Series 11a brakes

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Tim65fastback

New Member
Posts
5
Location
West Devon
Hello everyone, I am new here and this is my first post. OK some background. I bought my series 11a 88-inch back in 1997 to tow the daughters pony. I had been previously a 110 County owner and sort of became bitten with the Land Rover bug (is that what it is ?). Anyway, the brakes on my Landy have never been very confidence giving and with one or two oil leaks in evidence in the end the annual visit to the MOT station got the better of me a couple of years ago so Landie has been in the barn ever since. Anyway I digress. A friend offerred me the running gear from a rather rusty 1982 series 111 and I jumped at the opportunity. So I now have front and rear axles and an overdrive gearbox to fit. The axles clearly have larger (11-inch) drums. So do I need to change the master cylinder ? I have saved the servo assisted 1982 master cylinder with plastic rectangular reservoir, but will this work, or do I need to think about a series 11a 109-inch master cylinder or will my original work those bigger drums ok ? Sorry to turn it into a story but being an old fart I do tend to go on. Oh and thanks for any answers, Tim
 
Ideally you need a LWB m/c. People have got away with the SWB one, but it only just moves enough fluid so if there are any other minor problems you'll be back on hear asking lots of questions.
The Ser III cylinder and servo should fit, but you may have to make/get made some custom brake pipes, and drill & tap the manifold. It might be easier to find a manifold from a servo fitted vehicle.
 
thanks everyone, all really appreciated. I have splashed out on some parabolic springs front and rear,new shocks a clutch kit and am planning to swap in the overdrive box from the 111 into my 11a as well as making into a truck cab rather than a soft top, so when I get into the job am sure I will be back on here with some more stupid questions. Until then, merry Xmas to all
Tim
 
Hi,

I disagree ...... but think I am alone in this.

The 11" front brakes have the same number of PISTONS as the 10" brakes. But the pistons are SMALLER, so how can they need more fluid ..... all else being equal?

However, the 11" rear cylinders (identical to 10" fronts) are bigger, so will need more fluid. The question is, do you need 11" rears on a SWB? I say you don't, others say you do.

There is a side isue ......... you can fit 11" rears onto SWB front, and retain SWB cylinders, which should give you 10% better breaking at front. Equally, you can fit 11" rears onto SWB rear using SWB rear cylinders, which will give you 10% better breaking at rear. Fitting 11" rear drums and cylinders onto SWB may give you too much breaking at rear. Remember the LWB was designed to be heavier (just a bit) and carry a heavier load. Also, LWB was designed for bigger tyres, which will REDUCE your braking by 10 - 15%. Think about it!

Last time I did my sums, the LWB master cylinder had an 80% bigger cross sectional area (CSA) than the SWB. That means that fitting a LWB M/C will reduce your pedal travel by nearly half (great!), but nearly double the effort required. Simple principle of levers, albeit hydraulic.

Personally, I would fit the 11" front brakes only. If I find that I can lock the rear wheels on tarmac, I would leave it at that. If I can't lock the rear wheels. I would ask myself why .... they should lock. If its close, I might fit 11" rear brakes with 10" rear wheel cylinders.

Whatever, take it one stage at a time. Front 11" brakes, test. Rear 11" brakes, test. Big master cylinder, test. Do all three at same time, and you won't know what has done what. Also consider the efficiency of brakes on the horse box. If they are not very good, fitting the big master cylinder might be a stage too far. Only you can decide.

There is another matter that I am unhappy with. The LWB is heavier than the SWB, carries a heavier load, and has bigger tyres. All suggesting that more pedal effort is required. But LR fitted a bigger master cylinder which requires even more effort. ?????

BUT, the SWB pedal box is a different part number from the LWB pedal box, and I have read that they are NOT interchangable. I do not know what the differences are, and wonder if the Velocity Ratios are different. Does anybody here know?

Of course, if you are also getting a servo, all bets are off. Does it have a pressure limiter on the rear brakes.

Be aware, that bleeding 11" front brakes requires the adjusters to be wound right OFF. The pistons need to be right in, to minimise the amount of UNBLEEDABLE air above the outlet port/bleed nipple. Treat rears normal.

602
 
Hi,

10" brakes have one wheel cylinder but with a piston sticking out each end. IE ... 2 pistons.

11" FRONT brakes have two wheel cylinders, each with one piston. IE ... 2 pistons.

10" brakes have one leading shoe, and one trailing shoe.

11" fronts have two leading shoes.

11" rears are one leading shoe and one trailing shoe. The trailing shoe is needed so that you have some braking when reversing.

One particular pre-war car had leading shoes on all four wheels. It had a reputation for running down hills backwards when the drivers failed to do a hill start.
 
w3526602 said:
Hi,

I disagree ...... but think I am alone in this.

The 11" front brakes have the same number of PISTONS as the 10" brakes. But the pistons are SMALLER, so how can they need more fluid ..... all else being equal?

However, the 11" rear cylinders (identical to 10" fronts) are bigger, so will need more fluid. The question is, do you need 11" rears on a SWB? I say you don't, others say you do.

There is a side isue ......... you can fit 11" rears onto SWB front, and retain SWB cylinders, which should give you 10% better breaking at front. Equally, you can fit 11" rears onto SWB rear using SWB rear cylinders, which will give you 10% better breaking at rear. Fitting 11" rear drums and cylinders onto SWB may give you too much breaking at rear. Remember the LWB was designed to be heavier (just a bit) and carry a heavier load. Also, LWB was designed for bigger tyres, which will REDUCE your braking by 10 - 15%. Think about it!

Last time I did my sums, the LWB master cylinder had an 80% bigger cross sectional area (CSA) than the SWB. That means that fitting a LWB M/C will reduce your pedal travel by nearly half (great!), but nearly double the effort required. Simple principle of levers, albeit hydraulic.

Personally, I would fit the 11" front brakes only. If I find that I can lock the rear wheels on tarmac, I would leave it at that. If I can't lock the rear wheels. I would ask myself why .... they should lock. If its close, I might fit 11" rear brakes with 10" rear wheel cylinders.

Whatever, take it one stage at a time. Front 11" brakes, test. Rear 11" brakes, test. Big master cylinder, test. Do all three at same time, and you won't know what has done what. Also consider the efficiency of brakes on the horse box. If they are not very good, fitting the big master cylinder might be a stage too far. Only you can decide.

There is another matter that I am unhappy with. The LWB is heavier than the SWB, carries a heavier load, and has bigger tyres. All suggesting that more pedal effort is required. But LR fitted a bigger master cylinder which requires even more effort. ?????

BUT, the SWB pedal box is a different part number from the LWB pedal box, and I have read that they are NOT interchangable. I do not know what the differences are, and wonder if the Velocity Ratios are different. Does anybody here know?

Of course, if you are also getting a servo, all bets are off. Does it have a pressure limiter on the rear brakes.

Be aware, that bleeding 11" front brakes requires the adjusters to be wound right OFF. The pistons need to be right in, to minimise the amount of UNBLEEDABLE air above the outlet port/bleed nipple. Treat rears normal.

602
Click to expand...

I'd go along with what you're saying. That's an interesting point about the sum of cross sectional areas of all the pistons in the LWB system being less than that in the SWB system, but the LWB master cyl. piston having a cross sectional area greater than the SWB master cyl. piston. Have you actually driven an 88" with the 11" twin leading shoe brakes on the front and the 10" brakes at the rear with the SWB master cylinder? Did it work well?

I'm planning to put twin leading shoe 11" brakes on the front with 10" drums at the back but with the hydraulic wheel cylinders from the 11" rear drums. After what you've said I'll keep the SWB master cyl. and pedal box and see how it works.

Another thing to consider is the front to rear weight distribution of an 88" compared to a 109". I'm guessing that a 109" will usually have a greater proportion of it's weight on the rear axle than an 88" in most situations and therefore it would seem to make sense that an 88" should have a braking system with more of a bias to the front brakes than a 109", which is what you'd get by retaining the 10" drums on the rear axle. However in reality a pre 1980 88" has a 50:50 front to rear brake bias but a 109" system is biased to the front.

My conclusion is: We've probably spent more effort in thinking about the braking systems on leaf sprung Land-Rovers than the engineers who designed the systems ever did!
 
Hi Fenby,

Yes, my S1 bitza (S3 galv chassis, S2 mechanicals) had 11" fronts, 10" rears, small M/C, and could lock the rear wheels on tarmac.

Be aware that EARLY 11" front brakes required the shoe steady-pins to be adjusted every time the shoes were replaced. I replaced the rusty slotted screws with 2" x 5/16" BSF socket head screws (Allen screws). Not only that, I got a mate to drive foreward, stop, and hold the pedal down, while I crawled underneath to tighten the lock nut. I didn't trust the shoes to centralise themselves, just by pressing the pedal. But each to his own.

I also did the same hydraulic set-up on a 1965 LWB Safari, which later went to Holland. It wouldn't surprise me if it was still on that set up ...... although the new owner is now aware. He hadn't noticed until it came up on the S2 forum.

As I said, do it one step at a time. If you can lock the rear wheels, there is no point in making them easier to lock. If front wheels lock, car goes in straight line. If rear wheels lock, rear end slews sideways. Well, sometimes.

The bigger master cylinder gives a lovely feel to the pedal, but you have to push it really hard. Crippled me - Bakers Cist, something like having a knee cap behind your knee too.

Important! Bottom of pedal should be 6.25" verticaly above the floor. This can make an AMAZING difference to pedal travel. Pedal should dangle freely with about 1/2" free play. My pedal had about 1" total movement. I've already told you about winding the front adjusters right OFF when bleeding.

602
 
Thanks guys, all really informative and like the stage by stage idea especially. However I think I may have explained this wrong in the beginning. The 'donor' is a 1982 swb s111 truck cab diesel with 4-speed and overdrive, found on a local farm with only 50,000 miles but very damaged and quite rusty. The axles,brakes,gearbox and truck cab were all good though. I have all those parts complete together with both pedals, cylinders,servo etc.. The receiving vehicle is a 1965 s11a 88-inch which I think was originally hard top but when i bought it in 1997 had been converted to full canvas. when I bought it the engine was apparently an ex military 2.2 petrol but the rest of it seemed pretty original. The brakes were leaking and so were the axles so I serviced new wheel cylinders shoes etc and also tried to fix the leaking gearbox into handbrake drum. All fixes were of limited success because 10 years on everything was leaking again and I had probably only done about 200 miles a year. Landy has sat on a trailer in the barn for the last 2 years. So when this s111 came up seemed like an opportunity to refresh and improve. Apart from being diesel, the donor is an 88-inch not a 109, where I probably confused the issue in my question was to ask if I should fit non servo m/c from an s11a 109, or use the dual circuit later cylinder with servo. Anyway, I am going to do just as you suggest and do it in stages. The less I have to do, the faster the old girl will be back on the road !
Thanks again
 
I can't argue with all the figures quoted here, all I can say is over the years I have come across a number of people with 11" brakes, initially working fine, but later having problems, with the peddle needing pumping. They have tried all the usual things, bleeding, adjusting, new shoes etc, but in each case they finally solved the problem by fitting a LWB master cylinder.
If it isn't necessary to work LWB brakes, why did LR fit it?
 
Davec said:
I can't argue with all the figures quoted here, all I can say is over the years I have come across a number of people with 11" brakes, initially working fine, but later having problems, with the peddle needing pumping. They have tried all the usual things, bleeding, adjusting, new shoes etc, but in each case they finally solved the problem by fitting a LWB master cylinder.
If it isn't necessary to work LWB brakes, why did LR fit it?
Click to expand...

I had a LWB series II alota years back, got best results bleeding air outa cylinders and lines by parking on as steep a slope I could find, very very steep, and crack the bleeders (one a time) on uphill axle, and proceed in the usual manner, got rid of all air & spungy feel and could skid wheels no worries.

A lot of the spungy comes from shagged hoses long past their useby date also.
 
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