Brake problems with my 2a.

[Benny_IIA]

Hi guys,

I have fully rebuilt the braking system on my IIA, However when the height of pedal is adjusted by the threaded rod connecting the piston to the brake pedal in order to obtain a good pedal and also lower the brake pedal, inline with clutch pedal the brake pedal losses all its feel and goes to the floor unless pumped prior to use. It is possible to obtain a good pedal however the brakes bind badly after only a short time.

Is there any benefit in lengthing the tread on the rod in order to obtain more adjustment. Or say try and space the master cylinder out further from the pedal box with metal washers. Any ideas or explanation on what is happening would be graetly appreciated.

[JDNSW]

It is a bit difficult to follow what is happening from your description. Pedal height is not set by the adjustment on the rod. Pedal height is set by the stop on the back of the pedal box so the bottom of the pedal is 158mm from the floor. The pushrod is then adjusted to give 1.5mm free play. The spring on the pedal must be present and must hold the pedal against the stop.

You should follow the adjustment procedure in the manual. The important point is that the piston must fully return (and there should be about 1.5mm free play to ensure this) . It sounds a bit as if the problem is that the piston is not fully returning, but there is a possibility of their being a fault with the master cylinder - which type is it?

John

[Bearman]

Hi Benny, Its a long time since I played with 11A brakes, however I do remember exactly the same problem I had when I reconned my brakes years ago. Mine had the cast steel master cylinder with the big nut on the end of it. From memory I seem to remember that the problem was with the brake shoes and not the m/cylinder. As you say you can adjust the m/c pushrod to obtain a hard pedal but then the brakes bind up and do not release and I seem to remember that this was because the brake fluid was not returning when you took your foot off the pedal.The m/c piston would not return far enough because of the lengthened push rod - does that make sense. Anyhow I seem to remember that I found the problem (after much heartache and profane words) in the exchange brake shoes I had fitted. The bonded shoes had been fitted wrongly on some of the shoes and the snails lugs were in the wrong position on a couple of the exchange shoes. If you have changed your shoes compare them with your old ones if you still have them to compare lining and lug position....Bearman

[Blknight.aus]

check the brakes orientation as mentioned and also check for collapsed hoses holding brakes on. theres also a chance that your master cylinder is leaking back to the resivior at a certain position.

[Benny_IIA]

Hi, The master cylinder in question is the cast one with the large nut at the rear. The shoes were relined and the drums machined to suit.
Thanks Ben.

[Aaron IIA]

the brake pedal losses all its feel and goes to the floor unless pumped prior to use. It is possible to obtain a good pedal however the brakes bind badly after only a short time.

I would suggest that the brakes are mis-adjusted. You need to adjust them to the point of binding, then slacken them off just a little bit.

Do you have a short wheel base master cylinder on a long wheel base vehicle? The short displaces less fluid, while the long slaves need more.

When you have pumped up the system, does the pedal creep down? If so, then the re-couperating valve is most likely leaking (internal leak).

When pumped up, is the pedal rock hard, or a little spongey? It should be rock hard, as there is no booster to suck the pedal down. If spongey, even a little bit, then there is air in the system. Even if you have used a pressure bleeder or a venturi sucker, you still may have air in the lines.

You have the compression barrel master cylinder (big nut). Is this mounted on an angle (original, early bracket), or level (updated, later bracket)? The angle mount has a habit of trapping a bubble at the nut end, which can not bleed out the pipe. To bleed it out, park on a steep hill, or raise the front wheels about two feet from the ground. This will make the master cylinder level, so you can remove the brake line and bleed the air from the master cylinder.

Aaron.

[defi]

Had a similar issue with my series 2 (i have 6 cyl brakes which makes matters even worse) I fitted a red (10psi ) Wilwood residual pressure valve (check valve) and all is now well before fitting the valve I was forever adjusting the brakes to get any sort of pedal, now the pedal is hard halfway down.
I think what is happening is that when the pull off springs pull the shoes back they move so much fluid back into the master cylinder that most of the travel is taken up moving the pads against the drums, using the check valve holds the pads tensioned against the springs so less pedal travel is needed to get the pads to touch the drums.
link
Wilwood Engineering - Residual Pressure Valves

[JackM]

Ben,

I guess there are a number of possibilities - from your description, it does sound like a master cylinder adjustment problem (assuming the master cylinder is working well internally), but if that fails to solve the problem, check what TeriAnn Wakeman has to say:

Land Rover FAQ - 109 rear brakes



Jack

[Benny_IIA]

I forgot to mention that the only time the brakes went all the way to the floor was when the landy was on a very step incline and I was reversing down, the pedal went all the way to the floor with no pressure at all. All of the posts have been very helpful and I will investigate the suggestions on the weekend.

[UncleHo]

G'day Benny_11A

First of all the master cylinder with the Nut is the CB type 1inch bore, on a LWB, (the SWB has 3/4inch bore) the m/c push rod should have 1-1.5 mm freeplay in it down the bore, you adjust that by the threaded rod and lock nuts on the pedal collar (under the inspection plate) the pedal height to floor is adjusted by the bolt and lock nut at the back of the pedal box housing, (clutch has one too) that should get your M/cylinder sorted out.
WARNING: do not fit a 3/4 bore Master cylinder to a LWB vehicle as there is not enough fluid displaced to operate the wheel cylinders correctly, I am aware of a couple of FATAL accidents because of this.

Brake shoes: the rear shoes are "Handed" that is there are Left and Right rear shoes, and also Front and Rear shoe, the position of the adjustment pegs to the snail cam is the secret, just check (with the shoes off the vehicle) that you have 2 shoes with the pegs in one location, and 2 shoes with the pegs in a slightly different position, if so you are OK, one shoe of each goes to each rear wheel,line up the peg to the snail cams before fitting, (with snail cam backed off) make sure that the snail cam turns when the adjusting nut is turned, as often the snail is loose on the shaft.
I have lost count of the number of rear brakes that I have had to rebuild after some "specialist" brake mob has fitted wrong shoes to wrong sides, as the cams and pegs don't line up and then you cant get brake adjustment or good pedal,

Note: when you go to bleed the brakes, adjust all wheels up tight, then bleed, as then you have a good chance of getting good pedal height without needing a pressure bleeder, then back off so you can just hear them touching the drum


Hope that is of some help

cheers