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LA10 Brakes

chrisjb
Posts: 35
Joined: Sun Jul 16, 2017 1:26 pm
Location: Harlington, UK

LA10 Brakes

Post by chrisjb »

My 1933 LA10 had serious corrosion problems in the hydraulics probably because the fluid had been left for too long. I honed and polished the wheel cylinders and replaced the seals and boots. They slid very nicely. I replaced the master cylinder completely. Having drained off and refilled with DOT 5 I bled the system until totally air free.
The rear nearside brake was jamming hard on. I released the adjusters and “jacked” the drum off with two screws. The shoes were free to move. Using a spanner at 9 and 3 o'clock between the rim of the backplate and the shoe I could easily push the shoe back in but the opposite shoe moved out like a seesaw. If I cracked the bleed screw the pressure in the cylinder was released and the shoes returned to normal just as though there was a non return valve there. I now realise that this problem existed before the work as sometimes the engine would labour just to move.
There is a lot of free movement on the foot pedal, about 2”, even if I tighten up the brakes to hard on. Is there any setting up to do with the push rod?
Any ideas please?

Graham
Posts: 343
Joined: Sun Feb 21, 2016 12:05 am
Location: Wirksworth , Derbyshire

Re: LA10 Brakes

Post by Graham »

Chris if the 10 is the same as the lj200 the actuators on the rear brakes should not be bolted up tight allowing the shoes to move up and down and centralise themselves. Slacken the locknuts off a turn and grease where the actuators slide on the back plate

Simon Hyslop

Re: LA10 Brakes

Post by Simon Hyslop »

The Lockheed brakes on these 10s, I am most sorry to say, don't have the sliding cylinders of the later Girling units. The shoes are held in position each on a separate pivot at the bottom with a washer and split pin, so they can only move relative to the wheel cylinder pistons. It is worth checking that the shoes aren't seized on the pivots. A good place to have some copper grease.

I've had similar but slightly different problems with mine but here goes with some things to think about and look at.

1) From your description, this sounds a likely possibility. Is the rear brake hose in good condition inside? They can collapse inside allowing the fluid to go the wheel cylinder but not return. This should affect both rear wheels as there is only one hose. If the hose is ok, has a pipe got squashed anywhere along the back axle?

2) Does the handbrake mechanism , which is entirely separate to the hydraulics, allow the shoes to return completely off? Test by pulling the levers on the axle casing right off from underneath the car and see if it makes any difference. This has come up before as an issue owing to the lack of lubrication points in the spindle on the axle casing which can seize. If the shoes are stuck on, you will have excess pedal travel because the pistons have to travel out to reach the shoe and the adjusters will not be able to do their job properly.

3) These double ended pistons can be a bit of a nuisance if one end sticks. I've had this and while the one piston goes in, the other sticks solidly where it is binding the wheel. However, taking it all apart and cleaning the bore with 600 or 800 paper has solved the problem for now. I know you've said you've been at these but if it wasn't recently and the car has been standing, if left in damp conditions (Scotland in an average winter, in my case!) the trouble can reappear. While I think about it, the cylinders had the springs inside them, between the pistons, I suppose?

Maybe you've tried all these. If so, do write back to say so in case there's something we can all learn from, which is important !

AlanCoombs
Posts: 27
Joined: Sun Sep 18, 2016 10:07 am
Location: Cambridgeshire

Re: LA10 Brakes

Post by AlanCoombs »

Hi Chris,


Your description sounds very much like a very common problem with old hydraulics that have been sitting around for too long - as I found with one of my 18's. Although it seems unlikely, the hydraulic flexible hoses degrade from the inside as well as the outside, and eventually collapse internally, forming an ideal one-way check valve. This wouldn't explain just one side locking on at the rear though, but given that these systems are so simple and you've changed/fixed everything else, I would change the flexible hose to the rear Axle.

chrisjb
Posts: 35
Joined: Sun Jul 16, 2017 1:26 pm
Location: Harlington, UK

Re: LA10 Brakes

Post by chrisjb »

Thanks for the advice. Basically too much "crud" clogging up everything. I swapped cylinders over and the fault stayed. The wheel cylinders were full of crystals and brake fluid that had turned to grease. Anyway. All cleaned and working. I will replace the hoses just in case. I fitted bleed nipples from the start. They are a regular size and thread. Strimmer cord is ideal for breaking through the pipes etc.
One point of concern though. Everyone says that wheel cylinders can stick. Over the years the bores get bigger and the pistons get smaller. I think that they were chromium plated too. The result is that the piston could jam because it isn't being pushed off centre. I provided a small rounded chamfer on mine to help with this. The push pins are not square from the cup of the piston to the cup of the shoe thus the piston is pushed or pushing over to one side. The bottom shafts that the shoes sit in are too heavy to bend. If there is wear here then the return springs tend to pull them into the back plate. I haven't thought of a solution to this one yet.
Chris

Simon Hyslop

Re: LA10 Brakes

Post by Simon Hyslop »

I'm writing this away from home at a rally and I was thinking about this squareness problem. Girling had on their post war systems little steady posts and I wonder if it might be possible to make a similar arrangement for these Lockheed brakes.

It would need a hole drilled and tapped, or maybe a nutsert or a nut spot welded to the plate. Then, a post made from a bolt or stud. The shoe would need a bearing piece maybe Araldited on to it. In the Girling design the post bears on the shoe through a felt roller which should be kept greased. Screwing the post in or out moves the shoe nearee or further to the backplate.

I'm not saying this should be done but it does look as if kit could be !

chrisjb
Posts: 35
Joined: Sun Jul 16, 2017 1:26 pm
Location: Harlington, UK

Re: LA10 Brakes

Post by chrisjb »

I've been playing. Just a test using pan headed screws with the head rubbing on the back plate, bits of wood and penny washers. With the drum off the shoes certainly snap back quicker. The shoes were then limited to simulated the drum using a ratchet web. The brakes are working fine so I have put this down as a winter job. All sorts of zero maintenance options from ball castors to PTFE/Teflon etc. I will be in touch later.
Chrisb

chrisjb
Posts: 35
Joined: Sun Jul 16, 2017 1:26 pm
Location: Harlington, UK

Re: LA10 Brakes

Post by chrisjb »

Two months on, cleaned and polished all 5 cylinders, replaced all seals and hoses. Metal pipes cleaned etc and still the same problem. The rear NS sticks on. The pedal pressure is rock solid, 1" and the brakes are on. No leaks etc and they bleed beautifully. Take the drum off the rear NS and push the pedal. The shoes move out and stay there - for ever! It takes a huge amount of mechanical effort effort to get them back and then not completely. However, crack the bleed nipple and they slam off. I even swapped over the two rear cylinders and the problem remained near side. I thought that the return springs might be weaker and they may be but the pressure required to get the shoes back in is huge. The rear off side works fine.
I've got a very simple fix for the push rods in the pistons not being square and will send photos. It won't upset the purists because they wouldn't notice!
A bit of head scratching would be appreciated. I'm missing a trick somewhere. One interesting thing about visiting shows is that everybody says that Lockheed brakes stick and it always seems to be the rear.
Chris

Norfolk Lad
Wise Man
Wise Man
Posts: 713
Joined: Wed Feb 10, 2016 8:23 pm

Re: LA10 Brakes

Post by Norfolk Lad »

So on releasing the bleed nipple all returns as it should, does this work if any nipple is cracked open or are we taking about the one which is on the locked brake.
If it is only the one why not try working your way along the brake pipes to release fluid, as Alan has said earlier a possible blockage in a pipe causing the locked wheel.
You have said flexi pipes replaced but it may be something acting like a non return valve in the other pipes or unions ,if on one wheel only should narrow it to one length of pipe.

JT7196
Extremely Wise Man
Extremely Wise Man
Posts: 1535
Joined: Sat Feb 13, 2016 7:22 am

Re: LA10 Brakes

Post by JT7196 »

Hi, yes I'm surprised that you haven't removed, cleaned or replaced the metal feed pipe yet, it does seem obvious to us "Old Fellers" that this is the way to go, give it a try, and let us know how you get on.

Best wishes, "Old A'l" :D :D :D

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