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#1 |
1970 Daily Driver
Join Date: Jun 2007
Location: Glenns Ferry IDAHO
Posts: 1,037
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Need disc brake help
Well I have a 1970 that I converted over to Disc brakes in the front a few years back. My power brake booster and master came out of a 1982ish Chevy truck and I used 1972 parts for the brakes themselves. When I put the disc brakes on I could not remember if when I added power brakes a few years even prior to that time, if I had put the proportioning valve from the newer truck that would be disc/ drum or if it was the old drum/ drum. So I put it all together without knowing and everything worked great and has been for the last few years of daily driving.
I am now up grading to a nicer duel piston aluminum caliper (wilwood D52) on all four corners. I thought the fronts would be an easy switch out of the calipers and done. So I swapped them out last night. Only problem is that when I got them bleeded there is now too much preload on the pads and it is hard to move the rotors even without any pressure on the brake pedal. I thought where everything worked with the GM calipers that it would work just the same with the new Wilwoods. Everything is the same as before the only parts I changed out were the calipers and I switched to stainless steel brake hoses. The rotors and pads are the same ones I was running with my GM calipers. Any advice would be appreciated as this is my daily driver. I had to borrow a friend’s car to go to work today and hope to get my truck fixed tonight.
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It's not truly yours if you didn't build it yourself or if you don't do your own maintenance. Last edited by lts70; 10-14-2010 at 11:10 AM. |
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#2 |
Registered User
Join Date: Sep 2010
Location: Tyler,Tx
Posts: 25
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Re: Need disc brake help
maybe the calipers are a little smaller, i have seen this before and the brake pads are actually rubbing the rotor , sand the pads downa little , or maybe the brackets have the caliper to far from the rotor and the front is dragging.
on the proportioning valve i dont run them, i throw them in the trash on all the race cars i build and just run the lines right out of the MC to the breaks, i have never had a problem with them, and i drive the race cars on the street also.. |
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#3 |
1970 Daily Driver
Join Date: Jun 2007
Location: Glenns Ferry IDAHO
Posts: 1,037
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Re: Need disc brake help
I hope not. The pads I have on are already worn down quite abit from use. I oredered these specificaly for a 1972 setup.
Their tech line is telling me to bench bleed my master and bleed my lines again including my rears. Does that make sence?
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It's not truly yours if you didn't build it yourself or if you don't do your own maintenance. Last edited by lts70; 10-14-2010 at 11:35 AM. |
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#4 |
Registered User
Join Date: Sep 2010
Location: Tyler,Tx
Posts: 25
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Re: Need disc brake help
well you didnt change the MC did you? it should still be bled, i wouldnt see the need in bleeding the backs , you didnt do anything with them. have you drove the truck since you have put these on , try driving it a block or so and then check to see if it is any better. when the presure is released the pistons should go back in and the caliper it self should have a little play also they dont mount rigid.
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#5 |
Old Skool Club
![]() Join Date: Jun 2001
Location: Benton, AR "The Heart of Arkansas"
Posts: 10,880
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Re: Need disc brake help
What actually causes the pads/caliper to retract when there's no pedal? Look at those parts and be sure they aren't subject to binding. Beyond that, look at the pedal ass'y and be sure that it isn't putting any pressure on the M/C push rod.
It's gotta be something simple....
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Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was. |
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#6 |
Account Suspended
Join Date: Aug 2007
Location: USA
Posts: 1,223
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Re: Need disc brake help
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#7 | |
Account Suspended
Join Date: Aug 2007
Location: USA
Posts: 1,223
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Re: Need disc brake help
Quote:
you either have something not lined up right or the pressure is not releasing from the master, Are all four calipers stuck? Iv seen a bad brake hose hold a caliper, but not all four at the same time. if all four are stuck i would say its either the valve or the master. one of those two is not releasing the pressure. |
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#8 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: Need disc brake help
Let me know what you come up with, im having EXACT same problem NEW everything
are your soft lines new too? they collapse over time internally
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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#9 |
60-66 Nut
![]() ![]() Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,247
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Re: Need disc brake help
Lane, On those Wilwood calipers did you install the sleeves into the calipers that allows them to slide on the caliper mounting bolts? I have noticed that the Wilwood D52's that I have didn't have those installed. I'm thinking that if those sleeves aren' installed and you tightened the claiper bolts, the caliper can't move and may be the binding you feel. Does that make sense?
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Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
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#10 |
1970 Daily Driver
Join Date: Jun 2007
Location: Glenns Ferry IDAHO
Posts: 1,037
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Re: Need disc brake help
oldblue1968chevy I have new stainless soft lines. they were the only other items I replaced besides the calipers.
Captainfab I put the little collar sleeves on the inside side of the caliper bolt hole before I bolted her down. It is so weird, they are not stuck or grabbing. They work like normal except they do not release pressure all of the way off when the brake pedal is released. Where I have ran GM D52 calipers for the last few years with no problem this really has me stumped. I am really bummed on this one. I want to get the d52's on the back as well but can’t get this front figured out. It seems like the simplest task are getting the best of me these days.
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It's not truly yours if you didn't build it yourself or if you don't do your own maintenance. |
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#11 |
67-72 parts collector,…
![]() Join Date: Nov 2002
Location: Mid-MO
Posts: 22,699
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Re: Need disc brake help
It sounds like
1) you still have some air in the lines. I would bench bleed the M/C on the truck. (just like you would in a vise,... but slowly move the pedal to remove all air in the M/C). Then hook up the lines and bleed them at the wheels. 2) Is there any chance that you got the wrong D52's? They make 4 different ones. 2 fronts and 2 rears. (different width rotors and different piston sizes) I wondered if by chance you got a set of D52's made for 1" rotors and they actually fit your 1.25" wide '72 rotors since your using your old worn brake pads? Maybe they're not backing off enough when you release the pedal. The worst part,... is when you decide to add your rear calipers,... you're going to have to change the proportioning valve and bleed everything again.
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Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 Last edited by lolife99; 10-14-2010 at 11:48 PM. |
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#12 |
Registered User
Join Date: Jul 2000
Location: NC
Posts: 987
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Re: Need disc brake help
I had a similar issue with my brakes. New M/C, lines and calipers. The front brakes would drag after applying them. It turned out that the prop valve button was not returning to an extended position. I replaced that with a wilwood adjustable valve and the front calipers would release properly. Just a thought....
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#13 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: Need disc brake help
Ok, going to throw this in..
I never 'bench bled' the MC..I have the brakes bled now, the fronts slightly still hold? And my aftermarket prop. valve AND my stock one, had a button on the front, whats this do? lol
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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#14 |
1970 Daily Driver
Join Date: Jun 2007
Location: Glenns Ferry IDAHO
Posts: 1,037
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Re: Need disc brake help
Well I installed a new wilwood adjustable proportioning valve and that did not solve my problem. I drove it to work and back 64 mikes to see if things would seat in but no luck. I opened my bleeder and that did not back off any pressure, so I think it is something mechanical with the calipers. So I pulled the caliper off again and found that my pads are digging into the willwoods because the point of the pad is the only thing in contact with the aluminum caliper. On my old GM setup it has a full 3/4" of flush surface that the pad and caliper engage. I think this might be what is holding up my brakes. What do you guys think? The first three shots are of the willwoods and the last two are the GM calipers. Look for the red arrows. The pad is flipped to better show the problem, not how I have them installed
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It's not truly yours if you didn't build it yourself or if you don't do your own maintenance. Last edited by lts70; 10-27-2010 at 12:04 PM. |
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#15 |
Account Suspended
Join Date: Aug 2007
Location: USA
Posts: 1,223
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Re: Need disc brake help
the one thing I notice is the anti rattle clip the factor caliper used one and i think it held the pad up off the caliper does the wilwood use them as well? if not they may be the problem. just a thought
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#16 |
1970 Daily Driver
Join Date: Jun 2007
Location: Glenns Ferry IDAHO
Posts: 1,037
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Re: Need disc brake help
Here is an out line of my Brake pad and where they engage the calipers.
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It's not truly yours if you didn't build it yourself or if you don't do your own maintenance. |
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#17 |
Account Suspended
Join Date: Sep 2010
Location: hingham ma
Posts: 1,721
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Re: Need disc brake help
ok. on these trucks 4 wheel drum system is the residual valve in the master ports or the proportioning valve..
if in the valve, there is your issue, as that valve (resilual) keeps 10-15psi on the system to keep the springs in a drum set up from backing off the shoes to far and cause'n a low petal.. used with disc it'll hold the calp on the rotor.. |
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