2004 110 TD5 Rear Brake Biasing - How Is It Done?

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FlatbedPilot

FlatbedPilot

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I've been looking on t'internet to try to find out how the braking effort on my rear brakes is controlled and I can't find anything definite for my model. I assumed there would be a bias/compensating type valve in the line to the back brakes but I can't see anything. I've also looked in the workshop manual (admittedly the copy I have is for '99 to '02 model years) and there is no mention of any valve for the rear brakes.

I ask because mine has now failed it's MOT twice because of the back brakes not performing effectively enough. After it failed the first time I changed both rear calipers and today it failed again with the exact same numbers as the first time.

What am I missing?
 
DefenderPilot said:
I've been looking on t'internet to try to find out how the braking effort on my rear brakes is controlled and I can't find anything definite for my model. I assumed there would be a bias/compensating type valve in the line to the back brakes but I can't see anything. I've also looked in the workshop manual (admittedly the copy I have is for '99 to '02 model years) and there is no mention of any valve for the rear brakes.

I ask because mine has now failed it's MOT twice because of the back brakes not performing effectively enough. After it failed the first time I changed both rear calipers and today it failed again with the exact same numbers as the first time.

What am I missing?
Click to expand...
master cylinder is split front and rear brakes, smaller pistons are also used and only 2 per caliper compared to 4 in the front
 
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I've had a crawl around underneath for another look. The item highlighted in the picture below is in the brake line from the servo to the rear brakes. Is this just a joint or could it be a valve? It's about 2" long.

I'm anticipating problems (seized unions) when disconnecting the brake lines from the master cylinder so I'm probably going to run new copper brake pipe to the back tee piece. If that is just a joint I'm presuming I can just do the line in one run from the cylinder to the tee piece?

defenderrearbrakes.jpg


Also, as I'm almost 100% sure I'm going to replace the master cylinder, would this be suitable?
 
Thanks for the link @Scooby22. That diagram looks like a dual circuit set up and is much more complicated than mine. Mine is only split front and rear single circuit, with one outlet from the master cylinder going to the back axle. Item number six (in line connector) in the diagram is probably what I've highlighted in my picture. It's probably there to make brake line installation easier in the factory as steel brake lines can't be bent nearly as much as copper. I feel pretty confident in what I'm doing now, which is to replace the master cylinder and rear axle flexi pipe and also run new copper brake line all the way back. I've already installed new copper brake lines on the back axle as the old steel ones were in a pretty poor state and had to be cut out as they were seized in the unions at the calipers. I will then have an all new rear brake system from the master cylinder to the rear calipers.

Thanks also to @jamesmartin for the info re the master cylinder.

I'll report back once I've done all the work and resubmitted it for the MOT.
 
DefenderPilot said:
I've had a crawl around underneath for another look. The item highlighted in the picture below is in the brake line from the servo to the rear brakes. Is this just a joint or could it be a valve? It's about 2" long.

I'm anticipating problems (seized unions) when disconnecting the brake lines from the master cylinder so I'm probably going to run new copper brake pipe to the back tee piece. If that is just a joint I'm presuming I can just do the line in one run from the cylinder to the tee piece?

View attachment 163047

Also, as I'm almost 100% sure I'm going to replace the master cylinder, would this be suitable?
Click to expand...
thats a joiner its just a way to connect 2 pipes when repairing the pipe work
 
If I were you I'd buy 5 litres of brake fluid before you start work - a new system from the cylinder back can take quite a bit of bleeding. A pressure or vacuum bleeding kit will make life easier, but you'll still need to pass quite a bit of fluid through before you get a firm pedal.
 
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Before major brake work, crack the first union and then wedge the brake pedal down with a bit of wood (doesn’t have to be jammed against the floor). You’ll barely lose a drip of fluid this way.

Once finished, unwedge pedal, top up master, open the caliper bleeders on the affected parts of the system and go make a cup of tea. Once the bleeders are dripping steadily, pedal bleed as normal. Two or three pumps should be all that’s needed.

Since I moved to Scotland I’ve got pretty familiar with replacing brake lines, and have also recently rebuilt my rear calipers with st steel pistons. I can assure you that the above method is much better than hosing litres of brake fluid through the system as I’ve seen some do.
 
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Replacing the brake fluid was part of the plan and I'll lose loads taking the master cylinder off anyway. I have a pressure bleeding kit and I can usually do a full bleed using less than a litre.

@guineafowl21 Shetland is even worse for corroding the hell out of everything. Having spent most of my life inland in England and Wales I was completely gobsmacked to see how quickly stuff rusts up here. Buying second hand cars here isn't best advised.
 
DefenderPilot said:
Replacing the brake fluid was part of the plan and I'll lose loads taking the master cylinder off anyway. I have a pressure bleeding kit and I can usually do a full bleed using less than a litre.

@guineafowl21 Shetland is even worse for corroding the hell out of everything. Having spent most of my life inland in England and Wales I was completely gobsmacked to see how quickly stuff rusts up here. Buying second hand cars here isn't best advised.
Click to expand...
I have a pressure bleeder too, but hardly ever use it because the ‘drippy nipple’ technique is so good.

It’s good for changing the brake fluid, though.
 
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