The Morris Minor early wheel cylinders for the Series MM cars are listed as being available as patten parts only from Morris Minor specialists - but as I have new Lockheed wheel cylinders fitted as part of my back-plate kit I would not wish to change this!

But the set-up on LS's car looks very neat.

I have ordered some parts from three different suppliers - grub screw, banjo & banjo bolt, I have just been told that the UNF banjo that I had ordered is not longer available - the ones available for the Morris Minor are UNC, which is not a problem as a UNC connection could be made, but the layout in Stuart's set-up would need to be varied as the brake hose end is UNF!

Once I get the parts I will see how the fit together and then post the results here to share.

Gary

Location: Saltdean, Brighton

I've been round to see my RP owning friend (who hasn't moved into the computer age) who experienced the same problem Ruairidh. Brakes binding because the brake shoe springs weren't strong enough. Apparently there are a variety of master cylinders for the Morris Minor-13/16" and 7/8" dia and some have a pressure sustaining valve set to maintain 8 psi in the system with the brakes off. Also there are different brake shoe springs. His solution was to remove the pressure sustaining valve. Your solution of fitting stronger springs sounds better.

Location: Stockport

Thanks Dave.

R

Chaps, here she is ....... (the smaller one of the two)



My modified Swallow two seater - not to everyone's taste, but great fun. Originally built in 1930, then modified in the early 50's after the tail was damaged.

Location: Bunkerton Castle

Thats certainly different your lordship.But I like it!

Location: Worksop Notts

Having read all the inputs with interest, I think we need a little clarification of principles.
Firstly, brake efficiency and brake effectiveness. Brake efficiency can be defined in two ways:
1] the rate of retardation of the vehicle expressed as a percentage of "g". Where "g" is the acceleration of a falling body due to gravity. "g" being accepted as 32 feet per second per second . Or 9.81 meters /sec/sec. Thus, if your Box saloon will slow you down at a rate of -16 feet/sec/sec. Your brake efficiency is 50%.
2] The total braking force applied by the four road wheels, expressed as a percentge of the total weight or mass of the vehicle. Thus if your Box Saloon weighs 1000 Lbs, and your four wheel can apply 500 Lbs braking force, your braking effiency will be 50 %.
Effectiveness is the ratio between brake pedal pressure and brake efficiency.
Leading Shoes/ Trailing Shoes. As has been stated, a leading shoe expands in the same direction as the brake drum rotates. On contact with the brake drum, the drum tends to pull the brake shoe into contact with the drum. "Self Servo Action". A trailing shoe expands in the opposite direction as the brake drum rotates. On contact with the brake drum, the drum tries to push the brake shoe "off".
Both systems are capable of producing the same brake efficiencies! Rate of retardation or braking force at the road wheels. The leading shoe arrangement is more effective as it requires less brake effort at the pedal.
Twin trailing shoe arrangements where commonly used to provide the earliest forms of automatic brake adjustment, in combination with vacuum servos on large saloon cars in the mid fifties. Only being outdated by disc brakes.
So the only advantage of leading shoes over trailing shoes, is lower effort at the brake pedal! They are more effective not more effecient! So if you have been using front twin trailing shoe systems for years, and can cope with the pedal pressure, why change?
We now need to the consider the advantages of hydraulic braking compared to mechanical systems. The major advantage is the equal application of braking force at the four wheels. [We can ignore front/rear proportionality for now] Mechanical systems can never match hydraulic systems in ths respect. Even when very carefully set up, cable or rods will never match a hydralic system for even brake force application at the wheels.
lastly we need to consider the design defects inherent in the Austin 7 braking system.
Firstly, the centres of expander cam and the brake shoe pivot of the standard Austin are fixed. As the leading shoe is more effective than the trailing shoe, it will wear at a faster rate. So we reach the position where the trailing shoe is pushed hard against the brake drum, but the leading shoe, being worn has limited contact. This reduces effectiveness. This problem was overcome, by Girling and Bendix mechanical systems,by allowing the expander unit to move or "float" on the back plate. Hydralic systems do not sufer from this problem.
Secondly, the Austin front brakes are applied by pulling the brake levers backwards at the bottom of the back plates. As the brakes are applied the front axle twists and reduces the tension in the brake cables, So you have to press harder on the pedal! The Bowdenex conversion, pulls the front brake levers forward, so the twisting axle increases the the cable tension! The system is more effective, it reduces pedal pressure.
Hydraulic systems eliminate this problem.
However, all braking force is applied through the 5/16 diameter bolt locating the radius arms to the ball joint and chassis. while this is adequate for for the cable brakes, the radius arms were "beefed up" for the semi Girling brakes. I wonder are they upto a twin leading shoe hydraulic arrangement.

Location: south wales, slightly drier

The Bowdenex system does not increase cable tension.
As the axle twists forward, so does the outer cable anchorage move with it, assuming it's mounted on the backplate.
And if it isn't mounted on the backplate, I can't imagine where it'd be!

Location: Richmond, Texas

Bowdenex cable tension does increase with brake application. One inner end is attachhed to the brake shoe lever, the other end is chassis mounted at the cross shaft. The outer cover is only a guide.

Location: south wales, slightly drier

I'm sorry to disagree John but, all Bowden cables operate on the same principle, i.e. that the "pull" of the inner is against the restraint of the outer. The outer most definately is NOT only a guide.

Location: Shropshire

Thank you Ian, saves me explaining it!

The ultimate proof is to disconnect one or other of the outer attachments and ask the doubter to hold it in place while you apply the brake pedal. Why would it move with such vigour if it were only a guide?

I'd also quarrel with the argument about the 5/16" bolt. It only holds good if the rest of the ball joint and bushes are clapped out. The bolt serves only to secure the radius arms and their bushes to the ball. The bolt should never be in shear.

Location: Richmond, Texas

Roger,

Correct on both points. The Bowden Cable outer sheath is a compression member. At the pedal end the inner cable is pulled against the outer sheath fixed at this end to the chassis, at the brake end the inner cable also pulls against the same outer sheath fixed to the chassis via the hub back plate to operate the brake lever.
The 5/16" bolt through the ball joint holds the arms with two brass cups to the chassis ball by tension, not shear. If it so loose it is in shear then the whole assembly will fail.

Tony.

Location: Melbourne, Australia.

If, as is often suggested, you do a forum search on, say, Bowden Cable you will see this has been discussed before, with some Austin 7 expert having the wrong story on how a Bowden cable works also, which has probably lead others astray. Have a look at a bicycle brake system to confirm the way it works.

Tony.

Location: Melbourne, Australia.

Just a note to bring matters up-to-date on the extra parts needed to make the wheel cylinder connections work for a twin-leading shoe set-up.

It has not been as easy as I would have thought to get the parts, I guess the demand for the components is low and these are no longer stocked/made.

Anyway, I have almost achieved success - one part I am not totally happy about!

So, the parts I have obtained are as follows:-

1. UNF grub screws for use with an Allen key, these were obtained from

www.modelfixings.co.uk

- these come in a packet of 5 for £1.50, but there is a minimum order of £3.00, so I had to buy 10! I will keep 2 as spares, but that leaves three pairs - if anyone wants a pair, private e-mail with your address and I will post to you.

2. UNF brass banjo adapter female - this is 30-degree angle fitting, which actually will work better than a straight connection, but anyway was the only one that is available now, the other shown on the website is not! - this came from Think Automotive -

www.thinkauto.com

Part Number BF41-3, cost each £8.91 each plus VAT and postage.

3. UNF Brakelight switch banjo bolt - this is for a Mini, and obtained from

www.minispares.com

Part Number 7H7995, cost £5.38 each plus VAT and postage. It is this bit that I am not too happy about - the thread (for the brake light switch when used on a Mini) does not seem quite right for a UNF, I have tried fitting different brake light switches and I am wondering if this is metric! If so, then I will need to introduce metric threads into the equation!

Here are photos of the parts I have bought and I have quickly put on the back-plate just to show how they go, once the thread issue has been sorted out I will properly plumb the brakes together.

Very many thanks for all the comments and observations made by members, much appreciated!

Gary

Location: Saltdean, Brighton - where it was sunny today!

I forgot to mention in my last post that the grub screws need a suitably-sized ball bearing to cover the drilled hole.

I did not buy these, I had some spare in the garage. The grub screw has a convenient depression to locate the ball bearing, which is great!

Gary

Location: Saltdean, Brighton - sunny today!

Just to bring matters up-to-date following my last post - nearly three weeks ago - it has taken that time to get an acceptable solution!

In the last post, I mentioned that I was not happy with the banjo bolt, which I had high hopes, but not any more.

The reason for the disatisfaction were two-fold.

Firstly, with the brass banjo adapter (which I really wanted to use), the length of available thread to screw into the wheel cylinder was only about 3-4mm, whilst the banjo would screw in, I was concerned over the security of the fixing particularly due to stripping the threads when fully tightened in position.

Secondly, the female thread was not UNF and I tried to find out from the supplier what it was, but they never bothered to reply, but speaking to another specialist, it could be NPT, which would not be any good for our purposes!

So, that meant that this banjo bolt was not going to be any good, which was a shame as if it had worked it would be been a neat solution.

Then, as an alternative (I had given up by now in trying to find a fully male/female UNF banjo bolt, these seem to be impossible to find now) I considered a banjo bleed bolt.

Instead of having the 3/8" UNF female connection, there is a bleed nipple (1/4" I think), which would make for a neat solution.

Furthermore, using a single port for two connections could give rise to air becoming trapped in the wheel cylinder due to its inverted orientation, so having the bleeding operation at this point may help purge air from the system, but as I have not got that far as yet with the plumbing so, too soon to say!

The manufacturer, Goodridge, had listed a product that should have been perfect, a banjo bleed bolt that had a 25mm dimension between the hex and the end of the thread - necessary to allow the brass banjo adpater to be used with sufficient thread to get a secure fixing.

Unfortunately, Goodridge no longer manufacture this item and their standard banjo bleed bolt has a 20mm dimension between the hex and the thread end and with this screwed in place, the problem is the same as the first banjo bolt that I had with an insufficient thread for a secure fixing!

Oh dear, I tried to source alternatives, but there was no old stock or anything else suitable that I could find and I really did not want to use a double bolt, which would have worked ok, but I felt that this looked a bit on the messy side and a bit DIY.

I had considered having the brass union machined to reduce the thickness at the business end by 2-3 mm, there is sufficient scope to do so, but I am unwilling to undertake such an alteration without the manufacturer's consent just in case there is a compromise on safety and I do not have the necessary expertise to determine this, so that was out of the question.

So, after much consideration, chatting to Goodridge themselves, who were trying to be helpful, but could not suggest a solution other then to refer me to their largest distributor of their products, CAM Auto.

I contacted CAM and they were very helpful (interestingly, they suggested machining the brass banjo adapter!) but when I gave a negative response they proposed an alternative.

In the absence of sourcing a suitable banjo bolt, I have decided to change tact and go with their proposal, which meant changing the banjo adapter and ditching the brass item that I already have.

The parts came today and I trial-fitted these and I have to say that the result will be acceptable and will work very satisfactorily even if the parts look a bit too modern, but if I cannot get the bit I want there really is not much choice. Anyhow, once fitted, they will be out of sight, so long as they perform, then that is ok with me!

So, I now have an UNF banjo bleed bolt (standard length) with a banjo 70-degree adapter with a 3/8" UNF (JIC), to make a female connection to the bridge pipe with brass union (obviously, the pipe flare will be JIC to match). The bolt & adapter are in stainless steel, which are very good quality and are nice to use.

Here are the pictures: -



Showing the NSF, at the trial-fitting, good clearance.



Here are the parts.



Here they are all together.

So a change to what I had originally proposed and I am still keeping an half-eye for a 25mm long banjo bleed bolt so I can use the brass banjo adapter, but not important!

I thoroughly recommend CAM Autos, very helpful, interested in the project and keen!

If anyone is interested in copying what I am doing, here is my updated parts list:-

1. UNF grub screw and ball bearing - see previous post

2. Banjo bleed bolt (cw bleed nipple) 775-03BNC, cost £18.28 plus VAT each (this is for stainless steel, zinc-plated steel is MUCH cheaper), Banjo 70-degree adapter SBK570-03C, cost £7.13 plus VAT each, again, stainless steel.

These are both manufactured by Goodridge and I think these actually made in the UK factory!

Supplier is CAM Auto Developments, Web: www.camauto.com, Tel: 01727 827717, E-mail: sales@camauto.com.

You can order on-line, but it is cheaper to speak to them as they discount the on-line prices!

The stuff is available from other suppliers, so better prices might be possible, or fit a cheaper material, although I think the banjo adapters only come in stainless steel, not sure on that though!

I will post photos when I have plumbed the new parts in so you can see how it looks, after starting to feel despondent with all the dead-ends, I am now quite excited!

Thanks.

Gary

Location: Saltdean, Brighton

And now for the handbrake-
I have a special I converted many years ago and use an external handbrake with cable pulling a rod one side and the cylinder arm on the other. It was quick and easy to fit but I cant remeber what the cable came from.
On my new car, a Pearl, I want to retain the original brake so intend to use one side cable to the rear cylinder arms.
I wondered if you have sorted this out for your car yet ?
I managed to find banjos for the front brake rear cylinder , although I had to machine slightly to fit.

Charles, I have not got around to the handbrake as yet, although I have Morris Minor cables to attach to the original handbrake lever, I am going to remove the brake cross-shaft as this will not be needed and just connect onto the lever itself.

I did not see the point in retaining the original cables as their operation (for rear brake cylinders that are Morris Minor) is in the wrong direction to pull the wheel cylinder levers, and to use them would entail re-routing when it can be simpler to use a direct line ulitising the bowden principle of cable operation.

Haven't got there yet, but I am hoping that this will be a much easier exercise than the arrangement for the front brakes!

I was interested to read that you had your brass banjo machined, have you got pictures of this? How much metal did you have removed?

Gary

Location: Saltdean, Brighton

Gary, here`s my solution for the hand brake on the special.The crosshaft is one I made up, as my lever is on the outside of the car.One end of the morris minor cable,outer sleve is attached to a bracket on the axle tube the othere is fastened to the rear cross member There`s four photo`s%%bbCodeItem_1%%

cheers Ian

Location: Worksop Notts

Gary

I think I have e-mailed a photo to you.
My banjo was the unf type and the bolt had the bleed nipple included. I had to turn the banjo depth down and machine under the hexagonal head of the bolt to increase its depth to fit as it was not intended for this banjo originally.
All of this was far easier on the special with dropped radius arms!


For the handbrake I intend to use one (longer inner and outer type) side cable in the original postion , to a yolk and rod along the length of the back axle. I have a similar arrangement on my special with a simple bearing for the rod on the diff case.

The hydraulic master cylinder I have , is to be mounted close to the brake light switch on the chassis cross member. At this low level I will be using a remote reservoir- possibly hidden in the battery box.

Charlie

Thanks Charles,

For the benefit of the others, I have uploaded your photos (I use photobucket to get these on here), which I hope you don't mind, I like the look of what you've done, nice and neat!

The brass banjo adapter that you have only seem to be available now with a UNC thread, which is not a problem, all that has be remembered is which way the unions go!

Location: Saltdean, Brighton

Hi I have Hyraulic twin leading shoe brakes on my A7 special. Most of the brake system is Morris 1000, BUT the back plates are alloy. I have seized pistons in the Twin leading shoe front brakes and think thes pistons are NOT Morris. I do not know what they are. Does anyone have a similat set up. The brake cylinders are alloy all round.

There are 2 styles of Morris cylinder. The early 7 inch brakes from 1948 to 1953 use alloy bodies and the later ones are steel. New early ones are about £35 and the later ones as low as maybe £7 each.

If you can get a photo up they can be identified. I have both types here if you need any help and can let you know where to get the early ones.

Location: 10 miles west of Cardiff

Gary

Twin leading shoe is possible if you grind the lower port area of the rear front wheel cylinder and fit a blanking plug.
You then have to fit a banjo to the top port on the rear cyclinder to enable a bleed screw and a pipe fitting at the same port.
I have picture of mine on my Pearl if you e-mail me.
My master cylinder on my Pearl is under the drivers footwell floor with a remote resorvoir under the drivers seat.

I converted special during building but used a reliant robin pedal box with twin master cylinders.

Location: southampton

No bad thing to re-invigorate this thread.
I've just been head-scratching to work out the leading vs trailing issue,and comparing the backplates on all the pictures.

Am I right in thinking that the best way for simple ID of the relative position of the backs of the cylinders in the backplate, viewed from the rad:

trailing set up = lower at the front

leading set up = higher at the front

Or not?

For leading shoe operation when the car is driving forwards, the piston pushing the shoe is in the direction of rotation the drum and it is the self-servo effect of the drum rotation that "pulls" the shoe harder than would be the case with a trailing shoe, so pedal effort is more effective for the same pressure and to answer your question, if the back plate layout is following a "standard" pattern, then as you say, leading set-up is slightly higher at the front than at the rear, with the piston at the front pointing downwards & at the rear, the piston is pointing upwards so that the operation is in the direction of the forward motion.

Of course, when the car is in reverse, the front brakes are twin trailing and much less effective and more pedal pressure is required to apply the brakes.

Location: Saltdean, Brighton

Location: Brittany