4 wheel manual disc brakes?

[Northeast Rod Run]

just looking for some experienced input here.

right now I have power front discs and rear drum brakes on my big block '69 Camaro. Even with a vacuum canister, it's never produced great vacuum because of my cam profile.

So i'm wondering if i went with manual 4 wheel discs, would the car still stop good or would it maybe stop worse than my current set-up? I also started thinking about this because I like the idea of a cleaner firewall without the booster and vacuum lines.

it's been so long since the car had manual brakes, and it never had discs all the way around. I just remember, back in the day, with manual drums it used to be a SOB trying to stop at the end of the quarter mile (and that was only high 12, low 13 second times with a small block)

anyone have some good input for me?

[speedjohnston]

I did exactly what you are talking about in the past for the exact same reasons. I had stock style front brake discs that and a set of lincoln style discs in the back because I had a ford 9". I bought a new manual brake master cylinder from MP brakes and some good brake fluid. The track I used to bring the car to is considered to have a short shut down area and I could stop long before the end and it ran 10.60's at 127. I actually didn't find it any harder to stop since I never had much vacuum anyway.

[moparnut]

I did the wilwood 4 disc setup and master cylider and it was great. I like manual brakes over power anyday. Just remember, your bore size will determine, to some extent, the required pedal pressure to get you where you want to be. Bigger bore size will be harder but travel less, smaller bore will be easier but travel farther.

[Northeast Rod Run]

thanks for the input guys:cheers:

I guess if I go with this set-up, I'd go with the smaller bore size because I would rather have an easier pedal in traffic, for an easier panic stop. I never knew that stuff about bore sizes

[70rs]

thanks for the input guys:cheers:

I guess if I go with this set-up, I'd go with the smaller bore size because I would rather have an easier pedal in traffic, for an easier panic stop. I never knew that stuff about bore sizes

Look up Tobin at Kore3 here. He has conversion kits. They use a lot of Corvette factory parts. (C5/C6 calipers, pads and rotors) The benefit of that is being able to walk into just about any parts store for replacement parts when the time comes. He also has OUTSTANDING customer service and great prices. Good luck with it!:cheers:

[turbo67camaro]

With large diameter rotors, large calipers, high friction pads, the right master cylinder, and good pedal ratio or a dual master cylinder with balance bar pedals, I hear manual brakes work great.

What I don't know is how much you can sacrifice in some of those areas and still get good results.

[BRIAN]

Just remember that OEM single piston calipers will need more pressure at the pedal than say wilwood 4 pistons.

There is a great 5 page write up ON HOTRODHEAVEN.COM

Either way just make sure you ge the right sized master it is the key to the whole set up.

[GregWeld]

Several -- in fact -- MANY factors to consider crucial to proper braking - regardless of the power vs manual question. Consider this - how many RACE CARS have power brakes? Almost NONE.

There are several guys on this board that REALLLLLLLLY know about all this stuff... But I'll give you just SOME things to keep in mind. From there - it's up to you to educate yourself on what you need/want.

The key to all of this is to have the proper size of EVERYTHING in the system - because brakes are like the Cam and Head combo - one without the proper other - is a dog...

There's more to it than just the Master cylinder... and the rule of thumb here is the larger the mc bore - the LESS pressure it will make... the smaller the bore - the More pressure they make. A 1 1/8" bore will make about HALF the pressure of a 7/8" bore.

Pedal ratio is critical - 6 to 1 minimum on a MANUAL system. Most P/B systems use 4 to 1. Think about this -- 100 #s of "effort" on a 4 to 1 makes 400 #'s of effort -- vs the 6 to 1 ratio which makes 600 #'s... and DISC BRAKES are all about PRESSURE (there's a volume issue too - but now we're getting technical).

Brake lines - Disc brakes use 3/16" lines -- Drums use 1/4". If you want to make pressure at the master cylinder - and have this pressure all the way to the actual brake - you need the smaller diameter lines... if you go DISC brakes - change the lines if you need to. Why waste all the money and effort on fancy brakes and MC's only to have it not work correctly. Think about headers - fancy cam - fancy heads - poopie little header size is the choke point. (okay - lets not go there with the small pipe torque argument - this is just a basic discussion...LOL)

Brake Bias/Proportioning valve - You want the FRONTS to lock up BEFORE the rears... many factors here - tire size - brake size front vs rear etc... so not every system needs a proportioning valve... if you have huge rear tires and smaller fronts, the tires themselves might set your bias... but - big butt - It's one of those "better to have it, and not need it, than to need it, and not have it" parts. IMHO. The COMBO valves are for factory set up - engineered for a particular tire size and brake size and car weight etc - so an ADJUSTABLE version is what you need. It goes to the REAR brakes - in order to REDUCE the pressure to them - to get the fronts to lock BEFORE the rears. You lock the rears first - you spend a lot of time driving backwards. :rofl:

Master cylinder BENCH BLEEDING - Skip this part at your own peril. Many "skippers" try to do this after the cylinder is mounted on the car... or don't do it at all. They're dumb and lazy and deserve the hassle they just set themselves up for. There's lots of instructions available for this - but take my word for it - you leave some little itsy bitsy air bubble in the MC - IT WILL reduce the pressure you can make and it WILL poke it's ugly head up just before you hit that tree.

Residual valves - Typically there should be a 10# residual valve (think "check valve") to the rears IF you're running DRUMS (in the rear)... This will "hold" the shoes "at the ready" and not let the wheel cylinder collapse all the way back... Different system -- IF the MC is mounted LOWER than the brake system - you need to run a residual valve to both front and rears. In this case 2# valves for disc system... and the 10# for a drum system - you need these in BOTH lines -- one to the fronts and one to the rear depending on the size examples as given.

Do some research and some reading... don't rely on what your friends "think" you should do... this is too important. The manufacturers have good techs that will help you work towards a solution. Kore3 - Baer - Wilwood - Brembo... all good people that are interested in setting you up with a great braking system.

[Apogee]

Just remember that OEM single piston calipers will need more pressure at the pedal than say wilwood 4 pistons.

There is a great 5 page write up ON HOTRODHEAVEN.COM

Either way just make sure you ge the right sized master it is the key to the whole set up.

Buyer beware...we've had several customer purchase master cylinders from H-R-H and they have always supplied oversized master cylinders for late-model, C5/C6 big-brake conversions.

You can't say that an OEM single-piston caliper will need more pressure than a 4-piston Wilwood without stating what the piston diameters/areas are for each specific caliper. There are several piston sizes for the OEM cast iron calipers, however they are 2-15/16" diameter for the '69 Camaro application and most other early muscle cars. That piston diameter equates to a 6.77 sq inch piston area and is typically matched with a 1-1/8" bore MC in a boosted application and 1" bore MC in a manual application. Don't assume that all vacuum boosters are equivalent...just because a single 7" diaphragm booster will fit does not mean that it will do the job required.

A C5/C6 2-piston caliper has double the pistons (40.5mm) and not even 2/3 of the overall piston area at 4.00 sq inches. The Wilwood Superlite 6-piston calipers are very similar at 4.04 sq inches. We would run a 15/16" to 1" bore MC in a boosted application and a 7/8" to 15/16" bore MC in a manual application assuming a matched rear disc application. Just for reference, the 4-piston SL calipers range from 2.22 to 5.18 sq inches with all of the various piston sizes and staggers.

Based on the areas stated above, the single piston caliper will need less pressure and more volume than any of the "big-brake" options, and this is true for the majority of the aftermarket big-brake kits on the market today. CPP's kits may be the exception that proves the rule since they use big truck calipers with their kits specifically so that their customers can retain their facotry MC/booster arrangements to save on cost.

"BIG-BRAKES" does not mean big caliper pistons. The rotor is what takes the heat and abuse, so bigger rotors (and pads to a certain extent) are what allow you to brake harder and longer. While smaller caliper pistons reduce the effective brake torque of the system, they give better driver feedback and are more responsive making threshold and trail braking that much easier. Assuming the brakes can achieve lockup with reasonable levels of pedal effort, any brake torque in excess of that is unusable. Once the tires are at their limits, you're done...I don't care how big or small your brakes are.

Tobin
KORE3

[GregWeld]

Good response Tobin -- Thanks for jumping in there and adding your masterful thoughts!

I'm not "technical" enough and didn't want to get into the whole "volume" discussion... figured he'd get that info if he starts researching... I wanted to toss in "food to think about"... and you've done a great job (as usual) in discussing the various systems.

Funny -- Back in high school - everybody wanted to run a 750 Holley on their 283's - cause that's what all the big boys were running.... But when you're in high school you're too lame to really LEARN and RESEARCH what carb you SHOULD have had.... and WE (including myself here) NEVER checked our brakes... it was only a "hurst shifter" and big carb story. NOW, of course, we should be a bit better at these things.... yet the most misunderstood parts of the "hobby" that I encounter almost daily -- BRAKES... and the same guys are making the same mistakes... and there's really quite a bit to learn about this subject. Yet - the "basics" are just that... pretty basic. What I see the most - is the "lipstick on a pig" cover ups... i.e., "My brakes suck" -- so I'll put on a double whammy big doowhop chrome booster... and when that fails... they learn to live with it.

Can't tell you how many "conversions" I've seen where the master cylinder is hooked up backwards... because NOT ALL MC's go front reservoir to front brakes... Or that they're using 1 1/18" MC on all disc system and still have 4:1 pedal ratio... and so on blah blah blah. I do more HOT RODDING than PT shows etc -- and it's really really rampant in the HR scene.... PT folks seem to be a lot more interested in "the facts". Thanks for being here and helping us all!
:hail: :hail: :hail: :hail:

[Northeast Rod Run]

Good response Tobin -- Thanks for jumping in there and adding your masterful thoughts!

I'm not "technical" enough and didn't want to get into the whole "volume" discussion... figured he'd get that info if he starts researching... I wanted to toss in "food to think about"... and you've done a great job (as usual) in discussing the various systems.


you've given me plenty more to think about, than I thought I ever would, but that's exactly why I figured I'd ask first. I hate doing something wrong, just because it was "easier" to do it another way, and I was too ignorant to listen to other's advice.

seriously though, I would have never given that much thought into going from stock power disc/drum, to manual disc/disc. I just figured a simple master and adjustable proportioning valve change would do it. all this info overload almost makes me think I want to stay with my current set-up, but I guess I have all winter to research more details before I finally make up my mind

thanks

[GregWeld]

That my friend.... is why we're all here! This is a community... with all the support systems you've ever wanted... and some you probably don't... :lol:

Seriously though --- we might have made it info overload for you - but that's why you can just keep posting questions here until you've got it all figured out.

It's all pretty simple really - and like most things - only seems complicated until you "do it" or learn about it...

And by the way -- you don't have to do $12,000 carbon fiber brakes to have "decent" braking - and you don't have to do Wilwood or Baer to be a part of :lateral: Many of our cars have a real nice set of GM discs up front and they will throw you thru the front window when you hammer 'em... :woot:

[GregWeld]

One last thought -- because I just re-read your original post.

Your vacuum is low because of your cam profile... thus you probably have a "hard pedal" and feel like the effort it takes to apply the brakes isn't translating into stopping power?

So -- have you thought about installing a vacuum pump and resevoir... to help with your low vacuum condition? Are you aware of this kind of thing for your brakes? Something simple like this might be all you're looking for - and would make a world of difference.

[Northeast Rod Run]

One last thought -- because I just re-read your original post.

Your vacuum is low because of your cam profile... thus you probably have a "hard pedal" and feel like the effort it takes to apply the brakes isn't translating into stopping power?

my pedal isn't a "hard pedal". I can't really explain it, but I guess I would say that it has always had a "dead spot" where you can feel the vacuum is missing and you have to wait for it to come back. I did install a canister when I built the car 10 years ago, because I used to have a highrise and dual quads and it really sucked then. the entire brake system was brand new stock. the car still has under 10k since it was built

back when I originally put the car together, there wasn't much aftermarket support, I didn't know anything, and I didn't have much money. now the aftermarket is great, I know enough to get myself in trouble, and I have a little bit of play money, so I think it's time to do some small upgrades, and rims, tires, brakes, and overdrive (I'm currently only getting about 8MPG on the highway) are at the top of the list

[GregWeld]

Well the pic you posted of that bb certainly looks nice!

Yes -- the cannister will "help" and will give you maybe one or two brake applications before it's drained...

Here's something that people kind of forget about the canister. If your motor only makes 14 inches of vacuum -- that is ALL the canister will be - it can't be HIGHER -- and is lower after just one application of the brakes. It will help but they're so small - they just can't smooth out the lack of vacuum.

GOOD power brakes need vacuum in the 17 inches or MORE.... of vacuum. Do you know what your vacuum is? Because that would really help you to design a solution. If you're making 12" -- there's just no way you're going to run P/B's off the motor. This is why people have gone to the (IMHO way too complicated - and UGLY) Hydroboost hydraulic systems... if they want power brakes. The vacuum pumps are noisy and slow to recover in stop and go traffic... I finally just gave up on mine and went with manual and have been so damn happy I did. I have less plumbing - less clutter under the hood.. less equipment to 'fail' etc. BUT each person has his or her own agenda and desires. I totally get that.

[BRIAN]

Kore...I was referring to a GM style single piston vs any say 4 piston,6piston etc type caliper. I may be wording this wrong but what I am getting at is there has to be some pressure required to actuate a single piston cyl before pressure is applied to the rotor? I am not talking cyl sizes. If you were to take two equal sized volume single vs multi piston calipers would there be a difference?

Theory is great but I have swapped wilwood 4 pistons onto a car that had GM singles and there was a difference. Was it piston bore size? Maybe?

Not arguing just looking for good info.

Thanks

[Northeast Rod Run]

thanks for the compliments :cheers:

I forget what I am pulling for vacuum. I used to have a working gauge on my canister but the car rattled it apart. 17" of vacuum? I don't think I pull 10" (that didn't sound right did it?).

all I can remember, is that after I originally put most of the engine together back when, I was looking to go the fuel injection route but I learned something then. they told me that I would be pulling nowhere enough vacuum to run fuel injection on the car, so that's when I said "screw it" and went with dual quads at the time. if you can't join 'em... beat 'em, or maybe it's supposed to be the other way around...hahahaa

I do get one "ok" hard stop and then probably one "not so good" stop after before I'm empty. I definitely want to go manual for the more constant safety factor, and the coolness of a cleaner looking set-up.

[GregWeld]

Too funny -- glad to see you have a good sense of humor! LOL

AND NO!! That 10" thing just wasn't right!! :rofl:

I really am happy with my manual system - YES I have to pick up my leg and "push" with my leg -- it's not just a "toe" thing like modern power brakes -- but I find I drive that way anyway.

When you're ready - I'd PM (assuming you know what I mean and how to do it) Tobin at Kore 3 (or just go to their website - shown down the left side of these pages - they're sponsors so have links there) - and discuss your 'desires' and system -- because I'm not really sure what master cylinder you should use in a mixed system like that - and or whether or not you should use residual valves etc ---- and I wouldn't want to advise anyone about that kind of stuff -- Tobin and those guys are pros and know all the ins and outs of brakes.

Okay -- now for the Fuel injection -- YOU can run fuel injection and big cams - You just have to have someone that knows their way around the system - usually (I THINK) if you don't have vacuum - you'd have to run "batch fired" instead of "sequential" but I don't really know that either... but I've seen some real bad ass engines that are major lumpy - running EFI.

The coolest one out now - is like a direct bolt on for your carb - FAST EZ-EFI... it's self tuning - fire it up - and it tunes it's self. Theres a thread on it here somewhere - most likely under the EFI "section".

[69MyWay]

Here is a hijack while we have some great brake experts to share their .02

I'm setting up my car (by default) at this time using manual 4 wheel disc brakes. This car is a factory manual brake car - so the pedal, small m/c bore...and all are intact. It is a 69 Vette - and will be my first manual brake car in...forever!

I was bleeding the brakes after bench bleeding the m/c the other day. I was letting them gravity bleed while doing other things. The fronts came on-line after a bit and I was able to get pressure in them.

The rear after over an hour of being open didn't bleed. Tried to pump them...with no result.

So....what is the trick to get those rear babies to come on-line?

And...I am glad to see so much positive response on this thread about running manual brakes. I'd like to upgrade the m/c later due to the poor visual of the heavy cast - soon to rust - stock m/c.

[Apogee]

Kore...I was referring to a GM style single piston vs any say 4 piston,6piston etc type caliper. I may be wording this wrong but what I am getting at is there has to be some pressure required to actuate a single piston cyl before pressure is applied to the rotor? I am not talking cyl sizes. If you were to take two equal sized volume single vs multi piston calipers would there be a difference?

Theory is great but I have swapped wilwood 4 pistons onto a car that had GM singles and there was a difference. Was it piston bore size? Maybe?

Not arguing just looking for good info.

Thanks

If I understand your first question correctly, yes, there is some pressure required to actuate the pistons and that pressure is basically whatever is required to overcome the friction in the system, both mechanical from the seals and the fluid. That said, those pressures are so low relative to the max system pressures, it's virtually zero for all practical purposes.

Two calipers with the same overall piston area, regardless of whether it's a 1-piston floating caliper or a 8-piston fixed caliper, will exert the same clamping force. The advantage to 4 and 6-piston calipers is that they allow you to run larger brake pads and better support the backing plates. Single piston calipers tend to bend the pads over the piston under severe use.

When you swapped to the Wilwood calipers from the single piston GM calipers, changes in rotor diameter, pad coefficient of friction, MC bore and pedal ratio are all part of the equation. Without more info, it would just be speculation as to what was the primary cause for improvement.

In my experience, most people rarely upgrade fully functional, good condition brakes with high-quality components. We wait until the rotors/caliper/pads/hoses are basically falling off the car and then decide it's time to upgrade. While it tends to make for a huge improvement in braking performance...so would have new OE brakes most of the time (and I'm not talking about the cheapest parts you can buy from a discount auto parts store).

This site is great for good info, good folks and some amazing cars.

Tobin
KORE3

[GregWeld]

Here is a hijack while we have some great brake experts to share their .02

I'm setting up my car (by default) at this time using manual 4 wheel disc brakes. This car is a factory manual brake car - so the pedal, small m/c bore...and all are intact. It is a 69 Vette - and will be my first manual brake car in...forever!

I was bleeding the brakes after bench bleeding the m/c the other day. I was letting them gravity bleed while doing other things. The fronts came on-line after a bit and I was able to get pressure in them.

The rear after over an hour of being open didn't bleed. Tried to pump them...with no result.

So....what is the trick to get those rear babies to come on-line?

And...I am glad to see so much positive response on this thread about running manual brakes. I'd like to upgrade the m/c later due to the poor visual of the heavy cast - soon to rust - stock m/c.


You might need to apply some VACUUM to get them to bleed - sometimes I tap the caliper with a small dead blow hammer to "shake" the air bubbles. BUT I have a handy dandy air driven vacuum bleeder so it's easy on my end and a one man job -- ALSO make sure you have fluid in the MC --- keep it topped off... When bleeding brakes - you ALWAYS start with the furthest away - meaning you should have gotten all the air out of the passenger Rear FIRST... then the driver rear - then the passenger front... then do it all over again.

Stop the rusting master cylinder with some "cast blast" rattle can paint from Eastwoods or similar - it makes it look like brand new cast iron. Just don't spill brake fluid on that paint! So when you're done - make sure you clean everything with some mineral spirits or similar.

[69MyWay]

Awesome! Thanks

Yep..I got in a hurry to get some brake action so I could move the car under its own power for the first time before the sun went down last weekend.

Had just enough (manual shift car) to get it to move in the driveway and call it a success.

I'll check out that paint - but it seems hard as you try, a little fluid trickles down and eats the paint off - leaving a rust trail soon behind.

By the way - if I use a siphon air gun and hook the siphon hose to the brake bleeder - then deposit the air out tip in a bucket...will that work to pull a vacuum? (poor man's tool).

[GregWeld]

Awesome! Thanks

Yep..I got in a hurry to get some brake action so I could move the car under its own power for the first time before the sun went down last weekend.

Had just enough (manual shift car) to get it to move in the driveway and call it a success.

I'll check out that paint - but it seems hard as you try, a little fluid trickles down and eats the paint off - leaving a rust trail soon behind.

By the way - if I use a siphon air gun and hook the siphon hose to the brake bleeder - then deposit the air out tip in a bucket...will that work to pull a vacuum? (poor man's tool).


Yes -- that should work - just remembering that the brake fluid WILL FIND IT'S WAY TO THE PRETTIEST PAINTED PART IN THE SHOP... Maybe try covering the bucket in a dampened towel - and wire tie or duct tape it tightly to the top of the bucket and then just poke your "deposit end" through a hole in the towel/shop rag. You wouldn't want a fine mist of brake fluid floating around in the air and getting on something!!

It's like a hammer -- a hammer is used to find the most expensive part nearest the item you're trying to hit.

[69MyWay]

Since I have hijacked this thread...might as well keep rolling.

Hey Greg...I'm stumped. I re-bench bled the m/c. Getting plenty of flow to the front - all is perfect there.

On the rear (which is also on the rear of the m/c) I am able to get all the air out and it seems to flow well.

When I hook it to the car, I can't get any flow to work down the line. All these lines were new and dry.

I opened it up at the distribution block - and when pressing the pedal can get it to squirt out there, but not much.

I have opened the lines and can't get it to gravity bleed at all.

I tried my siphon technique. It is making good suction, but it won't pull anything to the rear.

I'm stumped.

[Vegas69]

A mechanical vaccum pump will work or pump the hell out of the brakes for a couple minutes.

[GregWeld]

Right -- you're just pushing the air out of the lines and displacing it with fluid...
It will take a bit - full new lines - and calipers...

I had trouble getting my rears (not my rear) started when I did this -- and was surprised at the "effort" it took -- and I have a one man air operated vacuum bleeder!

[69MyWay]

Hey Greg,

Okay...I'm going to go with pump the snot out of it.

However, here is my question.

Pump it with the bleeder open or closed?

Pump it closed a whole lot...then go through the pump down, hold, bleed...

Or....leave the line open and just pump???

[wedged]

69- (a different Greg responding here) - get a piece of hose that fits the bleeder fitting on the rear caliper- if you don't have any, the vinyl hose at hardware stores is perfect. Open the bleeder and install the hose then put the open end of the hose into a soda bottle with enough fluid to cover the open end of the hose- 1/2" will do. Then slowly pump the pedal about 6-10 times. Check the level in the bottle to see if it raised and in the MC to see if it dropped. This is a great quick way to push the air out & fluid in. once you have fluid from all 4 wheels, then go back and bleed your favorite way. Putting the hose end into fluid prevents the back flow of air when the MC piston returns. Instead it will suck up some fluid.

[69MyWay]

Thanks Greg II ! LOL

Done that many times. I have just never had one that refused to move fluid to the rear. I have done a dozen of these old Corvettes (first manual brake model - not that it matters) and have not had such an issue moving the fluid.

Seems like there is nothing happening outback - but I know it is moving fluid at the mc as I have a clear bleeder tube that you can watch it move the air around until it is all gone.

Yep...I'll re-bleed at the m/c on the bench, then hook the hose to the rear and commence pumping. My wife has really nice strong sexy legs...maybe I can convince her to come out and give them an extra work out! She is always handy to pump while I bleed - but this one will take an OVER time commitment.

[wedged]

My wife has really nice strong sexy legs...maybe I can convince her to come out and give them an extra work out! She is always handy to pump while I bleed - but this one will take an OVER time commitment.


:ttiwop:



oh- another thing- On occasion, I have had a similar thing happen. You may want to try closing all of the bleeders, then give a hard, swift STOMP on the pedal. Then re-try the hose trick and see what happens.

[GregWeld]

Well thank goodness someone is taking my place!! I'm 100 miles from Vegas!! Just stopped at a bobs big boy... Never stopped at one before. And now I know why.... LOL

hard to respond to these threads with my iPhone and drive 80 mph! Good god these Californians drive fast!!


Anyway. I hope your next post is with news of sucess.

[70rs]

They don't drive fast Greg, you just drive slow.:geezer:

:rofl:

[GregWeld]

They don't drive fast Greg, you just drive slow.:geezer:

:rofl:

Well the BIG AZZ truck was doing 80 and they were whizzing by me like I was OLD...

Just arrived in Vegas --- a little early - but had a nice breakfast this morning with Ned and Monet and his two wonderful children... I heard all about "trick or treat"!

I think I passed Roger at least twice on the way over...

[70rs]

Good to hear you made it there safe. Have a great week! LOTS OF PICTURES!:thumbsup:

[J-440]

Use DOT 5 brake fluid. It won't eat the paint and has a higher boiling point. Wilwood sells some.