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dirtyninety

dual front brake pipes?

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now then, Can someone explain quite what the point in the dual brake pipes on the front of my 93 200tdi disco?

Id like to convert to single brake pipes, so what calipers should i use and also what brake cylinder should i use?

thanks for any light and the matter :)

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Haven't any info on an alternative but dual line brakes are designed to keep working on one circuit if you loose pressure on the other, if yours is the same as mine (same year) it is split so that you will always retain at least one set of pistons on each of the front calipers. I am curious as to why you would wish to remove a safety feature. Also I would have thought that the insurance companies and powers that be would take a pretty dim view of downgrading your braking system

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Hi

Does it matter which pipe goes to which hole on the caliper and does the d/s side need to be the same as the p/s? I was told it did not matter, so I plumbed it in as it looked best to me. :o I have not had any problems as yet on a 1990 Disco 200 tdi. :)

Just wondering, old age setting in I think.

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Well they must have downgraded this safety feature with later models since the 300 TDi only has single port calipers and a 2 port master cylinder. Indeed the early Discos used the same setup as the Range Rover which was quite advanced and, no doubt, quite expensive to produce. I am guess that one of the cost cutting exercises done on the later disco was a swap to the simpler (and cheaper) system as found on 90's....

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Safety and insurance isnt an issue, im building a discovery challenge truck, so i would like to convert to single port calipers and a 2 port master cylinder, cheers orgasmic farmer!!

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I am just about to plumb mine up like this, planning to put a t-piece near the caliper. Just need to work out which port does what on the master cylinder.

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If you are goung to single circuit then the primary goes to the front and the secondary to the back. the 300 Disco had a much cheaper ABS system compared to the RRC hence the single circuit callipers.

If you have dual circuit callipers then the top should be the primary IIRC and the bottom is the secondary same as the rear but it's worth checking a manual.

I'm not sure if the master cyclinder is the same either and if it isn't there will be a good reason.

Performance wise there will be no difference, if you fit single circuti callipers then you could use 130 Defender ones which are bigger.

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Hi dont change your calipers just take a copper pipe from one of your flexible pipe entrys and route it to your top of your caliper where you can remove a bleed nipple and discard it connect copper pipe into this port and job done you will then use the other bleed nipple on the caliper to get rid of air.

This does away with the need for two flexible pipes or tee fitting

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Hi dont change your calipers just take a copper pipe from one of your flexible pipe entrys and route it to your top of your caliper where you can remove a bleed nipple and discard it connect copper pipe into this port and job done you will then use the other bleed nipple on the caliper to get rid of air.

This does away with the need for two flexible pipes or tee fitting

Would this be road legal?

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For the dual circuit to be effective from a safety perspective, I think there needs to be no communication (or very limited) between the two fluid circuits...

That would mean that if you eliminate one flexi, you'd have to tee the two lines on the caliper together externally, this both fluid circuits are still fed fluid from the one common supply.

By simply removing a bleed nipple and replacing with a fitting that goes on one of the lines which originally fed the caliper the risk is that you may have created a loop with insufficient supply, thus reduced the closing pressure from some of the pistons.

Years ago I removed a fluid input line and simply replaced with a bleed nipple, the brakes still worked and I had a good pedal but could lock the rears before the fronts.

On my current rebuild I am keeping the dual systems on the calipers with dual braided flexis but fitting a tee at the top onto the single line back to the master cylinder.

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The T idea sounds good.. I was thinking about something like that rather than the bleed nipple idea.

what are the thread/size are the brakes lines?

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Sorry to bring this back to life but in looking over my 92' MY Disco the rear brakes are fed off the R/H front caliper line and the L/H has a whole channel all to itself, should this be right? I am looking for a brake line diagram but can't find one on the WWW.

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Where is the Hero smiley when you need it!

Cheers for that Les.

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@dieseldog

I can put you all manuals on a dvd, come and collect it when you bring the wheelnuts

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@dieseldog

I can put you all manuals on a dvd, come and collect it when you bring the wheelnuts

TOP!!!

Henk you have PM :i-m_so_happy:

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The non-ABS brake systems all have two circuits, but there are tow versions. In the earlier version, the front callipers have two hoses, and the big circuit does half of each front calliper and the rear callipers, while the smaller circuit powers just the other half of each front calliper. Later systems went over to a simplified setup, like on the Defender, where the big circuit did all of the front calliper pistons and the smaller circuit the rear callipers. The contradiction to this is ABS equipped vehicles, which still have twin hose front callipers because each calliper has a piston pair connected to the valve block and the front callipers have a hydrostatic (direct mechanical pedal movement creating hydraulic pressure to the other half, independent of the ABS system - in other words, five circuits (individual ABS controlled to each calliper and then the hydro to both fronts).

I suspect early thinking was to ensure that the front brakes always had stopping power by configuring the two circuits the way they did, but in practice the loss of one system tends to make the other pretty ineffective too, as the leaking half permits pedal movement without pressure build up by either MC piston to activate the fault-free circuit, leading to the adoption of the simpler system split front/rear.

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there are 2 different split brake circuits used on various vehicles [not just LR's]

a I - I circuit has the front & rear as seperate but when working with no circuit failure they work as one circuit , if the fronts fail then the rears can still slow/stop the vehicle & vice versa

the other type is a H - I circuit, so one is front & rear brakes [& in normal no failure use] if the H circuit fails the I circuit still works & vice versa

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I have a 1996 300TDI auto (not ABS) with the single front pipe arrangement, which needs new discs and pistons, and I also have to hand all the parts for a dual front pipe system with vented discs (almost new) from a 1991 RRC. I have thought about using these to change the Discovery to dual pipe vented brakes. Is this a good idea, please, or a bad one?

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I suspect early thinking was to ensure that the front brakes always had stopping power by configuring the two circuits the way they did, but in practice the loss of one system tends to make the other pretty ineffective too, as the leaking half permits pedal movement without pressure build up by either MC piston to activate the fault-free circuit, leading to the adoption of the simpler system split front/rear.

The idea in any split braking system, is that the piston inside the MC bottoms out on the leaking side, then you build pressure as normal on the second cylinder. That means you end up with a much longer pedal, and half the braking effort, but still have working brakes. I've been lucky never to have brakes fail, but my mum once drove a Mk5 transit home from the supermarket with (unbeknowst to her) a burst front brake hose. She got home and told me the pedal had "gone a bit funny" but it otherwise seemed to stop ok :o

Pic of MC internals and what happens when you blow out one line:

master_cylinder2.jpg

You can see the yellow piston has bottomed out against the end of the housing, allowing the grey piston to operate normally.

there are 2 different split brake circuits used on various vehicles [not just LR's]

a I - I circuit has the front & rear as seperate but when working with no circuit failure they work as one circuit , if the fronts fail then the rears can still slow/stop the vehicle & vice versa

the other type is a H - I circuit, so one is front & rear brakes [& in normal no failure use] if the H circuit fails the I circuit still works & vice versa

Many cars also use a diagonal split.

Two port master cylinder with a constant bore, each port running one front and the diagonally opposite rear.

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The diagonal split was common a while ago, but I think most modern cars have symmetrical systems to make sure the car pulls up straight under braking. I can see the logic behind the split master cylinder, but I found on my SIIIs that in practice it didn't seem to work - the travel required to pressurise the serviceable side was just too long (and the brake systems were well cared for, not worn, leaking and mal-adjusted). It might work better on disc brake systems, though, as they have less fluid transfer.

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Hi and appoligies for poking this back to life.

Can't beleive I am asking this again 3 years on. Last time I just plumbed it in as I thought it looked best. :-( It went through MOT twice ok but now I have the calipers of for a refurb and I would really like to know how to do it "right".

So can anyone lead me astray and explain the proceedure. ;-)

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I had searched this topic and was reading it over and I thought one of the threads was very similar to what I was asking.

When I scrolled over and seen it was mine :$ form 3 years past.

Must say in my defence I was using a mobile to read it. :-D

Seriously can anyone help on this matter. A diagram would be most helpful.

By the way mine does not have abs.

I suppose it will have something todo with the brake pipes coming out of the master cylinder.

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Anyone any info at all on the correct way to bleed the dual front brake pipes with NO ABS and solid disks on an early Discovery.

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