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  #1  
Unread 10-26-2009, 07:18 PM
Northeast Rod Run's Avatar
Northeast Rod Run Northeast Rod Run is offline
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Question 4 wheel manual disc brakes?

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?

Last edited by Northeast Rod Run : 10-26-2009 at 07:23 PM.
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  #2  
Unread 10-26-2009, 08:34 PM
speedjohnston speedjohnston is offline
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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.
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  #3  
Unread 10-26-2009, 09:14 PM
moparnut moparnut is offline
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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.
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  #4  
Unread 10-26-2009, 09:55 PM
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Northeast Rod Run Northeast Rod Run is offline
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thanks for the input guys

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
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  #5  
Unread 10-26-2009, 10:29 PM
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70rs 70rs is offline
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Quote:
Originally Posted by 1969 SS View Post
thanks for the input guys

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!
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  #6  
Unread 10-27-2009, 12:02 AM
turbo67camaro turbo67camaro is offline
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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.
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  #7  
Unread 10-27-2009, 07:52 AM
BRIAN BRIAN is offline
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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.
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  #8  
Unread 10-27-2009, 11:56 AM
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GregWeld GregWeld is offline
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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.

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.
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Last edited by GregWeld : 10-27-2009 at 01:08 PM. Reason: added residual valve discussion
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  #9  
Unread 10-27-2009, 12:03 PM
Apogee Apogee is offline
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Quote:
Originally Posted by BRIAN View Post
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
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Last edited by Apogee : 10-27-2009 at 12:07 PM.
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  #10  
Unread 10-27-2009, 12:58 PM
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GregWeld GregWeld is offline
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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!
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I have some tools...I would someday like to have some skill using them...

I love this line:

You must be fast cause you were haulin azz when I passed you!!

'40 Ford Pickup project @ Pinkee's Rod Shop
'32 Ford Roadster
'33 Speed Cabriolet
'65 Mustang Fastback "Track Car"
'08 Lotus 2 Eleven "back up Track Car"
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