Brakes

[Nickol]

I have often found it helpful in the past to write about a Problem and in doing so, sometimes the solution manifests itself, so.......

I have never been too happy with the Brakes on my 68 Traveller in the 10 years I have had it. Despite having a brake servo, have always had to exert pressure on the pedal to stop. When I did my LHD conversion I found the MC to have faulty innerds and I replaced them. I also put in new aftermarket front wheel cylinders and hoses as the braking was uneven.

Last week as the temperatures in my Garage approached 0 degrees and felt positively springtime like, I installed a new Lockheed MC and also new front Lockheed wheel cylinders. Also the rear Flex hose, that being the only Thing not new. The shoes are Mintex all round, again almost new ( perhaps no more than 1000km worth)

Now I have bled the Brakes twice, have tweeked up the shoes and inspected for leaks. There is no obvious loss of fluid in the MC even after prolonged pressure but........the pedal travel is a disaster, going almost to the floor before the Brakes bite. But at least hey do work. In fact to me, all the symptoms of air in the lines. But on bleeding, only fluid now Comes out, no bubbles.

The late Roy mentioned that the brake servos can be a sod to bleed. My servo, I have checked, is mounted correctly. I did in fact short it out of the System but before the new work to see if it made any difference. It did not.

So I have new components all round ( drums front and rear by the way) and adjusted the Brakes right up, one notch off locking up. and still this pedal travel that is spongy anyway even after pumping exists. There is an improvement when the handbrake is on but still not right.

My conclusion is there must be air in the line somewhere, but where? I am away for easter and will have another go next week in the desperate hope that perhaps, the new MC Needs time for "bedding in" . Die Hoffnung stirbt zuletzt.

[liammonty]

You don't mention having adjusted the master cylinder operating rod - if you've changed the master cylinder, it's likely that this will need tweaking. Is the pedal firm, despite being low, or does it sink further having 'bitten' (indicating air in the system)? Does the pedal get higher with pumping (suggesting shoes that need adjusting)? If the answer to both of these is no, then I suspect it's the adjustment of the rod.

[Nickol]

Good Point, worth a try. Thanks for that.

I had as an Elimination process tightened up the shoes on all 4 wheels until locked to see if that makes a difference to the pedal travel. Only slightly if at all was my conclusion. I would say, having not really tested it like you mention, that the pedal is not firm in its low Position. The Brakes do work though at slow Speeds. I have only tested at 30km/h.

Pumping only makes for a marginal improvement anyway and then by sustained pressure the pedal goes down slowly.

Next week now. We will get there.

[mowogg]

I had a problem for years like this without a servo gitted. The brakes would work but the pedal travel was often quite high unless the brakes were used regularly (every 10 mins). I eventually found it was air in the system under the brake light switch.

To clear i removed the switch with rag around it to check the level was to the top and reinserted the switch. The difference was quite amazing.

If you look at the design you can see why this happens.

Note during the period of the air bubble being present the brake lights worked perfectly

Hope this helps

[RobThomas]

Have you clamped off each flexi hose in turn? I did this on ours and one corner was found to have air in the caliper (disks, but still might help) so it made the problem easier to diagnose.

[oliver90owner]

Pumping only makes for a marginal improvement anyway and then by sustained pressure the pedal goes down slowly.

That indicates a leak in the master cylinder.

[simmitc]

If pumping brings the pedal up to a good level then air is present. If travel is still too far after pumping then the actuation rod needs adjusting. If the pedal sinks slowly after initially being firm then there is a leak. If the fluid level is dropping then check the whole system for leaks. If the fluid level is not dropping then the leak must be in the MC. I know that you have already installed a new MC, but defective seals and/or a corroded bore in the MC could contribute to your problems.

Picking up on Mowogg's point, when fitting new brake light switches I always fill the switch with fluid (hold the switch inverted and use a syringe) before fitting, just be quick to engage the thread when fitting to avoid losing the fluid. This is a good reason to use silicone fluid as it avoids paint damage if any fluid is spilt.

Good luck.

[Chipper]

Perhaps try pressure bleeding the system, using something such as Gunson's one-man bleeding kit, which uses pressure from a car tyre to force the fluid around the system.

[biomed32uk]

Just to stick my bit in for bleeding I use one of the vacuum bleeders, attached to the bleed nipple to pull the fluid through.

You need a good wipe of red grease around the bleed nipple threads to seal them, but the method works a treat.

I can have the whole system bled in half an hour single handed and with a nice firm pedal. Up to now I have not had any nightmares with bleeding the system. You just need to keep an eye on the MC level as its easy to get carried away and empty it.

[GavinL]

i've used the Gunson Eezibleed for years which has always worked well. They sell them in Toolstation, which isn't the first place i would have looked for them

[Trickydicky]

Do you need to have the brake pedal depressed when using the gunson device? Or do you just open the bleed nipples in turn?

[Nickol]

After a rather rainy easter Weekend away I tackled the Brakes this morning in the sunshine.

Although it was a distinct possibility about the actuating rod, this was checked to be ok within a few seconds.
I also felt that having left the whole System alone to settle down for 5 days, the movement of the pedal felt firmer, although not optimal. Perhaps wishful thinking on my part?

But I re-bled the System carefully once again, but this time with another perhaps firmer new tube on the bleed nipples and indeed minimal turns opening them so as not to give air Ingress a possible way in. A few small bubbles did appear in the tube this time, especially with the furthest back brake. Nothing noticable on the fronts.

A test drive or rather test brake indicated much better braking and a firmer pedal. I would not say it is perfect but still effective and acceptable. What should you expect from a 50 yearold car with drum Brakes anyway?

I will inspect regulary to see if any minor leaks are there - a single drop I wiped off a connecting pipe but that could well be from the time I had disconnected it before and fluid escaped.

Thread over for the time being, I think and thanks everybody for the good advice as ever.

[liammonty]

Excellent result!!!! Happy Minoring

[Nickol]

Forgot to mention - when I bled the System before I had the handbrake on which is not recommended, I understand. This morning it was off. Whether that should have made a difference???