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#4G63510 Brakes

Posted: 22 May 2019 19:54
by jeffball610
This will be an updated thread on progress, questions, and issues associated with my specific braking system. And boy do I need some help :?

I've been posting in this thread http://the510realm.com/viewtopic.php?f=29&t=31150 here, but I feel it has gone beyond what that thread was intended for. I've also since switched things that may no longer be relevant to that thread.

The current low down:
7/8" Master Cylinder (rubber valves and springs in the ports are still present)
Wilwood rear proportioning valve
FRONT
S12 V6 struts
Z31 hubs and rotors
Z31/J30/Q45 2-piston calipers
Parts store pads
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REAR
Z31 non turbo 5-lug hubs and caliper mount
Z31 non turbo solid disk rear rotor
Maxima rear calipers (parking brake cable fit best with these)
Parts store pads

When I started my build in 2005, I made it a point to replace nearly everything in all systems of the car due to corrosion, age, or outdated technology. The brakes and brake lines included. The car has 100% new lines that I bent up while building the car. Due to the size of the calipers, I chose to go with the largest master cylinder I could in hopes of getting all the fluid to the calipers without the assistance of a vacuum booster. I ran a 15/16" MC for over a year and a half and approximately 11k miles.
The brake pedal was always stiff, but I was able to lock the rear brakes with great force if needed. I only tried once, and it wasn't impossible. However, with more track days in my future, I chose to upgrade the system with a B210 brake booster to get more modulation out of the pedal travel. After installing the booster, all pedal feel went away and braking performance suffered greatly. I had a very soft pedal with light caliper engagement on the first portion of travel that eventually turned into the brick wall I previously had. It was still possible to lock the rear brakes up once going past the stiff pedal as before. However, because of these two very different brake pedal feels, I felt this was a failure of the whole system.
I completely bled the system several times with both traditional "pump the brakes and hold" as well as vacuum bleeding. I also attempted a reverse bleed of the system, removed calipers and extended the pistons, and anything else I could think of to make sure there was no air in the system.
I felt that either my MC had an issue, or that it was too large for my particular system, so I swapped in a 7/8" unit. After bench bleeding the new master cylinder and installing it, I made sure that pedal travel was acceptable and that the pushrod was engaging properly. All systems seem to work properly, but I still had the same basic brake feel as with the 15/16" unit. In a move of desperation to restore proper braking power, I removed the booster and went back to manual brakes.
The car now mimics my original manual set up with a little more pedal travel as expected with a slightly smaller MC. However, the car does not seem to have enough power to actually stop the car. During the most recent autocross, the car felt as though the brakes were completely faded and no amount of pedal effort would lock up the brakes or stop the car in haste.

At this point, I'm at a loss. I will of course bleed the system one more time, but I am confused as to why I cannot get any stopping power from these components. I know the brake pads are not a performance part, but the sheer size should easily stop this car or at the very least, lock up with some effort. I don't know of anyone else running these calipers on the front, and they could well be the issue. I have verified that the caliper pistons do in fact move and therefor should stop the car. I am open to any suggestion. I'm trying to make this system work to its fullest, but the long term plan is to either run an aftermarket setup or swap the entire front steering, suspension, and braking system with S13 units and any available upgrades for that geometry.

Re: #4G63510 Brakes

Posted: 29 May 2019 17:03
by jeffball610
Still no progress on this. Everyone I speak to seems just as confused as I do.

I do have one theory, though it's not very good. The front calipers have banjo fittings rather than straight fittings. Is it possible that there is a restriction in that style of fitting that is not allowing enough fluid to pass through?

My only other thought are the "restrictors" in the MC. Everyone says to take these out, but when I did that to the 15/16" MC, the brakes got worse. (granted I put the booster on at the same time) These don't seem to do anything other than not let fluid flow backward too much, but seem to allow some fluid to pass. These don't seem to be the same restrictor that is used with drum brakes.
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These are currently still installed in my 7/8" MC.

Re: #4G63510 Brakes

Posted: 29 May 2019 17:11
by duke
Have the pads been properly bedded in?

Re: #4G63510 Brakes

Posted: 29 May 2019 22:13
by icehouse
Sounds like shit pads to me. Toss them and while you have the rims off getting the RE’s mounted slap in some decent pads. I got Porterfeilds since They make them for stock 510 brakes which I have on my tan 510. I also put them on my sunny.

My wife had a Nissan altama coupe, it did the same thing. First 20 percent was fine any more and the pedal force almost made the braking worse. Got some new pads and it fixed the issue.

Re: #4G63510 Brakes

Posted: 30 May 2019 08:51
by duke
I second the Porterfeild advice. I have run the R4S pads for years and have been happy with them the whole time. Never experienced any fade in all of the autocrosses and hillclimbs that I have done.

Re: #4G63510 Brakes

Posted: 30 May 2019 09:33
by Fred_L-P
Sorry, I don't want to Hijack the thread, but thanks for answering my brake pad question I didn't even ask :D

Fellow Canadians, is there a good place online to buy Porterfield pads?

Re: #4G63510 Brakes

Posted: 30 May 2019 13:19
by WxMan
I got mine from rallysport.ca and was very happy with their customer service. http://www.rallysport.ca/Brakes/brakes2.htm

Re: #4G63510 Brakes

Posted: 30 May 2019 17:23
by icehouse
duke wrote:
30 May 2019 08:51
I second the Porterfeild advice. I have run the R4S pads for years and have been happy with them the whole time. Never experienced any fade in all of the autocrosses and hillclimbs that I have done.
I've never faded mine during compititon. After that they have free drive time. After about 3 runs back to back the stock brakes do start to fade. How much you ask? Not even to stop driving!

Re: #4G63510 Brakes

Posted: 03 Jun 2019 08:33
by jeffball610
Order placed today through Porterfield. I tried to order some over the weekend, but they don't have a method of confirming SCCA discounts on their site. Thankfully I'm only 1 day shipping from their location, so I should get these before I leave for the Powerland meet on Thursday. I'll report back if there is any change in brake feel. I'm really hoping this does the trick :fingerscrossed:

Re: #4G63510 Brakes

Posted: 03 Jun 2019 16:43
by datzenmike
jeffball610 wrote:
29 May 2019 17:03


My only other thought are the "restrictors" in the MC. Everyone says to take these out, but when I did that to the 15/16" MC, the brakes got worse. (granted I put the booster on at the same time) These don't seem to do anything other than not let fluid flow backward too much, but seem to allow some fluid to pass. These don't seem to be the same restrictor that is used with drum brakes.
Image
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These are currently still installed in my 7/8" MC.

Not restrictors. Those are the residual valves. They maintain a couple of PSI on the disc brake pads to keep them up close to the rotors. This serves two purposes. One, the pad is instantly ready to go to work and two it keeps the rotor clean and squeegees away water. If you have drum brakes they are 3-4 times that amount so don't mix them up or your calipers will rub excessively and over heat.

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Re: #4G63510 Brakes

Posted: 03 Jun 2019 18:53
by Fred_L-P
How do we know which one is drum and disc? I bought a 7/8 MC and both residual valves were identical.

Re: #4G63510 Brakes

Posted: 08 Jul 2019 20:51
by jeffball610
I haven't updated this thread, but I did install the brake pads. They felt a bit better, but only have a few miles on them. My car developed a rough idle due to a leaking exhaust valve. Time to rebuild the head, so I can't very well test the brakes :/

Re: #4G63510 Brakes

Posted: 09 Jul 2019 16:53
by icehouse
SR swap?