ipace Posted September 23, 2013 Share Posted September 23, 2013 Hi Guys, I have a problem which is getting me all confused.... maybe one of you can shed some light.... I fit a defender pedal box including servo and MC to my Series 3 which already has power assisted brakes however it was very weak. Apart from the fact that it used to pull to one side, which i believe is a hub seal issue. I now have a worse problem than i used to with my brakes!! Basically no matter how much you bleed them the pedal still remains soft. You pump it up it hardens but you can barely stop the car at 15KMph!! Any idea what it might be? I have set the shoes as much as i could just in case it's does not have enough travel but to no avail!. Its good to mention that the defender pedal box has been idle for over a year could it be a seal issue on the MC? Would a series MC fit this servo maybe since it's bigger it would help? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 23, 2013 Share Posted September 23, 2013 I'm a touch confused, is that a twin outlet master with a T-making it a single-line system? Do you know the master cylinder is any good? Quote Link to comment Share on other sites More sharing options...
Gazzar Posted September 24, 2013 Share Posted September 24, 2013 Right. Lets get some more information. What wheel base is the S3? Does it have a pressure warning differential apparatus(PDWA)? Because if it's a LWB with Twin Leading Shoes (TLS) and a PDWA then you will need to power bleed it, that is using pressure on the master cylinder reservoir to push the fluid past the various low points and valves between the reservoir and the bleed nipple. Other points - that Tee piece is a bodge, one of the benefits of having a Defender master is you get dual circuit brakes. That looks bad, and suggests that the rest of the system is also bodged! I presume the photo is from the side and the reservoir is actually fitted correctly. If you are only doing it to test if the system works, fine, but don't let it on the road like that. Why? Because the copper lines are not supported, are carrying excess weight and could crack through stress fracturing: each time the vehicle hits a bump the lines move a bit (just a tiny bit). The copper hardens up (gets worked) until it can't flex, so it sheers off. Instant loss of all brakes. I'm also wondering if the defender master cylinder has cross circuit dual circuit brakes - a system where the front piston drives the front right brake and the back left brake, so that in the event of a piston failure you retain some brake on each axle - I doubt it, but your comment about one side being weak caused me to think that. Also, the defender MC may be designed for disk brakes - the volume of fluid moved on disk brake systems is quite different from that on drum systems, this could be part of your problem. Personally I'd be for stripping down and checking the wheel cylinders, fixing leaking hubs and changing the rubber hoses before working on the MC - You'd want that right anyway. Then I'd check over the steel pipes for leaks, and finally I'd put the Series Master cylinder and servo back on. The Series master cylinder is quite capable of stopping a fully loaded 109 with a 3 tonne trailer behind it, locking up the brakes on the trailer. I know, done it more than I want to. Sorry if I'm down on you, it's just that brakes are one of the things you HAVE to get right - if you don't, and your LR goes over with 3 or 4 people on board, then we all have to pay for it through our insurance premiums. I'm just being selfish! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 24, 2013 Share Posted September 24, 2013 Thanks Gazzar, I think you said what I was thinking Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 24, 2013 Share Posted September 24, 2013 Your problem is mixing a 4-disc brake master cylinder with drum brake slaves - disc brake master cylinders produce higher pressure but lower volume than Series masters, and are incompatible. You need the correct SIII pedal box, servo and master, and be warned that there are two different masters for dual line servo assisted brakes, one for SWB and one for LWB. As mentioned, that unsupported Tee is poor - it could result in vibration induced fatigue cracking of the pipes or unions, resulting in brake failure. You would have been better off using a blanking fitting (as used on brake callipers to blank of cross-drillings) in one of the MC ports and a single brake line to the other. I don't wish to sound unpleasant, but when it comes to braking, steering and suspension work, people should not be touching them unless they really understand what they're getting involved in. Replacing like for like is one thing, but when the inexperienced and untrained start swapping non-specification second hand parts over to save costs, they are risking their lives and the lives of other road users to save money, and that is a very dangerous attitude. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 26, 2013 Share Posted September 26, 2013 A late Series 3 servo + MC would probably be a better idea as Snagger says. Or early Defender, which are similar. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.