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  #11  
Old 10-27-2009, 11:41 PM
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Northeast Rod Run Northeast Rod Run is offline
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Originally Posted by GregWeld View Post
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
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  #12  
Old 10-28-2009, 12:05 AM
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GregWeld GregWeld is offline
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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...

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 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...
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  #13  
Old 10-28-2009, 12:11 AM
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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.
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  #14  
Old 10-28-2009, 10:22 AM
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Northeast Rod Run Northeast Rod Run is offline
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Originally Posted by GregWeld View Post
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
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Old 10-28-2009, 10:44 AM
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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.

Last edited by GregWeld; 10-28-2009 at 11:45 AM.
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  #16  
Old 10-28-2009, 11:36 AM
BRIAN BRIAN is offline
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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
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  #17  
Old 10-28-2009, 11:56 PM
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Northeast Rod Run Northeast Rod Run is offline
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thanks for the compliments

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.
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  #18  
Old 10-29-2009, 12:14 AM
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Too funny -- glad to see you have a good sense of humor! LOL

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

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".
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  #19  
Old 10-29-2009, 10:25 AM
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69MyWay 69MyWay is offline
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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.
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  #20  
Old 10-29-2009, 10:46 AM
Apogee Apogee is offline
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Quote:
Originally Posted by BRIAN View Post
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
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