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#2381878 - 10/04/17 03:50 PM 70 Challenger brakes
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
Brake question- Driving the Challenger and noticed a front brake dragging. Eased it home and ordered a set of calipers from Napa. Bled it out today and both front brakes are tight. Checked the metering valve and the pin is not moving when the brakes are applied. I can tap it in and it comes out when when brakes are applied but doesn't go back in on its own. Seems like I took it apart and cleaned it when I built the car 15 years ago. Does this sound like a metering block issue or maybe something else? 70 RT with disc brakes.
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#2381887 - 10/04/17 04:01 PM Re: 70 Challenger brakes [Re: Carsavior]
VCODE Offline


Registered: 01/10/06
Posts: 1841
Loc: New York
Also check to see if the master cylinder rod is adjusted and has about .30 play and is not keeping the brakes on.
Bob
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#2381898 - 10/04/17 04:14 PM Re: 70 Challenger brakes [Re: Carsavior]
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
Car has been built since 2002. Brakes have always worked great. I used a later aluminum master cylinder with stock line routing. 11.75 front discs and Imperial rear discs. This is the first issue it has given me.
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#2381919 - 10/04/17 04:19 PM Re: 70 Challenger brakes [Re: VCODE]
amxautox Online   content
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Registered: 05/13/03
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Originally Posted By VCODE
Also check to see if the master cylinder rod is adjusted and has about .30 play and is not keeping the brakes on.
Bob
Make that .03" Not .30".

.30 is almost 5/16th of an inch, which is more than 1/4 inch, WAY too much. :-)
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#2382027 - 10/04/17 05:26 PM Re: 70 Challenger brakes [Re: Carsavior]
71birdJ68 Offline
master

Registered: 02/09/12
Posts: 3351
Loc: Morristown Tn.
Check the hoses, if they collapse the brakes will drag.

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#2382038 - 10/04/17 05:58 PM Re: 70 Challenger brakes [Re: 71birdJ68]
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
No hoses. All braided stainless lines
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#2382040 - 10/04/17 06:05 PM Re: 70 Challenger brakes [Re: amxautox]
VCODE Offline


Registered: 01/10/06
Posts: 1841
Loc: New York
Originally Posted By amxautox
Originally Posted By VCODE
Also check to see if the master cylinder rod is adjusted and has about .30 play and is not keeping the brakes on.
Bob
Make that .03" Not .30".

.30 is almost 5/16th of an inch, which is more than 1/4 inch, WAY too much. :-)


thanks, turned number around while typing.
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Mom & Dad let me buy a brand new 70 Challenger R/T 440 Six-Pack Super Trac Pack when I was 17 (Robert what is a 440 Six-Pack)

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#2382082 - 10/04/17 08:10 PM Re: 70 Challenger brakes [Re: VCODE]
ahy Offline
master

Registered: 01/22/07
Posts: 7367
Loc: IN
I have had the "hoses collapsed" front dragging. It is possible with stainless also I think if the liner collapses... but not likely both at once.

I am not an expert on prop valves... but generally seems like they are a potential problem and limited benefit. The fronts usually run fine on a simple "T" and rears, adjustable valve only if needed.

I you bring her home with front brakes tight, try cracking a front bleeder one at a time. Does that loosen one wheel? Or both?

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#2382132 - 10/04/17 09:17 PM Re: 70 Challenger brakes [Re: Carsavior]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32540
Loc: Lincoln Nebraska
new calipers & it is still dragging? Both sides dragging or just one? You might jack up the front end & hit the brakes to get em dragging then loosen a caliper bleeder to see if it is a psi or a mechanical (caliper) problem tho with both sides acting up at the same time all of a sudden for sure sounds like a psi issue. As said if power then check the pushrod round nub clearance. Post how it turns out. EDIT If power I would remove the 4 MC nuts & space the MC slightly forward from the booster with some washers & see if that resolves it & if so then I would go ahead & seperate the MC from the booster & measure the gap/shorten the rounded pushrod nub to get ~.020" gap.


Edited by RapidRobert (10/05/17 11:31 AM)
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#2382719 - 10/05/17 08:38 PM Re: 70 Challenger brakes [Re: RapidRobert]
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
Loosened master. No change. Holding pressure. Took off flex lines. They're good. Pulled proportioning valve and metering valve. Isn't there a combination valve or something that people use to get rid of the metering Valve? Since I've got these off I'm going to replace them. They're only 48 years old...
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#2382720 - 10/05/17 08:41 PM Re: 70 Challenger brakes [Re: Carsavior]
Supercuda Offline
I Live Here

Registered: 09/04/07
Posts: 12425
Loc: West Texas
The combination valve is a combination of proportion and metering in one assembly.
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#2382766 - 10/05/17 09:52 PM Re: 70 Challenger brakes [Re: Supercuda]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32540
Loc: Lincoln Nebraska
I'm assuming when you crack the "out" line from the prop valve forward to the front calipers that they release?
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#2382775 - 10/05/17 10:12 PM Re: 70 Challenger brakes [Re: RapidRobert]
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
Is metering valve really necessary? If anybody has a proportioning valve similar to the stock one I can probably reroute the lines to fit. With the 4 wheel discs I'm wondering if i really need a metering valve...
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#2382821 - 10/06/17 12:19 AM Re: 70 Challenger brakes [Re: Carsavior]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32540
Loc: Lincoln Nebraska
iirc a guy used no valve at all with 4 wheel discs & it was fine. You could get some short lengths of prefabbed 3/16" brake lines & some double female 3/8-24 connectors at your parts house & bypass it & see how it acts. Not exactly the same but I added '76 A (2.75 bore) discs to the front of my 65 dart & kept the OE splitter & no added prop valve and a dual bowl 1&1/8" alum MC & it worked flawless. It would lockup the rears (10x2 or 2&1/4 (whatever the BBP 7&1/4 is) with hard brakeing but no issue. Ceramic pads in the front. No pad wear that I ever noticed. EDIT the connectors are double female IFF inverted flare female (will have a recessed conical seat on each side of the brass connector)


Edited by RapidRobert (10/06/17 11:01 AM)
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#2383126 - 10/06/17 06:59 PM Re: 70 Challenger brakes [Re: RapidRobert]
Carsavior Offline


Registered: 01/19/03
Posts: 881
Loc: Monroe, LA USA
Thanks.
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#2383146 - 10/06/17 07:50 PM Re: 70 Challenger brakes [Re: Carsavior]
SportF Offline
super stock

Registered: 01/08/08
Posts: 701
Loc: Minn
What most everybody here is calling a "proportioning" valve is the valve that gives you dual (individual front and back) brakes. Without it, you don't have dual brakes.

Kinda defeats the dual master cylinder install.

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