Thread: Roadster pickup getting front disc brakes----

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And here we are, all painted up pretty. The blue stuff is anti squeak goop that is supposed to keep the brake pads from vibrating and squealing when the brakes are applied. It is applied to the rear surface of each pad when they are installed in the calipers. I finished the drivers side this morning, and it went very quickly. I checked under the car, and I was smart enough to put a 10 pound residual check valve in both the front and rear lines when I plumbed the brakes 5 years ago. (I couldn't really remember.)---Now if I'm really lucky, all I have to do is swap out the 10 pound residual check valve for the 2 pound unit I bought to go with the disc brakes. I was able to re-use my existing flexible brake lines, so as soon as I get that residual check valve changed, I should be able to bleed the brakes. Don---I checked the passenger side steering arm and the tie rod---its fine. Maybe the picture you were looking at made it look a bit funky due to parallax. thanks for the tip about e-bay.

Brian I missed this thread! You brought back memories of my first truck project, which was converting over the front to disc brakes. My truck came with a kit from Classic Performance Parts. The instructions were minimul with generic stuff. Funny thing is, I remeber the grinding of the nub on the calipers, the emoring down of the spline to get the adapter bushing on and the pounding out of the inner race to replace it with the new one. The kits must be pretty universal. The worst part for me was stairing at the caliper mount thinking there is no way in hell that is going to work, then realising I was right. They had put the wrong brackets in the kit!
I wish you did this two years ago and posted it back then, it would have made my job a lot easier!
The nice thing is for a small amount of effort you get a big amount of safety and performance in return! When do you go on your long distance road trip?

Stovens--If nothing gets in my way (health, family disaster, etc.) I am scheduled to leave on the 03-July.

I just discovered something strange when I went to bleed the brakes. The bleeder on one caliper has a 5/16"-24 thread on it. the bleeder on the other caliper has a 3/8"-24 thread on it. Sometime betweem 1979 and 1987 Chev must have changed the bleeder thread size. Everything else on the calipers were identical.

My spider senses were right again!!! (They've been tingling about these brakes for the past 2 summers.) After the big garage clean-up today, I took a few minutes to examine the old drums and shoes that I removed. The lining on the shoes on both sides of the car were down to (and almost through) the rivets. One drum has some very light scoring on it, but will clean up allright on a drum machine. Both wheel cylinders were in perfect shape, with no leaking at the rubbers.

When I look back over a mostly happy marriage, it seems like the bitterest fights that my wife and I have had resulted from me getting her to help bleed the brakes on various cars/hotrods.---I will not go thru that anymore. Five years ago when I built the Wild Canary, I dicovered "SpeedBleeders" from russell. www.russellperformance.com These things are wonderfull. They allow you to bleed the brakes by yourself, and they work very, very well. So----I just picked up the phone and ordered a set to match the new disc brake calipers. They will be in this week, and that should hopefully (barring any leaky fittings) be the end of my brake story.

Question---how much "drag" if any should there be between the pads and the disc, when the peddle is not being applied? I have installed a 2 pound residual check valve in the line leading from the master cylinder to the front disc brakes. (This is what is recommended for a master cylinder under the floor application.)---It is installed with the arrow pointing in the correct direction---away from the master cylinder. I haven't bled the brakes yet (I'm waiting for some "speed bleeders" from Russell)--however, when I pump the brakes up the pads definitly grip the discs and hold them---but after I release the pedal and the pads "back off" the passenger side ends up with very little "drag" while the drivers side has quite a bit of "drag" on the disc. (I can still rotate the disc by hand.) The mounting bolts and bushings are well lubricated with silicone base grease (which is recommended.) ---is this unequal drag just because everything is brand new?

Originally Posted by brianrupnow

Question---how much "drag" if any should there be between the pads and the disc, when the peddle is not being applied? I have installed a 2 pound residual check valve in the line leading from the master cylinder to the front disc brakes. (This is what is recommended for a master cylinder under the floor application.)---It is installed with the arrow pointing in the correct direction---away from the master cylinder. I haven't bled the brakes yet (I'm waiting for some "speed bleeders" from Russell)--however, when I pump the brakes up the pads definitly grip the discs and hold them---but after I release the pedal and the pads "back off" the passenger side ends up with very little "drag" while the drivers side has quite a bit of "drag" on the disc. (I can still rotate the disc by hand.) The mounting bolts and bushings are well lubricated with silicone base grease (which is recommended.) ---is this unequal drag just because everything is brand new?

Brian I'm curious about this too. Mine don't drag much, you can still turn the wheels and push the truck easily, but they do drag a bit. I'm wondering if an adjustment to the brake pads, on the metal tabs on top would change this. I also want to thank you for the tips on the noise reducing blue stuff, and the reminder, that I still haven't greased the bushings and the bolts they travel on, could have been a big issue on the road!

Stovens--As I understand it, the purpose of the 2 pound residual check valve is to ensure that there is always at least 2 pounds of hydraulic pressure on the caliper piston even when the pedal is released, to keep it from fully backing off. Apparently 2 pounds of pressure is enough to keep the piston from backing off to the far end of its cylinder, but not enough to cause any serious wear on the brake pads. Thats why disc brakes never need to be adjusted---the piston is always "right there" so that when you hit the brakes the piston, and consequently the pads don't have to travel thru a distance to get to the disc. That in itself could be what accounts for a bit of "drag" when I go to turn the rotors by hand. It just doesn't explain the unequal "drag" I feel between the drivers and passenger side wheels. I don't really know, but I assume that there is a spring in the caliper which holds the piston in a "normally retracted" state.---Do you know if this is right?---Brian

Brian,
The drag you feel is normal at this time.

The drag will mostly disappear after you have finally seated the pads and started burnishing the rotors. Recall that these rotors are either cast iron or cast steel and when they are turned, they leave little spurs pointing in one direction based on how they were manufactured. When you assemble the brakes, one side will always be AGAINST the direction of manufacturing rotation.

If you were to use machined drums, you would have this "phenomenon" with them as well. Many times in the good old days of drum brakes, I would encounter this with customer cars when doing the initial adjustment.

The 'return spring' is the seal that goes around the caliper piston. Usually it's a square cut O ring that flexes just enough to allow extension and retraction of the piston.

Your installation - it looks great and you will be happy. One item you might have to install is an adjustable proportioning valve to control rear brake application - but of course drive it first.

Ah yes - wives and PUMP IT and HOLD (DAMMIT!!! I said hold). I too, for obvious reasons use the Speed Bleeders. Dorman also makes them and they are a bit cheaper without Vic Edelbrock's cut from his Russell products

Originally Posted by IC2

Brian,
The drag you feel is normal at this time.

The drag will mostly disappear after you have finally seated the pads and started burnishing the rotors. Recall that these rotors are either cast iron or cast steel and when they are turned, they leave little spurs pointing in one direction based on how they were manufactured. When you assemble the brakes, one side will always be AGAINST the direction of manufacturing rotation.

If you were to use machined drums, you would have this "phenomenon" with them as well. Many times in the good old days of drum brakes, I would encounter this with customer cars when doing the initial adjustment.

The 'return spring' is the seal that goes around the caliper piston. Usually it's a square cut O ring that flexes just enough to allow extension and retraction of the piston.

Your installation - it looks great and you will be happy. One item you might have to install is an adjustable valve to control rear brake application - but of course drive it first.

Ah yes - wives and PUMP IT and HOLD (DAMMIT!!! I said hold). I too, for obvious reasons use the Speed Bleeders. Dorman also makes them and they are a bit cheaper without Vic Edelbrock's cut from his Russell products

Dave---I put an adjustable proportioning valve in the rear brake line when I built the car. I expect I will have to adjust it as part of this exercise. It is set pretty well wide open now, as I have up untill this point beens running drums front and rear.---Brian

man that is a beautiful truck! love the tire and wheel combo! nice job on the brakes!

Evolvo--Yes, I have heard that reason also, and it makes more sense to me than what I had first posted. However---If the residual check valve does indeed hold that "residual pressure" in the lines, wouldn't my first explanation be true as well????

my current set up has a proportioning valve to balance the pressures front and back. I'm running front disc rear drums. the difference is 2lbs and 10 lbs, can't remember which is which, but it is a factory preset for this setup, guessing 2 to the disc and 10 to drums.

Originally Posted by stovens

my current set up has a proportioning valve to balance the pressures front and back. I'm running front disc rear drums. the difference is 2lbs and 10 lbs, can't remember which is which, but it is a factory preset for this setup, guessing 2 to the disc and 10 to drums.

Yes, that is the recomendation. 2 pound for discs, 10 pound for drums. You also need a proportioning valve to set which brakes actually come on first. You want the rear brakes to engage first to hold the car straight, then the fronts to come on and give most of the actual stopping power.