Converting to dual reservoir brake master cylinder

Upgrades, downgrades, modernizations, alterations or just being creative.

Postby moore_rb » Tue Jul 08, 2014 6:40 pm

I've begun researching the process of converting my green patrol to use a dual reservoir MC on the brakes -

There is one VERY major primary benefit of doing this - the factory Patrol MC is a single pressure source, single reservoir system, so any loss of hydraulic brake pressure will impact all 4 corners of the vehicle- this is obviously potentially very dangerous.

I have reduced my candidates for this conversion down to 2 master cylinders with 1 inch bores--- I'm sure there are many others out there that could also work, but these two seem like fairly simple DIY-style swaps. Below I will list some of the pros/cons I see with each option.

The first one is the Wilwood MC that we discussed in this thread started by River Patrol:

viewtopic.php?f=23&t=2595

I found this Wilwood unit for $117 shipped from the following source:

http://raceconsultingagency.com/i-17948 ... oCp5bw_wcB

Pros:
1) Fairly simple swap - remove the stock MC, enlarge a couple holes, and bolt this baby on, and then add one new length of brake line.
2) Styling- Looks similar to the design of the original MC, with just a second reservoir sitting on top.
Cons:
1) Only 2 outlets - so there is no provision for the brake light switch- a tee will have to be installed in one of the outlets to drive the pressure switch for the brakes.
2) plastic reservoirs are not nearly as robust as a solid cast housing with a steel cap

The 2nd MC I am considering is the early Corvette style dual reservoir, which I found on Ebay for the smokin price of only 55 bucks:

http://www.ebay.com/itm/Tuff-Stuff-2020 ... 95&vxp=mtr

Pros:
1) Cheep - less than half the cost of the Wilwood unit
2) Solid, cast iron reservoir housing - drop it on your foot, and a broken toe is almost guaranteed.
3) The rebuild kit for this MC is pretty much 100% compatible with the rebuild kit for the stock Patrol MC, so rebuilding this one in the future would be very familiar to DIY Patrollers.
4) it has 4 outlets, all threaded with the same 3/8 inch, 24 thread fitting as the stock patrol brake line, and the brake pressure switch (you would have to plug the 4th outlet).
Cons:
1) Styling- It's an American car part, that looks like an American car part, so the other Datsun fans at the Saturday evening meet are going to see it and instantly form a negative opinion of your brake system decisions :P
2) the mounting bolts are oriented horizontally, and there is not much room for it to be oriented on the firewall - more serious modification will be necessary to make this one fit the firewall, as opposed to simply hogging out the existing mounting holes an extra 1/8 inch, to fit the Wilwood unit.


So that's where I'm at - I haven't decided which one I'm going to order... :think: I am leaning toward the Wilwood piece, simply because I know it will fit the firewall.

thoughts? opinions? Are there any other inexpensive dual reservoir MC's out there I should also be considering...?
ImageImageImageImage

L-R:
White 65 Hardtop L60-3-00617 (undergoing restoration)
Red 65 hardtop 4L60-002565 (scrapped for parts)
66 Hardtop "El-Bondo Patrol", L60-00511 (Restored, then sold June2020)
Blue 67 Hardtop (sold March1997)
Green 62 Softtop L60-2-00504 (undergoing restoration)
moore_rb Offline

User avatar
Administrator
Administrator
 
Posts: 2460
Images: 70
Joined: Wed Jul 03, 2013 11:49 pm
Location: Arizona
Has thanked: 814 times
Been thanked: 1291 times
Location: Arizona

Postby Coyote Patrol » Tue Jul 08, 2014 6:53 pm

If you went with the corvette MC you could build a spacer out of pipe and flanges on each end. One flange to fit Patrol firewall pipe in between and then another flange for the corvette MC to bolt to. And of course lengthen the push rod. I would go with the corvette myself or the MC for a 70s chevy pick up. But as you say the wildwood looks more original, but i dont think too many people would rib you for an upgrade such as this. :D
Coyote Patrol Offline

User avatar
I love driving my Patrol!
I love driving my Patrol!
 
Posts: 1203
Images: 24
Joined: Fri May 10, 2013 5:35 pm
Has thanked: 653 times
Been thanked: 635 times
Location: Winslow

Postby bosque » Tue Jul 08, 2014 7:13 pm

Those wilwoods look the best and I bet you could find the extra 50bucks in change behind the seat cushions, on the dresser, in the ashtrays, your kids dresser...this is important big kid stuff kids!! Rebuild kits might be easier and cheaper for the wilwood too (?). :P ;) :P
Good luck, great mod, make it happen!
bosque Offline


Helping others revive their Patrol…
Helping others revive their Patrol…
 
Posts: 1621
Images: 62
Joined: Thu Oct 04, 2012 8:35 am
Has thanked: 311 times
Been thanked: 177 times
Location: USA

Postby mdawg4x4 » Tue Jul 08, 2014 7:27 pm

I want to do the same thing. I was planning on adding a vacuum booster at the same time. Just haven't had time to work on anything. One day. Patience.
63 Nissan Patrol project, 1967 Nissan Patrol, 2012 Nissan Xterra (daughter's), 2017 Jeep JKUR, 1998 Jeep TJ
mdawg4x4 Offline


I love driving my Patrol!
I love driving my Patrol!
 
Posts: 965
Joined: Thu May 16, 2013 2:06 pm
Location: Madison, MS
Has thanked: 355 times
Been thanked: 305 times
Location: Madison, MS

Postby RiverPatrol » Tue Jul 08, 2014 7:58 pm

Retort Tor con #1 on the Wilwood: you can always use the later style switch that is activated by the pedal. I think schluderm sells them on eBay.

Retort to con #1 on the GM: are you seriously concerned about styling on a Patrol with SOA? :lol: I doubt that the new owner of the El Paso Patrol will be buying is for it's near original condition. ;)
Beyond any hope for intervention

Image
RiverPatrol Offline

User avatar
Administrator
Administrator
 
Posts: 7423
Images: 959
Joined: Thu Oct 04, 2012 10:42 am
Has thanked: 6753 times
Been thanked: 2280 times
Location: Temecula, CA

Postby Flaggoni » Tue Jul 08, 2014 9:34 pm

Aargh... Just spent 45 mins typing on iPhone a dissertation on why a dual 1" NON-boosted master cyl. won't be a great match...then accidentally deleted it!
Basically, since you would effectively be doubling the square inches of MC piston area the same boot force will only produce half the original psi. The pedal travel would also be halved, but that's not a problem.
1" boosted dual may be great, though.
I made a series of hypothetical hydraulic system sketches a couple months back to explain this stuff to myself. ;)
If anybody wants a copy, or wants more discussion, PM me with IM or email contact info.
Flaggoni Offline


You know you own a Patrol when…
You know you own a Patrol when…
 
Posts: 286
Joined: Thu Dec 13, 2012 2:02 pm
Has thanked: 256 times
Been thanked: 270 times
Location: Tulsa, Oklahoma USA

Postby moore_rb » Wed Jul 09, 2014 12:03 am

Flaggoni wrote: since you would effectively be doubling the square inches of MC piston area the same boot force will only produce half the original psi. The pedal travel would also be halved, but that's not a problem.



True, wequal foot pressure, you would generate half the PSI in half the pedal travel if the volume in the bore was increased - but what this means in the real world is that your lockup point would still be in the same pedal position - you just might have to push harder to get there.

For me, foot pressure is a secondary consideration

But, for $30 more than the Wilwood, I could just get one of these:

http://www.ebay.com/itm/7-powder-coated ... c8&vxp=mtr

This one has a 1-1/8 bore and a 7 inch booster - this Patrol would stop on a dime, even with the big fat 33's on it.


options, options, too many options...
ImageImageImageImage

L-R:
White 65 Hardtop L60-3-00617 (undergoing restoration)
Red 65 hardtop 4L60-002565 (scrapped for parts)
66 Hardtop "El-Bondo Patrol", L60-00511 (Restored, then sold June2020)
Blue 67 Hardtop (sold March1997)
Green 62 Softtop L60-2-00504 (undergoing restoration)
moore_rb Offline

User avatar
Administrator
Administrator
 
Posts: 2460
Images: 70
Joined: Wed Jul 03, 2013 11:49 pm
Location: Arizona
Has thanked: 814 times
Been thanked: 1291 times
Location: Arizona

Postby Johnny Roadkill » Wed Jul 09, 2014 5:25 am

in my limited experience, pedal feel and travel are hugely dependent on master cylinder bore...adding a booster to a standard 7/8" Datsun 510/1600 master cylinder gave it a squishy feel with too much travel and light-switch brakes ( nothing...nothing...nothing...STOP !!! ). I was going to go for a 1" master but a local 510 guru insisted that would be going too far. 15/16" master installed - perfecto ! Of course, he'd been there and knew that...

Sucks to be pioneering a brake system - using others as guinea pigs saves much time and money. :lol: If you can grab a second-hand cylinder in the bore you are thinking about and test the complete system before dropping your cash on new parts that may save some heartache...?

cheers,
D
'71 P510 Wagon - the smile generator.
'74 G60H - strawberry farm patrol.
'78 G60H Ute Cab - the cherry on top.
'80 G61H - the start of things to come.
'92 Pulsar Ti - my SR20 powered daily driver.
'01 Kessner 7x4 - the pack horse.
'07 Challenge Camper - home away from home.
'09 Prado - the family fourby and her daily driver.
'14 200EXC - a chainsaw with wheels.
Johnny Roadkill Offline

User avatar
You know you own a Patrol when…
You know you own a Patrol when…
 
Posts: 233
Images: 255
Joined: Sat Mar 23, 2013 1:41 am
Has thanked: 42 times
Been thanked: 246 times
Location: Adelaide, South Australia

Postby Esteban » Thu Jul 10, 2014 6:13 pm

Good ideas in this topic. Good luck with your mod, and please post some pictures. Ron's idea will be great if you decide later on to install a power booster.

Flaggoni wrote:Basically, since you would effectively be doubling the square inches of MC piston area the same boot force will only produce half the original psi. The pedal travel would also be halved, but that's not a problem.
1" boosted dual may be great, though.
I made a series of hypothetical hydraulic system sketches a couple months back to explain this stuff to myself. ;)
If anybody wants a copy, or wants more discussion, PM me with IM or email contact info.


I have to disagree with this. The pressure in the system will remain the same. The piston in the back pushes the fluid that in turns pushes the piston at the front. The simple fact is to brake a Patrol with a single circuit you do the same effort with the one with a double circuit. I've own both at the same time, and my daughters used to drive both also. Not a problem.

http://www.carbibles.com/brake_bible_pg2.html

For me, what started as just another mechanical improvement, with my Bendix Hydrovac power booster decades ago, keeping the original single circuit master cylinder, evolved to a dual circuit Ford master cylinder and behind it a Master Vac from a Datsun pickup. Partly because the original master cylinder (actually the 2nd one) was beyond repair, and because I had the Master Vac out of my other totaled Patrol. I'm not a purist in this department, and for me function is more important that being period correct.

The Ford master cylinder has two outlets facing towards the engine when installed, very similar to the Corvette one, but easier to route the pipes and no need for plugs. It is a 1" bore. A picture of my system is here:

http://www.60patrol.com/forum/viewtopic.php?f=23&t=2595&p=16529&hilit=ford#p16529
Owner of the same Patrol since 1967
Esteban Offline

User avatar
Patrol Fanatic!
Patrol Fanatic!
 
Posts: 2849
Joined: Sat Feb 23, 2013 11:28 am
Location: Lutherville, MD
Has thanked: 5548 times
Been thanked: 1432 times
Location: Lutherville, MD

Postby faux40 » Fri Jul 11, 2014 12:48 am

-- UPDATE July 14, 2014 by jjb --
Since I originally posted this, I've discovered that parts were, shall we say... incorrect! Anyway, I wanted to leave it here for posterity, but keep anyone from relying on it. I've added a strike through to the graphics that were flawed as a big warning flag. Keep in mind that some of the text is wrong as well (the parts referring to psi where it should have been pounds to describe external pressures)



Okay, I got curious – Had to figure this out for myself...

To start, I am assuming that all the hydraulic cylinders have the same square area and that we can ignore friction and other losses.

First, looking at just travel distance, if the pedal moves four inches, then the combined movement of the slave cylinders must also be four inches since they all have the same area. Therefore each must move one inch.

1m_4s_x 2.jpeg


If we add a second master cylinder and split the slaves into two pairs, again all one square inch cylinders, then four inches of input must yield must input eight inches of travel. Remember, we have moved the two master cylinders four inches each so each slave will move two inches.

2m_2x2s_x 2.jpeg


Of course, this is for distance and what we ultimately care about is pressure… how hard the brakes grab the wheels. So back to the first example but this time let’s ignore distance and simply use pressures. If the master has 100psi applied, then combined pressure of the four slaves must equal 100psi, since combined they have four times the area, then each must press with a quarter of the pressure which is 25psi each.

1m_4s_f 2.jpeg


Fantastic, now I want to use a dual-master system so I don’t die when my self-rebuilt wheel cylinder fails. Again, we split the system in half and add a second master cylinder. With 100psi input, we now yield 50psi at each slave cylinder. This is because we’ve effectively doubled the pressure applied at the master cylinders. In this case, the 100psi input is at each master cylinder for a total input of 200psi.

2m_2x2s_f 2.jpeg


What we actually do is add that second master cylinder and link the input together with the original master cylinder. In this case, the mechanical linkage splits the 100psi between the two master cylinders so each actually only sees 50psi (which I suspect makes each master cylinder less likely to blow out from extreme pressure... which is good). The slave cylinders then must each get ½ of the pressure input to each master cylinder. So, 25psi appears at each slave… just like in the original single master cylinder example.

2ml_2x2s_f 2.jpeg


Now, let’s bring travel distance back in… On the original one-master to four-slaves, it took four inches of travel to yield one inch of slave travel; on a split system, it only takes two inches of master travel to yield the same one inch of travel. Since we push both masters in unison, then only 1/2 the master cylinder travel distance is required. Therefore the pedal travel must be halved.

2m_2s_fx.jpeg


As for the brake pedal travel distance, in a perfect world, it should be 1/2 what it was with the single cylinder, but since there are so many places for slop such as in the linkage, flexible hoses, the tiny gap between the brake shoe and drum, even the pad on the pedal adds some, only a relatively small portion of the travel distance is actually used to ramp up the pressure therefore only the distance involved in that segment would halved. This means that the pedal travel would be shorter, but by less than half the distance.


Can someone check my logic here? Makes sense to me, but then... Anyway, that’s my two cents… and worth every penny! ;)

John
You do not have the required permissions to view the files attached to this post.
faux40 Offline

User avatar
Administrator
Administrator
 
Posts: 1206
Images: 1310
Joined: Sun Jul 28, 2013 12:45 am
Has thanked: 636 times
Been thanked: 1116 times
Location: Roseville, California

Next

Return to Modifications

Who is online

Users browsing this forum: No registered users and 1 guest

cron