Duff brakes - still!

Braking efficiency with a drum brake should be as good if not better than discs due to a larger braking area.

Not so. Disc brakes can dissipate heat much better than drum brakes because the heat does not have to be conducted through the drum. Brake fade was a common problem before discs came along. (When descending steep hills how often do you "Keep in low gear" as road signs suggest, it was necessary with drum brakes).

Overbraking on the rear axle is a problem and dangerous at it induces spins. Most vehicles ,with or without discs on the rear have a pressure limiting valve in the line to the rear wheels to reduce the effectiveness of the brakes, so the performance of disc brakes is not required.
One of the problems of using discs on the rear is the provision of a hand brake. If the same cylinders are operated mechanically, then a further leakage possibility is introduced into the hydraulic circuit. Also pads operate on to a flat surface and are much more critical in adjustment than drums which have some self-servoing action. Remember the run-away Citroens we saw a few years back? Some cars with discs on the rear have small drums inside the discs to provide the handbrake facility.

vic.middleton said:

Braking efficiency with a drum brake should be as good if not better than discs due to a larger braking area.

Not so. Disc brakes can dissipate heat much better than drum brakes because the heat does not have to be conducted through the drum. Brake fade was a common problem before discs came along. (When descending steep hills how often do you "Keep in low gear" as road signs suggest, it was necessary with drum brakes).

Overbraking on the rear axle is a problem and dangerous at it induces spins. Most vehicles ,with or without discs on the rear have a pressure limiting valve in the line to the rear wheels to reduce the effectiveness of the brakes, so the performance of disc brakes is not required.
One of the problems of using discs on the rear is the provision of a hand brake. If the same cylinders are operated mechanically, then a further leakage possibility is introduced into the hydraulic circuit. Also pads operate on to a flat surface and are much more critical in adjustment than drums which have some self-servoing action. Remember the run-away Citroens we saw a few years back? Some cars with discs on the rear have small drums inside the discs to provide the handbrake facility.

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With the open type of road wheels now used dissipation of heat should no longer pose the major problem of years gone by when ventilation of drums was restricted. With most braking systems spilt 80/20 ish overheating of rear drum brakes should no longer be a major issue, brake fade associated with overheating can also occur on disc brakes especially when harder pads are used. Rear discs with a separate parking brake caliper were fitted to early Jaguars (1961 E type for example), also most Mercedes with a foot operated parking brake have rear discs with pads for the service brake and drums and shoes for the parking brake.

Well, the EBC pads are better, but once the bedding in stuff had gone it was clear they had not solved the problem...

Went to change the disgusting brake fluid, but could not undo the rear bleed nipples. I shall work on this back at base as I don't want to be stuck miles from home with sheared nipples. Ooer.. Anyhow, removed and changed the fluid in the reservoir and bled through the front lines with fresh. Should make it easier once I get the backs ones free.

Now awaiting a new servo as I'm running out of ideas. Noticed a whooshing noise every time I depress the brake pedal so maybe a leak in the vacuum? Would explain the initial bite at speed but only a gummy when actually trying to stop..

Spacemonkey... said:

Well, the EBC pads are better, but once the bedding in stuff had gone it was clear they had not solved the problem...

Went to change the disgusting brake fluid, but could not undo the rear bleed nipples. I shall work on this back at base as I don't want to be stuck miles from home with sheared nipples. Ooer.. Anyhow, removed and changed the fluid in the reservoir and bled through the front lines with fresh. Should make it easier once I get the backs ones free.

Now awaiting a new servo as I'm running out of ideas. Noticed a whooshing noise every time I depress the brake pedal so maybe a leak in the vacuum? Would explain the initial bite at speed but only a gummy when actually trying to stop..

Click to expand...

I thought you'd mentioned you'd bled the fluid already...?

No, I said the fluid 'was fine'. Once removed and compared with new it obviously isn't 'fine'!! However, it has never felt like it was spongey so I'm still gambling on the servo. Even after doing the fluid the brakes feel the useless, just a harder pedal.:doh:

Spacemonkey... said:

No, I said the fluid 'was fine'. Once removed and compared with new it obviously isn't 'fine'!! However, it has never felt like it was spongey so I'm still gambling on the servo. Even after doing the fluid the brakes feel the useless, just a harder pedal.:doh:

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Ah, sorry I mis-understood that... but you haven't fully bled the brakes yet right - so still got the gunky stuff in all the slave cylinders and calipers, plus all the brake lines....

In my experience, a brake fluid change and good bleed can have a profound affect on the braking... especially if they haven't been bled properly before, they could have air in the system too. As I'm sure you know, the fluid is hydroscopic and over time mixes with water from the atmosphere - water has a MUCH lower boiling point than brake fluid so could explain why you're experiencing pretty dramatic brake fade.

My TD4's brake pedal does make a 'whooshing' sound also when you press it - not really noticeable when on the move but you can hear it when the engine's off. My other cars do it too so it could be normal but obviously difficult to comment on a noise on a forum!

I'd defo change the fluid and fully bleed the brakes first, with fresh, unopened bottle of Dot4 and see what it's like.

That's the plan! I've got a quiet day today so hopefully get it changed properly. As you say, I've still got crud in the back lines- fronts done, but will do the whole system again to ensure all crap out.

cool, cool. Hope it works out...

You mentioned that the EBC brakes seem to have 'gone off' since the bedding in stuff has gone. What do you mean by that?

I was thinking about it and for bedding in, I tend to use this process:

"During the bedding process the driver must NOT drag the brakes by applying continuous pedal effort with his left foot to induce heat into the braking system. This will cause heat build up too quickly and result in glazed pads.


Likewise, the driver must ensure that the following procedure is adhered to and sufficient heat is generated in the braking system, otherwise the pads are prone to glazing if run too cold during the early stages of the pad’s life.
Whilst bedding, brake applications should be consistent and using constant pedal effort, which is progressively increased throughout the procedure.

1. 5 light snubs*, light pedal application: 50mph – 30mph
2. 5 medium snubs, medium pedal application: 70mph – 40mph
3. 3 hard snubs, hard pedal application (no ABS activation): 100+mph – 30mph**
4. Cool down period – 5 mile run with very little brake (Do not sit at side of road with foot resting on brakes when hot, this is likely to damage the disc).
5. Stop and examine discs – discs should show evidence of heat cycle (colouration in flange) and possess an even transfer layer of pad material on surfaces.
6. Bedding procedure should now be complete.

* Snub is the term used for the deceleration of a vehicle from a relatively high speed to a low speed using constant brake pedal effort.
** PFC is not responsible for any convictions as a result of this bedding procedure. The location as to where the brakes are bedded is at the driver’s own discretion and entirely his/her own responsibility."


Taken from: Bedding In Performance Friction Brakes « Co-ordSport Performance Parts – Technical Blog


I find it works well for my other cars although I haven't used it on the Freelander. But basically all new pads have a solvent in them that must fully evaporate / burn off so just the pad friction material is left. This requires a fair bit of heat - after bedding in properly, you should be able to 'smell' the brakes. It does generate a lot of heat so you have to be careful you don't warp a disc (especially if the disc isn't vented) - but as long as you don't stop and you can keep cool air flowing over the disc for a few miles after this procedure, it should be okay.

Anyway, like I said, I've found it works well and I've never warped a disc this way.

have you considered the vacuum pump may be tired / leaking , its on the alternator I believe

Yes, considered the vacuum pump, but that would need an alternator swap wouldn't it? A £22 servos is cheaper for now. Feels a good vacuum from the pipe even at tickover.

Changed the rear cylinders and fluid again. feels slightly better I think, but hard to tell as I've only pootled around town today. Big drive tomorrow so shall know more.

EBC Greens have a special bedding in compound on the friction surface. Once I fitted them they seemed great but after a few miles were back to normal as the stuff wears off. Trouble is, because the brakes are so dire and you really do not feel as if you're going to stop or rely on them, you tend to creep around and engine brake, thus it's hard to bed them in properly. I've made a point of trying when roads are empty, but tbh, in the past I have just driven normally and had no problems bedding in.

Hmmm.... I see your point about driving quick when you don't have much confidence in the brakes! It's a tricky one, that's for sure.

Does it stop like it should if you really stamp and press hard on the brake? - i.e. does it stop but just feel unassisted - if so, then probably is the servo. But if it's still not stopping if you really really stamping on it then it seems unlikely the servo is the only cause...?

Well they're fixed¬!!!!

Changed the fluid, and bled and re bled them. Better but still not feeling like they wanted to finally stop. Finally received my replacement servo. I notice they're all rusty along the bottom edges, so cleaned mine up with an angle grinder and painted it. Then fitted it. Haynes Book of Lies says simply unbolt and remove- as usual- but forgot to mention the bloody great pipes in front! Eventually got the new one in and went for a spin! Flipping heck, nearly went through the screen... Guess it was the servo all along!

Hallelujah!!! Your brakes are obviously working well now then! Virtually new all round.

Glad to hear the happy ending Spacemonkey.
During the thread there were a few mentions of drum verses disc brakes....according to the Haynes Freelander book, LandRover decided on drums on the rear instead of their usual rear disks for a few reasons; - the Freelander was aimed at car drivers who were used to the vehicle not moving when the handbrake was applied, unlike true LRs which use a transmision type brake, where the vehicle can move slightly before the transmision 'locks'. As they wanted it to still have offroad ability, it was thought the usual cable and lever arrangement used for disc type handbrakes would be a mud trap, and brakes aren't usually very good when full of mud.