Dual master brake cylinder piping quandary

[Moat Creek]

Hello:

I have installed a dual master brake cylinder in my 1960 Series II 88 and am working on installing/routing the piping. I am getting conflicting information on which of the outlets from the master cylinder goes to the front or rear brakes circuits.

I purchased my part from British Pacific Part # 64676942-34FCG & on their website & when I picked it up they indicated that: "On 88 dual brake systems the front master cylinder (near radiator?) outlet powers the front brakes and the rear outlet (near bulkhead) powers the rear brakes". Also, I noticed on TeriAnn Wakemans wonderful website under "brake upgrades" she notes that "the 88 master cylinder has the front of the cylinder going to the front brakes".

My problem is when ordering the piping from this sites sponsor they indicated that the outlet on the master cyclinder nearest the bulkhead (which is the larger size diameter hole) is for the front brakes and the smaller hole is for the rear brakes.

So can anyone out there help me with sort out what the correct connections are for my dual master cyclinder or are the pistons the same size & it doesn't matter?

Thanks in advance!!

Eric

[bkreutz]

On most American cars, the rear reservoir is for the fronts, it has a larger capacity reservoir. Not sure if this has any application in this case, but it's pretty important to know which. Typically the valving in the master is that the rear brakes come on just a bit prior to the the fronts but the fronts have a higher pressure.

[I Leak Oil]

If you bought an 88" dual master cylinder then the front port goes to the front brakes. If you bought an MC listed for a 109" then the rear port goes to the front brakes.

[martindktm]

On mine the rear port is the front brake. Master cylinder #569671.

[TeriAnn]

I have installed a dual master brake cylinder in my 1960 Series II 88

Also, I noticed on TeriAnn Wakemans wonderful website under "brake upgrades" she notes that "the 88 master cylinder has the front of the cylinder going to the front brakes"

I did my best to explain it as plainly as possible including labeled pictures of both 109 and 88 master cylinders (the 109 cylinder was mounted in my truck when I took the picture, the 88 cylinder was new & unmounted).

I got my 88 plumbing information by looking at US spec SIII 88s and tracing the factory piping. I got my 109 information out of a Stage I workshop manual and plumbed my own 1960 109. I'm pretty sure I got it right.

If you have any suggestions on what I could do to make my dual brake conversion page easier to understand I would love to hear them.

On second thought, I think the front and rear cylinders on an 88 master cylinder are the same volume. If it is I don't think it matters on an 88 which goes where. But the factory did plumb US spec SIII 88s so that the cylinder closest to the radiator is the front brake circuit.

[Moat Creek]

Teri thanks for your additional input!!

I found your dual brake upgrade write up to be very useful and the pictures made it very clear how to hookup the brake pipes for my 88. I cannot think of anything to add/improve on what you wrote.

I was making good head way hooking the new brake system up as you illustrated (& per the guys at British Pac) until I had to order a new front pipe.

What really hurt my head was when I ordered the master cyclinder to front brake pipe from Rover N. the pipe came with the big fitting for the outlet near the bulkhead. I called to verify & the response was that the large outlet (near bulkhead) was for the front brakes.

Maybe it is a east coast vs west coast thing!!! In any case I am going to stick with how I originally started to hook the system up (large fitting on master cyclinder will go to the rear) with the assumption that both cylinders/pistons are the same.

Eric

[TeriAnn]

What really hurt my head was when I ordered the master cyclinder to front brake pipe from Rover N. the pipe came with the big fitting for the outlet near the bulkhead. I called to verify & the response was that the large outlet (near bulkhead) was for the front brakes.

Maybe it is a east coast vs west coast thing!!!

Maybe Les will pipe in on this thread. Or maybe not.

My guess is that on an 88 it doesn't matter which cylinder you use while on a 109 the rear cylinder goes to the front brakes. So if you just carried one part instead of two you would carry a 109 pipe and sell it for 109s & 88s.

The world of replacement Series parts is shrinking rapidly and whenever a single part can be used for multiple applications the other single application part gets discontinued. It is like the seal that goes between the hard top and hard top sides. These days you buy the 109 seal and cut them down to fit an 88.

RN probably buy their brake lines from a company that offers a "universal" brake line for 109 & 88 front brakes.

When I plumbed my system I bought brake tubing at my local auto parts store, cut one flare, threw away the US spec threaded ends, installed British spec threaded ends, cut the pipe to length after bending it and made a new flare for the end I cut off.

Last time I looked Rovers North stocked the bare fittings.

[Terrys]

I gave up, long ago, trying to figure out why the factory did what on what truck; I just go with the flow and work up a plan on each one I work on.
Here's another item to throw into the mix: US series 3 88s didn't have a proportioning valve in the rear brake circuit, but it seems ROW trucks did. The idea is to get more braking on the fronts, so the proportioning valve restricted pressure to the the rear, but logic (?) would dictate that the MC was different between trucks with and without the valve.

[Moat Creek]

Terry:

When I am done I will probably have a brake setup real similar to a series III since I am not using the proportioning valve. I would assume that normally there would be a difference between the front and rear outlet on a dual master cyclinder. Usually I try to look at things from a engineering perspective or do the research required to sort out the best way but in this case they answer may not be forthcoming unless I take the dual master cyclinder apart.

Working on rover is always interesting! Originally I bought a brake pipe kit for a dual master cyclinder setup. The kit I purchase seemed pretty complete, had real basic numbers and pointers to where pipes go. Unfortunately one of the pipes was not long enough to route the way I wanted. I then ordered a replacement pipe that goes from master to front 3-way (wishing to avoid buying a flaring tool & using stock piping). As I mentioned in the original post the part I got from RN was for the larger outlet by bulkhead that per RN goes to the front. I then ordered the other pipe from RN that is for the front outlet on the master thinking it would have a the smaller male fitting on both sides & I would be set. When it came it had a small male fitting and a larger female fitting on the other. So I went to my local tool supplier bought nice automotive flaring tool and am working on adapting the pipes I have to my layout.

Interesting thing is that the pipes from RN come with a bubble flare vs a 45 double flare on the master cyclinder side where my original kit has the double flare on all fitting....another quandry!

I guess if anyone reads this that is working on a conversion I would recommend you either start from scratch on the piping by buying a flaring tool and 3/16 pipe from NAPA or buy the pipe kit and plan on spending some time and energy on tweaking the setup. If you are not comfortable with flaring pipes then either practice or take the vehicle to a shop. In the end it is not all that hard but with braking systems you need to have a proper hydraulic system in place when you are done!

Many years ago I had a old MG that had a crushed brake line in the driveshaft tunnel that eventually leaked. I can still rememeber the day I pushed the brake pedal coming up to a busy intersection and the brake pedal went to the floor with out slowing the vehicle down. In the end I turned into a nearby snow drift and all ended well but I certainly don't want to have a repeat in rover.

[JackIIA]

I agree with you on flaring your own. Maybe you've already found it, but FedHill has some great explanations of the different flares, fittings, and identification of them. I found it very helpful. While it shouldn't, I've found different flares on the same tubing (different pieces (old and new) for the same run). Who knows if that's a PO stupid trick or what. Looking at the fittings used help to make sure you're running the correct flare. Are you running Copper/Nickel?

[Moat Creek]

I bought a Automec copper pipe kit for the 88 with the dual master. Kit seems pretty complete but the one pipe that is too short for my routing will end up being steel probably. I will have to check the master again to see what the outlets look like to see if double 45 deg flare would be correct. Thanks for the Febhill site info!

[jac04]

^^The MC outlets usually require a bubble flare.