moore101 Posted September 27, 2009 Share Posted September 27, 2009 my lightweight will be getting range rover axles under it retaining the original springs and im wondering whether i can keep the existing master cylinder or whether it wont be up2 the job of the range rover discs. the master cylinder i have is a lwb item as i have 2.6cyl front brakes at the moment and the master cylinder does look considerably bigger than the range rover item. hopefully someone will tell me its ok to use my existing master cylinder so that i dont have to find someway of grafting the range rover item on. cheers, al Quote Link to comment Share on other sites More sharing options...
rtbarton Posted September 28, 2009 Share Posted September 28, 2009 You will need a servo with discs. Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted September 28, 2009 Share Posted September 28, 2009 Series servo/master cylinder is not up to creating the hydraulic pressure for disks. Remote servo or 90/110 pedal servo and cylinder assembly is required. Been there, seen it & done it before in this case. Quote Link to comment Share on other sites More sharing options...
missingsid Posted September 28, 2009 Share Posted September 28, 2009 Hmm, Check a previous thread (last month or so) a comment was made that a SWB Series on a LWB master cylinder and servo was over braked and he took off the servo? I am not qualifying it, just suggesting more references. Marc. Quote Link to comment Share on other sites More sharing options...
rtbarton Posted September 28, 2009 Share Posted September 28, 2009 Hmm, Check a previous thread (last month or so) a comment was made that a SWB Series on a LWB master cylinder and servo was over braked and he took off the servo? I am not qualifying it, just suggesting more references. Marc. Yes but I think he retained the drums (& fitted 2LS to the front). You need more servo power for discs. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 28, 2009 Share Posted September 28, 2009 Early Defender master cyl & servo will bolt on with a ~10mm thick adapter plate and a small notch in the wing top. Quote Link to comment Share on other sites More sharing options...
Cartman Posted September 28, 2009 Share Posted September 28, 2009 So where did you fit the 10mm plate Jon. That servo looks v.similar to the one going on my 109. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 28, 2009 Share Posted September 28, 2009 So where did you fit the 10mm plate Jon. That servo looks v.similar to the one going on my 109. In that picture it's only 4mm plate, between the servo & pedal box. Unfortunately that didn't allow the master cylinder to release properly and the brakes sometimes bound. Washers sorted it temporarily, a new thicker plate sorted it properly. Quote Link to comment Share on other sites More sharing options...
moore101 Posted September 28, 2009 Author Share Posted September 28, 2009 How much extra force does an early defender servo produce over a series servo? The reason for asking is that we rebuilt our 101 servo with defender inners (original servos not available and early defender servos are the same apart from mounting stud position) and the 101 servo doesnt seem to make the brakes any easier than on my lightweight. cheers for replies, al Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 29, 2009 Share Posted September 29, 2009 How much extra force does an early defender servo produce over a series servo? The reason for asking is that we rebuilt our 101 servo with defender inners (original servos not available and early defender servos are the same apart from mounting stud position) and the 101 servo doesnt seem to make the brakes any easier than on my lightweight. That's a bit of a combo there - the servo is only generating push, the braking effort required to stop the vehicle is down to the master cyl and ultimately the effectiveness of the drums on the 101. If they're not great to start with, it doesn't matter how hard you push the pedal you won't stop any quicker. What I'm talking about is fitting a set of matched components that were designed to work together - if you have disc brakes all round then fitting the servo & master cylinder from a vehicle with discs would seem to make sense. And I know it works because the same setup has been on my truck for 3 years working perfectly Quote Link to comment Share on other sites More sharing options...
moore101 Posted September 29, 2009 Author Share Posted September 29, 2009 having learnt to drive in a series 1 with no servo i dont mind a heavy pedal due to no servo. the main thing i want to know is whether the series master cylinder will physically shift all the pistons in all the calipers and from comparing the size of it to the size of the range rover one (and the picture of a defender one) i reckon it should do. extreme care shall be taken and plenty of checking that all the brakes work will be done before i put it on the road, and i shall look into getting a defender servo and master cylinder to replace existing so i know that it will all function exactly like original al Quote Link to comment Share on other sites More sharing options...
Jon White Posted September 30, 2009 Share Posted September 30, 2009 When I first fitted discs to my series I used the standard (late) series dual circuit master with the series servo. Frankly you needed both feet on the pedal to get it stop if you needed to brake hard. A swap to an early defender servo and pedal box assembly improved things greatly. The defender pebal box will bolt straight onto the series bulkhead. You then have a choice when I comes to master cylinders. Series or defender. Externally they're identical, but the difference is in the bias. The series one is biased 50/50, the defender ones are biased more towards the front (something like 60/40 but i cant remember exactly) The series one will bolt up to the defender servo. I'm still runnign the series one, which I find is adequate, but if I was putting it onto a LWB or something that I tended to run heavily laden I'd be more inclined to use the defender master. HTH Jon Quote Link to comment Share on other sites More sharing options...
missingsid Posted September 30, 2009 Share Posted September 30, 2009 Yes but I think he retained the drums (& fitted 2LS to the front). You need more servo power for discs. Well spotted forgot to engage brain first. Time to stop posting again Marc. Quote Link to comment Share on other sites More sharing options...
MECCANO Posted September 30, 2009 Share Posted September 30, 2009 When I first fitted discs to my series I used the standard (late) series dual circuit master with the series servo. Frankly you needed both feet on the pedal to get it stop if you needed to brake hard. And i have and early one.. and its still a bit "glidey" and not as sharp as i would like. Quote Link to comment Share on other sites More sharing options...
RPR Posted September 30, 2009 Share Posted September 30, 2009 I have Wilwood disc brakes and a LWB master cyl on a single line system. It was run through a remote servo from a jolly great truck of some description. In any event, they work well and don't take too much braking force. At some point, the vacuum line to the remote servo came undone and the sevo stopped working. I barely noticed the difference. I'm braking very heavy doubly thick Marsh rock wheels mounted with nigh on 36" tyres, so not exactly light. If you can fit a servo, I would do so, but you may be fine without one. Quote Link to comment Share on other sites More sharing options...
moore101 Posted October 11, 2009 Author Share Posted October 11, 2009 Got the axles on and i can say that a standard series 3 servo and lwb master cylinder does operate all the calipers off a dual system rangerover. The only thing i can say is that the pedal is possibly slightly heavier but having driven the series 1 recently while mine was off the road a heavier pedal isnt a problem. I dont think its really noticeable as you dont ever have to press the pedal very hard due the extra efficiency of the discs. Best bit about the discs, they work in reverse unlike series drums al Quote Link to comment Share on other sites More sharing options...
Snagger Posted October 31, 2009 Share Posted October 31, 2009 I have a 109 with standard late SIII brakes, ie. trin leading shoe front drums, dual circuit and a vacuum servo on the pedal box. I'll be fitting a Discovery I front axle and disc braked Defender Salisbury axle. The rear callipers are the same on most late models. The front callipers differ between Defender and Discovery/RRC axles, with the piston capacities being identical but the Defender callipers being fed by one hose to each calliper and the dual circuits being split front/rear (like the 109), while RRC and Discovey brakes have a primary circuit to a piston peai in all four callipers and a secondary circuit to the other piston pair in the front brakes (ie. two hoses to each front calliper). On the RRc and Discovery, the rear brakes operate at a lwer pressure than the front, and a balancing valve is incoprorated between the line to one of the front callipers and the main line to the rear axle to reduce the pressure on the aft brakes. I believe the same occurs on the Defender brakes, but with the dual circuit split being fore/aft, the balancing may be incorporated in the master cylinder. however it is done, balancing of the brakes is imperative, or rear lock-up and skidding will occur. Brake pedal effort for a certain level of retardation is affected by not only the level of servo assistance (greater on coil sprung models' servos), but also on the design of the master cylinder. The SIII 109 dual circuit master cylinder appears shorter and wider than the Defender, RRC or Discovery units. that means that while their cubic capicity is similar, the amount of force needed on the pedal to p[roduce a specific level of hydraulic pressure is greater - the same psi but with more square inches needs more force on the pedal. I was hoping to be able to use the 109 master cylinder and servo with the disc brakes (both being very new and in mint condition), with a Discovery's balancing valve in the rear line, but it sounds like this may need excessive pedal force to achieve reasonable braking performance. We'll see at the time. Quote Link to comment Share on other sites More sharing options...
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