Defender 110 csw (300tdi) rear brake circuit plumbing

[MR-HIPPO]

A quick question for those more knowledgeable than myself.

 

I am adding disc brakes to the rear of my 1989 110 CSW, all the parts are from a disc braked Salisbury rear axle.

I have also got the newer brake pedal box with the larger diameter servo and 3 outlet master cylinder. (Removed from a 1996 300tdi csw)

My old set up had a twin outlet master cylinder with the back and front brake lines then passing through what I understand to be a PDWA switch

This is my old master cylinder:.

 

The new master cylinder looks like this one

From what I have read it looks like the two front ports are for the front brakes (one for each wheel) and the rear port goes directly to the back axle;

With no PDWA or bias valves fitted in the system

Is this correct?

When I asked the breaker who supplied the parts he seemed to think that there was a valve on the bulkhead and that all 110 Defenders were fitted with valves.

 

Thanks in advance, Hippo.

[western]

on later bigger servo, master cylinder connections are the rear connection to rear brakes, the 2 front connections to front brakes each using separate pipes, 

first photo is original connection with rear drum brakes, second & third for your new pipe runs with rear discs, use the upper diagram in third photo & read drum for disc at rear 

I converted my '89 110 to rear disc, I kept the original pdwa valve & original type master cylinder with no adverse affect on braking system

[western]

additional to my reply above, look at page 499 front brake pipes  in http://www.retroanaconda.com/landrover/parts_books/110/6_vehicle_controls_brakes_fuel_air_p472-579.pdf

 

[MR-HIPPO]

So nothing on the bulkhead but a G Valve on the chassis rail.

 

That is certainly not the answer I was expecting, I did not know they used G Valves on 110's

 

Thank you, Hippo

[neil110]

Not all 110s are equal. At one stage I was running a couple of them, the older vehicle (1984) CSW had a PDWA valve and drums, the newer vehicle (1994) hardtop did not and that was fitted with discs. An oddity I noticed on the 1994 vehicle was that it would get through 4 sets of rear brake pads in the time it took to get through 1 set of fronts

[western]

G valve on hardtop [van] models, my CSW has the PDWA on the bulkhead below the brake servo/clutch master cylinders. 

[neil110]

The 110 hardtop i had was fitted nothing in the way of valves in the braking system. 

Interesting price comparisons here by the way.

http://www.brit-car.co.uk/search.php?query=anr2503&xBrand=&part_type=&xSupplierID=&product-sort=&xPerPage=10

http://www.brit-car.co.uk/search.php?query=anr1415&xBrand=&part_type=&xSupplierID=&product-sort=&xPerPage=10

[western]

probably only on the '90' vehicles only then to prevent rear brakes locking up before the front brakes. 

[MR-HIPPO]

Given the chassis range of the donor vehicle for the brake donor 96 TA99.....

And the sellers comment about the valve on the bulkhead.

Page 506 in Westerns link would seem to suggest that it is valve ANR1415 that I need, as per Neil's second link.

Perhaps it is the later master cylinder 110's without this balance valve that suffer rapid rear brake pad wear?

 

Thanks, Hippo.

[MR-HIPPO]

Looking around online at the ANR1415 PRV, some have red tags, and some have green.

Are they all the same?

 

Hippo

Edited July 22, 2017 by MR-HIPPO

[western]

don't think there is any difference, but you don't need one, just split the front brakes at the 'T' piece [remove the T piece out of the circuit] on right front spring mount, then pipe from the remaining original pipes to the respective ports on the later master cylinder, it'll save a lot of frustration trying to reroute a new pipe around to left front brake, I had to make a new left front pipe on my 110 during the chassis change, it was a 'pig' to get the curves right, 

as your 110 is the same year as mine, here's my front brake pipe route with the original type brake master cylinder, the 2 pipe in lower right are one [darker copper colour] to rear brakes from PDWA  & 1 from Front brake port on the PDWA. I'm sure you can see which is which. 

[MR-HIPPO]

Thanks for posting that, a picture is worth a thousand words and all that.

So if I understand correctly, you think I should take the "No Valve" approach, as per the diagram on page 499, and items 2 & 3 on page 506.

 

Thanks again, Hippo.

Edited July 22, 2017 by MR-HIPPO

[western]

YES I wouldn't worry about changing the valve over, I was going to swap the the later 300tdi type servo, but changing the brake pipe routing made me decide not to, as I said retain the PDWA & do the pipes as mentioned in my earlier reply, changing the vale just for the sake of making the brake system 300tdi style just isn't worth the effort IMHO. 

[MR-HIPPO]

If I understand correctly, the PDWA switch is just a passive  indicator of low pressure in either the front or rear brake circuits, and has no effect on the operation of  the hydraulic brake system.

In the event of a leak the PDWA simply illuminates a dashboard warning light.

That being the case, with two independent front brake lines running back to the master cylinder, only one of them would be able to pass through the PDWA, meaning that a leak in the other front line would not cause the dashboard warning light to illuminate. This would kind of defeat the object of having a warning light.

Or is this simply another case of my comprehension of the subject being way off?

 

Yet more thanks, Hippo.

Edited July 22, 2017 by MR-HIPPO

[western]

The PDWA actually closes off the circuit that is leaking, so the other circuit still operates leaving the vehicle with a set of brakes to come safely to a stop, it would probably be easier to delete the PDWA & just use the low fluid level float master cylinder cap, as LR did for the 300tdi models. 

I adjusted the PDWA wiring so the low fluid level cap works as well. 

[cackshifter]

I have a 97 110 built as a csw as opposed to a conversion. No valve.

[MR-HIPPO]

So just a master cylinder from the factory.

Thank you.

[cackshifter]

Yes, exactly that. Do you need any pics? I think you may need the valve with rear drums but not discs,as drums need less pressure.

[MR-HIPPO]

I would certainly be interested to see the route of the pipework / electrical harnesses around the engine bay.

 

Many thanks, Hippo.

[cackshifter]

Ok, well it has been rebuilt so may not be totally original, but i will post some when i get home later.

[cackshifter]

Sorry it was dark when I got in, so I took a quick pic this morning (in good clothes so I couldn't burrow underneath). If you need more let me know.  On mine the top front pipe goes round the outside(offside) of the servo and master cylinder; originally it went more directly down the nearside, but it was difficult to get a new pipe in on that route. It then turns down past the fusebox, and through the gap between the inner wing and chassis to the nearside hose.

The lower front pipe drops to the bulkhead and runs across to the o/s chassis leg, then through the gap between the inner wing and chassis to the hose.

The rear pipe drops down the bulkhead, then along the top of the o/s chassis leg and dropping to the side of the chassis to the rear hose. The hose connects to a tee on the top of the axle. There is no valve. 

 

[MR-HIPPO]

Thanks for sharing.

Taking the nearside pipe behind the pedal box is an interesting idea, it certainly keeps it out of the way.

 

Many thanks, Hippo.

[western]

on a 300tdi that's the normal route for the front left brake pipe, its shown in the parts diagrams

[Troll Hunter]

My 1991 110 CSW, V8 in Middle east spec, has rear discs and no brake balancing valve.  I suffer no excessive rear brake wear, checking/adjusting them about every 3000km.  My front pads last, I don't know how long, but for ages, but I rarely use my brakes in anger, driving mainly on my engine and gearbox.  

Mike