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Author Topic: Late series 3 Swb 11” front brakes on 2a - what master cylinder?  (Read 1991 times)

MJOLandy

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Evening all -
Question -I’m  fitting Late series 3 Swb 11” front brakes to my 1969 Swb 2a - what master cylinder do I need? It needs to be single circuit as it is now and imperial brake pipe fittings.
« Last Edit: August 22, 2019, 10:55:29 PM by MJOLandy »
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Smokey 11a

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #1 on: August 23, 2019, 12:19:44 AM »

I did this conversion 12 years ago or so, not impressed, pain to bleed, reverted back to 10 inch then 8  years ago when i had my knee replaced  fitted a remote servo which made the world of difference. First thing is to make sure everything is working as it should and go from there,  IIRC I fitted a 6 cylinder master cylinder as my shoes were the 3 inch type. I'd be looking at a Standard 109 Master cylinder of the type fitted to the later 2a.

If you can lock the wheels with 10 inch 11 inch shoes will not make that much if any difference.

https://www.paddockspares.com/parts-and-accessories/land-rover-series-2-and-3/brakes/master-cylinder.html
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Romahomepete

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #2 on: August 23, 2019, 06:11:12 AM »

I used a lab CV socket when I did mine, I also have a remote servo.

No problem bleeding the brakes and I can drive in traffic knowing that I can stop as quickly as the car in front.

Peter
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Formerlyjeremy

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #3 on: August 23, 2019, 07:21:14 AM »

This was the standard post 1980 SWB system with 10 in rear brakes and probably had a servo mounted on the pedal bracket - so why not use that system.  I wonder what your search engine will produce if asked for a S3 parts catalogue?

The vehicle I had with this system worked really well.

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Mowersman

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #4 on: August 23, 2019, 10:50:13 AM »

It all depends on your back brakes. 11" TLS fronts with 1" cylinders on the back requires a SWB master cylinder, 1.25" rear cylinders requires a LWB master cylinder. I would use a late 2a CV type for non servo applications. I have 11" all round on my 88" with 1.25" rear cylinders, LWB CV master cylinder, non servo, single line. Its stops very well indeed.
Andrew
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #5 on: August 23, 2019, 01:59:53 PM »

Hi,

First thing to remember ... you don't count the wheel cylinders, you count the wheel cylinder pistons. SWB have 4 cylinders, and LWB have 6 cylinders. But they both have 8 pistons.

By my calculation, LWB front cylinders have about 80% more piston CSA, so will use 80% more fluid (at the front), but also give 80% more pressure on the brake linings. I didn't bother calculating the rear cylinders. Feel free to do it yourself

I was reluctant to trust a SWB master to pump enough fluid, so I fitted a LWB master. Something in between would probably be best ... but as my slide-rule was smoking, I didn't bother doing any more sums. Er ... if you keep SWB slaves on the rear, it will give a better feel to your pedal, and reduce the risk of rear lock-up, but you will need to press harder to stop your truck rolling backwards down a steep hill ... I suspect a lot harder, due to bigger master and only two small shoes(one per drum) doing any work. Do I need to clarify that?

Just an idle thought. LWB front slaves could be sleeved (£40 each?) to accept SWB pistons. That way you could keep the SWB master, but benefit from both the 10% bigger drums, and TLS on the front. Are there any volunteer guinea pigs?

I wouldn't bother converting the rear brakes to 10", unless I was regularly carrying heavy loads ... or reversing down hills. But hey, if you fitted 11" to the rear, with sleeved cylinders ...??? Is +10% on the rears worth the effort/expense?

Time to get my coat.

602
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #6 on: August 23, 2019, 02:08:19 PM »

PS,

You could always fit 11" brakes to the rear, but use sleeved wheel cylinders ....

... hang on  while I rethink my suggestion to sleeve the front cylinders. Hmm! It might work, but different type cylinders will mean its not as easy as I thought. Not impossible!

Wilkie ... come to Daddy!

602

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MJOLandy

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #7 on: August 25, 2019, 11:40:47 AM »

Thank you all for your replies, I know about option of fitting servo but I don’t want to do that, besides 2a 109’s don’t generally have a servo,.
All I want to know is what master cylinder with a part number if possible, to use.
The axels I’m refurbish for my 2a came off a late 3 so has 11” front and 10” rear so due to the fact there will be increase in breaking surface area the brakes should in theory be better.
Currently my Swb 2a 10” set up work Well  but never been able to lock them up! Last year back and front brakes were overhauled with Delphi cylinder s, new master cylinder, mintex shoes, new springs, hoses and all brake lines replaced, all adjusted correctly.
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Mowersman

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #8 on: August 26, 2019, 01:31:55 AM »

Thank you all for your replies, I know about option of fitting servo but I don’t want to do that, besides 2a 109’s don’t generally have a servo,.
All I want to know is what master cylinder with a part number if possible, to use.
The axels I’m refurbish for my 2a came off a late 3 so has 11” front and 10” rear so due to the fact there will be increase in breaking surface area the brakes should in theory be better.
Currently my Swb 2a 10” set up work Well  but never been able to lock them up! Last year back and front brakes were overhauled with Delphi cylinder s, new master cylinder, mintex shoes, new springs, hoses and all brake lines replaced, all adjusted correctly.
Both 10" SLS and 11" TLS front brake systems use the same volume of fluid to operate them as they both have 4 pistons, all of the same diameter. It all boils down to what the 10" brakes on the back have. If they have the original 1" cylinders for rear brakes, then a SWB master cylinder is what you want. If they have been upgraded to 1.25" cylinders to increase rear braking force, then you will need a LWB master cylinder.
Andrew
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #9 on: August 26, 2019, 08:25:18 AM »

Both 10" SLS and 11" TLS front brake systems use the same volume of fluid to operate them as they both have 4 pistons, all of the same diameter.

Hi Andrew,

Are you sure the 11" TLS front wheel cylinders are the same diameter as the 10"?

If they are the same size ... why do they need a bigger master cylinder, which if everything else was equal, would give you shorter pedal travel, but require a stronger right leg.

I fitted a 109" master to an otherwise standard 88" system. It crippled my right knee.

From memory, an 88" has 1.25" front cylinders and 1" rears., and ...

a 109" has 1.25" rears and, er, I can't remember the size of the fronts  ... possibly 1.175" (I'm guessing there).

One point I haven't mentione in a couple of years or so .... the location of the bleed nipples on the 109" front wheel cylinders are on the centre line of the pistons. In theory, it is impossible to expel the air above the centre line.

I have two solutions....

Before fitting the back plate to the axle, I assemble the brakes shoes, lay the unit, shoe side down, on a milk crate, hoses connected, which means the bleed nipple as at the top, then bleed.

Thereafter, hopefully never, I wind the adjusters fully off, which reduces (eliminates?) the size of the trapped air between the pistons.

NEVER FIT A RIGHT HAND BACK PLATE TO THE LEFT HAND HUB, OR VICE VERSA. Twin trailing shoes can be quite frightening.  :agh

OT, on more than one occasion iI have met (not done) disc brake calipers fitted to the wrong end of the axle. That puts the bleed nipple at the bottom. Nothing appears to be wrong (unless you know) but the brakes will not bleed, despite there being no bubbles.  :stars  Hands up those who ......!

602
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #10 on: August 26, 2019, 08:31:03 AM »

Hi,

Google, via the search bar at the top of the screen (much quicker) says a 109" front wheel cylinder 1.125" dia. (That's assuming my short term memory is not failing).

602
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #11 on: August 26, 2019, 03:17:15 PM »

You could always fit 11" brakes to the rear, but use sleeved wheel cylinders ....

Hi,

Doh! Anno Domini strikes again. :thud

SWB front and rear wheel cylniders are interchangable ... physically... Yes?

LWB rear cylinders are the same as SWB front cylinders ... so no need to sleeve , as suggested above ... IF you fit LWB brakes to the rear of your SWB (I never have) just fit SWB rear slave cyinders. That should also cure excessive pedal travel on a LWB ... but weigh up the implications. Probably not a good idea if you carry heavy loads, or tow a heavy trailer ... or reverse down steep hills a lot.

602
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oilstain

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #12 on: August 26, 2019, 09:41:46 PM »

I have REAR 109 LWB 11" back plates/shoes on the front of my SWB, retaining SWB master, slaves all round, this works well :)
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w3526602

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Re: Late series 3 Swb 11” front brakes on 2a - what master cylinder?
« Reply #13 on: August 26, 2019, 10:49:20 PM »

Hi,

Just to complicate things, The Aunt originallly had ... doh, memory fails me. Lets just say that with a strip of steel and the adroit application of a file, you could fit "fiddle stick" hand brake levers - lock either, or both, back brakes.

602
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