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Posted By: ssaxman 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 12:15 AM
I'd like to convert the single-reservoir master cylinder on my 1952 3100 to a dual-reservoir master. I'll be keeping non-power, stock-style drum brakes. I found this kit at Performance Online (POL) and was wondering if anybody had used it. I've not ordered from them before so wanted to get some feedback first.

Additionally, has anybody done a write-up or have pictures of how they routed the brake lines when doing this conversion? I tried searching the interwebs and came back with lots of pics and threads about the actual master cylinder swap, but not much about running the lines. Any links, tips, tricks, or pics would be much appreciated. Thanks!!
Posted By: Elmo Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 03:57 AM
It is super simple to convert your single reservoir to the dual. I would really recommend the swap!! Easy peesy!!


Elmo
Posted By: showkey Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 01:39 PM
Easy peasy ??????

Maybe the swap is a “5” on difficulty scale of 1-10. But highly dependent on your skills, experience and tools available.

1. The master should “bolt right up”.........key word should.

2. You have to run a few new brake lines which means buying premade lines then bending to fit or buying line and fittings then cutting and flaring custom lines to fit. Not rocket science........but does take some skills and few common tools.
Depends on the age of the current lines........but all new lines and rubber hoses might be a good idea.

3.After it’s installed bleeding and adjustment would be similar to the stock. Even bleeding can be a challenge for some. Bench bleed the master is good idea and critical step in some situations. The height of the master compared to wheel cylinders can be part of the bleeding challenges.
Posted By: WE b OLD Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 02:11 PM
Mine has been done but I had it done. One thing I do remember is to fill it is difficult it has a plastic bottle with a long bent tube to fill from underneath. I believe because of the hole in the floor does not line up anymore so I had a remote fill installed on the engine side of the firewall. I just got back from a 1400 mile trip and I could tell the pads had worn so checked the remote fill and it was halfway down so I filled it. I always take some along.This might help
Posted By: ssaxman Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 07:04 PM
This is the kind of feedback I was looking for. The installation of the new master and bracket is pretty straight forward, but I wasn't sure if I could use the existing lines. The lines were all replaced during the restoration a few years ago. With the stock master, there's one small line that comes out of the back and goes to the left front wheel; then there's a fat line that runs to the passenger side frame rail and tees off--one line goes to the front right wheel and then one line goes to the rear axle where it tees again to go to both rear wheels. With the front wheels having completely separate lines on either side of the truck, how do I get them both on the same line to the master? It also seems like I would have to run a new line for rears from the master to the existing tee on the passenger side frame rail and probably replace that tee with a 90--removing the right front line and keeping the existing line that goes to the rear. This is why I was hoping someone had done a write-up or could share pictures of how they did their lines.

As for the remote fill, I looked into that, however all of the remote fill kits I've seen are for dual bail masters and all of the drum/drum masters are single bail so I don't think the remote fill would work. I'm not too terribly worried about this as it's not a terrible PITA to get under the truck and check the fluid so long as I have enough room between the top of the master and floorboard.
Posted By: 66flea Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 09:07 PM
text me i have picture on my phone
Posted By: Hotrod Lincoln Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 09:36 PM
Be sure you do your homework on master cylinder and wheel cylinder diameter and stroke, and the other physical properties of the brake system. A master cylinder that's used with a power booster will be totally different in diameter and stroke than one for a non-boosted system. The size of the reservoirs will be different also. Just because somebody's willing to sell you something they claim will fit doesn't mean they'll be there with a wheelbarrow full of cash to pay your defense lawyer when your poorly-engineered brake system causes you to run over a mini-van full of curtain climbers.
Jerry
Posted By: ssaxman Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 10:57 PM
Thanks for the pics, 66flea!

@Hotrod Lincoln - Definitely good advice. I've been scouring the web about this type of conversion for a few weeks now to make sure I've got my P's and Q's in order. Thank you!
Posted By: Skooter Re: 1952 3100 Dual Master Cylinder Conversion - Wed Sep 11 2019 11:48 PM
I used the POL bracket and ordered the dual master from Rockauto (for '67 Chevy pickup if I recall, was the first year for dual master??) I bought a 3 inch hole saw to cut a new access for filling the master because the POL bracket does shift it backwards a ways. Bought a second rubber floor plug for the second master hole. POL bracket was a nice piece of kit, included push rod and all bolts, everything fit nice. Will see if I can find and post a few pictures this evening.
Posted By: ssaxman Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 12:02 AM
Thanks , Skooter!
Posted By: Skooter Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 01:58 AM
I've kept original drum/drum front and rear. Zero issues due to locating dual master under floorboard. Seems to be about same level as the wheel cylinders, maybe.

1. Shot from underneath shows old floorboard hole in front of new master. Tee also visible at bottom of pic.
2. Line from master back port goes into left side of tee. Lines from right side of tee and bottom of tee goes to the two front brakes. Line from master front port goes to rear brakes.
3. Shows the extra floor hole cut for new master. Master lid can lift out through the 3" hole pretty easily.(use a big syringe or turkey baster for easy fill) My oldest ugly floormat goes against floorboard. On top of that is sound/heat mat. Those two were cut to fold over and weighted down for easy access. Nice floormat on top.
4. Last pic shows my bench bleeding setup. Be advised the reservoirs are much smaller than modern disc masters, so FILL OFTEN as you bleed wheel cylinders. I ran them dry on first bleed because they're so small! Had to remove the master and bench bleed all over again. dang

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Posted By: ssaxman Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 02:33 AM
Originally Posted by Skooter
I've kept original drum/drum front and rear. Zero issues due to locating dual master under floorboard. Seems to be about same level as the wheel cylinders, maybe.

1. Shot from underneath shows old floorboard hole in front of new master. Tee also visible at bottom of pic.
2. Line from master back port goes into left side of tee. Lines from right side of tee and bottom of tee goes to the two front brakes. Line from master front port goes to rear brakes.
3. Shows the extra floor hole cut for new master. Master lid can lift out through the 3" hole pretty easily.(use a big syringe or turkey baster for easy fill) My oldest ugly floormat goes against floorboard. On top of that is sound/heat mat. Those two were cut to fold over and weighted down for easy access. Nice floormat on top.
4. Last pic shows my bench bleeding setup. Be advised the reservoirs are much smaller than modern disc masters, so FILL OFTEN as you bleed wheel cylinders. I ran them dry on first bleed because they're so small! Had to remove the master and bench bleed all over again. dang


This is awesome, Skooter! Thanks so much for posting the pics and descriptions. This will help a LOT! I'm hoping to find the time to get this completed sometime this month or next and will definitely post some pics of my install. Thanks to everyone who's replied; the help is much appreciated!
Posted By: klhansen Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 07:01 AM
Looking at scooter's install photos, I'm wondering what would prevent moving the master farther forward to use the original fill hole in the floor. Maybe it's because the dual master mount flange is wider than the old master where the original bracket is.
Posted By: ASU Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 09:25 AM
maybe I am missing something...On Skooter's set up, If there is 1 line coming from the master, which tee's and goes to the front and back brakes, Isn't this the same as the original system, only with a different MC? 1 leak anywhere in the system would render all the breaks useless. The purpose of a dual reservoir system is to separate the front brakes from the back brakes, create 1 reservoir and piping system for the front, and 1 for the back, so you don't lose everything at once.

Jon
Posted By: showkey Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 12:37 PM
Originally Posted by ASU
maybe I am missing something...On Skooter's set up, If there is 1 line coming from the master, which tee's and goes to the front and back brakes, Isn't this the same as the original system, only with a different MC? 1 leak anywhere in the system would render all the breaks useless. The purpose of a dual reservoir system is to separate the front brakes from the back brakes, create 1 reservoir and piping system for the front, and 1 for the back, so you don't lose everything at once.

Jon


His step 2 sounds like he has separated the front and rear:

2. Line from master back port goes into left side of tee. Lines from right side of tee and bottom of tee goes to the two front brakes. Line from master front port goes to rear brakes
Posted By: ssaxman Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 05:41 PM
Will residual pressure valves be needed when converting to the dual reservoir setup?
Posted By: showkey Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 07:28 PM
Originally Posted by ssaxman
Will residual pressure valves be needed when converting to the dual reservoir setup?


Depends on the master..........some have the residual valves built in.
Posted By: 52Carl Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 08:48 PM
Originally Posted by ssaxman
Will residual pressure valves be needed when converting to the dual reservoir setup?

That is where the "fun" comes in to play. The stock configuration with the original single master cylinder incorporates different sizes of brake lines (on some models) in order to supply front and rear wheel cylinders with the appropriate balance.
With adding a dual master which is not designed to work on our trucks, you now have to rely on seat of the pants information to determine if you need to add a proportioning valve to make it work.
Then while trying to determine if you have a front-to-back brake balance problem, you won't know for sure whether the imbalance is actually caused the dual master, or due to new brake shoes which are not yet arced to mach the contour of the drums yet, or improper brake shoe adjustment.
A set of challenges, but doable over time. Just don't do any tailgating in the meantime.
Carl
Posted By: klhansen Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 09:19 PM
Originally Posted by 52Carl
The stock configuration with the original single master cylinder incorporates different sizes of brake lines (on some models) in order to supply front and rear wheel cylinders with the appropriate balance.

Sorry, but line sizes have absolutely no relationship to balance between front and rear. It's strictly controlled by the ratio of master cylinder and wheel cylinder diameters.Differences in line flexibility would be the only thing that would impact balance and there's no real flexibility in the lines. Unless one of the lines is essentially microscopic (and they're not) it would not be able to restrict flow of the fluid going to the wheel cylinders.
A dual master cylinder without a proportioning valve and the same size bore on both circuits would work just like the original single reservoir master.
Posted By: Skooter Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 11:34 PM
Originally Posted by showkey
[quote=ASU]maybe I am missing something...On Skooter's set up, If there is 1 line coming from the master, which tee's and goes to the front and back brakes, Isn't this the same as the original system, only with a different MC? 1 leak anywhere in the system would render all the breaks useless. The purpose of a dual reservoir system is to separate the front brakes from the back brakes, create 1 reservoir and piping system for the front, and 1 for the back, so you don't lose everything at once.

Jon

His step 2 sounds like he has separated the front and rear:

2. Line from master back port goes into left side of tee. Lines from right side of tee and bottom of tee goes to the two front brakes. Line from master front port goes to rear brakes


Showkey is correct thumbs_up

"On Skooter's set up, If there is 1 line coming from the master, which tee's and goes to the front and back brakes..."
No. One master port goes to the tee, then tees to both front brakes (left and right). The other master port goes to the rears.
Posted By: Skooter Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 11:36 PM
Originally Posted by klhansen
Looking at scooter's install photos, I'm wondering what would prevent moving the master farther forward to use the original fill hole in the floor. Maybe it's because the dual master mount flange is wider than the old master where the original bracket is.

I very much wanted to use the original hole but there was absolutely no way to get the new master underneath it with the bracket and master I used.
Posted By: Skooter Re: 1952 3100 Dual Master Cylinder Conversion - Thu Sep 12 2019 11:37 PM
Originally Posted by ssaxman
Will residual pressure valves be needed when converting to the dual reservoir setup?

Not needed with my setup.
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