Fitting a brake servo into a series 3

When I get the station wagon back together -series 3 SWB - I want to put a servo onto the brakes. It will have a 2.5N/A Diesel in it so I can use the vacuum pump from that.
My question is the existing master cylinder has a single port and I want to use a combination of a 90 pedal box and servo with a disco master with 2 ports (why you ask .... well thems the bits I've got laying around doing nothing at the moment). What type of union will I need to split the pipes to front and rear?
I'm thinking I need one pipe to the rear and 2 for the fronts, does anybody know if I can run one pipe straight from the master to the rear and use a one into 2 type valve as found on the back axle of just about any landrover in the last 60 years to go to the 2 front brakes.
Any ideas welcomed.

You may find the inner wing may need a bit taken out to clear the servo.
Some master cylinders have two front outlets,one on the side and one underneath at the front.If not then use the T joint as you describe.[it is not a valve]

As above - if you don't want to cut the inner wing, you can use a remote servo....

Yes the defender one has one outlet at the back and 2 outlets at the front, if I run the front ones to the front brakes I wouldn't need a joint.
I've never created a system like this from scratch and don't want to do anything daft. There seems to be quite a few different servos put onto coil sprung landys (what are type 50 and type 80 servos? the one I have from a mid 80's 110 doesn't seem to match the description of either of them) and its confusing the crap out of me. I guess if it all fits together and holds pressure then it should work........

I don't mind a bit of fettling to get it in just as long as it works, I'm in the process of welding the chassis back together at the moment

Its one pipe to the rear flexy which goes to a T on the axle. One pipe (on a S3 master cyl) down to the chassis rail where it Tees, one forward to that side and one rear then across under the bell houseing to the other side. The thing you have to get right is the master cylinder cross sectional areas in relation to the slave cylinder areas so that you have a safe front rear balance, get it wrong and one will lock dangerously before the other. For this reason I would get a complete S3 master and servo then you know the areas are right for the wheel cylinders. On an S3 the front and rear sections of the master are not the same area.

I was wondering about that, so really what your saying is dump the bits I've got leftover from rebuilding the 90, and get a series servo.
If I get one could I just use the single outlet master and leave the pipe setup as it was originally?

The other question that occurs to me is will this fit onto a non servo series 3 pedal box?

What’s wrong with fitting an S3 servo? It doesn’t need the wing cut. My servo pipe popped off the manifold yesterday you notice the change immediately. Required some force to get the brakes working.

My S2A has an S3 pedal box, servo and master cylinder and it all works fine. I think the prices are up a bit on used pedal boxes and servos as its the easiest solution, servo fits without cutting and the bores are right, remember its front connection to rear brakes. You may have to cut the bulkead for the pedal travel, mine has been, but the 6 bolts for the pedestal are in the same place. Its a worthwhile mod as the brakes get noticabley better (ie less awful). If you go down the Defender master cyl route you will probably have to fit a brake balance valve to stop the rear locking and be prepared to adjust it for different loads. I've seen this on some series but i have no expreince of them.
This is as good an explanation as any, I certainly found it helpful:
http://www.expeditionlandrover.info/dual_brake_conv.htm
It also explains which master cylinders and why.

Must admit I thought the Series tandem master cylinders were constant bore size and the balance was done through the slave sizing. I have SLS drums front and rear and used a tandem master cylinder from a late Series 3 Lightweight which has the same setup, I may be wrong but I though that Series 3 SWB with servos all had TLS fronts which require a larger bore master cylinder.

Thanks I'll have a look.

I am running standard 10" single cylinder brakes with a series servo and single line master cylinder works great.

Good to hear that , I'm thinking thats the way to go.

Mine has been modified to dual circuit (and servo) and I feel safer with the dual ciruit, its not a lot of work to make the change so I would recommend going dual circuit if you are making changes to the brakes. If you have single cylinder fronts the upgrade to the 2LS is also worth it. I agree with above, I think single cylinder brakes are equal size master (and can therefore be single circuit) and 2LS require different sizes so they would always be dual circuit (do correct me someone). I would not use any parts from 90/Def if they have discs as the master cylinder area and volume are completely different and these wil be designed for front disc and read drum.

Twin leading shoe front brakes have a bad reputation for performance in reverse if your doing any trialling or serious off roading.
They are also a lot harder to bleed.

I've mastered the bleeding but you are quite right, TLS are about 50% effective in reverse and as I've lerend the hard way , you need the trans brake to hold well on a hill!

A good compromise are 11" SLS rears from a LWB on the front of a SWB, has an adjuster for both shoes rather than the sprung trailing shoe like the 10" drums. Its also a wider than the 10". I found the 10" setup at both ends tended to lock the rears rather prematurely, running the 11" with the larger of the two available slaves seems to give a good balance between front and rear.