreadsheet and crunch some numbers. I don't have the specs on the calipers but you can probably grab them from product info on Rock Auto.

Posted By: ntsqd

Re: 800psi enough for manual disc brakes ? - 07/05/14 07:14 PM

For manual brakes I shoot for 93:1 to 95:1 total system ratio for the fronts. then tune in the rears as needed. That is hydraulic ratio multiplied by pedal ratio. Can go over 95:1, but go under 93:1 at your own peril. Below 93 the pedal will rapidly trend towards being rock hard with low line pressure. Above ~100:1 will definitely feel 'mushy.'

800psi enough for manual disc brakes ?