|05-30-2009 05:57 AM|
|barnym17||we're going to find out as soon as I get the honey do list out of the way.|
|05-29-2009 01:15 PM|
I have found that the low drag calipers you get from parts stores are mixed in with the standard ones.
Example: I bought a GM metric caliper to use a a mockup in the shop, bought it from my local parts house, a small franchise that uses the Parts + brand. Even though I specified a 77 Monte Carlo..I got a low drag caliper in the box...
I made a thread about the dreaded low drag calipers a few weeks ago.
The Raybestos brake technician's service manual I have says that GM started putting these on cars in 1980. It does not specify which cars they came out on initially.
I'm really interested to see how the S-10 master will work in a non boosted application.
|05-29-2009 11:28 AM|
|Triaged||From everything I have read '83 was when GM started using low-drag calipers and step-bore master cylinders.|
|05-29-2009 11:16 AM|
|barnym17||Triage what about oem calipers pre-83 would this help the issue?|
|05-29-2009 11:14 AM|
|barnym17||Yes I did, removed it as I changed masters (I think ) this build has been going on to long.May give the s10 master another try.|
|05-29-2009 10:34 AM|
|05-29-2009 08:48 AM|
|barnym17||I thought of that but for some reason all the parts stores such as napa the zone etc. are showing the same # for the calipers from 79 to 87 like they consolidated and .Build either all low drag or all non low drag calipers to save money.Tried the s10 manual master no volume to the rear brakes.Again could have been a bad master.Switched to 79 camaro with bigger cyl and got brake pressure now.Just have to remove the residual pressure valve, this weekend project.This thing should hit 100 or more in the 1/8 so I really want to be able to stop.|
|05-28-2009 01:38 PM|
Why not just put pre-83 non-low-drag calipers in the rear?
Sounds like you were looking at a manual brake S10 master cylinder which should be a good fit with what you have.
|05-24-2009 07:18 AM|
|barnym17||Mikey you got what my dad called "Gotta see how it works itis"Or when he said this to me as a kid was" What did ya tear up now?"|
|05-24-2009 07:16 AM|
|barnym17||If memory serves early 90's 1/2 ton pickup.|
|05-23-2009 02:21 PM|
|05-23-2009 01:45 PM|
I have used 10# inline RPVs on low drag fronts with no problems, it cuts the piston retraction back to about .010" from .020", so you don't have a brake drag problem with that setup. I don't know what RPV rating is in the MC you have, stockers can be as much as 16#, that extra residual line pressure is what might be making the rear brakes drag in your case, with your current setup.
You can test the RPV, the setup is simple.
Adapt a 0-30 psi gauge to the outlet. (in this case I am testing an inline wilwood)
To test an RPV in a mastercylinder, just adapt a gauge anywhere downstream from the outlet, youcan even plumb it into a bleeder on the caliper.
Apply about 20 psi, the let off the pressure...The gauge will tell you what the residual pressure rating is.
That is a valve that I took apart and installed a better spring, it now holds about 12 psi. I test them for pressure, as well as time it takes to leak down. It should hold indefinatly, any less than 20 minutes at the rated pressure and I would consider the valve junk.
Yes, as you can see all of my info is gotten from books.
|05-23-2009 01:15 PM|
|barnym17||By the way Thanks for all your help.|
|05-23-2009 01:14 PM|
|barnym17||Thanks Mikey, I will try the 1 1/16 cylinder first, was over at a buddy's we were yacking and 7/8 is the size on the dual master setup.He is using a 2lb residual valve to keep the pads from pulling so far off the rotors eliminating the need for the quick take up master one front and one rear.He uses this setup on all his hobby stocks and e-mods he builds with good success so it stands to reason we should be able to do it with a stock dual master cylinder, same difference still using two pistons one front and one rear.I will pull the residual valve like you show see how it works if the pedal is still low I'll try the 2lb valves . These setups work well on dirt but you can't use as much brake so we'll just have to experiment.If I can get it to lock up I can adjust bias from there.The best part about the bird cyl. is it is only $29.00 vs. $100.00 for a wilwood which is just a dodge truck master anyway.|
|05-23-2009 01:00 PM|
The residual pressure valve is easily removed with an easy procedure. I went out and did one for ya in one of my mockup/visual aid master cylinders ..took about 5 minutes, including taking pics.
Tap the male flare seat with a 6-32 tap.
Screw a nut onto a 1" x 6-32 screw, stack up enough washers on the screw to keep the nut from falling into the port, then screw the whole stack into the tapped port.
Crank down on the nut and that seat will pop right out.
Remove the RPV valve and spring, (you will see that the RPV prevents the chips from tapping from going in the bore) clean everything with a bit of brakekleen, then reinstall the brass seat. You can seat the brass seat with a tubenut of the appropriate size.
You can probably run that 1" mc for a while, if it develps enough volume, but a 1 1/8" might be necessary. You'll have a low pedal with the 1", but you can see what the pedal effort is like.
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