Front Axle Assembled

The Discovery front axle had been reassembled.  I have attached the brake callipers but have not fitted the pads or brake pipes yet, but they’re simple jobs that won’t take much time or effort.

The Discovery callipers have twin hose configurations, while the Series Land Rovers (and Defenders) use only one hose to each front wheel.  There are several ways around this:

a) Copy the entire Discovery brake system, using the three-port Discovery master cylinder and two front brake circuits;

b) Use the Defender master cylinder and use the blanked port on the SIII 109 PWDA (the brake failure shuttle valve below the driver’s foot well) to run a parallel system to the front brakes with twin hoses;

c) Use tee-pieces to spur the standard 109 pipes off into twin hoses;

d) Use the existing brake pipe system and a single hose, with tee-pieces above the swivel pins to run to both input ports on the calliper;

e) Use the bleed port of one half of the calliper to supply the input port of the other half, externally mimicking  the internal configuration of Defender callipers;

f) The obvious neatest solution of using Defender callipers (too costly for genuine for this project).

There is little benefit in duplicating most of the brake lines, and it introduces added vulnerability and potential for damage or failure, so that narrows the choices down to “d” and “e”.  I have concerns, though, over “e” – the angle at which the bleed port is drilled would require the new connecting line to be very close to the wheel, and any debris trapped inside the wheel could hit the line with considerable force.  I’ll have  a close look at it, but at the moment, I think that “d” is the likely solution, and I have seen it done very neatly and securely on other similar project vehicles.

The Discovery track rod is serviceable, but no good for this application. I inverted the axle and sat the as yet unfitted third leafs for the front parabolic springs onto their saddles to check steering rod clearance.  The clamp on the adjustment section of the rod and the steering damper brackets fouled the leaf springs on a test fit, so I need a plain tube track rod from a Defender.  I am considering a Sumo Bar, which is far stronger and stiffer, but that would run quite close to the springs with its larger diameter.  However, the standard diameter steering rod has approximately 6mm or 1/4″ clearance from the springs at full camber, with greater clearance when the springs are under load.  Adding shims between the spring and saddle is very simple, if it transpires to be required, but I’m hoping to see enough clearance on the loaded springs that it won’t be necessary.

Using the standard front spring plates (the plates underneath the springs that clamp them hard against the axle’s saddles) would result in the track rod heavily fouling the dampers, but by using the rear plates from an 88″, the dampers will be brought forward by approximately 38mm (1.5″) and thus easily clear the track rod under all conditions – the only reason the standard front plate mounts the damper so far behind the axle is in order for the damper to clear the swivel housing/axle tube mating flange, but on these new axles, that flange is well outboard and that clearance is unnecessary.

So, I need to source the 88″ rear plates and the Defender track rod.  Making up the brake lines is simple enough.  The only  puzzles left are working out the drag link from the standard Series relay drop arm to the coiler swivel (I think the relay’s axis is further inboard than the PAS box on a coiler, so the Defender drag links may be too long) and the fabrication of a very irregularly shaped U-bolt for the inboard right hand bolt, where it has to pass over the canted tall section of the diff housing.