Thread: Brake issue has me stumped

Hi All,

Another thing i forgot to mention was the noise or clunk from the pressure reducing valve (PRV). When you are stationary with the engine off and press the brake pedal quite hard the PRV emits a clunk - it sounds like the plunger is hitting one end of its stroke.
Is this normal?


Basically the car feels like it doesnt want to stop in that last 10 meters.
It feels kinda like when you overheat your brakes and they just dont stop like they should.

In response to some of the questions in no particular order:

I did not skim the discs when i fitted the new bendix 4wd pads. Perhaps i should have - ill put it on the list of things to try.

Yes the bendix pads are the 4wd ones in the red box.

The new pads had a 'titanium strip' that claimed you didnt need to bed-in the pads, i'm not sure it helped that i did try to bed them in. ill try deglazing the pads with a file when i skim the rotors.

Tyres are not standard size anymore - i have 245/75/16's. another reason to try and improved the stock braking system.


Wheel bearings were adjusted 6 months ago, but ill check again.


The main thing that has me stumped is the electronic brake checking gizmo says my brakes have good front to rear balance - So why would skimming my front rotors, or changing front pads improve the overall braking performance?

thanks, Steve

Originally Posted by Jim621

Hi All,

Another thing i forgot to mention was the noise or clunk from the pressure reducing valve (PRV). When you are stationary with the engine off and press the brake pedal quite hard the PRV emits a clunk - it sounds like the plunger is hitting one end of its stroke.
Is this normal?


Basically the car feels like it doesnt want to stop in that last 10 meters.
It feels kinda like when you overheat your brakes and they just dont stop like they should.

In response to some of the questions in no particular order:

I did not skim the discs when i fitted the new bendix 4wd pads. Perhaps i should have - ill put it on the list of things to try.

Yes the bendix pads are the 4wd ones in the red box.

The new pads had a 'titanium strip' that claimed you didnt need to bed-in the pads, i'm not sure it helped that i did try to bed them in. ill try deglazing the pads with a file when i skim the rotors.

Tyres are not standard size anymore - i have 245/75/16's. another reason to try and improved the stock braking system.


Wheel bearings were adjusted 6 months ago, but ill check again.


The main thing that has me stumped is the electronic brake checking gizmo says my brakes have good front to rear balance - So why would skimming my front rotors, or changing front pads improve the overall braking performance?

thanks, Steve

You don't state what year model Disco 1 you have, but some Disco 1 front brake calipers have "3" bleed nipples, 2 that you can see from the inside (under car) and 1 on the outside that you can't see unless you have the wheel off.
Now if your calipers have the 3 bleed nipples and you haven't bled the outside nipple you will have the problems you have mentioned. The problem is that if you don't bleed these 3 nipple calipers in correct order you will have crap brakes, (see Land Rover Workshop Manual). I had the same problems you have and worse, I would lose all braking after prolonged downhill travel, the crap fluid in the section of the calipers that hadn't been bled would boil and leave no brakes until the boiled fluid cooled. Not saying that this is your problem, it was mine and bleeding correctly fixed the problem, BTW my 94 Disco has 2 bleed nipple calipers the 93 had 3, check yours, Regards Frank.

The titanium stripe pads still need a fresh surface to bite onto.
If your
Rotors are worn at angle, polished or glazed then whilst balance may be correct, the pad bite may be poor.

And bleeding as above is also important.

the bendix pads are your problem pitch them to the ****house if you want it to stop fit lucas/trw pads if the rotors are anything like most discos have them machined or replaced if there not flat it does not matter what you fit it wont stop .

I have a similar issue.

Driving around town you don't realise the brakes are not 100%. Didn't know until I was towing the camper recently and the trailer plug inched its way out so no electric brakes. Went to stop to turn off the highway and missed the turn! Admittedly I tried to brake hard as I didn't see it to the last minute but it was a surprise all the same. I didn't always have brakes on the trailer and only put them on for hilly dirt roads.

Haven't tried it in the dirt but can't lock up the wheels on the bitumen without the trailer on either.

Mine is a MY95 V8 with SS braided brake lines and 245/75 16 Maxxis Bighorns on factory steel rims. Used to have standard tyres on factory mags so I guess braking was better with those.
Raised about 50mm. Never touched the rear proportioning valve if it has one.
Non ABS with two front flexible brake lines and one rear (3 in total for the car).

I bled the hoses but only one nipple per brake so will look for more on the front. RAVE doesn't mention multiple nipples.
Bleeding the brakes I think improved it but I may be just getting used to the idea.

Front pads are Bendix 4wd and rears OEM. Both have plenty of life but are about 3 years oldish.

A kit went through the master cylinder about 4 years ago when the cylinder holding rubbers leaked.

There is no vibration in the brake pedal.
No squeal.
Front discs are shinier than the rear discs.
No movement in the wheel bearings.

No idea when the braking started to deteriorate like this.

I'll chase up some of the ideas from earlier posts too.

Originally Posted by Tank

BTW my 94 Disco has 2 bleed nipple calipers the 93 had 3, check yours, Regards Frank.

Hi Tank.

Before I get in trouble for working on my LR while the in laws are here and being anti social etc etc, Where are the nipples on your 94 front calipers?
I bled the upper nipple that is located between the two bolt heads that is a real ***** to get at.
It is shown on RAVE under 'Brakes-Repair-Front brake calipers' on the Disco1 update model CD.

Thanks

Originally Posted by Utemad

Hi Tank.

Before I get in trouble for working on my LR while the in laws are here and being anti social etc etc, Where are the nipples on your 94 front calipers?
I bled the upper nipple that is located between the two bolt heads that is a real ***** to get at.
It is shown on RAVE under 'Brakes-Repair-Front brake calipers' on the Disco1 update model CD.

Thanks

Sorry for taking so long to answer, I pulled my wheels off today and guess what, there is only one bleed nipple that I can see, I wrongly assumed as there were 3 nipples on the 93 that the 94 had 2, I'll have the calipers off tomorrow and if I find that elusive (supposedly) 2nd nipple I'll let you know, Regards Frank.

Has anyone suggested the brake booster? My Defender had similar symptoms. Changed front pads to bendix 4wd, bled, no change. Discovered the booster leaking vacuum through a hair line crack near where the master cylinder bolts up. For a temporary fix I covered the crack with blu max sealant and brake performance is back to normal.