Advice for 64SS for front brakes & suspension - Impala Tech
Brakes & Suspension Conversion Questions & more

 
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post #1 of 10 (permalink) Old 04-22-2016, 01:18 PM Thread Starter
 
 
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Advice for 64SS for front brakes & suspension

I recently purchased a 64SS and I want to upgrade the front brakes with a disc conversion kit the car has 15" American Racing rims. I've been seeing many complete kits that include master cylinder and combo valve and GM style calipers some have small diameter dual diaphragm booster others have single diaphragm larger diameter, advantage of each? Combo metering/proportioning valve or adjustable proportioning valve. I've also read some posts here to stay away from the economy priced conversion kits because of foreign made parts with poor machine work and fit, what are your experiences?


On the suspension I'm also considering front 2" drop spindles and later installing air suspension down the road, is it still advisable to go with drop spindles with air ride?

1964SS
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post #2 of 10 (permalink) Old 04-22-2016, 09:46 PM
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Disc brake kits are either cheaply made out of import parts or expensive with OEM quality American made parts. All of the parts can be found on later model GM cars once you have a disc brake spindle (the dropped spindle is usually set up to accept a bolt on caliper for disc brakes.


The size of the dual master cylinder (all brakes made after 1966 used a dual circuit master cylinder for safety) is determined by whether the brakes are going to be powered by a vacuum booster or your foot. Since the power assist can generate additional pressure the brake master cylinder uses a larger diameter bore piston. Manual brakes used a smaller diameter. If it used a booster it required a longer brake activation rod that didn't penetrate the back of the cylinder. Also the activation rod bolted onto the brake pedal at a higher location when manual than power assist (there are two holes punched in the brake pedal).

The wheel cylinders also changed size to match the master cylinder as they all have to follow the same hydraulic law that multiplies the force you apply to activate the brakes. Since disc brakes require twice the line pressure that drum brakes do to operate you have to restrict the line pressure to the rear drum brakes with a proportioning valve or the rear brakes will lock up first. If you don't know what parts you have a variable or adjustable valve is the easiest to install.


Brakes are one of the most complex in terms of getting the parts mixture just right (GM offered five different systems based upon vehicle weight) This makes getting the right parts difficult for beginners. There are lots of lists complied of replacement GM service parts to install disc brakes on Chevelles, Novas and Camaros but not a lot of information that I have seen for the heavier Impala. I would look on early model Chevy pick-up boards for a list of parts as they where about the same weight back in the early fifties.


Or you can buy a cheap kit and replace the parts one at a time with better made ones after they fail (assuming you live through the failures).


Big Dave
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post #3 of 10 (permalink) Old 04-22-2016, 11:19 PM Thread Starter
 
 
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What was the first year that disc brakes came out on impalas?
Would the combo valve and master cylinder be similar if the car weights were close?
My 64 has factory power brakes could the booster be kept and replace the single resiviour with a drum/disc master cylinder off a similar size fm car with front disc?
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post #4 of 10 (permalink) Old 04-23-2016, 08:11 AM
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There is a lot of companies out there selling this kits. On of site sponsors is Classic Performance Products. I installed a 2" drop spindle disc brake kit from them in my 66 Impala and was very happy. They are very knowledgeable and could answer all of these questions for you with products in mind. The other long time vendor for these kits are Master Power Brakes (MPB)Disc Brake Conversion Kits | Master Power Brakes.

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post #5 of 10 (permalink) Old 04-23-2016, 10:21 AM
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Quote:
Originally Posted by 1964SS409 View Post
What was the first year that disc brakes came out on impalas?
Would the combo valve and master cylinder be similar if the car weights were close?
My 64 has factory power brakes could the booster be kept and replace the single resiviour with a drum/disc master cylinder off a similar size fm car with front disc?
The first year for disc brakes was 1967. Chevrolet engineers took the caliper and disc rotor out of the Corvette parts bin and put them on the front only.


Yes the size of the master cylinder and combo valve are similar for similarly equipped vehicles of the same weight. By similarly equipped I am referring to the brakes being either manual or power assist.


Yes you can bolt on a dual reservoir master cylinder in place of your single and replace the brake lines to match the master cylinder. (you can splice into the brake lines and attempt to bend them and double flair the ends again, but they are probably pretty rusty by now and probably should be replaced)


The problem with your year car is that the steering knuckle had a forged steel spindle pressed into the cast iron steering knuckle. This two piece design makes it hard to upgrade to disc brakes. By buying a replacement one piece steering knuckle (either standard ride height or dropped two inches) with the cast iron spindle induction hardened to accept the wheel bearings you get the added material (tabs) needed to bolt on the calipers. This is required unless you go to a bracket that bolts onto the factory two piece casting and will require a lot of machine work and shimming to get everything aligned.


Just keep in mind that if you have the original unmolested factory springs that you are already riding an inch and a half to two inches below the factory ride height due to spring sag. So new springs and a standard ride height will actually raise you car up noticeably. If someone has heated or cut the springs before you bought the car your ride height could be considerably lower than how it left the factory. You may want to measure what you have and compare that number with what was published in the Chassis Service manual for 1962 (1964 cars required you to buy the 1962 factory manuals and then to also buy the 1964 addendums to the 1962 manuals).

I can also recommend the better kits sold by MPP and Classic Performance Products. Just keep in mind every one sells cheap kits with cheap parts in them just to keep the Wal Mart shoppers happy. Brakes and suspension parts are an example of "you get what you pay for!"

Big Dave
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post #6 of 10 (permalink) Old 04-23-2016, 11:23 AM Thread Starter
 
 
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Thank you sir you are a wealth of knowledge.

Some of the drop spindle kits mentioned issues of improper steering geometry resulting in bump steer. From some of the pics of the steering knuckles some are cast with the arm that the outer tie rod attaches to and the others look like you have to reattach the original to the back of the steering knuckle what would you recommend.
Also car originally had a 327 and I'm quite sure the 409 will add a few more pounds up front, I have no idea if the front springs have ever been replaced so it might be safe to assume they are original.

1964SS
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post #7 of 10 (permalink) Old 04-23-2016, 04:48 PM
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Bump steer problems are usually the fault of the tie rod ends attaching to the steering arm at a different height than where the tie rod is located so that as the wheel goes up or down the angle of the wheels changes more or less than desired. This is a notorious issue that never gets mentioned ion the sales literature of people selling rack and pinion steering kits off of a Ford Pinto to install on a car that weights twice as much (such that the dynamic forces are four times as greater than the Ford engineers ever anticipated when they designed the steering system for the Ford Pinto/Mustang II). Along the same lines Ackerman angle issues are associated with the difference in track between the upper and lower ball joint introduced when people install tubular A-arms because they are the "in" automotive fashion right now.


As to using a bolt on steering arm as opposed to one that is cast along with the steering knuckle, that would depend upon the position of the tapered hole on the end of the arm. If it aligns with the original; all is well and good. If not, expect steering geometry issues. It would be probably better to buy one that reuses the bolt on steering arms as there are different length and height arms available off of various GM made cars that could be substituted to improve your turning radius, or correct bump steer issues.


Big Dave
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post #8 of 10 (permalink) Old 05-12-2016, 10:47 AM Thread Starter
 
 
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Residual Valves

Big Dave I ordered a SSBC kit that includes rotors, calipers, booster and dual bowl master cylinder from Jegs but it's on back order and I also ordered a block with adjustable proportioning valve and light switch.
My question is I'm going with front disc and original rear drum do I need to get residual valves 11 psi for rear drums and 2 psi for front discs with this kit?
I also called MP brakes before I ordered my kit and asked the tech if I needed residual valves and he said no because the master cylinder is mounted higher than the calipers and wheel cylinders. But remembering back to my 30 plus years ago taking automotive tech course when we covered brake systems that the residual valves help maintain slight pressure on pads and shoes.
What would you recommend?
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post #9 of 10 (permalink) Old 05-12-2016, 10:41 PM
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Residual valve on disc brakes is used mainly to wipe off any water on the disc rotor if you drive through any water on the road as disc brakes don't work so long as they are hydroplaning over the rotor. Rear brakes are activated faster and it keeps the brake shoes properly spaced (aka adjusted) if you never back up and tap the brake pedal a few times (this is how the self adjusters operate). Without adjusting the brakes properly pedal travel increases, as does your stopping distance with brake shoe wear).


But the brakes will sort of work in a fashion without them, just not optimally.


Big Dave
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post #10 of 10 (permalink) Old 05-16-2016, 09:56 AM
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Someone had installed front disc on 64 SS I recently bought. I have no complaints as far as driving goes. I only wish I could fit stocks on the car which I cannot. I might remove them because I really like stock hubs with whites.
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