When a another Bedford restoration is barely enough

Thank you, 180wannabe

I never thought of vacuum v pressure, I will search the links you provided

Interestingly the engine spluttered and died when I pumped the brakes and the brake pedal resisted retuning to its normal position after that event

Also, what do people estimate the vacuum reading should be if functioning normally? Also I never attempted to pull or push the lever attached to the gauge and what effect that would have on the reading

Thanks again

Michael

A few searches suggest 15 inches of vacuum at idle is common/normal.
I think pumping the brake pedal would have used up any stored vacuum you had, to assist the application of the brakes, and so vacuum was drawn "from" (into) the engine intake to replace it, therefore leaning out the idle mixture, causing the engine to stall.  I think i have got that right?  Just as if you were to remove the plug from the large hose at the rear of your truck when the engine is running, the engine will stall almost instantly.
Moving the hand control lever probably won't do anything "as is".  When you have a trailer hooked on, my understanding is the large hose "supplies" vacuum to the trailer, and the small hose (operated by the handle) activates a relay valve on the trailer to apply the brakes.  I think some trailer brakes were operated by the handle only, when ever the driver felt the need, whereas others fitted with a "reaction valve" took a signal from the brake pedal, and applied the trailer brakes accordingly in unison, (albeit after some delay).  Not sure if i have explained all that just right, but hopefully it will make a bit more sense with other information you might find.

Brett.

I think your getting a little lost here, or at the very least I am getting lost

If a brake is dragging or stuck on you need to fix that first
Maybe jack up each wheel and see if you can work out which one is dragging

Vacuum guage and trailer brakes have nothing to do with the brakes on the truck so fiddling with this is only going to complicate things

The truck brakes really aren't much different than normal car drum brakes, been a Bedford the main thing you'll notice is just how bad they are, Bedfords were never regarded as having good brakes

Anyway, see if you can work out which wheel is dragging and report back

Maybe all 4 wheels are dragging

Paul

Can you post a picture of the master cylinder?     It's very easy to determine if its a vacuum or air over hydraulic system.

Either way, start by completely servicing the drums on all 4 wheels.  That will need to be done.

Remember, you're starting with zero history of the vehicle. So, you need to get in a known trustworthy state.  Everything will need to be serviced.  Start with the drums first. Once you've got some confidence with those, then move on to the master.

Also, post a picture of the rear inside drum.  It will help us understand which type of "slave" cylinder you have.  Some Bedfords had bisector systems which can be very tricky to sort out and make reliable.
 

Typically Bedford hand brakes used the same "cylinder' (called a bisector) as the hydraulic on the rear, and without use would be jammed on. There is a trick to dismantling the rear brakes and best to have someone guide you.
For vacuum trailer brake spares look for wrecks at bottom of hills because that is where they all ended up.

The Bedford Bisector.... run while you can.

You have to keep the shoes adjusted perfectly, a lowish pedal is a critical warning that they need adjusting.

 

Wind everything off, adjust the shoes, then the handbrake.
Make sure the little wheel thing doesn't extend past the slopey thing at rest or under full travel. (due to poorly adjusted shoes.)
If the wheel thing (3) travels past the slopey thing, then eveything jams up.
Then it's a full disassemble to resolve.  wheels off,  axles out, hubs and drums off, resolve by stipping down the bisector, hubs and drums on, bearing preload set, axles in, wheels on. 

repeat every brake bleed, keep everything rust free, beware of a rock hard pedal.... indicating siezed bisectors.    

when underneath, always give the handbrake cable a little tug to see if the shoes move... ahh all good if they do. too much and adjust

and then, the brakes are good for 2 crash stops if your lucky!

Hi All, thank you for replies

Mrsmackpaul, yes, I sometimes believe / hoping I’m over thinking this, truck is not quite ready to bring into the shed yet, remove flattop bed, degrease etc, thinking how I might be able to free up the brakes to enable moving the vehicle more easily for now. Pre purchase , without any truck experience I was hoping of just doing as you said, dissasemble brakes etc, its funny as when I got it home I was looking for the master cylinder and had me stumped for some time until I googled Bedford brakes and I discovered the Clayton Dewandre system, then / now I’m assuming its inabilty to move easily is tied up with air / vacuum etc

Jon_ d, yes I’ve previously ventured under the vehicle and located the Master Cylinder, but today we’ve had thunder storms and rained all day, tommorow I will attempt to take a pic of the Master cylinder.

Jon_D and mammoth, thanks for pics of Bisector, I have located them on the rear axle, again, until I remove the bed etc then I’m hoping for more clarity

In my youth I changed clutchs, brakes, axles etc on my holdens, valiants etc, I’m hoping I haven’t bitten more off than I can chew, but I am looking forward to the challenge

Thanks again, keep you posted

Cheers

Michael

now I’m assuming its inabilty to move easily is tied up with air / vacuum etc

Michael,

The truck is 51 years old. (1972)

The master and wheel cylinder bores are cast iron.  The pistons are steel.   The fluid will be contaminated. There will be rust and seized parts everywhere. 
Even the drums could be seized onto the shoes.

Everything will need to be to be stripped down and overhauled.   If you don't, you'll always be wondering if the brakes will fail when you need them the most.

And beware; there will be asbestos.

Sorry to burst your bubble....   My bubble bust about 15 years ago when I went through the same thing.

Hi jon_d

Yes, I agree, I will be disassembling he whole braking system

As stated here are two pics of master cylinder and air tank, lose of grease and down there

Cheers

Michael

 

 

You might be able to access the master cylinder through a panel in the floor. A set of new seals should be available from Power Brakes in Sth Aus. If the bore is rusty send it to them for fitting a stainless sleeve. Underneath the master is the booster which helps to provide more pressure. The vacuum tank you can ignore or remove and blank the pipe off where it is fed from the engine. Keep the controller for decoration, they are sought after.
Your bisectors might be OK, trouble is more likely to be in the cylinders not shown complete in the diagram. No 2 is connected to a pull rod coming from the cylinder. From memory I don't think you need to take the drum off to remove the cylinder but as I said there is a trick to disconnecting it, which I forget. so could stand corrected .
One bite at a time you will get there.