Brake pressure

[SpeedAgent]

What is the deal with the initial brake pressure in Disco II's? I have replaced rotors and pads, bled brakes, installed stainless lines and I still can't get good initial pressure.....what gives? A second pump gives good pedal pressure, the same pressure you would expect each and every time, but only on the second pump. What to do?

Chris

 

[overlander]

My wifes Disco II has no issues with brakes. Sounds to me like yours just isn't fully bled right.

 

[R_Lefebvre]

Maybe you got air in the TC system. I think you'll need to have a Testbook bleed to get that out.

The brakes in my truck are fine, so it's not a 100% design issue.

 

[SpeedAgent]

I used a pressure bleeder yesterday after installing the stainless lines and there was virtually no improvement. I have heard of others with this same issue, but no real recommendations. I did hear someone suggest changing the calipers to an 03' model, but I don't know why so I won't spend that money.

What is a Testbook bleed?

thanks,

Chris

 

[ntsqd]

Do you feel any oscillation in the pedal? Another cause could be excessive pad (& piston) knock-back causing a need for greater fluid volume to push the piston back out to where it is supposed to be. If LR ever did a "high piston retraction" type caliper design and you have those calipers without also having the related booster & m/c this is a very likely issue.

 

[SpeedAgent]

No, no oscillation, just very soft on initial push.

 

[Oilburner]

I have heard that the Testbook OBD system is required to properly bleed DIIs with ABS. I don't know if there is a workaround, but based on your description it sounds like an air entrapment issue.

 

[SpeedAgent]

I'm sorry, I don't know what that means. What is Testbook?

 

[Pad]

I'm not framilier w/D2 brakes but I have done a complete bleed on RR w/ABS. You should be able to find online a tech. manual in PDF or some other printable form, start with that. On the RR I went through about 12 steps that started in the engine bay with the plastic ball looking things (real words escape me) then on to the calipers, back up lines first (the emergeny path should a brake hose fail) closes to master cylinder first then on to the regular lines. During my process, my assistant (10yr old) flinched for a sec. during an 'open' time, his foot wasnt just right, I ended up sucking some air in front caliper, by the time I realised this I was all done bleeding. Not wanting to start the whole process again, I resorted to the 'short-cut' bleed. With the ign. off, pump brake pedal 20 times, slowly and steady and firm, then ign. 'on' ,no start, wait for booster pump to represurize system and cut-off, then ign. off and pump pedal again 20 more times, then continue entire process about 10 times. The theory is the air bubble will work its way back up the line to the highest point, your master cylinder. Hope some part of all this babble helps. Keep master cylinder cap closed while doing this.

Cheers,
Pad

 

[Oilburner]

Pad, the DII has a totally different procedure than a Classic Range.

SpeedAgent, the testbook (or T4) is the diagnostic computer that Land-Rover dealers use. It is required for many diagnostic and repair procedures on the Disco II including brake bleed, transmission fluid level check, door lock repair, air suspension repair (if fitted), etc. It's nothing but a Panasonic Toughbook with some proprietary software. And it SUCKS. Worst piece of dealer interface equipment I have ever dealt with. There are aftermarket systems like RovaCom that are also capable of doing this sort of thing.

 

[SpeedAgent]

It sounds like I need to take this to a real shop or even the dealer??? I haven't done this in years on any of my cars.

Thanks for all of the help.

Chris

 

[Oilburner]

If you're looking at servicing this thing yourself, look into a RovaCom license. I have the equivalent for my VW TDIs and it's pretty sweet to have full-on diag ability at home (or on your laptop, in the car, on the side of the road).

 

[sven]

If you're looking at servicing this thing yourself, look into a RovaCom license. I have the equivalent for my VW TDIs and it's pretty sweet to have full-on diag ability at home (or on your laptop, in the car, on the side of the road).

Yeah but the VAG-COM is way cheaper than a rovacom.

 

[SpeedAgent]

What are we talking about in costs? A quick search turned up prices from $1500 to $6500.

What is VAG-COM?

 

[Oilburner]

Yeah but the VAG-COM is way cheaper than a rovacom.

You can say that again... But if he plans on doing more than oil changes to this vehicle on his own, it wil likely be a worthwhile investment.

Edit: Vag-com is the equivalent volkswagen system for fixing VW cars. The comparable aftermarket system for Land-Rover is Rovacom. It's silly expensive at about 1500$ for a "homeowner" non commercial license. At 1500$ I might try and find a local shop that can help you, but most shops charge 100$ an hour, it adds up quick.