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  #16 (permalink)  
Old 11-28-2005, 04:56 PM
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I run 4whl drums on both of my cars, stock and I have no intensions of changing them, they stop fine for being over a ton.

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  #17 (permalink)  
Old 12-06-2005, 04:50 PM
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Quote:
Originally Posted by matt167
I run 4whl drums on both of my cars, stock and I have no intensions of changing them, they stop fine for being over a ton.
Both of my projects are 4 wheel disks - if I can help it I will never run drums again. Disks are soo much simpler, and on top of that.. they actually stop!
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Old 12-06-2005, 04:53 PM
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BTW the main reason I swapped is I got sick of adjusting them or having them adjust on their own or blowing wheel cylinders or...

Just too much to go wrong with drums.
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Old 12-06-2005, 09:15 PM
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Hydroboost Systems

The reason most hot rods have poor brakes is the lack of vacuum in high performance engines. Othe changes have come up from modernizing older cars. The older cars had manual trans, for the most part. With auto trans, hot cam, f.i. turbos, overdrives, etc. the car can not stop the way it came from the factory. Another problem is valve cover clearance. As far as the question; are rear discs better than drums, rarely are they. Air brake trucks still use drums, because the rotors will melt going down a mountain with 80,000 lbs. The drums can and will "lock up" because of their self-energizing action. Discs, by design don't lock. To make a disc brake work, the piston size is increased from the basic 1.125" to 3" piston, and requires a 1200psi booster. drums usually lock up at 600psi. That is the function of the proportioning valve, to hold down the rear line pressure from a disc brake booster. Rear disc brake systems require the same high pressure as a front disc, but with the increase from a 1" rear wheel cyl to a 2.5" rear caliper, the piston size (volume) of the master must be increased to fill them. Increasing the piston size lowers the line pressure. The power booster output must be increased to bring the pressure back up. All new cars with 4 disc have huge vacuum boosters. Not good for hot rods. The best alternative now is the Hydroboost system. It runs off of the power steering pump, and requires "no vacuum" It can generate up to 2000psi, push a master cyl up to 1.625" and clear the valve covers of a hemi or 572 Chevy.

Last edited by Deuce; 01-29-2006 at 11:33 AM.
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  #20 (permalink)  
Old 12-06-2005, 10:10 PM
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Why to consider rear disc brakes....

1. Rear drum brakes have a non-linear response to fluid pressure, so the proportioning valve needs to be matched to all of your vehicle characteristics including the rear drum brake design.

2. Rear drum brake linings often become "grabby" when wet or in a high humidity environment. The resulting rear brake lockup is particularly nasty in slippery conditions.

3. The people making rear disc brake conversion kits could use the money.
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  #21 (permalink)  
Old 12-06-2005, 10:16 PM
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Quote:
Originally Posted by POWERBRAKEBOB
The reason most hot rods have poor brakes is the lack of vacuum in high performance engines. Othe changes have come up from modernizing older cars. The older cars had manual trans, for the most part. With auto trans, hot cam, f.i. turbos, overdrives, etc. the car can not stop the way it came from the factory. Another problem is valve cover clearance. As far as the question; are rear discs better than drums, rarely are they. Air brake trucks still use drums, because the rotors will melt going down a mountain with 80,000 lbs. The drums can and will "lock up" because of their self-energizing action. Discs, by design don't lock. To make a disc brake work, the piston size is increased from the basic 1.125" to 3" piston, and requires a 1200psi booster. drums usually lock up at 600psi. That is the function of the proportioning valve, to hold down the rear line pressure from a disc brake booster. Rear disc brake systems require the same high pressure as a front disc, but with the increase from a 1" rear wheel cyl to a 2.5" rear caliper, the piston size (volume) of the master must be increased to fill them. Increasing the piston size lowers the line pressure. The power booster output must be increased to bring the pressure back up. All new cars with 4 disc have huge vacuum boosters. Not good for hot rods. The best alternative now is the Hydroboost system. It runs off of the power steering pump, and requires "no vacuum" It can generate up to 2000psi, push a master cyl up to 1.625" and clear the valve covers of a hemi or 572 Chevy. Check them out at POWERBRAKESONLINE.COM

I don't think most hot rods ever came with power brakes at all so none of that really matters unless you are talking about adding power brakes. I hear what your saying but on the two vehicles I have swapped from four wheel drum to four wheel disk there was a significant difference - and both remained NON power.

I come from the off road school where your not making vacuum simply because your barely moving so hydroboost is nice..
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  #22 (permalink)  
Old 12-07-2005, 02:52 PM
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Hope This Helps

IT was a hard choice to convert to disc brakes in the rear on my suburban rod--which tows a 12kl,lb trailer to boot.....However after all the proper evlauation of both systems, i went with all disc's .....

at the junk yards i got a set of front 77 chevy truck disc and 69 cady elderado rear discs with ebrake built in.....i got the bracketts to hook it all up to the dana 60 axles from ccp in calif as well as the 1' master cylinder and a 8' stainelss double booster....the ebrake cable came from lokar--but the real secert to having it all work great was a stainless vacum can from summit.....this stores all the vacum i could ever use and really helps pedal pressure.....it is pluged in directly to the vacum port under my stealth ram throttle body....

also going to a 1'' bore mc really helped pedal presure greatly and i ended up with more stopping-then the stock 12'' booster with the 1.5'' bore mc....and i kept the p-valve were it was with the original adjustments-60 up front 40 in the rear......and with a lil bardering got everything for under 500 dollars--that is before i chromed it all......But with it all chromed--lines and mc and booster and calipers, vacum tank and all braided ebrake lines and an vacum lines--i would put it up against any system costing thousands in any show.....

when you look at my system it is small enough to look great on a roadster but has the stopping power for a tank.....ALL MY TEC INFO CAME FROM REALLY GREAT FOLKS AT SPEEDWAY MOTORS--THEY SPENT MORE TIME HELPING ME GRASP WHAT WAS NEEDED-THEY ARE TOP SELF FOLKS INTO HELPING PEOPLE....AND ALSO THE FOLKS AT CCP WERE ALL KNOWING ABOUT WHATS NEEDED.....CHECK THEM OUT IF YOU NEED HELP....

Anyway i hope this helps and remember you do not have to spend alot of money to do this....BUT YOU DO HAVE TO INVEST SOME TIME TO GET IT RIGHT

ALASKAN
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  #23 (permalink)  
Old 12-07-2005, 06:13 PM
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Added the SSBC rear disc conversion for our 98 Durango, after adding 20" rims. The Durango had marginal braking before, and with the heavier rims (73lbs per corner as opposed to 54lbs) braking upgrade was necessary.

The brakes are 200% better now, and it stops effectivly even when we are towing (7000lbs)

I would call the braking on this suv almost acceptable, as opposed to marginal the way it was from new.

Incidentally the proportioning valve had the spring removed for equal pressure to all 4 corners, as instructed by SSBC.
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  #24 (permalink)  
Old 12-08-2005, 09:31 AM
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Pads are 90 % of stopping ability.
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  #25 (permalink)  
Old 12-29-2005, 01:14 PM
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Xntrik,

Who makes the best shoes in your opinion? Has anyone tried these folks? http://www.praisedynobrake.com/index.htm

I've got 4 wheel non-power drums on my 65 Rambler Classic, and just want to find the best shoes for it.
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  #26 (permalink)  
Old 01-03-2006, 01:43 PM
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It's easy to upgrade the front brakes of the Rambler to discs, provided you can find a 79-83 Concord or Spirit to rob the brakes from. Get the spindles and all, then bolt to the Rambler. Almost that simple! There's a small brake line issue, and you need to remove the residual pressure valve from the front brake portion of the master cylinder, but otherwise it's pretty easy. You don't have to have a power brake system either, but you will notice a slight increase in pedla pressure is needed with non-power front discs.
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Old 01-06-2006, 10:47 AM
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No disrespect but, where are you getting your info. on braking? A 60/40 braking bias is a recipe for disaster! The rear brakes do aid in braking but, ad more to controling the direction to which the car in steering.

The normal braking bias is 70% and 30% max this is greatly in due to the dive designed into most vehicles.

I highly recommend visiting http://www.stoptech.com to better understand the complexity of the braking systems.

Brake bias.

http://www.stoptech.com/tech_info/wp...formance.shtml

Some stockcars can achieve almost even brake bias front and aft due in part to anti-dive designed into the car.


Quote:
Originally Posted by Deuce
...........
It is generally accepted that the front brakes does 60 % of the braking and the rear does the rest ( 40 % ) .....on most vehicles.

Last edited by 63mrl; 01-06-2006 at 03:21 PM.
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  #28 (permalink)  
Old 01-06-2006, 02:39 PM
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Bang the drum

I had a 66 gmc 20 years ago that had manual drums. The stopping performance was so bad, I swapped in late model C10 power disk brakes, and as you would guess, braking improved dramatically. Fast forward to my current project, a 65 gmc. It has the same drum brakes, but it has a factory power booster. It stops better than the first truck did after modification.
If I were looking to improve braking on a rig, before I spent big money on a conversion, i'd Increase the pedal leverage, or increase the vacuum booster and see what happened. I hated drum brakes when I was younger, but I'm leaving mine in place.
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  #29 (permalink)  
Old 01-06-2006, 10:17 PM
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A lot of cars and trucks have 60/40 displacement. Of these, many also have the same size rotors, and same type pads, front and rear, but most are also set up to fade rear first. I dont think it is a recipe for disaster unless it does not match the car. Most FWDs are 80/20.

I'm not pretending that displacement is the same as braking torque, but it does play a major role, especially when setting up your own ride. A heavy car or truck can easily have 60/40 displacement. Proportioning valves are your friend, but they should be used to optimize braking, not fix an 'oops' in the setup.

The displacement info can be determined through mathematics, or looking up the specifications in either the service manual, if listed, or the AMA specs.
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Old 01-07-2006, 01:18 PM
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go drum

I have to say, once GM went back to rear drum in 1/2 ton pickups in 05, braking has dramatically improved and with our new york winters, we wont have to replace/turn rear rotors anymore
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