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Re: Brake pedal "meh" thinking about braided lines. [Re: Todd] #1594547
03/19/14 11:12 PM 03/19/14 11:12 PM
Joined: Jun 2005
Posts: 5,102
Western Md.
skicker Offline
"The Champ"
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Quote:

Quote:

yes,1/8 travel seems far too much.perhaps using a spacer
position those pistons further out and re assemble?


Spacer???
Maybe your forgetting how a disc brake caliper work
If your pistons are retracting 1/8" that's way to far.
Like I stated before the seals are pulling the pistons back to far.
They should only retract far enough to let the rotor spin without touching.



I think Todd nailed this correctly with his first post.
I have had this happen on the rear of a 4 wheel disc dirt car but have never had it on a dodge. It only stands to reason all calipers serve basically the same principle, they're just in different configurations.
Is it possibly caused by the phelonic piston rather than the steel?

...FAFO...
Re: Brake pedal "meh" thinking about braided lines. [Re: skicker] #1594548
03/19/14 11:31 PM 03/19/14 11:31 PM
Joined: Feb 2009
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Ontario.Canada
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can.al Offline
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let me explain..
take the calipers off the rotors and using a "spacer" narrower than
the rotor,force the pistons further out.
re assemble such that they are only about 1/32" off the rotors.
now there will be almost no travel.

Last edited by can.al; 03/19/14 11:32 PM.
Re: Brake pedal "meh" thinking about braided lines. [Re: can.al] #1594549
03/19/14 11:44 PM 03/19/14 11:44 PM
Joined: Jun 2005
Posts: 5,102
Western Md.
skicker Offline
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What is to stop them from retracting the 1/8" next time you apply the brakes? If they retract 1/8" wouldn't they retract the same each time?

...FAFO...
Re: Brake pedal "meh" thinking about braided lines. [Re: skicker] #1594550
03/19/14 11:50 PM 03/19/14 11:50 PM
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Ontario.Canada
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can.al Offline
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when the brakes are applied the pistons are pushed out until the pads hit the rotor,distorting the o ring.When released the rubber o ring
will go back to it's original shape,pulling the pistons back.
If the piston moved 1/32" and contacted the rotor,it will only move back 1/32" to it's original position.
Re: Brake pedal "meh" thinking about braided lines. [Re: can.al] #1594551
03/20/14 12:04 AM 03/20/14 12:04 AM
Joined: Jun 2005
Posts: 5,102
Western Md.
skicker Offline
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I get what your saying. Maybe I'm just skeptical...kinda maybe wanna see it for myself type thing.

...FAFO...
Re: Brake pedal "meh" thinking about braided lines. [Re: skicker] #1594552
03/20/14 12:10 AM 03/20/14 12:10 AM
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Ontario.Canada
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can.al Offline
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the o ring will only distort or roll over so far and at that point the piston will start to slide through,keeping the pads close as they wear.
1/8" of travel seems eccessive and would use a lot of fluid and pedal
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594553
03/20/14 09:39 PM 03/20/14 09:39 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
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A quick recap, since it looks like I found the problem.

1) Car was pulled into the garage with functioning 4 wheel drum brakes with a .960 manual disc brake master cylinder. No pedal problems.

2) In less than three hours the spindles were swapped out, new lines, rotors, reman calipers and pads were installed. The system was never allowed to bleed out.

3) Pedal quality was poor, multiple efforts to bleed out system with both helper and electric vacuum bleeder tool to no avail.

4) Swapped calipers from known good vehicle, pedal the same.

Tonight I installed a cast iron master cylinder with plastic reservoir and 2 to 4 bolt adapter from my '67 Dart (patiently waiting in the wings) which had manual disc/drum when I purchased it and it worked great. Don't even have an idea what year it is off, former owner mentioned late 80's truck and Autozone.

Did a half ass bleed with the unit in the car and then hooked up the lines. Bleed the master out again by cracking open the lines at the master with a helper.

Now I have an awesome pedal.

So, whats up with that?

Can't wait to road test, hope the ground is froze in the morning and I'll buzz it to work. Been raining here for several hours, driveway is mud pit.



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594554
03/20/14 09:48 PM 03/20/14 09:48 PM
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Lincoln Nebraska
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RapidRobert Offline
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Quote:

it looks like I found the problem.

Tonight I installed a cast iron master cylinder and it worked great. Now I have an awesome pedal.

So, whats up with that?



Bad M/C or air in it or a combination of both. I'm assuming it's bore dia was not so small that it took an inordinate amount of pedal travel to fill the calipers

live every 24 hour block of time like it's your last day on earth
Re: Brake pedal "meh" thinking about braided lines. [Re: RapidRobert] #1594555
03/20/14 09:52 PM 03/20/14 09:52 PM
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Oakdale CT
gdonovan Offline OP
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Quote:

Bad M/C or air in it or a combination of both. I'm assuming it's bore dia was not so small that it took an inordinate amount of pedal travel to fill the calipers



Something funky.

I'm 100% positive there was no air in it. Pedal was great when I pulled into the garage and the system was bleed several times after in a vain attempt to isolate the problem. Pedal was great when the line lock was on! Almost like there was a bad spot/pitting in the master bore and fluid was getting by? Maybe the further travel was letting the seal to reach that part of the bore.

I didn't even do a decent bleed job tonight, it was wham bam thank you ma'm, slap it in and hit the pedal a few times. If the road test is good I'll do a proper 4 wheel bleed this weekend.



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594556
03/20/14 10:01 PM 03/20/14 10:01 PM
Joined: Feb 2010
Posts: 1,377
Ohio
Todd Offline
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Re: Brake pedal "meh" thinking about braided lines. [Re: Todd] #1594557
03/20/14 11:44 PM 03/20/14 11:44 PM
Joined: Jun 2005
Posts: 5,102
Western Md.
skicker Offline
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Western Md.
I put the 4 bolt to 2 bolt adapter on the 69 Dart. It was aluminum master cylinder with the plastic tank. I got the entire set up from Rick Ehrenberg. I have had no issues with the brakes on the Dart whatsoever. I attributed it to the fact that the 73-6 disc spindles and calipers were used with the correct distribution block for manual disc brakes. I was fortunate the donor car was also a manual disc. Maybe I should get another kit from Rick and install that on the 70 Satellite. Glad everything seems to have worked out.

...FAFO...
Re: Brake pedal "meh" thinking about braided lines. [Re: barracuda7199] #1594558
03/21/14 12:07 AM 03/21/14 12:07 AM
Joined: Apr 2011
Posts: 280
GEORGIA
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Quote:

A new aluminum 1 1/32 master cylinder with adapter from doctor diff fixed your same problem on my car. Stops far better than it ever has and has the best pedal it ever had. His masters are going on all our cars from here on out.



Nailed it earlier! Glad you got it straightened out. I will say again that The good doctor diff has the best deal on the new lightweight masters with adapter.
Re: Brake pedal "meh" thinking about braided lines. [Re: skicker] #1594559
03/21/14 07:38 PM 03/21/14 07:38 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan Offline OP
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Road test was very successful! Was a riot banging through the gears and then heaving on the brakes watching the twins plastered against the seatbacks.

Would not mind a little more aggressive pad or a master with more pressure, might look into one of the Dr.Diff units!



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: Telvis] #1594560
03/23/14 08:29 PM 03/23/14 08:29 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
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So I have a question while we are still on the subject of brakes- If the St.Regis rotors and caliper adapters work on the A-body spindles does it follow the pads do as well?

Under A-body part numbers there isn't much for good pads but under St.Regis there is several police and taxi pad sets listed.

I was out road testing today and it felt like on the last application of the brakes it felt faded, I don't think the Wagner premium semi-metallic pads I have on there are going to cut it.



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594561
03/23/14 09:06 PM 03/23/14 09:06 PM
Joined: May 2003
Posts: 6,560
Downtown Roebuck Ont
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I'm not up on what caliper is what but if the A-body one is the same as the R-body then the R-body cop pads etc should work. If the calipers are different but you are using R-body adapters I would think you could then use R-body calipers instead and whatever R-body pad you wanted.

Kevin
Re: Brake pedal "meh" thinking about braided lines. [Re: Twostick] #1594562
03/23/14 09:21 PM 03/23/14 09:21 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan Offline OP
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Quote:

I'm not up on what caliper is what but if the A-body one is the same as the R-body then the R-body cop pads etc should work. If the calipers are different but you are using R-body adapters I would think you could then use R-body calipers instead and whatever R-body pad you wanted.

Kevin



The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.

I'm thinking the pads should interchange.



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594563
03/23/14 09:27 PM 03/23/14 09:27 PM
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Lincoln Nebraska
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RapidRobert Offline
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Quote:

The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.

73-75 A calipers are 2.60" & 76 A calipers are 2.75" & they (73-75 and 76) A calipers interchange (with each other) & take the same pads.

live every 24 hour block of time like it's your last day on earth
Re: Brake pedal "meh" thinking about braided lines. [Re: gdonovan] #1594564
03/23/14 09:36 PM 03/23/14 09:36 PM
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Ontario.Canada
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can.al Offline
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..what was the size of your new master cylinder piston compared to the size of the piston in the one that gave you problems?
Re: Brake pedal "meh" thinking about braided lines. [Re: RapidRobert] #1594565
03/23/14 09:37 PM 03/23/14 09:37 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan Offline OP
I Live Here
gdonovan  Offline OP
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Quote:

Quote:

The R body and A body Calipers will interchange, some cars got 2.75" piston calipers and others got 2.60" calipers.

73-75 A calipers are 2.60" & 76 A calipers are 2.75" & they (73-75 and 76) A calipers interchange (with each other) & take the same pads.



Now that I have a taste of good braking on the car I want more of it.

I think some calipers and pads might be on order soon.



"I think its got a hemi"
Re: Brake pedal "meh" thinking about braided lines. [Re: can.al] #1594566
03/23/14 09:41 PM 03/23/14 09:41 PM
Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan Offline OP
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Quote:

..what was the size of your new master cylinder piston compared to the size of the piston in the one that gave you problems?



The one that is in there now is a truck unit around 1.10" there was a .960 unit before.



"I think its got a hemi"
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