Defender Brakes

Red90 · May 06, 2015, 09:18 AM

That test is for the booster. Not much can go wrong with the master other than leak. You should first make sure you are getting vacuum from the vacuum pump and that the booster line is not plugged or the booster leaking. A vacuum tester is a good investment.

Soft pedal is air or a bulging flex line.

You should be able to lock up all four at any time without undo pedal pressure. They are really quite good brakes, for what can fit in a 16" rim.

As far as brake lines, stainless braided teflon lines are pretty low cost in kit form, so might as well do those.

Trevor · May 06, 2015, 01:19 PM

I always thought the booster was part of the master cylinder John. I gather that's not the case. I was looking over the workshop manual and wasn't able to find a "booster" listed. It would be right off the vacuum pump though wouldn't it?

Red90 · May 06, 2015, 02:53 PM

Land Rover calls it a "servo". Item 4. Master cylinder is item 1. They bolt together and are sold separately.

http://www.allbrit.de/UNI.cfm?PAGE=757483&SPRACHE=EN

Disconnect the hose at the engine end and see if you get suction with the engine running. Then check the other end. The hose can collapse. The NRV (item) 7 can fail or plug. It just pulls out of the booster. The booster diaphragm can fail.

Red90 · May 06, 2015, 03:25 PM

I was having a bit of a look and I guess the 300TDI vacuum pump is prone to failure, so that would be the first place to look. Quite a silly design, IMO. The earlier pumps are much nicer.

Trevor · May 07, 2015, 05:00 AM

Thanks John, that clarifies things nicely and should give me what I need to sort through this.

Alex C · July 14, 2015, 10:32 PM

price out an oem master cylinder from Bill, i put a new one on my 90 with the new shes and slaves, just have to do the fronts and will be good

Trevor · July 15, 2015, 06:32 AM

I changed out the rotors (EBC), calipers (OEM) put in new pads (EBC Green), and put in braided lines up front. It stops extremely well now. Locking up the brakes is no problem at all, things are much more responsive.

I do have a set of rear brake lines coming. The fittings on the existing ones are seized and I had to use vise grips to get them off the calipers. So both the copper line is weakened and the fitting is shot. They work, but far from ideal. So the replacement lines will arrive this week and hopefully I can get them swapped out without issue. The biggest problem is going to be removing the fittings that hold the line brackets to the axle. I'm pretty sure they aren't going to come off easily.

Matt H · July 15, 2015, 12:13 PM

You have hard brake lines made of copper?

They should be double wall steel. Copper can't take the pressures of a braking system very well and splits. This may be further compromised by the new braded brake lines not flexing as much as the old rubber flex hose.

Red90 · July 15, 2015, 12:27 PM

They are probably steel. But, "copper" brake line material is not copper. It is a copper-nickel alloy, which is designed and suitable for brake lines.

http://www.copper.org/applications/automotive/brake-tube/brake.html

Trevor · July 15, 2015, 01:25 PM

Quote from: Matt H on July 15, 2015, 12:13 PM
You have hard brake lines made of copper?

They should be double wall steel. Copper can't take the pressures of a braking system very well and splits. This may be further compromised by the new braded brake lines not flexing as much as the old rubber flex hose.

They're the stock lines still on the rear. I just assumed they were copper as they look like it, and are reasonably pliable like copper. Looking over John's link, that looks very much like what is on there now.

Matt H · July 15, 2015, 10:44 PM

Quote from: Red90 on July 15, 2015, 12:27 PM
They are probably steel. But, "copper" brake line material is not copper. It is a copper-nickel alloy, which is designed and suitable for brake lines.

http://www.copper.org/applications/automotive/brake-tube/brake.html

I've seen regular copper pipe used quite a few times. More often than not on owner "restored" vehicles. It is out there.

Matt H · July 15, 2015, 10:49 PM

Quote from: Trevor on July 15, 2015, 01:25 PM
Quote from: Matt H on July 15, 2015, 12:13 PM
You have hard brake lines made of copper?

They should be double wall steel. Copper can't take the pressures of a braking system very well and splits. This may be further compromised by the new braded brake lines not flexing as much as the old rubber flex hose.

They're the stock lines still on the rear. I just assumed they were copper as they look like it, and are reasonably pliable like copper. Looking over John's link, that looks very much like what is on there now.

Not sure if stock Defenders came from the factory with exotic copper alloy brake lines or not? But judging by the rate folks in the UK need them replaced I'd say it's likely they used the steel lines at the factory. Perhaps someone changed it for copper alloy in the past?